The measurement of sulfhydryl (SH) groups in soymilk is very important, because they are closely related to the firmness of tofu-gel. However, soymilk is not transparent and therefore the determination of its SH groups by spectrophotometric method is quite difficult. The present paper deals with the spectrophotometric method, by which the SH groups in soymilk can be determined directly and easily, using 2, 2'-dithiobis-(5-nitropyridine) (DTNP). First, the effect of perchloric acid (deproteinizing agent) on 5-nitro-2-thiopyridone (NTP), the reaction products between DTNP and SH groups, was investigated. As a result, NTP was stable in 5% perchloric acid and its peak of the absorption shifted from 386nm to 376nm accompaning with the increase of the absorption intensity. On the basis of these facts, we developed a new method to determine the SH groups in a turbid solution, such as soymilk. Using this method, the changes of the SH groups in soymilk during a heating were examined. The result showed that the SH content in soymilk increased during the first 2 or 3min by the heating at 100°C.

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To study the effects of properties of wheat flour on its functionality, fat-binding capacityand baking quality were investigated using the flour of Canadian western No.1 (1CW) wheat.Gluten from 1CW wheat bound more triglycerides in hydrogenated rapeseed oil, hydrogenated fish oil (mp 43°C) and palm oil than in other oils. The bound lipid contained more C_18:0 and C_18:0 fatty acids than the original lipid. Bread baked using hydrogenated rapeseedoil, hydrogenated fish oil (mp 43°C) and palm oil possessed higher loaf volume. Loafvolume increase of each bread lineally correlated to fat-binding capacity of 1 CW-gluten, butnegatively correlated to the linolenic acid content of each lipid.

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Globin was prepared from porcine hemoglobin according to the method of TYBORet al. Succinyation of globin was carried out using succinic anhydride at pH 8.0-9.0 and some properties of the resulting succinylated globin were investigated. (1) Globin was soluble in water below pH 3.0, but not suffciently soluble at around pH 8.0. Succinylated globin was highly soluble above pH 6.0, though it was slightly so1uble at pH 4.0. (2) Fractional precipitation of globin and succinylated globin was carried out using ammonium sulfate. Globin (pH 2.0) and succinylated globin (pH 7.0) precipitated at 0.1- and 0.4-saturation, respectively. (3) The foaming tests of these protein solution were performed with a reciprocal shaker. The foamability of succinylated globin was superior to that of globin. However, succinylated globin was inferior to globin in foam stability. (4) Asuccinylated globin solution adjusted to pH 2.0 formed jelly-like gel by heating in boiling water for 10min, , whereas gel formation of globin solutions adjusted to pH 2.0, 4.5, 7.0, 9.0 and 11.0 was not observed under similar conditions. (5) Thermocoagulation of ovalbumin was considerably inhibited by addition of globin or succinylated g1obin. The inhibitory effect was maximal when globin-ovalbumin and succinylated globin-ovalbumin were heated at pH 4.0 and pH 6.0, respectively.

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Vinegar producton from starchy materials by the surface culture is devided into three processes in principle; saccharification of starch, alcoholic and Vinegar producton from starchy materials by the surface culture is devided into three processes in principle; saccharification of starch, alcoholic and Vinegar producton from starchy materials by the surface culture is devided into three processes in principle; saccharification of starch, alcoholic and subsequent acetic acid fermentation. The optimal condition for each process is differ from each other. In the presence of more than 1% acetic acid, yeast used for sake-brewing has a low alcoholic fermentation activity. In the present paper, Saccharomycodes ludwigii was selected as an acetic acid-tolerant yeast and investigated on its application to the rice vinegar production. By using the selected yeast, both alcoholicand parallel-combined acetic acid fermentation could be continued for a long period in the surface culture. Vinegar brewing was performed in mash containing saccharified rice-bran (10% as glucose), 5 vol% precultured yeast broth and 10 vol% seed vinegar broth. A profitable vinegar brewing with more than 1% initial acetic acid concentration was achieved in a parallel-combined fermentation using the acid-toleran yeast and acetobacters.

