Effects on the physical properties of whey protein gels of the addition of powdered chitin was investigated. The results obtained are as follows. 1. With increasing the protein concentration, the values of mechanical parameters corresponding to hardness, closeness to elastic body and elasticity of whey protein gel increased but those to fracturability of the gel unchanged. 2. The values of mechanical parameters corresponding to hardness of the whey protein gel decreased by the addition of powdered chitin, which differs from the change induced by the increase of protein concentration. However, the value of mechanical parameter corresponding to closeness to elastic body increased and that to fracturability unchanged by chitin addition, which resemble the results in the case of increasing protein concentration. 3. Effect of the chitin addition on the values of mechanical parameters corresponding to elasticity of the gel was different between 30min- and 60min-heated gels: the tendency to decrease occurred in the former and the increase in the latter. The results obtained here demonstrated that the change in gel hardness of whey protein by the addition of powdered chitin is quite different from that of egg white protein. It was suggested that effects of the addition of powdered chitin on the gel properties are different depending on the kind of proteins and gelation conditions.

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Four kinds of saturated fatty acids (numbers of carbon atom were 12, 14, 16 or 18) were bound to bovine serum albumin (BSA), and the emulsifying activity index (EAI) and structural stability of the complex were investigated. Lauric or myristic acid bound BSA showed a higher EAI than the non-bound BSA. The BSA which bound fatty acids with a longer carbon chain such as palmitic or stearic acid showed lower values of EAI. The binding of fatty acids lowered the surface hydrophobicity and surface pressure of the BSA solution. This effect of the fatty acid binding was larger with a shorter carbon chain fatty acid. The results of the circular dichroism spectrum and the fluorescence spectrum analysis of the fatty acid bound BSA indicated that the effects of the fatty acids on the structural changes of the BSA molecule depended on the length of the carbon chain of fatty acids. The stability of the fatty acid bound BSA against urea denaturation, heat denaturation, and tryptic hydrolysis were at higher level, but that against peptic hydrolysis was at the same level, as compared with the non-bound BSA. The results of the present study showed that the properties of BSA such as emulsifying activity and structural stability were changed by binding of fatty acids, which suggests the possibility of improving the properties of BSA as a food material.

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A new method for determination of ethanol was developed by combining a quinone-dependent alcohol dehydrogenase reaction and self-driven coulometry and applied for determination of ethanol in food. Enzyme reaction was carried out in a mixture consisting of MacIlvaine buffer (pH 5.0), ubiquinone-0 (Q₀), quinone-dependent alcohol dehydrogenase and a sample. An aliquot of the reaction mixture was then added to the self-driven coulometric cell to determine the amount of reduced Q₀ by coulometry. In a range of 0.1 to 30% (v/v) of ethanol, the measured total charge was almost the same of the theoretical and correlated with the ethanol concentration with a correlation coefficient of 0.9997, suggesting that ethanol was measured without calibration. Ethanol concentration in twenty daily foods determined by this method were correlated with those determined by gas chromatography with correlation coefficient of 0.9991 and coefficient of variation of ten trials was below 2%. The measuring time in the self-driven coulometry was 1 to 5min. After 100 trials of addition of a sample on the carbon-felt electrode in the self-driven coulometric cell, no effect on the total charge was observed. These results indicated that ethanol in food was rapidly determined by this new method.

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A new method for determination of n-glucose, D-fructose and sucrose was developed by combining quinone-dependent dehydrogenase reactions and self-driven coulometry and applied for determination of sugars in food. Enzyme reaction was carried out in a mixture consisting of phosphate buffer (pH 6.5), ubiquinone-0 (Q₀), quinone-dependent glucose dehydrogenase or fructose dehydrogenase. An aliquot of the reaction mixture was then added to the self-driven coulometric cell to determine the amount of reduced Q₀ by coulometry. In a range of 0.1 to 6% (w/v) of D-glucose or D-fructose, the measured total charge was correlated with sugar concentration and corresponded to the theoretical total charges, suggesting that these sugars were determined without calibration. In case that glucose dehydrogenase and invertase were used, sucrose was determined. D-glucose, D-fructose and sucrose in various foods were determined by this method and the results were correlated with those determined by high-performance liquid chromatography and enzymatic method. Coefficient of variation of ten trials was about 2%. Total concentration of the three sugars was also rapidly determined and the results were correlated with the Somogyi's method (r=0.9983).

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Influence of treatment temperature, cultivars and harvest maturity on keeping the firmness of strawberries by high carbon dioxide with short term treatment was determined. (1) 'Hokowase' fruits obtained from a wholesale market or harvested at three stages (30, 70 and 100% colored) were treated with high carbon dioxide mixing gas (CO₂:O₂:N₂=20:10:70) for 24h under 1 or 20°C and stored at 1 or 20°C. The firmness of fruits treated at every stage was harder than that of untreated ones stored at each temperature. The carbon dioxide treatment was more effective in 30% colored fruits. (2) In treated 'Hoko-wase' fruits, color development was delayed, showing lower content of anthocyanin especially at 30% colored stage. There was no difference between treated fruits and untreated ones of every stages in the contents of total sugar and ascorbic acid. In treated fruits, the content of water soluble pectin (WSP) decreased and that of hexametaphosphate soluble pectin (HMP) increased after carbon dioxide treatment. The mold growth on strawberry fruits was delayed by the treatment. (3) 'Tioga' fruits harvested at mature (100% colored) stages were treated with high carbon dioxide mixing gas for 24h under 20°C, and stored at the same temperature. The firmness of treated fruits was not harder than 'Hokowase'.

