Acid casein was hydrolyzed by protease M from Amano Pharmaceutical Co., Ltd. in a continuous Vortex Flow Filtration System. Permeate was composed of many peptides having molecular weight of 300-600 regardless of operating time and the concentration ratio of substrate to enzyme (S/E).
For the reaction in this system following the Michaelis-Menten's Model, we obtained Michaelis constant of 2.94% and maximum reaction rate of 33.56%·h^-1 Permeate flux increased with filtration pressure. However, a continuous reduction in the flux was observed throughout the high pressure run. High substrate conversion of 0.85 was obtained by low pressure, namely low permeate flux, of 35 kPa. This system yielded the maximum permeate flux, when operated under S/E=3.00%/1.00% and Taylor number of 678 at 1500 rpm. High productivity was obtained under S/E =3.00%/0.25%.

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On the soy protein isolate heated prior to freeze-drying, changing to gel from protein paste during cold storage were already reported by the author. In this paper, effects of saccharides, ethylene glycol and lipids as food additives on gelation of the heated soy protein isolate during cold storage were investigated. The gel strength of the cold-gels were decreased by addition of sucrose, but were not affected by addition of wheat starch. By addition of ethylene glycol, the gel strength and strain of the gels were decreased, and a gel was not obtained in 10% concentration of ethylene glycol. In the case of lipids, the effects of soybean oil and soybean lecithin on gelation were different. The gel treated with 2.5% of soybean oil was decreased about 20% of gel strength and 10% of strain compared to the control gel without soybean oil. On the other hand, the gel strength and strain of the gels treated with soybean lecithin were linearly decreased in proportion to increase of the concentration, and a gel was not obtained in 10% concentration of soybean lecithin such as glycol. Based on the above-mentioned results, it were suggested that the prevention on gelation of heated soy protein isolates during cold storage were caused by the strong affinity of sucrose with protein molecules, and by the hydrophobicity of ethylene glycol and soybean lecithin.

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Taste-related components such as sugars, organic acids and free amino acids in sweet corn kernels were determined. The samples were commercial four sweetness-enhanced cultivars available in current markets of fresh vegetables including yellow, white and bicolor kernel types. These new cultivars showed higher water contents in kernels at harvesting maturity than honey-bantam types which was previous major cultivars in Japan. The cooked kernels of the four cultivars exhibited a good taste in addition to juicy endosperms and soft pericarps. Sucrose was a dominant sugar and its accumulation (8.44-9.98 g/100 gFW) of the four cultivars was higher than those of the old types of honey-bantams. On the other hand, contents of glucose and fructose (0.5-1.0 g/100 g) in new cultivars were lower than those in old types. Starch including phytoglycans (2.4-4.3 g/100 g fresh weight) was present in the kernels corresponding to 25-50% of sucrose content. Activities of ADP-glucose pyrophosphorylase, a key enzyme of starch synthesis, were much lower in four cultivars than in normal corns. This was one of the typical properties of super sweet cultivars, and was consistent with low starch and high sucrose accumulations in kernels of those cultivars. However, no relationship was observed in four cultivars between the enzyme activity and starch (or sucrose) content. The levels of total free amino acids, glutamic acid and alanine was 300-400, 70-120 and 80-110 mg/100 gFW, respectively. Since pH of boiled kernel was estimated to be 7.1±0.2 in all four cultivars, glutamic acid would be present as mono potassium salt having umami-taste. The most abundant organic acid was malic acid followed by α-ketoglutaric acid, citric acid and succinic acid. Although the total contents were high (ca. 0.3 g/100 gFW), they would not affect sour-taste. There were no differences in the amounts of sugars, organic acids and free amino acids except sucrose synthase activities between white kernels and yellow kernels of the same ears in a bicolor kernel type.

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Changes in the surface color or baking color of white bread have been measured during baking processes under various oven temperatures ranging 140-300°C, using the samples made by the same manner of a sponge-dough method. The results showed that a certain relationship existed among the measured values of lightness, chromaticity and hue which expressed the baking color, and the values changed along a route termed as the characteristic color development curve in the 3 dimensional space of the Hunter notation system. The baking color developed with the increases in both the oven temperature and the baking loss ratio which was defined as the percentage of the mass of a dough lost during baking to the initial. It was also found that the amount of heat added to the dough by radiation had a correlation with the change in the lightness of the baking color. A heating operation factor was newly defined and introduced as a parameter to assess the heating condition from both the surface temperatures of the heat source and the dough. The factor has provided a linear relationship with the lightness of the baking color. A new method capable of predicting the characteristic color development curve was presented from the heating operation factor by utilizing these relationship.

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An apparatus for determination of the conductance of liquid foodstuffs without using electrodes, and consequently, without electrochemical influence of the electrodes has been developed. It comprises a radio-frequency resonant circuit, a solenoid coil for a measuring cell and a digital multimeter. The resonance magnitude (Ir) of the circuit, which reflects the electromagnetic loss of conductive materials put into the cell, was used for the index of specific conductance (κ) of the liquid foodstuffs. Using the aqueous solutions of NaC1 with various concentrations, relationship between κ and Ir at the resonance frequency of 10, 15 and 20 MHz was investigated. As the result, the minimum Ir and the maximum one in the Ir-κ curve were found at approximately 10-1 and 10 mS/cm, respectively. In addition, Ir-κ curves obtained from the solutions of KC1, NaOH, CuSO4 and citric acid were the same as that of the NaC1 solution. On the other hand, it was found that Ir was slightly decreased because of the presence of dielectric liquids such as ethanol, methanol or glycerol in the cell. Subsequently, when κ of uncertain samples were determined using the working curve predetermined, they were determined in the error of 4% on the average ranging from 10-2 to 102 mS/cm.

