The microbial count is an index of suitability of raw milk handling and also one of the most essential item to judge milk quality. Sometimes, the high microbial count is responsible for high titratable acidity and/or off-flavor, and inducesheat-unstability or contamination of heat-stable enzymes. Therefore, the high microbial count milk is not available for manufacturing. The measurment of the microbial count is usually carried out by direct counting with a micro scope or by colony counting on an agar plate. But these methods contain complicated procedures and need special techniques. To solve these problems a method by measuring catalase-activity was investigated, since all aerobic microbes have catalase. To separate the catalase-activity of microbes from that of bovine catalase contained in raw milk, the pH-profile of each activity and inhibitory effects of L-ascorbic acid were investigated. To measure the catalase-activity, an increasing rate of dissolved oxygen was measured by mean of an oxygen electrode just after the addition of hydrogen peroxide. The bovine catarase-activity tended to decrease definitely in the pH range higher than 9, but those of bacteria suspensions and raw milk had peak around pH 11. At pH11, there fore, the cat alase-activity was expected to be that of microbes. In experiments using 3 species of bacteria, a high linear relation was obtained between bacterial count and catalase-activity at pH 11, and the lowest bacterial count which can be estimated from the catalase-activity at pH 11, was spposed to be around 103/ml. In experiments using raw milk samples from a tank lorry, catalase-activity at pH 11 was shown to be highly related to the microbial count. A regression for mula to estimate the microbial count from catalaseactivity at pH 11 was obtained and was shown to be available for raw milk samples.

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Four types of hydrolysates with alkaline protease (EHB-1), acid protease (EHB-2) and hydrochloric acid (AHB) from porcine red blood cells and two kinds of protease from globin refined by the method of TYBOR et al. (EHG) were prepared in this study. The effects on the growth of Escherichia coli, Bacillus subtilis and Lactobacillus plantarum were investigated by using the medium containing these hydrolysates (0.39%, nitrogen conversion) as a nitrogen source. The results obtained were as follows: (1) The difference in amino acid composition among 4 hydrolysates seemed to be no effect on the growth of test bacteria. The molecular weights of peptides hydrolyzed enzymatically were distributed from 5OO to 3000, and hydrolysation of EHG was more noticeable than that of EHB-1 and EHB-2. (2) E. coli and B. subtilis abundantly grew whereas. L. plantarum scantily grew on the EHB-1 medium. Scanty or moderate growth of all test bacteria used were observed on the medium containing the other hydrolysates. (3) The growth of E. coli and B. subtilis were greatly enhanced when EHB-2 and EHG were partially replaced with AHB. In case of L. plantarum, the same tendency was recognized only to use the mixture EHG and AHB. (4) When the enzymatic hydrolysates were divided into retentate and permeate by ultrafiltration (M. W. 1, 000), the fractions did not possesed the growth promoting effect described above. (5) These results suggested that the growth factor in response to the type of bacteria existed in enzymatic hydrolysates, because the growth of test bacteria on the EHB-1 medium and the EHB-2 and EHG medium supplized by AHB were more abundant than that on the AHB medium, and both. retentate and permeate of hydrolysates by ultrafiltration were necessary for this effect.

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Surface activities of food surfactants (emulsifiers), such as sucrose fatty acid ester (SE), polyglycerin fatty acid ester (PGE) and sorbitan fatty acid ester (SOE), were found to be enhanced by blending with soya lysophosphatidylcholine (LPC) or soya lysophospholipids (SLP). The water solubility and acid/salt tolerance of SE and PGE of medium HLB value and of SOE increased due to addition of 20-50% (w/w) LPC or SLP. Surface tension of the mixtures (food surfactant/LPC or SLP) took a minimum value in a range of ratios from 60:40 to 50:50 (w/w), while a notable decrease of surface tension could be observed by mixing 10-30% (w/w) of SLP having about 50% LPC. Immersional wettability (penetrating power) of food surfactants incresed with addition of 10-20% LPC. Oil/water (o/w) emulsifying ability of food surfactant was fortified by mixing 20-30% of LPC or SLP, and the emulsions of vegetable oil became tolerant to salt and acid solution. Water dispersibility of fine particls and beta-carotene solubilization of food surfactants were also improved by addition of about 20% LPC or SLP. The results obtained may be brought by the following reason: The nonionic surfactant incorporate with LPC molecules, which have storongly hydrated head group, to form the mixed micelles which possess a similar property to that of small micelles of LPC.

