記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.ces.2021.117129

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/foods11030489

掲載種別：研究論文（学術雑誌）  

To develop new foods from plant-based protein, we prepared a soybean-based meat analogue. Soybean flour, sodium alginate, soybean-based fiber, and plant oil were used to produce a gel by cross-linking with calcium ion after freezing. The resulting gel was frozen again and thawed, followed by infiltration of soy protein solution to form a layered-porous structure. Effects of freezing on the formation of the structure and that of the presence of fibers on the texture were evaluated, showing the properties similar to animal meat one. Sensory evaluation also showed that the texture was significantly preferable to that of conventional soy-based meat analogue and was closer to animal meat. These results suggest that the proposed method would be promising for realizing soy-based meat substitutes with a texture closer to animal meat.

DOI： 10.11301/jsfe.22606

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jafr.2021.100231

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 粉体工学会  

DOI： 10.4164/sptj.58.656

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jafr.2021.100221

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.cep.2021.108511

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本食品工学会  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3775/jie.100.110

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jfoodeng.2020.110452

掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

DOI： 10.1111/1750-3841.15641

その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/1750-3841.15641

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本食品工学会  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本食品工学会  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.foostr.2021.100181

掲載種別：研究論文（学術雑誌）   出版者・発行元：Japanese Society for Food Science and Technology  

DOI： 10.3136/fstr.27.559

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：FFIジャーナル編集委員会  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.cherd.2020.08.017

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acs.iecr.0c03394

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本食品工学会  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jfoodeng.2020.110293

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1515/npprj-2018-0075

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.foodhyd.2019.105259

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jfoodeng.2020.110163

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本冷凍空調学会  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本冷凍空調学会  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本食品工学会  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：技術情報協会  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：化学工学会  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1080/07373937.2018.1528451

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/aic.16571

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.5650/jos.ess19161

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS INC  

DOI： 10.1080/07373937.2018.1463538

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：FRONTIERS MEDIA SA  

DOI： 10.3389/fchem.2018.00418

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier B.V.  

Glassy phase formation in a frozen product determines various properties of the freeze-dried products. When an aqueous solution is subjected to freezing, a glassy phase forms as a consequence of freeze-concentration. During post-freezing annealing, the relaxation of the glassy phase and the ripening of ice crystals (i.e. Ostwald ripening) spontaneously occur, where the kinetics are controlled by the annealing and glass transition temperatures. This study was motivated to observe the progress of glassy state relaxation separate from ice coarsening during annealing. X-ray computed tomography (CT) was used to observe a frozen and post-freezing annealed solutions by using monochromatized X-ray from the synchrotron radiation. CT images were successfully obtained, and the frozen matrix were analyzed based on the gray level values that were equivalent to the linear X-ray attenuation coefficients of the observed matters. The CT images obtained from rapidly frozen sucrose and dextrin solutions with different concentrations gave clear linear relationships between the linear X-ray attenuation coefficients values and the solute concentrations. It was confirmed that the glassy state relaxation progressed as increasing annealing time, and this trend was larger in the order of the glass transition temperature of the maximally freeze-concentrated phase. The sucrose-water system required nearly 20 h of annealing time at −5 °C for the completion of the glassy phase relaxation, whereas dextrin-water systems required much longer periods because of their higher glass transition temperatures. The trends of ice coarsening, however, did not perfectly correspond to the trends of the relaxation, suggesting that the glassy phase relaxation and Ostwald ripening would jointly control the ice crystal growth/ripening kinetics, and the dominant mechanism differed by the annealing stage.

DOI： 10.1016/j.ejpb.2018.02.027

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本冷凍空調学会  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society  

Crystallization behavior of rapeseed oil during isothermal storage was investigated by dilatometry, transmitted light intensity measurement, and differential scanning calorimetry. The volume and transmitted light intensity of the oil samples changed significantly after a certain period (induction period) during isothermal storage. In order to explain these changes, a kinetic model for the crystallization of rapeseed oil was proposed by assuming that stable crystals are formed through melt-mediated transition and metastable crystals grow via an "autocatalytic" mechanism. The crystallization process of rapeseed oil is well represented by the model, and it reasonably explains the peculiar relationship between the storage temperature and the induction period for crystallization.

DOI： 10.1021/acs.cgd.7b00789

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Taylor and Francis Inc.  

In this study, we obtained the liquid–solid phase diagrams of a ternary solution of sodium chloride, acetic acid, and water, and a diagram of the frozen ratio of this ternary mixture. Based on the data from differential scanning calorimetry (DSC) measurement, the phase equilibria of this ternary system were successfully visualized. The formation of the ternary eutectic phase occurred between −34°C and −35°C, and the formation of the binary eutectic phase was suggested around −22°C to −34°C. Higher concentrations of a component had a significant effect on the phase equilibrium. A diagram of the frozen ratio of the ternary solution of sodium chloride at −20°C was also obtained by a simple temperature measurement method. This diagram is useful for estimating the ice fraction at the phase equilibrium of a frozen food system containing sodium chloride and acetic acid.

DOI： 10.1080/10942912.2017.1354881

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY  

Freezing and thawing of oil-in-water (O/W) emulsion-type foods bring about oil-water separation and deterioration; hence, the effects of freezing and thawing conditions on the destabilization of O/W emulsions were examined. The freezing rate and thawing temperature hardly affected the stability of the O/W emulsion. O/W emulsions having different oil fractions were stored at temperatures ranging from -30 to -20 degrees C and then thawed. The stability after thawing depended on the storage temperature, irrespective of the oil fraction of the emulsion. A good correlation was found between the time at which the stability began to decrease and the time taken for the oil to crystalize. These results indicated that the dominant cause for the destabilization of the O/W emulsion during freezing and thawing is the crystallization of the oil phase and that the effects of the freezing and thawing rates on the stability are insignificant.

DOI： 10.1111/1750-3841.13764

Web of Science

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society for Food Engineering  

Egg yolk powder is industrially produced by spray-drying fresh raw egg yolk separated from shell eggs. Stress due to heat and dehydration causes denaturation of egg yolk proteins, so it largely affects the quality level of the resultant dried powders. In this study, denaturation kinetics of dried egg yolk powder were measured under isothermal and iso-humidity conditions. The denaturation level was evaluated by using color index, viscosity values of the slurry (made from the dried powder dispersed in water) and the agglomerated particle sizes. Fresh egg yolk was spray-dried and the resultant quality levels of the dried powders were evaluated in the same manner. Some of these quality factors would not simply relate with the temperature and RH. It was suggeted from the kinetic parameters and the spray-drying experiments that the residence times of products in the specific parts of a drying system (e.g. atomizer, chamber, pipe for transport, collector etc.) would have critical impacts on the product qualities. The kinetic parameters predicted that even under a relatively low RH conditions, a rate of a quality change would significantly increase when products are subjected to higher temperature above threshold.

DOI： 10.11301/jsfe.17486

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

? 2017 Japan Society for Food Engineering. A mathematical model that could simulate multi-dimensional freeze-drying operated by radiative heat was developed and applied to a freeze-drying process of instant soup. A model product (pre-cooked soybean paste soup) set in a cuboidal plastic cup was freeze-dried where drying progressed multi-dimensionally, that is, the surface area of the sublimation interface changed as a progress of drying. In order to simplify model equations, the relationship between the sublimation surface area and degree of drying was empirically estimated and applied to the model calculation. The simulation results of the present mathematical model were in good accordance with the experimental results. Based on the mathematical model, a method was shown to calculate the design space where rational choice in better drying conditions can be selected.

DOI： 10.11301/jsfe.17494

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier Ltd  

The crystallization behavior of rapeseed oil during isothermal storage was investigated using differential scanning calorimetry (DSC), and wide-angle and small-angle X-ray scattering analyses. Rapeseed oil is composed of many kinds of triacylglycerols. When this oil was cooled to its freezing temperature, a meta-stable phase was immediately formed. After a certain period, exothermal crystallization was induced. DSC analysis showed that the induction period, which is defined as the time from the beginning of isothermal storage until an exothermal change is detected, was affected by the storage temperature but not by cooling rate and sample size. Exothermal behavior after the induction period at −25 °C was different from those stored at −17 and −20 °C. X-ray scattering analysis clarified that this difference was due to differences in the formation of the meta-stable phase during the induction period. At −17 and −20 °C, the triple chain-length (3L) structure transformed to a double chain-length (2L) structure, where the β form was the dominant component. In contrast, at −25 °C, the 2L structure was formed while maintaining the 3L structure, and further structural changes were not observed during storage. It has been suggested that the induction period for the crystallization behavior of rapeseed oil during isothermal storage is governed by the kinetics of the meta-stable phase transition. It is important to understand this meta-stable phase transition for controlling the crystallization of oil in foods because the induction period are related to the subsequent crystallization behaviors that affects food quality, and is responsible for food deterioration.

DOI： 10.1016/j.foostr.2016.12.004

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ニューサイエンス社  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：美味技術学会  

CiNii Books

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC FOOD SCIENCE TECHNOLOGY  

Bioencapsulation of food additives or functional ingredients aims to protect sensitive core materials during storage and consumption, transport them to designated positions in the gastrointestinal tract, and release them at appropriate rates to maximize bioavailability. Bioencapsulation systems need to be designed with GRAS (generally recognized as safe) materials, and the physicochemical processes involved in matrix formation are crucial for realizing expected functionality. From an engineering perspective, it is important to develop a processing method for obtaining products with desirable features. The author has previously reported that a freezing step represents an interesting processing tool for controlling the properties of an encapsulation system. During freezing, the growth of ice crystals in an aqueous solution results in a cryoconcentrated (freeze-concentrated) phase that is controlled by phase equilibrium. The author's idea is to control matrix formation in the cryoconcentrated phase for optimizing encapsulation systems. This review summarizes this concept and future scope.

