Amorphous materials, comprised of sugar molecules, exhibit high hygroscopicity and the sorbed water exerts a major influence on physical stability of the matrix. To date, the water sorption behavior of amorphous sugars has been extensively investigated. However, most studies of the behavior of water, when sorbed to an amorphous sugar matrix, have implicitly assumed that all of the sorbed water molecules are in a single state: It is naturally expected that the random allocation and configuration of sugar molecules would result in heterogeneity of states for the sorbed water. Recently, we demonstrated the heterogeneity of state and functionality of water sorbed in amorphous sugar matrices by combining a Fourier transform IR spectroscopy and Fourier self-deconvolution technique; The sorbed water molecules were classified into five states, and the three of them mainly served to lower the glass transition temperature of an amorphous sugar matrix while the other two appeared to be independent of physical properties of the matrix.
The effect of the water sorption for the crystallization of disaccharides in corn starch-disaccharide amorphous mixtures was investigated. The water sorption isotherms at 25℃ of freeze-dried amorphous corn starch with and without the addition of disaccharide (sucrose, lactose, and trehalose) were measured by a conventional descicator method, and analysed according to a dual mode sorption model. The crystallization of disaccharide was evaluated by using the X-ray diffractometry. Glass transition temperature (Tg) was determined by using differential scanning calorimetry (DSC). The water sorption ability of corn starch-disaccharides amorphous mixtures were lower than amorphous corn starch without disaccharide at below aw＝0.35. Especially, the water sorption ability of the mixture with sucrose was the lowest. However, at a high aw region (aw＞0.75), the water sorption ability of the mixture with sucrose alternated the highest. The result by the X-ray diffractometry elucidated that the crystallization of lactose and trehalose in the mixtures occurred at aw＝0.75 but the sucrose did not. That is, it is harder of sucrose to crystallize in the mixture even at high aw. These results implied that the interaction inter the sucrose, starch molecules and water molecules is different from other disaccharides.
Thermal denaturation of protein in cured pork meat that contains different amounts of sodium chloride (NaCl) was analyzed using differential scanning calorimetry (DSC). Three endothermic peaks that correspond to myosin, sarcoplasmic proteins and collagen, and actin were affected by the curing process. Denaturation of actin occurred at a lower temperature in line with the increase in the amount of NaCl in the meat sample. In addition, the endothermic peak of myosin disappeared when the NaCl level exceeded 20 mg/g. The influence of the NaCl level on the kinetic constant of protein denaturation and temperature dependency were studied using the DSC dynamic method. As the level of NaCl in the meat increased, the thermal-denaturation rate constant of each protein increased. Especially, the rate constant for actin increased remarkably, e.g. rate constant at 70℃ increased from 0.1 min−1(2 mg/g of NaCl) to 1.75 min−1(40 mg/g of NaCl). Using both the averaged activation energy of each protein (Myosin: 2.41×102 kJ/mol, Sarcoplasmic proteins and Collagen: 3.26×102 kJ/mol, Actin: 2.50×102 kJ/mol) and the empirical equations that represent NaCl dependency of pre-exponential factor in Arrhenius equation, denaturation rate constant at arbitrary temperature was able to be obtained.
The effect of particle size reduction on the pasting properties of rice, wheat, corn (maize), potato, sweet potato, and cassava starches was elucidated. Before pulverizing, the mean particle size and the pasting properties of the starches differed by crop. With increased pulverizing, the mean particle size decreased in all flours (to＜10μm) and the pasting properties converged. Commercial flours containing the larger starch granules have the higher starch damage after pulverization.
This study aimed to investigate the carbonization rate and energy for carbonization of granular waste biomass by superheated steam (SHS) treatment combined with far-infrared heating (FIH) (SHS＋FIH). Cooked and dried rice grains were used as a sample. Carbonization temperatures ranging from 503 to 578K were adjusted by combining SHS temperatures with FIH temperatures. Carbonization rate determined by changes of sample weight during carbonization treatment depended on the carbonization temperature and obeyed the Arrhenius equation. The energy requirement per unit mass of carbonized product, Qc, decreased as carbonization temperature increased. In the combined treatment of SHS＋FIH, the apparatus heated easily and rapidly to the carbonization temperature only when 1/6～1/7 of heat flow (thermal energy rate) to generate SHS was supplied to the FIH heater, and the warm-up time of the apparatus decreased to about half that of the treatment with SHS alone. Results of the increase in productivity of the carbonized product and decrease in carbonization energy as carbonization temperature increased confirmed the energetic advantages of the combined treatment of SHS＋FIH. At carbonization temperatures higher than 623K, it is estimated that the combustion heat of the carbonized product would be several times higher than the carbonization energy.