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The effect of shredding modes on the storage stability of partially processed pepper fruits was investigated with reference to physiological and chemical changes. Bell pepper fruits were prepared as quarter (quartered lengthwise), line (cut lengthwise with 10mm maximum width), ring (cut crosswise with 10mm width) and fine (cut 'Line' with 10mm length) styles, and packaged hermetically in low density polyethylene bags (0.02mm thick.), followed by holding at 1°C and 20°C. (1) The fine pepper softened and decayed quickly from cut surface, then the line and the quarter ones followed. The deterioration of the circle ones was significantly slow among them but faster than whole pepper. It was obvious that not only the ratio of the wounded area, but also the wounded direction had an effect on the deteriorating rate. (2) The O₂ concentration in the polyethylene bags decreased, and CO₂ and ethylene concentrations increased during storage. The degree of the changes almost coincided with the deterioration rate, and the circle pepper showed less change than the line one. (3) There was a little change in chlorophyll, ascorbic acid, phenol and free amino acid contents in shredded peppers in spite of the rapid deterioration during storage, and there was little difference among the treatments.

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The composition of Ann granules (denatured cotyledon cells) in twelve varieties of Adzuki beans (Vigna angularis) cooked for an appropriate time was 0-2.4% ruptured and 0.9-10.9% damaged granules. Prolonged soaking in water before cooking resulted in the damage of the granules, although it has no discernible effect on the rupture. When beans were cooked at temperatures of 100 to 120°C for an apprpriate time, the higher temperature caused the rupture and damage of granules markedly. The cooking for over an appropriate time at 100°C or 120°C gave rise to the rupture and damage of granules. When beans were cooked in dilute hydrochloric acid solutions or buffer solutions of various pH values for an appropriate time, the proportions of both ruptured and damaged granules were the smallest at about pH6 and increased with increasing or decreasing pH, although the proportions of the damaged granules at pH1.4 were small due to the marked increase in the rupture of granules. These results suggest that the composition of Ann granules in Ann may be affected by the variety of Adzuki beans used and the processes of soaking and cooking in Ann manufacturing.

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Since high acidity in yoghurt which occurs during its storage and delivery is unpopular among consumers, the application of hydrostatic pressure to yoghurt to prevent its afteracidification (rise of acidity after packaging) was studied. Yoghurt was filled in flexible pouches and heatsealed. After applying hydrostatic pressure to the pouched yoghurt with a cold isostatic equipment MCT-150 S (Mitsubishi Heavy Industry Co.) under various pressures and temperatures, it was stored for two weeks at 10°C. The acidity, the number of vital Lactic acid bacteria and the texture of the yoghurt were evaluated periodically during the storage. The pressure treatment at below 200MPa for 10min at room temperature did not prevent the after-acidification, and the initial number of vital Lactic acid bacteria was maintained for two week storage. The pressure treatment at 200-300MPa for 10min at the same temperature prevented the after-acidification and maintained the initial number of vital Lactic acid bacteria. By the treatment at over 300MPa for 10min at the same temperature after-acidification was prevented and the number of vital Lactic acid bacteria was decreased as the applied pressure was increased. The texture of yoghurt was maintained regardless of the applied pressure when treatment temprature was below 20°C. Therefore, it was recognized that application of hydrostatic pressure at 200-300MPa to yoghurt was effective to maintain its quality during storage and delivery.