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Protoplasts generally regenarate in a high osmotic medium. However, Bacillus subtilis is easily affected by tonicity, because its optimum water activity value is low compared with those of yeasts and fungi. The optimum tonicity was investigated using sodium succinate under the condition where amino acid markers were expressed. Casamino acids (CA), which inhibit expression of amino acid markers, were indispensable for the growth of B. subtilis in a high osmotic medium. Only when their concentration were limited below 2mg/l, the markers were able to be expressed. The formation of colonies was depressed with increasing tonicity, especially when CA concentration was limited. Regenaration occured above 0.1M in tonicity, and, its maximum was observed between 0.16M and 0.25M. Both the most suitable tonicity and regeneration ratio depended on CA concentration. It was concluded that optimum tonicity that satisfied the requisite condition was 0.2M, less than half as reported one (0.5M). Fusion frequency between histidine negative and threonine negative mutants at the above condition was 0.20% to input minority bacteria and 0.52% to minority regenerants.

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In order to elucidate the varietal difference in contents of total g1ucosinolate and 4-methylthio-3-butenyl glucosinolate (MTB-GSL) of daikon (Japanese radish) roots, 20 cultivars sown in late summer at open field for two years were subjected to analyses. The contents were determined by a col-orimetric or gas-liquid chromatographic method. The range and mean of MTB-GSL contents was 42 to 345μmo1/100g of fresh weight and 210μmol/100g of fresh weight, respectively. A coefficient of variance of the estimated values was 39%. Among the cultivars examined, the highest in total glucosinolate content contained 2.3 times higher than the lowest. The mean content of MTB-GSL was corresponded to about 80% of that of total glucosinolate. The MTB-GSL contents in 13 cultivars harvested in two different years were positively correlated between them.

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Recently new cultivars of komatsuna are grown as salad vegetable in plastic houses. The quality of komatsuna for salad and the changes of vitamin content during storage were compared with those of cultivars grown in open field with chemical fertilizer or compost. In sald-cultivar 'Misugi', glutamic acid content was higher, while ascorbic acid and sugar contents were lower compared with those of 'Maruba' and'Jonan Komachi' cultivars grown in open field. Being relatively 1ow content and rapid reduction of ascorbic acid after harvest, it was considered that chilled temperature would be particuarly suitable for storage of the cultivar for salad. The result of sensory evaluation test showed that the color and the overall evaluation of salad-cultivar were best, but the hardness was worst among three cultivars.

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A product fibrously texturized was obtained from surimi by extrusion cooking with a twin-screw extruder. Raw material called surimi (fish meat sol), in Japan, was preconditioned to lower the moisture content down to 1.5-2.0 (dry base). Conditions of the extruder in this experiment were as follows. The range of the screw speed and the barrel temperature were 150 rpm and 160-180°C, respectively. The rate of the feeder was 30kg/h. The temperature of the die was kept around 10°C by using tap water. Properties of the product obtained were examined with a microscope and a Rheometer as well as by visual observations. The product had a clear fibrous structure, whose direction was directly related to the extruding direction.

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To improve the utilization of soybean proteins in meat products, the interaction of α-actinin and soybean protein with actin was investigated by cosedimentation and viscosity experiments. Analyses of the sedimented proteins clearly demonstrated that soybean proteins can bind to F-actin filaments to some extent under neutral (7.5) or slightly acidic (5.5) pH conditions at 25°C. However, no interaction between α-actinin and soybean proteins was observed. In the presence or absence of soybean protein, no appreciable differences were obsered in the amount of α-actinin that bound to F-actin under neutral pH condition. However, the amount of α-actinin that bound to F-actin in the absence of soybean proteins under acidic pH condition. These results indicated that α-actinin and soybean protein can bind to actin filaments simultaneously. By viscometry it was confirmed that α-actinin and soybean proteins can bind to F-actin.

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Commercial Bacillus natto was cultured in the liquid media containing various aminoacids, and effect of amino acids on formation of pyrazines was examined. Of all added amino acids, L-threonine promoted formation of pyrazines in the highest yields. L-Serine, the same analogous compound to L-threonine, also yielded pyrazines to the next degree. The main product of the L-threonine-culture was 2, 5-dimethylpyrazine, and that of L-serineculture were tetramethyl and trimethylpyrazine.

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[in Japanese]

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