The viscoelasticities of concentrated solutions of yeast protein, soybean protein and casein were investigated in order to clarity the fundamental rheological properties and the applicability to the theory of linear viscoelasticity. The results obtained were as follows: 1) The viscoelastic behavior of each protein sample was found to be applicable to "method of reduced variables", and the master curves of storage modulus (G') were obtained over a wide range of time scale. 2) The master curves were characteristic in each protein, resembling to each other among the same protein source. 3) Yeast protein and soybean protein were apt to form gel-like structure, suggesting the formation of cross-linkage. On the other hand, casein was acting very similarly to uncross-linked amorphous polymers. Their differences were especially apparent at terminal zone.

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Changes in contents of saccharides, enzyme activities related to starch-degradation and metabolism of sucrose during the process of after-ripening in chilling-injured banana fruit were compared with those of healthy fruit. In the chilling-injured fruit which was stored at 6°C for 9 days, are markable decrease in starch contents and increase in sugar contents (glucose, fructose sucrose and maltose) were observed on the 5th to 7th day of storage at 20°C accompanied with the softenning of pulp. During this after-ripening process, remarkable increases were observed in activities of α-amylase, β-amylase, apparent starch phosphorylase, maltase, sucrose synthetase and invertase. When the green-mature fruit was stored at 20°C, a similar changes in sugar contents, starch contents, and enzyme activities related to metabolism of saccharides occurred on the 6th to 8th day of the storage. These findings indicate that there are no significant differences in amylolysis (amylo-phosphorolysis and starch hydrolysis) during the process of after-ripening between chilling-injured fruit and healthy fruit, although our earlier findings suggested occurrence of gluconeogenesis during after-ripening in chilling-injured fruit.

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Hydrolyzating ratio of soybean protein by 10 kinds of protease preparation ranged from 5 to 34%. On the comparison of antioxidative activities among these hydrolyzates, the most effective antioxidative activity was recoganized in 6 to 9% of hydrolyzing ratio. In the case of eggwhite albumin hydrolyzates by 11 kinds of protease preparation, although hydrolyzing ratio did not influence on antioxidative activity of the hydrolyzate, synergistic effect of the hydrolyzate with d-δ-tocopherol was observed. Soybean protein hydrolyzates by 8 kinds of protease preparation were fractionated by gel-filtration with Sephadex G-25. In the comparison of antioxidative activity of each fraction, antioxidative activity patterns of hydrolyzates were classified into three types and the strongest antioxidative activity was found in the near fractions where the vitamin B₁₂ employed as a marker was eluted. In the same manner, hydrolyzates of milk casein, egg-white albumin and gelatin by protease were fractionated by gel-filtration with Sephadex G-25. The most effective antioxidative activity in all hydrolyzates was recognized in the peptides with a little higher molecular weight than that of vitamin B₁₂.

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Both miso (soybean fermented food in Japan) and soybean sauce showed antioxidative activity and their effects were proportional to the nitrogen content and coloring degree, respectively. Correlation coefficients between antioxidative activity and nitrogen content of miso and soybean sauce were 0.811 and 0.823 and the coefficients between antioxidative activity and coloring degree were 0.882 and 0.533, respectively. Although the hydrolyzing ratio of protein in miso is in the range from 12 to 30%, the lower was the ratio, the stronger antioxidative activity was detected. Copper and iron in soybean sance showed prooxidative activity on linoleic acid. Thus, correlation coefficient between antioxidative activity and copper or iron contents of soybean sauce was -0.624 and -0.601, respectively.

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The application of microwave dielectric heating to spray drying of mandarin orange juice was investigated by mobile miner type spray dryer of Niro Atomizer Company connected with a microwave generator with the frequency of 2450 MHz. The improvement of the yield of dryed powder was demonstrated by microwave heating. In drying of mandarin orange juice, sticking on the wall of dryer was observed by melting of dryed powder at higher drying temperature. On the contrary, adhesion on the wall resulted by insufficient drying was observed at lower drying temperature. It was concluded that the optimal drying conditions were critically in a narrow range, and that in this particular study, the optimal outlet temperature of hot air was determined to be around 55°C for mandarin orange juce and 70°C for the juice added with 3% of dextrin. Drying rate of mandarin orange juice rapidly decreased at less than 100% moisture content (dry basis), and microwave absorption efficiency for orange juice compared with that for pure water decreased also rapidly at 70-80% moisture content (dry basis). From this facts, it was suggested that concentrated quick microwave heating at about 100% moisture content should be effective for increasing the yield of dryed powder.