DOI： 10.3136/nskkk.64.328

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST CHEMICAL ENGINEERS  

Convective-air-dried Spirulina was investigated in terms of the resultant antioxidant properties, namely the phycocyanin content, total phenolic content, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging activities. The loss of the antioxidant properties was apparently dependent on the drying conditions, especially on temperature. When the drying temperature was set lower than 50 degrees C, the antioxidant properties were retained to a larger extent, whereas lesser quantities could be retained at a drying temperature of 80 degrees C. A simple mathematical model was employed to simulate the temperature profiles during drying, and the resultant phycocyanin content was predicted using the temperature profiles and the experimentally obtained kinetic data of the degradation. These model equations were simple enough to be solved using commercial spreadsheet software, and the profiles of moisture content, mean temperature, and remaining phycocyanin content were predicted as a function of time. Based on the simulation results, an attempt was made to dry at two temperature steps, namely at 80 degrees C during the constant rate drying period, and at 50 degrees C during the falling rate drying period. This attempt, drying with two temperature steps, could successfully reduce the total drying time and retain greater amount of antioxidants in the resultant dried products. (C) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.fbp.2016.07.014

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

Wheat starch dispersions of 10-40% (w/w) were gelatinized and the change in turbidity of each solution during storage was measured in the 400-1100nm wavelength range. The relative transmittance, defined as the ratio of transmittance at any storage time to that at the initial time, decreased when the solutions were stored at 5 and 30 degrees C; the decrease, reflecting the progress of retrogradation, was larger at 5 degrees C than at 30 degrees C. Most of the changes in relative transmission taking place over 14days were achieved during the first 90min. The change in the relative transmittance is inversely proportional to the energy required for deformation. The kinetics on change in relative transmittance can be expressed by Weibull equation. The larger rate constant at higher starch concentration could be ascribed to the state of the starch granules, which depended on starch concentration.

DOI： 10.1080/09168451.2016.1171698

Web of Science

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC CHEMICAL ENG JAPAN  

Yeast cells were immobilized in freeze-dried poly(vinyl alcohol) (PVA) foam, and the subsequent fermentation of glucose was studied. The immobilized yeast was produced by freeze-drying a PVA solution containing dispersed yeast cells, yielding a porous foam. The prepared specimens were rigid enough to be used repeatedly in aqueous solutions for more than one week. The fermentation performance of the immobilized yeast was found to be significantly higher than that of the crude (non-immobilized) yeast. The immobilized yeast produced approximately 1.5 times more ethanol than the crude yeast. The freeze-dried PVA also appeared to protect the yeast cells against the reaction inhibition effects of ethanol. Also, the PVA foam had a considerable a affinity for the yeast cells, whereas it had no significant affinity for ethanol. The kinetic constants obtained from the experimental reaction runs suggested that the improvement in the fermentation of the immobilized systems can be explained by the increase in the dissociation constant values in the Michaelis-Menten kinetic model, and that there is an optimal quantity of immobilized yeast that yields the best ethanol tolerance for this technique.

DOI： 10.1252/jcej.15we283

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：KARGER  

Noodles were prepared using wheat flour with 0 - 20% (w/w) added powdered gluten, and the transient changes in their moisture content during cooking were measured. Kinetic analysis of the water sorption process during cooking indicated that the process occurred in two distinct stages for all of the noodles. Water diffusion and consequent starch gelatinization predominantly controlled water sorption during the early stage, while relaxation of the gluten network structure was rate-limiting for the water sorption process during the latter stage. The moisture content, at which the rate-limiting factor for the water sorption process changed, was lower for the wheat noodles having a higher gluten content. Thus, it was suggested that the change in the gluten network structure induced by the addition of gluten to wheat flour affected the water sorption behavior of wheat noodles.

DOI： 10.3136/fstr.22.491

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

It has been known that the sublimation kinetics of a freeze-drying product is affected by its internal ice crystal microstructures. This article demonstrates the impact of the ice morphologies of a frozen formulation in a vial on the design space for the primary drying of a pharmaceutical freeze-drying process. Cross-sectional images of frozen sucrose-bovine serum albumin aqueous solutions were optically observed and digital pictures were acquired. Binary images were obtained from the optical data to extract the geometrical parameters (i.e., ice crystal size and tortuosity) that relate to the mass-transfer resistance of water vapor during the primary drying step. A mathematical model was used to simulate the primary drying kinetics and provided the design space for the process. The simulation results predicted that the geometrical parameters of frozen solutions significantly affect the design space, with large and less tortuous ice morphologies resulting in wide design spaces and vice versa. The optimal applicable drying conditions are influenced by the ice morphologies. Therefore, owing to the spatial distributions of the geometrical parameters of a product, the boundary curves of the design space are variable and could be tuned by controlling the ice morphologies. (C) 2016 American Pharmacists Association (R). Published by Elsevier Inc. All rights reserved.

DOI： 10.1016/j.xphs.2016.04.001

Web of Science

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Wheat noodles were prepared using flour to which hydroxypropylated tapioca starch was added, and the effect of this addition on the moisture distribution within the noodles during cooking was examined using a digital image processing technique. The addition of the modified starch slightly increased the moisture content and narrowed the flat distribution near the noodle surface. The distribution features reflected the changes in the water absorption behaviour caused by the properties of the modified starch and the reduction in the gluten content. Addition of the modified starch lowered Young's modulus and the energy for 99% strain of the noodles in the texture analysis to, at maximum 35% and 65%, and decreased the breakability of the noodles. These changes in the moisture distribution and textural properties have been ascribed to changes in both the state of the starch granules near the surface and the structure of the gluten network.

DOI： 10.1111/ijfs.13108

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

The thermal and rheological history of mayonnaise during freezing and its dispersion stability after the freeze-thaw process were investigated. Mayonnaise was cooled to freeze and stored at -20 to -40 degrees C while monitoring the temperature; penetration tests were conducted on the mayonnaise, which was sampled at selected times during isothermal storage at -20 degrees C. Significant increases in the temperature and stress values due to water-phase crystallization and subsequent oil-phase crystallization were observed. The water phase crystallized during the cooling step in all the tested mayonnaise samples. The oil phases of the prepared mayonnaise (with rapeseed oil) and commercial mayonnaise crystallized during isothermal storage after 6 and 4h, respectively, at -20 degrees C. The dispersion stability was evaluated from the separation ratio, which was defined as the weight ratio of separated oil after centrifuging to the total amount of oil in the commercial mayonnaise. The separation ratio rapidly increased after 4h of freezing. This result suggests that crystallization of the oil phase is strongly related to the dispersion stability of mayonnaise.

DOI： 10.1080/09168451.2015.1123611

Web of Science

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Freeze-dried casein nanoparticles that could entrap beta-carotene were produced after aging under frozen conditions. Structural changes that occurred during aging and simulated digestion were investigated. Freeze-dried specimens of casein particles prepared from sodium caseinate solutions containing dispersed beta-carotene successfully entrapped this dispersion in the resulting freeze-dried powders. The entrapped beta-carotenes were distributed between the surface (surface load) and interior (inner load) of these dried powders. Because of aging, the amount of the inner load decreased while the surface load simultaneously increased. The hydrophobicity of rehydrated casein particles indicated that a change, caused by the aging process, occurred in particle structure. These structural modifications increased the hydrophobicity in the dried specimens. When rehydrated, these hydrophobic surfaces reassociated with each other to cancel the net gain in hydrophobicity. SAXS measurements on freeze-thawed casein nanoparticles also suggested the formation of modified nano- and microstructures. These modified structures were formed by freezing and thawing, along with interactions between clusters or between clusters and ice. The kinetics of the proteolytic reactions of the freeze-thawed specimens in a simulated gastric fluid were measured. The degree of aggregation and processing conditions did not significantly affect the digestion kinetics of the casein clusters. The SAXS analyses, however, suggested that these conditions affected nano- and microstructure formation during digestion. When the aggregated casein clusters were exposed to the gastric conditions, the fractured clusters produced by the proteolytic reactions produced 2-3 times larger aggregates with hollow networks and rough surfaces created by the crosslinked casein clusters. Processing conditions, such as pH and aging time, likely affected these nano and microstructure formations under gastric conditions. These results may provide exciting future research opportunities if the structural modifications can impact the bioavailability of entrapped materials. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ces.2016.01.001

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

Wheat noodles cooked for different periods of time were stored at 5 degrees C, and color changes in their cross sections were quantitatively assessed by digital image analysis. The color of noodles with flattened moisture distributions whitened greatly during the early stages of chilled storage due to the retrogradation of starch, with the color change showing a significant correlation with the changes in noodle fragility. Color changes were also measured for wheat noodles and noodles containing modified starch with internal moisture distributions, and local changes within the noodles were kinetically analyzed. The addition of modified starch significantly reduced the color change in the noodle interior, where the moisture content was relatively low. Scanning calorimetric measurements indicated differences in the gelatinized state of modified starch and original wheat starch at low moisture contents, which affected the rate of color change in the interior of noodles containing modified starch.

DOI： 10.1080/09168451.2016.1220821

Web of Science

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN OIL CHEMISTS SOC  

The induction period of crystallization, which is defined as the time required for oil to start to crystallize, is useful indicator of the freeze-thaw stability of food emulsions such as mayonnaise. We investigated the induction period of vegetable oils with low melting points, such as rapeseed and soybean oils, which are commonly employed for mayonnaise production. The induction period was measured by monitoring the temperature of a specimen during storage at low temperature. The induction period depended on the type of oil and lipophilic emulsifier, emulsifier concentration, and storage temperature. The effect of the oil type on the induction period depended on the composition of the oil. Differential scanning calorimetry (DSC) analyses of the lipophilic emulsifiers suggested that the melting trend of the emulsifier is strongly related to the induction period.

