Polyphenol oxidase (PPO) of each fruit was added to each of acetone soluble fractions (AFs) prepared from various fruits, and the extent of browning of the reaction mixtures was determined. When the AFs from three fruits ('Delaware' grape, 'Sordum' plum, 'Hakuho' peach), containing the same amount of polyphenol, were added to PPO of each fruit, the AF of grape markedly inhibited PPO activity of all three kinds of fruit. The oxidation of the AF of peach was the strongest of the three and that of plum was intermediate. The PPO and AFs of 'Kosui' pear and 'Tsugaru' apple were also prepared by the same method as the other three fruits. Since the PPO of all five fruits had high substrate specificity for chlorogenic acid, the oxidation of chlorogenic acid was used as an index of the browning. The AF of grape inhibited PPO activity of peach, apple and grape, whereas the AF of plum inhibited PPO activity of peach and apple, but accelerated the PPO activity of pear, plum and grape. The AF of peach and apple was appeared to have a stimulative effect on PPO activity.

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The effects of whole egg, egg albumen or egg yolk on the lipid oxidation of cookies during baking and storage were investigated. Cookies which were prepared with linoleic acid by 40% (weight percentage to the wheat flour) were oxidized markedly during cooking and storage at 40°C for 7 days. When whole egg or egg yolk was added by 50% of the weight of the wheat flour for the preparation of cookies with linoleic acid, the lipid oxidation was suppressed entirely. The cookies containing linoleic acid were also prevented against oxidation during storage by the addition of egg albumen by 50% or whole egg or egg yolk by 25% or more. When cookies were prepared with lard not containing tocopherols by 75%, the lipids were oxidized weakly during baking and storage at 40°C for 10 days. When the cookies containing lard without tocopherols were prepared with the whole egg or egg yolk by 25% or more, the lipid oxidation was suppressed, and the cookies were also prevented against oxidation during the storage by the addition of egg albumen by 50% or whole egg or egg yolk by 25% or more, similar to the case of linoleic acid containing cookies. The cookies which were prepared with commercially available lard by 75% were not oxidized at all during baking, and also prevented against oxidation during storage at 40°C for 4 weeks. The slight lipid oxidation of the cookies after 6 weeks storage was suppressed entirely by the addition of egg albumen by 50% or the whole egg or egg yolk by 25% or more.

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Inhibitory effect of the hot water extracts prepared from various kinds of teas on the platelet aggregation induced by collagen or ADP was investigated by use of turbidimetry. A standard method used was the extraction with 40ml of boiling water for 3min on each 1g tea sample. Examination on various teas with the different manufacturing process indicated that the aggregation inhibitory effect was observed generally on any kind of tea extracts tested, though the activity differed from a strong one (e.g. Japanese green tea, the inhibition ratio is over 50%) to a weak one (e.g. Aoyagi tea, about 10%). Among the black teas, Kenya and Sri Lanka Uva teas showed strong activity, while Darjeeling tea was weak. Japanese green teas were generally effective and the activity was on the order of Sencha>Maccha>Gyokuro. Chinese semi-fermented teas gave only a weak activity. High-performance liquid chromatographic analysis on the main black and green tea extracts showed that the effective ones were rich in the content of catechins in the Japanese green teas and of theaflavin and catechins in the black teas. Among the purified samples of six catechins and three theaflavins and caffeine, (-)-epicatechin, (+)-catechin, (+)-gallocatechin, and theaflavin mono-gallate showed a marked inhibitory activity.

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The relationship between changes in stiffness of dried meat and changes in some properties of the myofibril prepared from pork during heat-drying was investigated. Solubility of myofibril prepared from the dried meat, which was purchased in a market, with 0.6M KCl (pH 7.5) or with 8M Urea and 2% SDS (pH 8.0) was measured. Shear force values of dried meat were associated with the solubility of myofibril; the higher the shear force value of dried meat was, the less the solubility of myofibril was. When sliced pork was heat-dried at 50°C, the solubility of myofibril prepared from heat-dried pork with 0.6M KCl (pH 7.5) decreased with the increase of its shear force values, and the moisture content of sliced pork during heat-drying; Ca-ATPase activity and solubility with 0.6M KCl (pH 7.5) of the myofibril prepared from the sliced pork changed according to a first order reaction rate. The order of changing rates was the rate constant of inactivation of Ca-ATPase>that of decrease in solubility>that of decrease of moisture content. This fact suggested that contractile protein started to denature in the very early period of heat-drying treatment, and then moisture of sliced pork continuously started to decrease in this heat-drying condition. From these results, we assumed that texture of the dried pork would be tender, if denaturation of contractile protein of sliced pork would be prevented during heat-drying process.