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In order to establish suitable production conditions of canned tea drinks, first of all, caffeine, catechins and L-ascorbic acid in commercial canned tea drinks were quantitatively determined as indicative substances of quality change by high performance liquid chromatography and colorimetric analysis. Secondly, canned green tea drink was prepared as a trial to examine the influence of pH of extraction media and of heat processing on the stability of caffeine, catechins and L-ascorbic acid. From the analysis of various kinds of commercial canned tea drinks including oolong tea, black tea and green tea, it was found that the concentrations of caffeine and catechins in commercial canned tea drinks were 1/2-2/3 of those in normal tea infusion. The drinks kept at lower pH had higher retention of catechins From the test production of canned green tea, it was found that, (1) catechins were less stable than caffeine in heat processing, (2) L-ascorbic acid was considerably stable in heal processing, (3) most catechins decreased by heat processing but (+)-catechin was remarkably increased, (4) the increase of (+)-catechin was possibly caused by isomerization of(-)-epicatechin, (5) the isomerization of(-)-epicatechin was remarkably depressed in slightly acidic extraction media containing citric acid. In conclusion, the most dominant factor affecting the stability of catechins in tea drinks was pH of extraction media.

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Volatile esters produced from banana, melon and straw berry fruits were investigated by analyzing head-space gas. In the case of banana, ethyl and butyl esters were found to be main esters and isobutyl and isoamyl esters followed. In melon, ethyl esters were predominant, and in strawberry methyl esters were mainly observed. In all cases of these fruits, acetate and butyrate were the main esters. Alcohol acyl CoA transferase (ester synthetase) was extracted from these fruits. A high reactivity of the enzyme was observed when propyl, isobutyl, butyl and isoamyl alcohols were used as the substrates, whereas a low reactivity was observed when methyl, ethyl and amyl alcohols were used. The enzyme from banana and melon reacted well with acetyl CoA, propionyl CoA and butyryl CoA, while the enzyme from strawberry reacted well with valeryl CoA besides the above three acyl CoAs. Branched chain acyl CoAs (isobutyryl and isovaleryl) were poor substrates for the enzyme. Ethyl alcohol was predominant among alcohols observed in pulp of banana and melon fruits, whereas methyl alcohol was predominant in strawberry. From these observations, it may be concluded that esters produced from fruits have alcohol moieties reflected alcohol contents in the pulps and have acid moieties reflected acyl CoA specificity of the ester synthetase.

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Angiotensin I-converting enzyme (ACE) inhibitory activities of the residues of 24 kinds of vinegars including 6 kinds of unpolished rice vinegars, 4 kinds of polished rice vinegars, 6 kinds of grain vinegars were determined fluorometrically. Among them, rice vinegars, especially unpolished rice vinegars, showed relatively stronger inhibitory activity for the enzyme. Amino acids and some related compounds in unpolished rice vinegars might affect the inhibitory activity, while organic acids were not related. However, the degree of inhibition of unpolished rice vinegar was stronger than that of glycine, which inhibits the ACE activity most strongly among amino acids. The results suggest that the ACE activity is inhibited not only by amino acids but by the other components in vinegars. Comparable study of the determination methods, colorimetry and fluorometry, was also done and showed that the fluorometric method was useful to assay of ACE in turbid sample solutions.

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The growth-promoting activity in fruit extracts (38 kinds) was screened using cultured human-derived cells in serum-free medium. A human-human hybridoma cell line (HB 4 C 5) and a human promyelocytic leukemia cell line (HL 60) were cultured in ERDF medium and in ERDF medium supplemented with insulin, transferrin, ethanolamine and selenite. Extract of various fruits promoted the growth of HB 4 C 5 and HL 60 in serum-free medium with or without ITES. A higher growth-promoting activity on HB 4 C 5 cells was shown by the extracts of akebi, grapefruit, grape, plum (dry), mango, melon, litchi, and that on HL 60 was shown by extracts of akebi, kiwi fruit, pear, banana, grape, plum, mango and melon.

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Abbreviations: G₂, maltose; CD, cyclodextrin; α-CD, α-cyclodextrin; β-CD, β-cyclodextrin; γ-CD, γ-cyclodextrin; G₂-α-CD, maltosyl (α1→6) α-cyclodextrin; G₂ G₂-α-CD, dimaltosyl (α1→6) α-cyclodextrin; G₂-β-CD, maltosyl (α1→6) β-cyclodextrin; G₂-γ-CD, maltosyl (α1→6) γ-cyclodextrin; HPLC, high performance liquid chromatography.

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[in Japanese]

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