DOI： 10.5650/jos.ess15170

Web of Science

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

A simple mathematical model was developed to predict the kinetics of freeze-drying where sublimation progresses multi-dimensionally in a product, and the model was adopted to the freeze-drying of peeled apple cubes. This model consists of classical heat and mass transfer equations, which are solved by assuming a quasi-steady-state energy balance at the sublimation interface. The radiative heat coefficient and mass transfer coefficient between the chamber and the condenser are included in the model, and were experimentally obtained by carrying out the ice sublimation tests with the freeze-dryer employed. The mass transfer property is a specification of a given freeze-dryer. This work suggested that it strongly influenced the drying kinetics and it would be an important parameter to meet scaling-up issue. When the sublimation progresses multi-dimensionally, the surface areas of the product exterior, the product bottom and the sublimation interface varied as a function of the extent of drying. These relationships were obtained from experiments with freeze-drying of peeled apple cubes and employed for estimating the mean thickness of the dried and frozen layers with a hollow spherical model proposed in the study. The model equations were solved using commercial spreadsheet software, and the weight loss during drying was predicted as a function of time. The calculation results were in good agreement with the experimental data. This approach allows to set a heating program and/or localized variances of microstructural parameters by manual input, and easily simulate drying kinetics and temperature history. This makes big advantage for planning a desired drying operation. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jfoodeng.2015.03.033

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The digestibility of casein clusters prepared from sodium caseinate solution (plain or pH-adjusted (pH = 6.0)) was studied. The prepared solutions were spray-dried at different inlet air temperatures (150 degrees C and 180 degrees C), and the properties (i.e. encapsulation efficiency, surface hydrophobicity, and digestibility) of the resultant powders were investigated. The specimens obtained from the pH-adjusted solution had higher encapsulation efficiencies than the specimens obtained from the plain solution. A higher spray-drying temperature resulted in lower encapsulation efficiencies and higher surface hydrophobicities. Simulated gastric digestion tests were carried out to study the digestibility of the obtained casein clusters, which was analyzed in terms of reaction kinetics and structural changes during digestion. The effects of drying temperature and pH on the amount of casein digested were not significant; that is, approximately 30% of casein was digested in 120 min for all specimens. Small-angle and ultra-small-angle X-ray scattering measurements were used to analyze the structure of the obtained clusters and their changes during digestion. The results suggested that all the obtained casein clusters, with an average size of approximately 428 nm, had a rough, fractal-structured surface with many dense primary clusters. These structures changed during digestion; specifically, the cluster size increased both in the overall diameter and on the primary structure scale. The fractal characteristics changed from surface to mass fractals, and simultaneously, the cluster density decreased. The drying temperature affected the cluster size during digestion, and the trends were different in the specimens obtained from the plain and pH-adjusted solutions. These results could be useful in the design of protein-based encapsulation systems with desirable digestibility and bioavailability. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.foodres.2015.05.049

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

? 2015 Elsevier Ltd. Spray-dried casein clusters were prepared from sodium caseinate solutions and applied to the encapsulation of β-carotene via hydrophobic interactions. The influence of cluster types (aggregated casein formed by adjusting the solution pH and re-assembled micelles prepared by the addition of salts) on the encapsulation properties (i.e., encapsulation efficiency and storage stability) was evaluated. The encapsulation efficiency of aggregated casein was higher than that of the re-assembled casein micelles; aggregated casein prepared at pH 6.0 had the highest encapsulation efficiency. The results of SAXS and TEM observations showed that the aggregated casein had dense and packed cluster structure, while the cluster obtained from the re-assembled micelle system had randomly grown branches. Aging the solution of casein aggregated at pH 6.0 for 120. h increased the encapsulation efficiency and simultaneously decreased the amount of free β-carotene. Dried powders obtained from the aged solution also showed good stability in terms of β-carotene retention and color changes under 11%RH and 75%RH over 21. d. Evidence of cluster deformation was observed by SAXS for the aggregated casein solution with pH 6.0. The data suggested that the stability and encapsulation efficiency of spray-dried powders were closely linked to the nanostructures of the original clusters; thus, the product quality may prospectively be improved by utilizing processing conditions that effect cluster formation and affect the resultant structure, with the consequent influence on the encapsulation efficiency and storage stability.

DOI： 10.1016/j.foostr.2015.05.001

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

? 2015 Elsevier B.V. Freeze-drying aqueous poly(vinyl alcohol) (PVA) solutions affords porous foam materials that show potential as an interesting entrapping matrix for enzyme immobilization. When an enzyme-PVA solution is freeze-dried, the enzymes are automatically entrapped in the architecture of the PVA matrix. The obtained PVA foams barely disperse in aqueous solution because of physically cross-linked PVA cryogel formation. This method is an in situ immobilization technique such that supporting materials can be produced in any space where the precursor solutions can be loaded. In this study, an attempt was made to prepare freeze-dried PVA foams in a microchannel to prepare an α-amylase-immobilized microreactor. Freeze-dried foams for amylase immobilization were demonstrated to be successfully prepared in microreactors with a ca. 18-μL microchannel volume, and were evaluated by conducting continuous starch hydrolysis reactions over 8. d. The macroscopic pore structures seemed to be only minimally affected by the apparent activities of the immobilized enzymes; however, the cryogel structures, affected by the freezing protocol, and the microchannel materials employed were suggested as the key to determining reaction performances.

DOI： 10.1016/j.cep.2015.03.010

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS INC  

Spray-dried microparticles with lipid cores that dissolve beta-carotene were prepared using a technique based on the complexation of soy protein and gum acacia. A freeze-pretreatment was applied to modify the resultant properties of the dried particles. An oil in water emulsion stabilized by soy protein isolate was mixed with gum acacia. The pH of the solution was adjusted to a selected value; this solution was frozen and thawed under controlled thermal protocols, then spray-dried to obtain the final products. Complexation was induced on the surface of the oil droplets owing to electrostatic interactions that occur below the isoelectric point (ca. pH 4.0) of the employed soy protein isolate. The freeze-pretreatment prior to spray-drying was expected to induce this interaction by freeze concentration and to control the kinetics of complex formation. When solutions with a pH of 4.0 and 3.0 were spray-dried, the encapsulation of beta-carotene had similar efficiencies. The freeze-pretreatment was observed to have a significant effect on the specimens prepared from the solution with a pH of 4.0. Slow freezing conditions successfully improved the encapsulation efficiency and simultaneously reduced the amount of surface oil. Moreover, this pretreatment augmented the mass transfer resistance of the shell matrix, so that the release rate of dissolved beta-carotene in the lipid core could be retarded.

DOI： 10.1080/07373937.2015.1010208

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Protease from Bacillus licheniformis was immobilized in a freeze-dried poly(vinyl alcohol) (PVA) micromonolith directly prepared in the microchannels of a microreactor. The prepared PVA micromonoliths had porous microstructures of similar to 10-30 mu m in size. Five microreactors were prepared, with microchannels consisting of interconnected straight and elbow segments or a plain straight segment. The system performance was characterized in terms of proteolytic reaction activities. The reactors demonstrated continuous proteolytic activity for 9 d with considerable reaction yields. The proteolytic performance was significantly influenced by the microchannel patterning, and was closely linked to the pressure drops in the reactors. The product distributions varied depending on the flow rates of the substrate solutions and the microchannel patterns. Fractions obtained from different reactors gave different product compositions even when operating under similar conditions and producing comparable yields. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ces.2014.07.054

Web of Science

記述言語：英語   掲載種別：論文集(書籍)内論文   出版者・発行元：Wiley Blackwell  

During the design of food systems or additives, engineers strategically apply encapsulation techniques to provide structures that retain a sufficient amount of flavor, stabilize the flavors during preservation (protect them from unfavorable oxidation), and release the flavors at the desired rate when consumed. This chapter summarizes the engineering aspects of nano- and microencapsulation of flavors in food systems. It discusses how flavor compounds are stabilized and retained in food nano- and microstructures. The chapter also discusses three processing methods of nano- and microstructures namely, spray-drying, freeze-drying and complex coacervation. Future prospects for encapsulation techniques, especially for food systems, would be to tailor nano- and microscale structures to generate novel food functionality via a rational processing strategy.

DOI： 10.1002/9781118292327.ch10

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本食品工学会  

? 2014, Japan Society for Food Engineering. All rights reserved. Food hydrogel was produced from an oil in water emulsion of soy milk and rice powder mixture. We investigated the rheological properties during soy milk gelation with rice powder on addition of an acetic acid coagulant. The pH value of soy milk decreased on addition of rice powder and an acetic acid coagulant. Soy milk with rice powder formed a weaker gel with increasing concentration of soy milk and decreasing concentration of acetic acid coagulant. The frequency dependence of dynamic viscoelasticity suggested that soy milk formed hydrogel on addition of an acetic acid coagulant and rice powder. The time dependent changes in dynamic viscoelasticity suggested that palm oil retarded soy milk gelation early and then promoted it a little later. It was suggested that the oil droplet which was acting as an inactive filler acted as an active filler after that the first stage.

DOI： 10.11301/jsfe.15.243

CiNii Books

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本食品工学会  

? 2014, Japan Society for Food Engineering. All rights reserved. Food hydrogel was produced from an oil in water emulsion of soy milk and rice powder mixture, and a processing technique with freezing was investigated in terms of the rheological properties of the resultant products. The emulsion specimens were stored at 4°C, −5°C, −10°C and −20°C for 1 day. The time dependent changes in dynamic viscoelasticity suggested that the gel formation above freezing point, that was 4°C, allowed to form a gel network covering its bulk specimen. Whereas, when the specimens were aged in frozen state, gel formations could occur at localized positions due to the geometrical limitation by ice. The characteristics of viscous liquid could be confirmed in these specimens by the linerly increased loss tangent values, and this trend was obvious in the order of −5°C, −10°C and −20°C . Gel specimens were cooked with an oven at 180°C in order to observe their melting behavior. It was found that the degree of melting correlated to the rheological properties, and this correlation was obvious when gels were aged at −10°C. The results of this study suggested that freezing could be a useful processing tool for tuning rheological properties of food hydrogels, that may allow to process food functionalities.

DOI： 10.11301/jsfe.15.251

CiNii Books

記述言語：英語   掲載種別：研究論文（学術雑誌）  

? 2014, Japan Journal of Food Engineering. All rights reserved. β-Carotene was encapsulated by self-aggregated caseinates, and the encapsulation efficiencies and storage stabilities of the resultant spray-dried powder were investigated. The pH of the sodium caseinate solution, which determined the degree of aggregation, tremendously af fected the encapsulation yield and storage stability of β-carotene in the spray-dried powder. We found that at pH 6.0, the resultant powder showed excellent encapsulation property compared to other pH conditions (pH＝6.5, 5.5). Small angle X-ray scattering analysis revealed that the representative sizes of the aggregates in the sodium caseinate solution at pH 6.5, 6.0, and 5.5 were approximately 91, 111, and 166 nm, respectively. This analysis also clarified that our system represented fractal growth aggregation while the surface fractal dimension increased with decreasing pH. Apparently, the encapsulation property was affected by the physical properties of the aggregates, and there existed an optimal aggregation degree, which maximized the performance of an encapsulated system.