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W/O Emulsions were prepared from food ingredients by using hydrophobic microporous glass membranes. We investigated conditions for preparation of a monodispersed emulsion by this technology, and a monodispersed emulsion could be prepared by selecting appropriate operating conditions ; the concentrations of emulsifiers and salts, the circulating velocity of a continuous phase, and the permeant pressure of a dispersion phase. The average dispersed droplet diameter of the emulsions was about seven-times greater than the average pore diameter of the membrane, under the conditions using corn oil for a continuous phase. But by changing viscosity of the continuous phase, the average dispersed droplet diameter of the emulsions was varied. The higher the viscosity was, the larger the produced droplet was. In this membrane emulsification system the dispersion phase flux is too low. In order to make this system practical for large-scale application, it is necessary to increase the dispersion phase flux ; the preparation rate of monodispersed emulsions.

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Effects of vegetable juice (42 species) and fruit juice (11 species) on the amount of N-nitoroso-dimethylamine formed by the reaction betweendimethylamine and sodium nitrite were in-vestigated. Vegetable and fruit juices were added to the reaction mixture of dimethylamine and sodium nitrite, and then the formation of N-nitrosodimethylamine was measured by HPLC analysis. Vegetable juices moderately in-hibited the formation of N-nitrosodimethyla-mine, but lemon juice greatly did. Inhibition ratios of the formation were 34.2, 45.7 and 54.2% at the additive amounts of 50, 100 and 200 μl of lemon juice, respectively. F1 and F2 superna-tant fractions separated from lemon juice by ultra-centrifugation inhibited the formation of N-nitrosodimethylamine by 64%, while dialyzed F2 solution inhibited the formation only by 18.8%. The ascorbic acid content in the dialyzed solution was as little as 0.2 mg/100 ml. Inhibitory ratios of the formation of N-nitro-sodimethylamine by the heated lemon juice were 65.6, 64.2, 71.6 and 72.1% at the heating time of 0.5, 15 and 30min, respectively, despite the gradual decrease in the ascorbic acid content from 44.0mg/100ml to 37.4 mg/100ml during 30min heat-ing. Inhibition ratio of the formation of N-nitrosodimethylamine was 0.6% by a solution which contained the same amount of ascorbic acid as lemon juice. These findings suggest that some inhibition factors other than ascorbic acid present in lemon juice and moreover, other inhibition substances are formed by heating.

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Fifty percent (w/w) solutions of whole egg (solid content 27.0±0.1%), commercial egg yolk (solid content 43.0±0.1%) and pure egg yolk (solid content above 49.0%) were prepared from fresh hen's eggs. Dynamic viscoelasticity of the solutions was measured at various pHs (4-12) and NaCl concentrations (free, 5 and 10%). Whole egg solution showed low dynamic viscoelasticity in all conditions employed. Dynamic viscoelasticity of commercial and pure egg yolk solutions increased slowly with time at pH4 and 12, indicating that certain structures were formed in solutions under given conditions. At pH4, dynamic viscoelasticity of commercial and pure egg yolk increased largely with increasing NaCl concentration. Although similar phenomena were observed at pH12, judging from their tanδ (loss modulus/storage modulus) values, we concluded that the gel like substances formed were more elastic at pH4.

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Freeze concentration is considered to be useful to maintain volatile and/or heat labile constituents and applied to concentration of coffee and fruit juice. It is important for freeze concentration to form bigger ice crystals. So we have tried to form bigger ice crystals by controlling the temperature difference between a sample solution and a coolant by using 13% aqueous ethanol. Smaller temperature differences between the sample and the coolant resulted in bigger ice crystals in crystallization process. Loss of samples decreased with an decrease in temperature differences, however, processing time for ice formation was increased. It was found to be the most suitable that the temperature difference between the sample and the coolant was kept about 0.4°C.

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Effects of gluten (G) to flour (F) ratios of gluten-dough on the specific volumes and honey-comb structure of "Yakifu" were studied. Among the G/F ratios studied, 500/300 gave the biggest specific volume. When wheat starch (S) was submitted for flour, the biggest specific volume was attained at G/S ratio of 450/350, although the value was much smaller. At G/F ratio of 600/200 or 550/250, only insufficient gluten-dough could be formed, suggesting the ratio of flour was too small to form uniform structure. When defrosted gluten was baked, it gave vacant structure with glassnized membrane. This implied the important role of starch in forming honey-comb structure of expanded products. Therefore, gluten-dough needs (1) to be formed well, (2) to containe optimum amount of protein, (3) to contain optimum amount of starch and (4) to involve optimum amount of water.

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The kinematic viscosity and density of six different liquid foods (milk, dry milk solution, skim milk, coffee, orange juice and apple juice) of concentrations between 5% and 40% (w/w) were measured at temperatures between 0°C and 60°C with an Ubbelohde type viscometer and a pycnometer, respectively. The solution viscosity calculated from its kinematic viscosity and density was correlated to temperature by using Andrade's equation. On the basis of these results, the effects of concentration and temperature changes on the viscosity were investigated, and the results suggested a quadratic relationship between the logarithm of viscosity and concentration. Therefore, a new experimental equation with six parameters relating temperature and concentration to the viscosity was developed. These parameters were determined by the least-squares method, and the measured results agreed well with the results calculated from the new experimental equation. Moreover, the kinematic viscosity could be written as a function of both temperature and concentration.

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