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Ice cream of desired taste and good mouthfeel is produced by employing specially designed formulation and a contrived production method. On production, it is important to control a fat de-emulsification rate and distribution of fat globules, ice crystal size, air cells and unfrozen matrix. We have investigated the relationship between fat de-emulsification, and a type and the revolution number of a dasher. Ice cream consisting of vegetable fat 9.0%, M.S.N.F. 9.5% and total solids 38.0% was prepared by freezing the mix in a CREPACO continuous freezer. Conditions were varied as follows. The dasher type was 15 dasher, or 80 dasher, the mix flow rate was 65l/h and the revolution number of the dasher was 110rpm and 220rpm. The particle size distribution of fat globules was measured by a Laser diffraction particle size analyzer. The fat de-emulsification rate was determined from the difference between the particle size distribution of fat globules measured in ice cream mix and an ice cream solution prepared by diluting ice cream at 5-10°C with 5 volumes of ion exchange water. Melting resistance was examined by the meltdown method. The fat de-emulsification rate increased when a dasher of larger was employed and this resulted improved melting resistance. Also, the fat de-emulsification rate increased using a higher revolution number and this resulted in improved melting resistance. Dryness of ice cream increased when a dasher of larger volume and higher revolution number were used. The particle size distribution of fat globules changed when the fat de-emulsification rate increased i.e. fat globules of below 1.2μm in diameter decreased and, un-expectedly, the proportion of fat globules of ranging from 7 to 15μm in diameter increased.

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In order to examine the gelatinization of starches inside cotyledon cells of legumes, cells were separated from faba beans (Vicia faba L.) without gelatinizing starches inside cells and subjected to measurements of the solubility, swelling power and loss of birefringence of starches inside cells, which were heated over gelatinization temperature range, and differential scanning calorimetry of cells. When cells separated and starches isolated from faba beans were heated in water, the solubility and swelling power of starches inside cells were extremely low, compared to those of isolated starches. The loss of birefringence of starches inside cells was also low in the temperature range of 60 to 80°C. The differential scanning calorimetric thermogram of cells showed an endothermic transition with a peak temperature at about 67°C which trailed a shoulder up to about 96°C, while that of isolated starches showed a single endothermic transition. The rupture of cells in advance resulted in the disappearance of a trailed shoulder of the endotherm. From the comparison of these results with those obtained for starches inside cells of adzuki beans, reported previously, it was concluded that the gelatinization of starches inside cells of faba beans was suppressed, compared to the gelatinization of isolated starches.

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Effects of gamma-irradiation on spores of Bacillus pumilus were investigated and compared with those of heat treatment. The turbidity decrease of the suspension of irradiated spores caused by germination was slightly larger than that of untreated ones, while the turbidity of heat treated spores did not decrease greatly. Heat treatment retarded the synthesis of protein and RNA and even sublethal heat treatment (180°C, 2.5min) delayed the start of their synthesis. Irradiation did not significantly influence the start of the synthesis of protein and RNA but lowered the rate of their synthesis.

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Starches were extracted from sweet potatoes differing in stages of development, tissue zone and variety. A series of maltosaccharides produced after debranching each starch with isoamylase were analyzed using high performance anion exchange chromatography equipped with a pulsed amperometric detector. Using this method, the chain length [degree of polymerization (DP), 6-17] distributions of amylopectin molecules were characterized to evaluate the influence of genetic and physiological factors on the properties of sweet potato amylopection. No significant changes were observed in the chain length distributions of amylopectins at various stage of development. In addition, no significant differences were observed in the chain length distributions of amylopectins from different tissue zones. Therefore, it was suggested that physiological conditions have very little effect on the molecular structure of sweet potato amylopectin. Only small variations in the chain length distributions of amylopectins were observed within 31 varieties of sweet potato. The proportion of short chains in the range of DP of 6-10 ranged from 28.7% (Tokai 5) to 37.6% (Kyushu 91) within these varieties.

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Using differential solubility in 70% ethanol, the polypeptide components of the reduced and cyanoethylated glutenin from the prepared dough were fractionated into three fractions (AF-1, AF-2, and AF-3). In these fractions, AF-1 was identified as an aggregative subunit of glutenin from the results of SDS-PAGE. The sugar composition of carbohydrates in AF-1 was determined by gas chromatography, which revealed the presence of arabinose, xylose, and mannose as well as glucose and galactose. The presence of arabinose and xylose as a major sugar component in AF-1 suggested a significant role for pentosan (hemicellulose component) in aggregation. However, the differences between the sugar components of AF-1 fractionated from fermented and unfermented dough were almost negligible except for decreasing the amount of glucose.

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