DOI： 10.11301/jsfe.15.51

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Hydrogel based oil encapsulation was attempted with a ternary system of colloidal chitosan, k-carrageenan, and carboxymethylcellulose sodium salt (NaCMC). Favourable formulations of this ternary system that caused irreversible sol-gel transition by freezing (cryogelation) were found in this study, and the oil phase that contained a selected model food ingredient (curcumin) was successfully encapsulated in this prepared cryogel matrix. The encapsulation yields were found to vary from ca 89-99%, and the values were influenced by the cooling protocol used during freezing, thereby indicating that the gel formation kinetics was intimately related to the degree of encapsulation. The release behaviours of the ingredient were investigated in aqueous systems. The release curves showed that both a burst release and a first order release were achieved simply by changing the freezing condition. Freezing could modify the gel formation of the present cryogel, and the resulting structural modification evidently controlled the oil encapsulation manner. Prepared cryogels were found to be sensitive to the ambient pH. It was suggested that the ternary system of chitosan, k-carrageenan, and NaCMC is an interesting matrix for designing controlled release system. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.lwt.2013.06.011

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Core-shell nanoparticles were prepared using a technique based on complex coacervation, and their characteristics were investigated after subsequent freeze drying. An oil-in-water emulsion was stabilized with a gelatin-acacia solution, and the pH of the solution was adjusted to a selected value with acetic acid. The solutions were frozen at a selected freezing rate and subsequently freeze dried. This is a strategic approach to produce particles upon freezing in order to tune their properties by controlling the processing parameters. It was found that particles with mean diameters in the range of 100-400 nm were successfully prepared under all of the selected conditions
however, the size distributions were highly dependent on the values of the variables employed. The efficiency of encapsulation of β-carotene dissolved in the oil phase was significantly affected by the specific processing parameters. Interestingly, the ratio between the surface and inner loads could be tuned by selecting the appropriate conditions. Furthermore, the freezing protocol affected the mass transfer properties of the shell membranes at certain pH values. Complexation of the gelatin and acacia during freezing was confirmed using in situ small-angle X-ray scattering analysis (SAXS) with oil-free gelatin-acacia solutions. A structural change on freezing of the solution was detected at a subzero temperature, and the structural features were found to be dependent on the acidity of the solution and the cooling rate during freezing. © 2013 Copyright Taylor and Francis Group, LLC.

DOI： 10.1080/07373937.2013.803197

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS INC  

Spray-dried casein-encapsulated -carotene powders were prepared for encapsulation efficiency studies with respect to structural changes in casein aggregates prior to drying. The use of casein aggregates as shell matrix materials for encapsulation is of interest in encapsulation research; however, the relationship between process conditions and casein aggregation is not completely understood. Here, we report the investigation of the influence of solution pH and storage time on casein aggregate structural changes, in addition to encapsulation efficiency after spray drying. Total -carotene loading quantities observed were higher when a solution with lower pH was employed in the dried powder preparation. Specimens obtained from a solution with pH 5.5 gave the highest total loading efficiency. Loading efficiencies were largely improved when the solutions were stored for 5 days prior to spray drying. Small-angle X-ray scattering analysis confirmed that surface structures and particle sizes were correlated to the solution pH used, as well as to storage time. At lower pH conditions (pH 5.5), particle sizes greatly increased over the entire storage duration, with a rough surface formed in the first 6h, followed by a gradual surface smoothing. At higher pH conditions (pH 6.0-7.0), a rough surface formed accompanied by an increase in the particle size in the first 24h, after which the size gradually decreased with the smoothed surface formation. The encapsulation efficiencies could be correlated with these structural changes during storage. The results obtained provide important insights into the encapsulation process and are expected to improve applications involving casein aggregation.

DOI： 10.1080/07373937.2013.800548

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Ice-templating is a simple, practical kind of template synthesis which consists of sol-gel polycondensation, unidirectional freezing of hydrosols or hydrogels, and pore-preserving drying method, such as freeze drying, thereby resulting in desirable porous materials. The unidirectional freezing may be achieved by either immersion freezing or contact freezing. Freeze-dried materials contain porous microstructures that are replicas of the ice crystals formed during the unidirectional freezing process. Two similar but slightly different applications of ice-templating will be investigated here. Fabrication of macroporous foam materials by unidirectional freezing of an aqueous suspension of carbon nanotubes (CNTs) dispersed by chitosan is a concrete example of functionalization of an electroconductive foam, which is a composite material made from a polymer and CNTs. As expected, their electroconductive properties can be controlled by the fabrication method and condition. Additional examples of porous materials synthesized by ice-templating are porous microfibers and microhoneycombs of silica, titania, silica-alumina, titania-silica, and even carbon. In the preparation, the morphology and porous structure can be controlled by the freezing conditions and synthesis conditions of the corresponding hydrogels, respectively.

DOI： 10.4186/ej.2013.17.3.1

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：KARGER  

Encapsulation of curcumin-loaded oil droplets with chitosan-based cryogels, made from a ternary system of colloidal chitosan, K-carrageenan, and carboxymethylcellulose (CMC) sodium salt, was carried out and the effects of the freezing condition (unidirectional freezing rate with and without post-freezing incubation) and the initial concentration ratio of carrageenan to CMC on the properties of the cryogel nanocapsules were experimentally investigated. Both the freezing condition and initial concentration ratio had significant effects on the gel fraction yield, swelling extent, particle size and zeta potential, as well as the curcumin release pattern. Specimen I-S1-02, which was made of polymer set 1 (carrageenan:CMC = 4:6) at a rapid freezing rate of -2 degrees C/min with 10-hr incubation at -10 degrees C, showed the slowest release rate (first-order type) of curcumin. In comparison, it was found that microcapsules obtained by spray-drying a similar O/W curcumin emulsion with dextran as stabilizer exhibited the fastest rate of curcumin release, similar to a burst release.

DOI： 10.3136/fstr.19.633

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The formation of casein-based nanoparticles from sodium caseinate and sodium caseinate-pectin solutions was investigated in a frozen system by protein self-aggregation and protein-polysaccharide complexation, respectively. Casein-based nanoparticles were prepared by controlling the pH levels of the solutions followed by freezing. The formation of precipitates was confirmed in the casein solutions at pH <5.5. However, an obvious effect of the freezing on the formation of aggregates could not be confirmed, although the freezing did have an effect on accelerating the formation of precipitates. The mean particle sizes analyzed from the produced nanoparticles suggested that freezing did not have any significant effects on altering the particle sizes. Similar trends were observed in the casein-pectin solution in terms of phase separation and particle sizes. A difference was confirmed in the solution at pH 4.6; that is, a clear phase separation was observed due to freezing. Nevertheless, it was found, both in the casein and casein-pectin systems, that the degradation rates of the freeze-thawed nanoparticles were considerably slower than that of the original nanoparticles. This suggested that the casein-based nanoparticles formed through freezing had structural features different from the ones in the unfrozen solution. It could be concluded from the SAXS analysis that the formation of the protein-based particulate systems certainly occurred in the cryoconcentrated phase associated with freezing. The present technique is advantageous for the encapsulation of heat-sensitive and/or acid-sensitive ingredients in protein nanoparticles. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfb.2012.10.052

Web of Science

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

Cryogel based oil encapsulation was attempted with a ternary system of colloidal chitosan, κ-carrageenan, and carboxymethylcellulose sodium salt (NaCMC). Favourable formulations of this ternary system that caused irreversible sol-gel transition by freezing (cryogelation) were found in this study, and the oil phase that contained a selected model food ingredient (curcumin) was successfully encapsulated in this prepared cryogel matrix. The encapsulation yields were found to vary from ca 89 to 99%, and the values were influenced by the cooling protocol used during freezing, thereby indicating that the gel formation kinetics was intimately related to the degree of encapsulation. The release behaviours of the ingredient were investigated in aqueous systems. The release curves showed that both a burst release and a first order release were achieved simply by changing the freezing condition. Freezing could modify the gel formation of the present cryogel, and the resulting structural modification evidently controlled the oil encapsulation manner. The prepared cryogels were found to be sensitive to the ambient pH. It was suggested that the ternary system of chitosan, κ-carrageenan, and NaCMC is an interesting matrix for designing controlled release system. © (2013) Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/AMR.701.98

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS INC  

Lactate dehydrogenase (LDH) solutions were freeze dried in order to investigate the redistribution of the remaining LDH activity in the dried cake. D-Mannitol and a polysaccharide (?-carrageenan, ?-carrageenan, or dextran) were mixed and used as stabilizers in freeze drying. It was found that the remaining LDH activity was significantly redistributed in the freeze-dried cake, and the enzyme concentration was not uniform along the axis of the dried cake due to variations in the freeze-drying conditions and stabilizer concentration. In some cases, active enzymes were highly localized in a specific portion of the dried cake. This was mainly due to the redistribution of the protein content. Further freeze-drying tests employing bovine serum albumin (BSA) and the above-mentioned polysaccharides showed that proteins (BSA) tended to accumulate in the lower portions of the dried cake, forming concentration gradients. Therefore, the concentration gradient in the freeze-dried cake was mainly due to the freezing process. This redistribution of protein content contributed considerably to the apparent redistribution of enzyme activity. The results suggest that a process that can control the redistribution of protein content in a freeze-dried cake would further improve the biological activity of freeze-dried proteins.