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This study was subjected to compare the qualities of food materials fried by soybean oils with different rancidity. Tofu and egg white gel without any batter were fried with the three types of soybean oils, namely fresh oil (S-0, foam extension length 27mm) and two deteriorated oils prepared by heating under air bubbling for 20 and 25 hours (S-20 and S-25, foam extension length 32 and 40mm), respectively. The quality of fried materials was evaluated by quantitative analysis of absorbed oil, measurement with a Texturometer, and histological observation. The results of this experiment indicated that the quality of the fried materials declained steadily from S-0 to S-20 with heating time, and abruptly to S-25 oil by more 5 hours heating. Soybean oil was proposed to use for frying food materials as S-0 to S-20 oil (foam extension length 32mm) in this experiment. This seems to be one of the beneficial factors for the quality control of fried food materials in food service industries.

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Heat resistance of Bacillus coagulans spores was determined for 44 strains isolated from food ingredients and spoiled canned foods to demonstrate distribution of D, decimal reduction time, and z, a temperature difference corresponding to the decimal change of the D, values. The spores were heated in a 0.01M phosphate buffer, pH 7.0, and then recovered by dextrose typtone agar. The minimum, maximum, and 95% confidential of D at 110°C were 1.1, 92, and 29-42min, respectively, and those of z were 6.8, 9.6, and 7.8-8.2°C, respetively.

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Lipoxygenase (EC 1. 13. 11. 12) from adzukibeans was partially purified and some characteristics were examined to understand the mechanism by which the stale cooked flavor was formed in stored adzukibeans. The adzukibean enzyme specifically acted on the free form of polyunsaturated fatty acids and was more labile than soybean enzyme (L-1 type). Incubation of linoleic acid with this enzyme yielded 13- to 9- hydroperoxides at a ratio of 48:52. The adzukibean enzyme, which has the optimum pH around 6.5 and is activated by calcium ion, is different from soybean (L-1 type) and rice germ enzymes in the composition of hydroperoxide isomers formed, and similar to the soybean isozyme (L-2 type), which is reported to play a main role in the development of n-hexanal in soybean flavors.

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The replacable method suitable for automatic execution of the alcohol-test which is used to estimate heat stability of raw milk, was developed. In the test heretofore in use, raw milk is mixed with the same volume of 70% v/v ethyl alcohol and the resulting mixture is observed whether it includes clots or not. The raw milk which clots is judged to be unstable for heat treatment but the one which does not clot is judged to be normal. We found that when raw milk was mixed with alcohol, the viscosity of the mixture increased depending on the extent of aggregation of casein micelles. In this study, the pressure drop which took place while the mixture flowed through a narrow tube with constant velosity was measured as an index of viscosity. In order to search the optimum measuring condition, samples prepared from raw milk with stepwise addition of lactic acid or calcium chloride solution were used as a measure of unstability. The optimum condition for estimation of the viscosity which refers to the unstability of raw milk was obtained. As for the measuring temperature, a maximum difference of viscosity among samples with different unstabilities was obtained at 25°C. The best mixing ratio of milk to 70% alcohol was 2 to 3 in volume. Under these conditions, fresh raw milk samples and the raw milk samples preserved for 3 days at 5°C were tested. The viscosity measured had high correlation with titratable acidity. The values of viscosity also referred to the differences between old samples and new samples. All samples judged "+" by the conventional method had higher viscosity-values than those of all samples judged "-". Moreover, "the viscosity method" can distinguish the grades of unstability. Accordingly, this method was expected to be useful as a replacable method of alcohol-test of raw milk, and to be suitable for automatic measurement.