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Egg yolk was fractionated into two lipoproten-containing fractions-low density lipoprotein (LDL) and high density lipoprotein (HDL)-by using ultracentrifugation. LDL contained 85.6% of lipid, 2.4% of total nitrogen, 1.0% of total phosphorus and 0.1% of total sulfur. HDL contained 27.3% of lipid, 10.9% of total nitrogen, 1.8% of total phosphorus and 0.6% of total sulfur. LDL showed only one band by protein stain in cellulose acetate membrane electrophoresis. This band was also stained by a oil red staining and schiff reaction of periodic acid. HDL was separated into five bands, one of which was stained by a oil red staining. Lipids extracted with chloroform-methanol (2:1) from these two lipoproteins differed in content and composition. The composition of tryglycerides, lecithin and cephalin was main difference of these lipeproteins. Nimety three point nine percent of non polar lipids and 27.0% of polar lipids were recovered with heptane from the chloroform-methanol extracts of LDL. On the other hand, 67.9% of non polar lipids and 18.0% of polar lipids of chloroform-methanol extracts of HDL were transferred to heptane fraction. Cephalin was more readily extracted with heptane than other phospholipids in LDL and HDL. Tryglyceride, lecithin and cephalin existed in chloroform-methanol extracts of LDL and HDL showed similar fatty acid composition. Heptane extracts of LDL and HDL contained larger amounts of C_16:0 fatty acid than that of the chloroform-methanol extracts.

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The characteristics of the phosphatase activity of dried soup mixes and their raw materials were examined and the stability of 5'-ribonucleotides was studied. The results are as follows. (1) Some of spices, such as red pepper, thyme and sage, had fairly high phosphatase activity, which affected the stability of 5'-ribonucleotides. Their phosphatase was perfectly inactivated by heating at 80°C for 10min. (2) Thickening agents with certain treatments such as roller skim milk powder and starches, had no phosphatase activity, but those from natural sources such as full fat soy flour, soft wheat flour and corn flour had high phosphatase activity. The stability of 5'-ribonucleotides depended on the moisture level of samples which had the phosphatase activity and it is certain that 5'-ribonucleotides were decomposed when samples absorbed more moisture than certain amounts. (3) 5'-Ribonucleotides were very stable in the dried soup mix, when the raw materials used had no phosphatase activity. Thus, it is desirable to use the raw materials which received heat-treatments or purification. If the raw materials with phosphatase activity are used, the moisture level of the dried soup mix should be kept below 5-8% to maintain the stability of 5'-ribonucleotides.

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The influences of processing condition in meat products, particularly sausage, on the stability of added 5'-ribonucleotides were studied. The results are as follows. (1) In case of sausage without smoking, the internal temperature of sausage was raised so rapidly in short time that added 5'-ribonucleotides were very stable. (2) On the contrary, in case of sausage with smoking, though the stability of added 5'-ribonucleotides depended on the smoking condition, they were fairly decomposed even in the case of small casing such as wiener and they were moreover decomposed in the case of larger casing such as frankfurter and bologna. (3) There methods, that is, (a) coating 5'-ribonucleotides with hydrogenated vegetable oil, (b) adding polyphosphate to sausage, and (c) adding glucono-delta-lactone and smoking at high temperature for short time, were studied to keep added 5'-ribonucleotides stable in smoking process. All these methods were found to be effective.

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"Nozawanazuke" frozen at -40°C to be stored at either -5°C or -20°C was microscopically investigated. More damages in parenchyma tissue were observed in the samples stored at -20°C than in the samples stored at -5°C. Obviously large ice crystal formation was found in the former. These phenomena became noticeable in about 7 days storage of the samples of 3.3% salinity, and in about 35 days storage of the samples of 5.9% salinity. Furthermore, the freezing rate in the initial freezing process was found to be much more important factor affecting on the size of ice crystal in preservation of the frozen "Nozawanazuke".

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