DOI： 10.1080/07373937.2012.723291

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

A freezing process was applied to control the kinetics of a gelatin-acacia complex coacervation technique for encapsulating emulsified oil droplets. An oil-in-water emulsion was stabilized with a gelatin-acacia solution, and the pH of the solution was adjusted to a selected value with acetic acid. When the pH of the emulsion was adjusted to 4.7, the system was visibly stable at ambient temperature for up to 12 h. Freezing the emulsion caused polymer phase separation (complex coacervation) in the cryoconcentrated phase and resulted in encapsulated oil droplets and the accumulation of a cream layer in the freeze-thawed solution. Observation by transmission electron microscopy clarified the formation of 50-4000 nm core-shell nano-microparticles, the surfaces of which were surrounded by polymeric membranes. The membrane properties of the particulate systems were dependent on the cooling rate that was used during freezing. For example, when an emulsion with a pH of 4.7 was frozen, a cooling rate of -1.0 degrees C/nun maximized the encapsulation yield, whereas a rate of -2.0 degrees C/min was effective in limiting the release rate of the ingredient (beta-carotene) from the oil phase through the shell membrane. The results of this study suggest that the formation of nano-microparticles could be highly associated with the kinetics of freezing, so their resultant properties could be fine-tuned using a freezing operation. This is a potential concept providing a novel strategy for engineering core-shell nanoparticles. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2012.07.010

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

The depolymerization reaction of poly(ethylene terephthalate) (PET) was analyzed on the basis of experimental and numerical data obtained from molecular orbital calculations. Various types of PETs polymerized by different methods and preheated by microwave irradiation were used to investigate the depolymerization mechanism. The activation energies obtained from the optimized structures of the ground state and the transition state were compared with the experimental data. On the basis of these comparisons, it was found that not only the crystallinity but also configuration changes caused by preheating were essential for realizing a high rate of transesterification reactions, such as depolymerization. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

DOI： 10.1002/app.34878

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Cryogel based encapsulation of curcumin, an herbal extract, was successfully carried out with a ternary system of colloidal chitosan. kappa-carrageenan, and carboxymethylcellulose sodium salt. The effects of chitosan concentration. kappa-carrageenan/CMC ratio of the polymer suspension and molecular weight of chitosan on the sol-gel formation were investigated. The effects of cooling rate during freeze-drying and oil phase composition on the encapsulation yield and the release behavior of curcumin from the hydrogel were determined. And so were the effects of pH of the phosphate-buffered media and oil phase composition on the swelling of the specimens. The microstructure of the resulting specimens revealed core-shell nanoparticles (i.e. oil droplet for core and cryogel membrane for shell) entrapped in the cryogel matrix. The encapsulation yield for two types of suspensions was in a range of 83.9 to 99.6% when a high-MW chitosan was used. Controlled release of the encapsulated curcumin in an aqueous system could be maintained for 4 days, and the releasable amount of curcumin was in a range of 41.1 to 59.9%. The encapsulation yield as well as the released pattern and releasable amount of curcumin were significantly influenced by the cooling protocol used during freezing. Irrespective of the introduced oil phase composition, controlled release of curcumin was achievable when the cooling rate was sufficiently high at -2.0 degrees C/min and, interestingly, either a burst release or a first order release could simply be achieved by changing the freezing condition. (c) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.msec.2012.01.027

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Made via sol-gel transition around the encapsulated ingredients, hydrogel is often employed in the formation of shell matrix composed of semipermeable membrane envelope. In the present study, the encapsulation of an oil-soluble food nutrient, curcumin, in hydrogels of natural polymer chitosan was carried out in the absence of any cross-linking agent. A curcumin-loaded oil-in-water emulsion was prepared and incorporated into a polymeric suspension consisting of chitosan and a suitable ratio of κ-carrageenan and carboxymethylcellulose sodium salt (NaCMC). The encapsulation of curcumin in chitosan was achieved by converting the resulting colloidal suspension into hydrogels via cryotropic gel formation. The frozen hydrogel samples were freeze-dried for preservation. The yield of curcumin encapsulation was found to depend on both the cooling rate and the ratio of κ-carrageenan to NaCMC. As the cooling rate increased, the encapsulation yield rose in tandem. Similarly, the release behavior of the encapsulated curcumin in an aqueous phase was shown to depend on the same two factors despite a difference in the oil-phase composition. Two types of release behavior were observed: a burst release and a moderate first-order release rate. In fact, when the ratio of κ-carrageenan to NaCMC was kept constant, the cooling rate was found to determine the type of release. Generally, the higher the number of cross-linkings in the polymer matrix and the stronger the bonding strength, the slower the release rate should become. A more balanced ratio of κ-carrageenan to NaCMC was shown to yield a pseudo-first-order rate release and by implication a stronger microstructure.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Lipase from candida rugosa was immobilized in a freeze-dried polyvinyl alcohol (PVA) matrix for investigating the enzymatic reactivity. This matrix was prepared in a microreactor to achieve continuous enzymatic reactions. The performances of the lipase immobilized microreactors were compared in terms of the micro channel type and the reaction conditions. The freeze-dried matrix made in the microchannel possessed porous microstructure with 2-20 !m of well-aligned pores. These pore structures were obtained as a replica of the ice crystals formed during the freezing stage. Experiments suggested that the enzymatic reaction with the immobilized lipase was a diffusion controlled system. It was found that the present microreactors exhibited approximately 10 times higher reaction performance than the large scaled plug flow reactor with the freeze-dried specimens. The freeze-dried microstructure fabricated in a microspace had a significant effect of improving enzymatic reactions. A solution flow in the microchannel is under an influence of both the porous microstructure and the channel structure. When the channel size was smaller than 1000 !m, the flow regime would mainly be controlled by the freeze-dried microstructure.

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC CHEMICAL ENG JAPAN  

The effects of freezing treatments on the activity of the lactobacilli-aggregating peptide QRCVNLQA were studied. The aggregation activity of the peptide solution was enhanced by rapid deep freezing in liquid nitrogen followed by storage for at least 1 d below -10 degrees C. The treated peptide strongly induced the aggregation of suspended cells of Lactobacillus rhamnosus GG to provide a clear supernatant after 1.5 h. The peptide was activated by oxidation of thiol groups, probably through dimerization of the peptide molecules to form disulfide bonds. Addition of the freeze-oxidized peptide to a suspension of lactobacilli promoted the adhesion of the lactobacilli to a monolayer of Caco-2 intestinal epithelial cells.

DOI： 10.1252/jcej.12we086

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS INC  

Microcapsules are of great interest to the food and pharmaceutical industries as vehicles to deliver active ingredients to the gastrointestinal tract. Drying plays an important role in stabilizing microcapsules to prolong their lifetime; however, drying often produces undesirable changes in the microcapsules, such as irreversible aggregation of the microcapsules and activity loss of the encapsulated ingredient. In this work, poly(epsilon-caprolactone) microcapsules containing a model bioactive compound (tocopherol) were prepared and stabilized in a freeze-dried gelatin matrix. This dried product was rehydrated and the aqueous redispersibility of the microcapsules and the tocopherol activity were investigated. The experimental results suggested that a kinetic balance between dehydration (caused by freezing) and gel network formation is a critical factor that affects the redispersibility and ingredient activity of the products. It was further suggested that a hydrogel-based product could be strategically freeze dried to maximize product quality by tuning its freezing process; that is, by employing a controllable dehydration process.

DOI： 10.1080/07373937.2011.645980

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST CHEMICAL ENGINEERS  

Freeze-dried macroporous foams were prepared from an aqueous colloidal suspension of chitosan/xanthan gum/Na(+)-montmorillonite nanoclay (MMT). The suspension formed gel structure as a consequence of freezing, named cryogel. Cryogel is defined as a gel formed due to the concentration increase of the substrates caused by the ice formation during freezing. This obtained cryogel was subsequently dried under vacuum condition to produce porous foam materials. Two freezing methods were employed in the present work in order to investigate the influence of the processing on sample characteristics, namely; contact freezing with a heat exchanger and immersion freezing in a cryo-bath. Based on the SEM observation, in the case of contact freezing; rapid freezing (-2 degrees C/min) resulted in randomly aligned pores as compared to the pore alignment obtained in the case of slow freezing (-0.25 degrees C/min); the mean pore size for rapid freezing and slowing freezing were 40 mu m and 68 mu m, respectively. However, in immersion freezing samples, aligned and bamboo-like straight structures with pore layer spacing of 22 mu m were observed. The different microstructures significantly influenced the mechanical hardness of the prepared foams nanocomposites. The MMT dispersion within the bionanocomposites was found to be characteristically exfoliated from X-ray diffraction and electron microscopy analysis. Small angle X-ray diffraction data indicated that the polymeric networks were modified by the exfoliated MMT and the MMT also improved the hardness of the prepared foams. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cherd.2011.02.023

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

Freeze-dried hydrogel was prepared from a colloidal suspension of chitosan and xanthan gum blend in order to encapsulate an enzyme (firefly luciferase), and the release behavior of the enzyme from the prepared hydrogels was investigated. Selected amount of firefly luciferase was homogenized with the original polymer solution, and was then stabilized in the resultant freeze-dried samples. The encapsulated enzymes showed their enzymatic activities through bioluminescence reaction and in terms of encapsulation stability, prepared samples were found to be sensitive to the buffer pH, that is, the release rate of the enzyme was larger in pH 6.0 than in pH 8.0. The addition of the montmorillonite nanoclay (MMT) significantly lowered the enzyme release rate due to strong influence on the structural modification of the bionanocomposites. Small angle X-ray scattering measurements suggested that this was due to the modification of polymeric network structures, and the polymer network affected the release behavior of the enzyme. Further, enzymatic activities of the encapsulated and the released enzyme were confirmed for over 30 days, suggesting that the hydrogel formulation could be an excellent support structure for encapsulating bioactive substances such as enzymes. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matchemphys.2011.04.043

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

The purpose of this study was to determine the effect of freezing process in the absence or presence of excipients on the stability of capsicum loaded nanocapsules (NC) during freeze-thawing and freeze-drying procedures. Capsicum loaded nanocapsules were prepared by the modified-emulsion-diffusion method combined with the microfluidization method. The prepared samples were frozen at freezing temperatures of -40, -20, and -15 degrees C to study the effects of cooling temperature on the properties of the capsicum oleoresin loaded nanoparticles. From results, a relatively high freezing temperature had an effect on the maintenance of nanocapsule size after freeze-thawing and freeze-drying. Regarding the addition of excipients, gelatin and kappa-carrageenan played roles as cryoprotectants and lyoprotectants, and represented R values of 1.01 and 1.13 in size comparisons before and after treatment, respectively. Furthermore, the morphologies of NC made with gelatin or kappa-carrageenan were conserved after freeze-drying showing spherical forms according to electron microscope observations. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jfoodeng.2011.02.042

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Used for biofuel production, fatty acids and their corresponding triglycerols are stored in most plants. At room temperature, saturated fatty acids and their triglycerols are solid, whereas unsaturated fatty acids and their triglycerols are liquid. Solid-liquid equilibrium data were measured for various binary systems of fatty acids and their triglycerols by differential scanning calorimetry. The freezing temperatures from liquidus curves for the binary systems containing tripalmitine were higher than those for systems containing palmitic acid. At the eutectic point, the melting temperatures for binary systems containing tripalmitine or palmitic acid were similar. The liquidus curves from the Solid-liquid equilibrium data were compared with the predicted values obtained by using the LLE-LTNIFAC model, and good agreement between the experimental and calculated results was found.