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The rapid and simple method for the estimation of the titratable acidity of raw milk was developed. As well known, the change of pH per unit volume of titre (pH/v) becomes largest in the neighbourhood of the equivalent point, when raw milk is neutralized with alkaline solution. Therefore, it is expected that the pH value of raw milk which was measured after addition of the equivalent amount of alkaline solution will be distributed in the wider pH-range according to the titratable acidity. The pH which was measured after addition of a defined volume of alkaline solution was named as the "Shifted pH". The titration curves were drawn for all raw milk samples and those containing known amount of added lactic acid or solids-not-fat. The correlation coefficient between the "Shifted pH" of each step of titre and titratable acidity was calculated. A plot of the correlation coefficient vs. the amount of titre also had a peak around the equivalent point. Linear regression formula was obtained between titratable acidity and the "Shifted pH" which had been measured after 8ml of 0.1N NaOH were added to 50g of raw milk sample. The titratable acidity was esimated by substitution of the "Shifted pH"-value of raw milk samples in the formula. The estimated values thus obtained coincided well with the values obtained by titration. Consequently, this method is effective for the rapid and simple estimation of the titratable acidity in raw milk, and is suitable for the automatic analysis.

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Sorghum brewing is a Chinese traditional solid state fermentation, which has been carried out in three consecutive cycles in Taiwan. In order to understand the thermal properties of solid mash we measured the temperature profile of solid mash with water jacketed cylinderical fermentors. The results were analyzed with one dimensional pseudosteady heat conduction model with neglected heat convection. This model could be used for the estimation of fermentation heat of sorghum mash. In addition, it could be used to predict the optimal diameter of fermentors. Two consecutive fermentation with the cylindrical fermentors illustrates the production of 23.03kg alcohol from 100kg of sorghum grains which is generally obtained by three consective fermentation in the traditional process.

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The effect of aqueous dialyzates from some freeze-dried vegetables on the mutagenicity of Trp-P-2 toward Salmonella typhimurium TA 98 and TA 100 was examined. Each dialyzate inhibited the mutagenicity of Trp-P-2 toward TA 98 and TA 100. Especially, the dialyzates of spinach, cabbage, nigauri and eggplant had a high inhibitory activity. Compared with these dialyzates, ones of Chinese chive, chingentsuai, kinusayaendo, onion and pumpkin showed lower inhibitory effects on the mutagenicity of Trp-P-2 toward TA 98. The dialyzates prepared from leaves of eggplant, cucumber, Japanese radish, and sweet potato, and roots of spinach inhibited the mutagenicity of Trp-P-2 markedly. These dialyzates examined in this study showed no killing effect and mutagenicity on Salmonella typhimurium TA 98 and TA 100.

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The aqueous dialyzate of spinach was partially fractionated to identify the desmutagenic principles on Trp-P-2 and the mode of desmutagenic actions of the fractions was examined. The dialyzate was separated into two major fractions of Pl and P 2 by a Sephadex G-100 gel filtration. The desmutagenic effect on Trp-P-2 toward Salmonella typhimurium TA 98 and TA 100 was found in the P 2 fraction. Pl fraction was lethal to Salmonella bacteria. P 2 fractions was separated into four major fractions (P 2-1, P 2-2, P 2-3 and P 2-4) by a Sephadex G-25 gel-filtration. Each fraction showed the desmutagenic activity, especially P 2-3 and P 2-4 fractions had higher desmutagenic activities. The desmutagenic activity of these fractions was retained after heating them at 100°C for 20min. These fractions were also desmutagenic toward benzo [a] pyrene and N-methyl-N'-nitroso-N-nitrosoguanidine. It was suggested that these fractions reacted with Trp-P-2 and S 9 mix to bring about the inhibition of mutagenicity of Trp-P-2. No killing and mutagenicity on TA 98 and TA 100 were observed in these fractions.

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Regarding vigorous production of ethylene in sweet potato root tissue when infected by black rot fungus, Ceratocystis fimbriata, the contribution of ethylene production by the fungus itself in diseased tissue was investigated, with four kinds of experiments. It is concluded that the ratio of the production by the fungus itself to the total production in diseased tissue was really small and the ethylene synthetic pathway of the fungus involved L-methionine (Met), but not 1-aminocyclopropane-1-carboxylic acid (ACC). One of the pathways of ethylene production induced in diseased tissue was the Met-ACC pathway, which was also found in pectinase-treated tissue. It seems likely, however, that in the boundary part between infected and non-infected parts, some other pathway was also induced in response to the fungal infection, and this assumption was also supported in the case of pectinase treatment. The above results may be useful to understand the mechanism on ethylene production in stored vegetables and fruits when infected by pathogens.

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