DOI： 10.1021/je101092j

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER/PLENUM PUBLISHERS  

The depolymerization reaction of polyethylene terephthalate (PET) was analyzed on the basis of both experimental data and numerical data obtained from quantum chemistry calculations. Various alcohols were used as solvents in the search for the reaction mechanism. The activation energy obtained from the optimized structures of the ground state and the transitional state was compared with our experimental data. Based on these comparisons, it was found that the formation of rings from alkoxyl groups and carbonyl carbon atoms at the transitional state is highly important when the ester bonds of PET are broken. Moreover, the most appropriate alcohol was suggested for the depolymerization reaction.

DOI： 10.1007/s10924-010-0263-3

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

To optimize the primary drying step of freeze-drying processes, it is very important to control morphological parameters of the frozen matrix. A mathematical model that simulates temperature profiles during freezing process of standard pharmaceutical formulations was set up and the ice crystal mean sizes were semi-empirically estimated from the simulated thermal profiles. Then, water vapor mass transfer kinetics during sublimation step was estimated from ice phase morphological parameters. All these numerical data were compared with experimental data and a quite good agreement was observed, which confirmed the adequacy of the present model calculations. It was confirmed that, for a given formulation, the mass transfer parameters during freeze-drying were strongly dependent on morphological textural parameters, and consequently, on the nucleation temperatures that fix the ice phase morphology. The influence of freezing rates was also predicted from the simulations, proving that an increase of cooling rates led to slower primary drying rates. (C) 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

DOI： 10.1002/apj.424

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

A nanocapsule (NC)-gelatin suspension was freeze-dried to produce a sample of dry food. The obtained dried product was rehydrated, and the dispersibility of the nanocapsules was investigated. It was found that the prepared freeze-dried food had different dispersion characteristics at different positions in the dried bulk sample, and this heterogeneity was dependent on the cooling program used during the processing. A model mathematical calculation was carried out in order to obtain the thermal profiles of the sample during freezing. The freezing front velocity and the viscosity of the solution at/around the freezing front were estimated by using the simulated thermal profiles. The dispersibility of the prepared dry food was found to correlate with these values. This suggested that the gel network formation of NC-gelatin would be advantageous for producing excellent NC dispersion characteristics after drying. A slow cooling condition is favourable for promoting sol-gel transition in the solution. However, the large scale of ices formed during slow freezing would damage the gel networks, leading to poor dispersibility. The present work discusses key processing factors for controlling the dispersion characteristics of nanocapsules stabilized in a freeze-dried food sample. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jfoodeng.2010.08.017

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

Freeze-dried macroporous solid foams were prepared from the multi-walled carbon nanotube (MWCNT) aqueous suspensions dispersed by chitosan. Thin film shaped CNT solid foams were prepared, and applied to the gas diffusion layers (GDLs) of a laboratory scale proton exchange membrane fuel cell (PEMFC). It was demonstrated that the prepared carbon foams in this study were useful to a fuel cell GDL material. The prepared cell performances were fairly comparable to the cell prepared with conventional carbon paper for GDL material. The microstructures of the prepared carbon foams were found to affect on the PEMFC performances. It was suggested that the interconnected carbon networks formed during the freezing step closely link to the cell performances. Hence, the defection of the interconnected microstructure lead degradation of the GDL quality. The impedance measurement made clear that the prepared foam materials were also advantageous for reducing the ohmic resistance in PEMFC assembly. The kinetic resistance values and the thermal conductive characteristics suggested that the freezing process would also control the degree of overlaps among single CNTs in a freeze-dried bulk that influenced on the electrochemical properties. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cep.2010.10.010

Web of Science

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ELSEVIER SCIENCE BV  

Considering severe security regulations for food and pharmaceutical ingredients, it would be ideal to make various types of encapsulants from a widely approved single substance. Use of cryogels for encapsulation would be an interesting idea. Cryogel is defined as a hydrogel where sol-gel transitions are induced by localized concentration increase of the substrate due to ice formation during freezing. It would thus be expected that gel network formations can be controlled by a freezing process, and the controlled polymeric structures are advantageous for release control. In this work, chitosan based cryogels were prepared for investigating encapsulation characteristics of a model ingredient. It was found that the release behaviour of the ingredient from the prepared cryogel matrix could be controlled by the freezing condition for the gel preparation, indicating that a freezing operation controlled the gel network formation that determined consequent release characteristics from the hydrogel matrix. The differences of gel network structures formed via the different freezing conditions were illuminated by SAXS analysis. A clear structural anisotropy appeared when the chitosan suspension was rapidly frozen. On the other hand, this strong anisotropy disappeared when the cooling rate was decreased. It is a clear evidence of polymeric structural modifications appeared in cryogels prepared via different cryo-processing. This cryogel based encapsulation would be a potential technique for realizing a structural design of the encapsulants simply by tuning the freezing conditions. (c) 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of 11th International Congress on Engineering and Food (ICEF 11) Executive Committee.

DOI： 10.1016/j.profoo.2011.09.289

Web of Science

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ELSEVIER SCIENCE BV  

Cryogel based encapsulation was attempted to entrap oil phase (containing curcumin) with a ternary system of colloidal chitosan, kappa-carrageenan, and carboxy methylcellulose sodium salt (NaCMC). The cryotropic gel formation was investigated by varying the cooling rate during freezing and type of polymer suspension. The microstructure of the resulting curcumin cryogels revealed oil droplets entrapped in the cryogel matrix. The encapsulation yield for two types of suspension was found to vary from 83.89 to 99.37%. Controlled release of the curcumin in an aqueous system could be maintained for 4 days, and the released amount of curcumin was found to vary from 41.1-59.9%. The encapsulation yield as well as the released pattern and amount of curcumin were influenced by the cooling protocol used during freezing. The release patterns were found to be sensitive to the ambient aqueous pH and, interestingly, either a burst release or a first order release was achievable simply by changing the freezing condition. These results suggested that freezing could modify the gel formation of the present cryogel, and the resulting structural modification evidently controlled the oil encapsulation manner. The present ternary system (chitosan, kappa-carrageenan, and NaCMC) is an interesting matrix for designing controlled release system in a food system. (c) 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of 11th International Congress on Engineering and Food (ICEF 11) Executive Committee.

DOI： 10.1016/j.profoo.2011.09.290

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Positron annihilation lifetime spectroscopy has been used to study a chitosan biopolymer, to which nanoclay has been added, and the effect of water absorption and cross-linking on the microporosity. All measurements were conducted at room temperature. The free volume size of the biopolymer samples was obtained based on the ortho-positronium lifetime, and the relative concentration of free volume cavities was measured by the ortho-positronium intensity. Using the PALS technique, effects of hydration were observed as a reduction in the measured pore size. Similarly, the cross-linked samples exhibited an increase in intensity of the smallest pores commensurate with the SEM observations. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2010.08.045

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Phenol-dye aqueous ternary solutions were employed as model eutectic solution, and concentration phenomena during freezing and thawing were investigated. The freeze-concentration level during freezing step and the concentration profiles of the melt fractions during thawing step were examined. It was found that the present freezing conditions did not effectively separate the solutes from frozen zone. Phenol component was slightly concentrated in the top frozen layer though the dye was almost equivalently distributed in the frozen domain. However, the concentrations of melt fractions obtained during thawing step were clearly higher than the concentration level of the frozen domains. Approximately 50% of the both solutes could be recovered from the initial 30% of the melt fraction. It was suggested that concentration behaviour during thawing would be controlled by thawing condition as explained by the kinetics of mass transfer of solutes in the frozen domain and at the frozen interface. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.seppur.2010.04.031

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST CHEMICAL ENGINEERS  

A novel freeze-concentration method was proposed to use solute elution from a frozen matrix as a concentrating operation. A batch crystallizer was made up to freeze solution with a jacket cooler, and a rod heater was set at the centre of the crystallizer in order to make the solution contact with the frozen zone. Commercial apple juice was employed as a model liquid food, and the concentration behavior was investigated with the present apparatus. It was found that the concentration clearly increased with time, and the concentrate was recovered at desirable level if the temperature of the jacket and the heater were properly selected. In fact almost all the solute could be recovered from the original apple juice. The present method would mainly be governed by the solute elution from a frozen phase to a liquid phase, therefore, would not require complicated operation. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cherd.2009.11.007

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Freeze-dried porous solid foams were prepared from carbon nanotube (CNT) suspensions via either contact freezing with a heat exchanger or immersion freezing into a cryo-bath. Microstructures in the freeze-dried foam cast by ice crystals formed during the freezing step. It was found that domains of the carbon nanotubes in the freeze-dried solid foams were fairly well interconnected, and the microstructures were largely influenced by the freezing condition and freezing method. A mathematical model was proposed to simulate the observed thermal history during the freezing step; then theoretical predictions of the microstructural features were attempted. The simulated thermal history was in good agreement with experimental result. The resulting mean ice crystal sizes L* could be estimated from the calculated freezing front velocity (R) and the temperature gradient in the frozen zone (G). Interestingly, it was found that a correlation based on the power law (L* proportional to R(-0-2) G(-0.2)) was applicable to the present system for both the contact and immersion freezing methods. Though the fundamental ice crystallization phenomena were essentially the same for both freezing methods, actual temperature distribution and movement of the freezing front through the whole freezing bulk could control the morphology of ice crystal in the frozen matrix. In other words, good control of thermal flow in the freezing system would greatly contribute to rational design of microstructures of the CNT foam. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ces.2009.10.014

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

The concentration phenomena during freezing and thawing were investigated to study the feasibility of freeze-thaw process as a concentration operation. An aqueous dye solution was employed as a model binary eutectic solution. The localised concentration in the frozen matrix was determined, and the concentration profile of the melting solution during thawing was examined. It was found that the solution obtained during thawing showed higher concentration than the original solution, and the concentration did not correspond to the amount of solute localised in the frozen matrix. It was suggested that the concentration phenomena during thawing would be governed by the melting droplet growth rate at the melting interface and by the diffusion rate of solute from eutectic phases to the droplet.

DOI： 10.1002/cjce.20213

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST CHEMICAL ENGINEERS  

Freeze-dried samples were prepared from D-mannitol solution by selected freezing conditions. Crystalline structures of prepared samples were determined by XRD analysis, and distributions of the various crystal structures of mannitol were obtained for each sample. it was found that the amount of each polymorph was quite well correlated to the freezing conditions, namely the ice crystal nucleation temperature and the cooling rate. In case of samples prepared at fast cooling rates, the samples where the ice crystals nucleated at higher temperature contained much more stable form than the samples nucleated at lower temperature. Besides, the samples prepared at slow cooling rates predominantly contained stable crystalline forms despite of the variation of nucleation temperatures. Moreover, the experimental results also indicated that the various polymorphs were also distributed vertically through the sample along the direction of the heat flux during freezing. The tendency of the polymorph distribution through the freeze-dried cake was also elucidated by using the simulated temperature profiles during freezing. Thus, the profiles of mannitol polymorphs after the freezing derived from the temperature distributions could predict the global tendency of polymorphism behaviour, and, consequently, would be useful to achieve quality control of freeze-dried formulations. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cherd.2009.01.008

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

The depolymerization reaction of polyethylene terephthalate (PET) was analyzed using a computational chemistry approach. The reaction is a type of transesterification reaction using alkoxide. In this study we employed the calculated optimum structure, electrostatic potential distribution, activation energy, electric charges and pathway to investigate the mechanism. We found that the tetrahedral intermediate produced by ring formation with alkoxide is an essential feature of the depolymerization process. Moreover, there is a possibility that a PET molecule is depolymerized by multiple alkoxides at the same time. However, the effects of degree of polymerization and the position of attack by the alkoxides do not strongly influence the reactivity. (C) 2008 Published by Elsevier Ltd.

DOI： 10.1016/j.polymdegradstab.2008.10.029

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

Macroporous solid foams, made of multi-walled carbon nanotubes (MWCNTs), having a high porosity of 97% were produced using a freeze-drying technique. MWCNTs were dispersed in a carboxymethyl cellulose (CMC) sodium salt (surfactant) solution. Placed on a heat exchanger, the solution was frozen and lyophilized to obtain a dry sample. The prepared solid foam specimen had a macroporous structure, and its resulting pore sizes were mainly controlled by the initial formulation and freezing condition. A faster cooling rate led to a higher degree of homogeneity and a smaller macropore network in the bulk matrix, as did a higher surfactant concentration or a higher MWCNT content. The shapes of the macropores were quite similar even when the cooling rate and/or initial formulation were different. Interestingly, the electric resistivity of the solid foams, which depended on the preparation conditions, could rapidly respond to an ambient pressure change. It was found that the prepared macroporous solid foams displayed hybrid characteristics of the original MWCNTs and the resulting bulk matrix with a controlled macropore system. These results suggest that the prepared solid foams have high potential to be used as a gas sensing material. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matchemphys.2008.05.067

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST CHEMICAL ENGINEERS  

To complete our first studies carried out on controlled nucleation with ultrasounds during freeze drying of pharmaceutical formulations, new investigations were performed on crystalline structure and permeability of freeze-dried mannitol systems. We observed that for solutions at 10 wt.% mannitol and for nucleation temperatures above -5 degrees C the 8 phase - the metastable form of crystallized mannitol - was predominant for both cooling rates investigated. This limit temperature corresponds approximately to an increase of the slope of sublimation rate curve as a function of nucleation temperature. For samples having a higher nucleation temperature, both mannitol concentration and freezing rate had an influence on freeze-dried cake permeability. As the permeability is directly related to the freeze-dried cakes morphology, SEM analyses were also realized. Sheet structure was dominating for high nucleation temperatures and this structure seemed to prevail in samples that present a maximum content of 8 phase. Finally, addition of surfactant to mannitol solution did not improve the nucleation triggering and induced unstable polymorph. Moreover, the uncontrolled power of the ultrasound pulse (very high power) might also lead to delta-phase polymorph. (c) 2007 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cherd.2007.11.009

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST CHEMICAL ENGINEERS  

Activated carbons were prepared from carbonized phenolic resins by steamactivation. Three different novolak type phenol formaldehyde resins were synthesized under different formaldehyde (F) to phenol (P) molar ratios (F/P = 0.3, 0.5 and 0.8) and were used as the precursors for activated carbons. The activated carbons obtained from resins synthesized under typical FIP ratios were microporous, which is characteristic for activated carbons derived from phenolic resins. However, it was found that by decreasing the FIP ratio of the precursor resin to values lower than those usually adopted for commercial phenolic resin production, i.e., values lower than 0.5, activated carbons with developed mesopores could be obtained. Structural information of the precursor resins obtained from Raman spectroscopy indicated that although typical novolak resin structures could be found in all the resins, the resins synthesized at lower FIP ratios included larger amounts of phenol and lower molecular weight substances. This is thought to have led to a large difference in their thermoplastic natures. The existence of low molecular weight substances was also confirmed through thermogravimetric analysis of the resins during carbonization. CO2, C2H6, n-C4H10 and i-C4H10 adsorption isotherms of the prepared activated carbons were also measured at 298 K for the better understanding of micropore development within the samples. The obtained data suggested that micropore development was not so much influenced by the FIP ratio of the precursor resin.

DOI： 10.1205/cherd06119

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JOHN WILEY & SONS INC  

A mathematical model that simulates temperature profiles during freezing process of standard pharmaceutical formulations (mannitol and BSA based) was set up in two-dimensional axsymmetric space, and the ice crystal mean sizes were semi empirically estimated from the resulting temperature profiles. Water vapor mass transfer permeability values during sublimation step were also estimated from ice phase morphological parameters. All these numerical data were compared with experimental data, and a quite good agreement was observed that confirmed the adequacy of the present model calculations. It was confirmed that, for a given formulation, the mass transfer parameters during freeze-drying were strongly dependent on morphological textural parameters, and consequently, on the nucleation temperatures that fix the ice phase morphology. The influence of freezing rate was also predicted from the simulations, proving that an increase of cooling rates led to slower primary drying rates. (c) 2007 American Institute of Chemical Engineers.

DOI： 10.1002/aic.11147

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC CHEMICAL ENG JAPAN  

Activated carbons were prepared from carbonized phenolic resins by steam-activation via a pre-treatment, that is mixing of raw materials with Ca(NO(3))(2)center dot 4H(2)O and acid-treatment after carbonization. This pre-treatment method has been reported as a method to produce mesoporous activated carbons. In the present work, three different novolak type phenol formaldehyde resins were synthesized under different molar ratio of formaldehyde (F) to phenol (P) (F/P = 0.3, 0.5, and 0.8) and were used as the precursors for activated carbons. It was confirmed that the pre-treatment method effectively enhances mesopores on activated carbons from synthesized phenolic resins prepared by F/P = 0.3 and 0.5, and their pore size distributions depended on the synthesizing conditions (F/P). Namely, it was found that by decreasing the F/P ratio of the precursor resin to the values lower than those usually adopted for commercial phenolic resin production, i.e., less than 0.5, activated carbons with developed mesopores could be obtained. The micropore developments of activated carbons were also influenced by F/P, and the influences were on the formation of pores larger than 0.40 nm. It was suggested that the thermoplastic nature of prepared resins (that can be changed by F/P) influence the porous properties of resultant activated carbons and the effect of the pre-treatments.

DOI： 10.1252/jcej.40.410

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

In order to optimize industrial freeze-drying processes of pharmaceutical proteins in vials, an ultrasound system has been designed and applied to control the freezing step. It was confirmed that during supercooling, nucleation temperatures of the sample could be controlled at selected values below the equilibrium freezing temperature. Because the main freezing elementary phenomena like nucleation and ice crystals growth are strongly related with ice crystal morphology parameters, the controlled nucleation by ultrasound effectively modified notably the primary drying duration. Thus, it was experimentally confirmed that the primary drying rates during freeze-drying of pharmaceutical formulations (i.e. mannitol, BSA, sucrose) were accelerated due to ice phase morphological modifications induced by the ultrasound control system. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cep.2006.03.007

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC CHEMICAL ENG JAPAN  

Microporous activated anthracite was produced from waste anthracite powders by the conventional steam activation. The activated anthracite was also treated by supercritical water reaction (SWR) by using distilled water and hydrogen peroxide solution as a liquid medium for SWR treatment. It was found that SWR treatment can improve the mesoporosity of the activated anthracite though the micropore volume was reduced by the treatment. In liquid-phase adsorption and supercritical water regeneration studies, phenol and organic dye RED 31 were selected as the representative adsorbates. The adsorption and regeneration characteristics of activated anthracite were compared with those of a commercial activated carbon. The results indicate that the activated anthracite prepared showed comparable phenol adsorption capacity but significantly lower dye adsorption capacity than the commercial one. However, supercritical water regeneration efficiency was remarkably high. The first/second regeneration efficiencies of commercial activated carbon and activated anthracite exhausted with phenol were 55/55 and 65/65%, respectively, and in the case of RED 31, 78/79 and 338/317%, respectively, with losses of activated carbon less than 4% per regeneration. Because of little loss of activated carbon during successive regenerations, this SWR regeneration method was suitable for regenerating spent activated carbon or anthracite.

DOI： 10.1252/jcej.39.661

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Liquid-phase adsorption-desorption characteristics and ethanol regeneration efficiency of an activated carbon prepared from waste tires and a commercial activated carbon were investigated. Water vapor adsorption experiments reveal that both activated carbons showed hydrophobic surface characteristics. Adsorption experiments reveal that the prepared activated carbon possessed comparable phenol adsorption capacity as the commercial one but clearly larger adsorption capacity of two reactive dyes, Black 5 and Red 31. It was ascertained that the prepared activated carbon exhibited less irreversible adsorption of phenol and the two dyes than its commercial counterpart. Moreover, ethanol regeneration efficiency of the prepared AC saturated with either dye was higher than that of the commercial AC. Because of its superior liquid-phase adsorption-desorption characteristics as well as higher ethanol regeneration efficiency, the prepared activated carbon is more suitable for wastewater treatment, especially for adsorbing similarly bulky adsorbates. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.watres.2004.12.044

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC CHEMICAL ENG JAPAN  

Activated carbons were prepared from LFG (wastes generated during Lactic acid Fermentation of kitchen Garbage). Activated carbons were prepared by conventional steam activation and via the acid treatment prior to the steam activation. Porous properties of the prepared activated carbons were evaluated from nitrogen adsorption isotherms at 77 K. Activated carbons prepared by steam activation from LFG had much more mesopores than a commercial activated carbon, and had unique broad-shaped pore size distributions. It was evident from the ultimate analysis at each preparation stage of the carbons that the activated carbons prepared from LFG contain much nitrogen as carbonaceous materials. It was found that the burnoff of nitrogen during steam activation of LFG contributes to the formation of unique pore size distributions of the activated carbons. Activated carbons prepared via the acid treatment had not only more mesopores but also more micropores than the commercial activated carbon. It was suggested that LFG was useful as a resource for practical activated carbons, especially, for mesoporous activated carbons. It was also beneficial to apply the acid treatment to improve the porous properties of the prepared activated carbons.

DOI： 10.1252/jcej.37.889

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Activated carbons were produced from several solid wastes, namely, waste PET, waste tires, refuse derived fuel and wastes generated during lactic acid fermentation from garbage. Activated carbons having various pore size distributions were obtained by the conventional steam-activation method and via the pre-treatment method (i.e., mixture of raw materials with a metal salt, carbonization and acid treatment prior to steam-activation) that was proposed by the authors. The liquid-phase adsorption characteristics of organic compounds from aqueous solution on the activated carbons were determined to confirm the applicability of these carbons, where phenol and a reactive dye, Black5, were employed as representative adsorbates. The hydrophobic surface of the carbons prepared was also confirmed by water vapor adsorption. The characteristics of a typical commercial activated carbon were also measured and compared. It was found that the activated carbons with plentiful mesopores prepared from PET and waste tires had quite high adsorption capacity for large molecules. Therefore they are useful for wastewater treatment, especially, for removal of bulky adsorbates. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.watres.2004.01.002

Web of Science

PubMed

記述言語：英語   出版者・発行元：公益社団法人 化学工学会  

Activated carbons were prepared from various food wastes, such as kitchen garbage, lactic acid fermentation residuals and saccharification residuals, by steam-activation of carbonized samples. The food wastes were carbonized at 773 K in inert atmosphere and the carbonized samples were activated by steam. Activated carbons, with enough BET surface areas compared with a commercial activated carbon, were successfully prepared. The effect of the heating rates at the carbonization stage on the porous properties of the resultant activated carbons was investigated by using nitrogen adsorption-desorption method. Activated carbons prepared at a slow heating rate showed high mesoporosity compared with the carbons prepared at a fast heating rate. Moreover, the carbonized wastes were also treated by HCl prior to the steam activation in order to improve the mesoporosity of activated carbons. It was found that the pores of the carbons developed by using the pre-treatment method in the region of the pore radii around 2 nm. The surface hydrophobicity of the activated carbons was also investigated by water vapor adsorption. The liquid-phase adsorption properties of phenol, bisphenol-A, and dye (Black-5) on the obtained activated carbons were examined through the long-period adsorption tests. Some of the activated carbons prepared from saccharification residuals showed higher adsorption capacities for phenol and Black-5 than the commercial carbon.

DOI： 10.11491/apcche.2004.0.453.0

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Adsorption of phenol and two organic dyes, Black 5 and Red 31, from aqueous solution on mesoporous activated carbon prepared from waste tire was carried out and, for comparison, an imported commercial activated carbon was also investigated. Phenol adsorption capacity of the prepared activated carbon was nearly equal to that of the commercial activated carbon because the micropore volumes of both carbons are almost the same. In contrast, the prepared activated carbon showed definitely higher adsorption capacities of both representative organic dyes because it had larger mesopore volume. It can be concluded that mesoporosity in the activated carbon prepared from waste tire makes it more suitable for removal of bulky molecular adsorbates from wastewater than the commercial activated carbon. © 2003, JAPAN MACRO-ENGINEERS SOCIETY. All rights reserved.

DOI： 10.11286/jmr1988.16.109

Scopus

記述言語：日本語   出版者・発行元：公益社団法人 化学工学会  

DOI： 10.11491/scej.2003f.0.496.0

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Activated carbons were produced from waste tires and their characteristics were investigated. Rubber separated from waste tires was first carbonized at 500 degreesC in N-2 atmosphere. Next, the obtained chars were activated with steam at 850 T. As a result, fairly mesoporous activated carbons with mesopore volumes and BET surface areas up to 1.09 cm(3)/g and 737 m(2)/g, respectively, were obtained. To further improve the porous properties of the activated carbons, the char was treated with 1 M HCl at room temperature for I day prior to steam activation. This treatment increased mesopore volumes and BET surface areas of the activated carbons up to 1.62 cm(3)/g and 1119 m(2)/g, respectively. Furthermore, adsorption characteristics of phenol and a dye, Black 5, on the activated carbon prepared via acid treatment were compared with those of a commercial activated carbon in the liquid phase. Although the prepared carbon had a larger micropore volume than the commercial carbon, it showed a slightly lower phenol adsorption capacity. On the other hand, the prepared carbon showed an obviously larger dye adsorption capacity than the commercial carbon, because of its larger mesopore volume. (C) 2003 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0008-6223(02)00267-1

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Activated carbons were prepared from carbonized PET by steam activation via pretreatment by mixing PET with a metal salt [Ca(NO3)(2).4H(2)O, Ca(OH)(2),CaCO3. ZnO, and AINH(4)(SO4)(2).12H(2)O], and with acid treatment after carbonization. The porous properties of the activated carbons were determined by the nitrogen adsorption method. The adsorption isotherms of CO2, C2H6, nC(4)H(10) and iC(4)H(10) at 298 K on the prepared activated carbons were measured to determine practical applications and to obtain a better understanding of the porous structure of the prepared carbons. Steam-activated carbons via pretreatment have a larger mesoporosity than carbons with no pretreatment. The metal salt used in the pretreatment for steam activation has no influence on the microporous structure. but it does influence the mesoporous structure of the prepared carbons. Activated carbons prepared via pretreatment show a large adsorption capacity for nC(4)H(10) and iC(4)H(10). These carbons are suitable as adsorbents for canisters, etc. Application of the potential theory to adsorption data for the prepared carbons suggests that the pretreatment contributes to the formation of pores larger than 0.50 nm at high burnoff. (C) 2002 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0008-6223(02)00404-9

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：KLUWER ACADEMIC PUBL  

Activated carbons were prepared from a carbonized RDF (cRDF) by steam-activation. The cRDF was obtained by carbonizing the RDF at 773 K. Different conditions of heating rate at carbonization were selected. The cRDF was also treated by nitric acid (HNO3) or hydrogen chloride (HCl) prior to the steam activation. Porous properties of the carbons prepared were determined by the nitrogen adsorption method, and the effects of the carbonizing condition and the acid treatment on the properties were elucidated. The hydrophobic surface of the carbons prepared was also confirmed by water vapor adsorption. It was found that the carbons prepared from the RDF were effective for a practical use.

DOI： 10.1023/A:1014395520344

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

A refuse derived fuel (RDF) was carbonized by partial combustion at 623 K and the carbonized RDF (cRDF) was steam-activated at 1123 K. The cRDF was also treated by 3.3 or 5.2 N nitric acid at a boiling temperature for 3 h prior to the steam-activation. Porous properties of the activated carbons prepared were determined by the nitrogen adsorption method. The porous structure of the carbon prepared without the pretreatment of nitric acid was not so developed as a commercial carbon for dioxin adsorption. On the other hand, the carbons prepared via the nitric acid treatment had BET surface areas of 515 and 828 m(2)/g and more mesopore volumes than the commercial carbon. During the acid treatment, the ash dissolution from cRDFs to nitric acid was observed and resulted in the formation of activation sites for developing mesopores. Hence, the carbons prepared could be used to remove dioxins from the incinerators. (C) 2000 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0008-6223(99)00208-0

Web of Science

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：WORLD SCIENTIFIC PUBL CO PTE LTD  

The method of preparing mesoporous activated carbons useful for the adsorption of large molecules is desirable. The development of mesoporosity of activated carbons using catalytic effects of metal compounds has been previously reported. However, a non catalytic activation method which produces pores whose radii range between 2 similar to 10 nm has not been reported as far as we are aware. The objective of present work is to propose a novel pre-treatment method for steam activation without gasification catalyst to improve the mesoporosity of activated carbons. In this article a calcium compound was mixed with raw material(PET), the samples were carbonized, and an acid treatment was then performed. We can completely wash the calcium compound out of the carbons by the acid treatment. After this pre-treatment the carbon was activated by steam. Although the catalytic activation was not expected, we can prepare activated carbons that have large mesoporosity.

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

DOI： 10.1016/S0008-6223(99)00162-1

Web of Science

記述言語：英語   著書種別：学術書

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