Oyster protein was hydrolyzed with eleven kinds of proteases for food industry and the taste of the hydrolyzed extracts were scored by sensory tests. The hydrolyzate treated with denazyme AP was the most preferable extract, and the hydrolyzate (PA-1) was tested for inhibitory activity against angiotensin I converting enzyme (ACE). The IC₅₀-value of PA-1 was 0.55 mg-protein/ml. The PA-1 was applied on a column packed with ODS resin and washed with water in order to remove salts and the water-soluble fraction. The active fraction was eluted with a stepwise gradient of ethanol. The most active fraction (A-3) was eluted with 25% ethanol and showed the IC₅₀-value of 0.085 mg-protein/m/. A peptide that inhibited ACE was isolated from A-3 by use of different modes of chromatography involving SP-Sephadex C-25 and Toyopearl HW-40 followed by three steps of high-performance liquid chromatography. The amino acid sequence and the IC₅₀-value of the isolated peptide was Leu-Phe and 126μM, respectively.

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Possibility of application of allylisothiocyanate (AIT) vapor for food preservation was studied. The minimum inhibitory concentrations (MICS) at 37°C of AIT vapor on Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella enteritidis and Salmonella typhimurium ranged from 45 to 180 ng/ml of head space. The antibacterial effects on gram-negative bacteria were higher than those on gram-positive bacteria. The MIC on Lactobacillus bavaricus was higher; 720ng/ml. Lowering in incubation temperature to 10°C decreased the MICS on most of the tested bacteria, . The spores and vegetative cells of B. subtilis were inhibited by AIT vapor at the same concentration. AIT vapor was applied for preservation of shredded cabbage, potato salad and sliced ham. AIT vapor was most effective for the preservation of sliced ham. Lower initial microbial counts and storage at a lower temperature increased the antibacterial effect of AIT vapor on lactic acid bacteria, whose sensitivity to AIT vapor was low.

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We have been focusing our research interests into application of ¹³C-NMR spectroscopy to component analysis and quality evaluation of tea and various vinegar. Several kinds of Kurozu vinegar, which is regarded as healthful food, but its active principles have not been chemically clarified yet, were subjected to ¹³C-NMR measurement. Thespectra of Kurozu vinegar samples made in the same factory resembled closely each other, even if their lot number were different. But each spectrum of Kurozu vinegar manufactured in different maker was very characteristic and considered to exhibit differences of the manufacturing processes. Most of the signals were assigned to main components of rice vinegar, but all Kurozu vinegar samples tested gave several signals unassignable to known vinegar constituents. Guided by the characteristic signals, 2, 3-butanediol (meso-: D-: L-form=10:9:1) and 4-(2-aminoethyl) phenoi (ca. 4 and 0.3mg/ml, respectively) were isolated as its main constituents from Kurozu vinegar. ¹³C-NMR spectroscopy analysis was also suggested to be useful for its quality control.

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It has been known that phenol oxidase (monophenol oxidase, o-diphenol oxidase and laccase) activities in shiitake mushroom were inhibited by internal and external ethyl alcohol. In this paper, proteins from shiitake were separated by gel electrophoresis and stained with CBB or phenolic substrates. Monophenol oxidase, o-diphenol oxidase and laccase were detected four different isozymes each at the same Rms, and their activity changes occurred during browning of shiitake. The enzyme bands of browned shiitake packaged in perforated polyethylene bags were thicker and larger than those of shiitake packaged in airtight polyethylene bags. The inhibition of phenol oxidase activities was also observed on the enzyme bands of shiitake exposed to ethyl alcohol vapor during storage. When the slices of shiitake were treated with an inhibitor of protein synthesis (cycloheximide 0.1mM), browning and o-diphenol oxidase activity in the slices were definitely inhibited. From these results, it was considered that ethyl alcohol was produced in the tissue of shiitake under an anaerobic atmosphere, and then it affected synthesis of phenol oxidases, therefore browning of shiitake was inhibited.

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Prevention of autoxidation of emulsified linoleic acid was determined by the method to measure the rate of discoloration of beta-carotene coupled with the oxidation of linoleic acid. By the method, antioxidant activity of forty-three kinds of vegetable extracts were examined. The results were as follows. (1) Thirteen kinds of vegetable extracts, such as garland, ginger and asparagus, that contained in 100g of vegetable weight, showed the activities corresponded to more than 25mg of authentic antioxidant BHA (high activity group). And the activities another thirteen kinds of vegetable extracts from pumpkin, cucumber and turnip et al., each also contained in 100g of vegetable weight corresponded to less than 5mg of BHA (low activity group). The activities of another seventeen kinds of vegetables corresponded to the intermediate level of high activity group and low activity group. (2) The correlation of the content of polyphenol and antioxidant activity of the vegetables extracts was 0.7694. (3) The main antioxidants of asparagus, ginger and garland determined by MS spectrum method were rutin, gingerol and hexahydrocurcumin, and isochlorogenic acid and acyl substituted isochlorogenic acid, respectively.

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The application of each of pressurization and enzymatic treatments to indica rice grains changed their cooking properties. Pressurization at less than 200 MPa and enzymatic treatments using cellulase, pectolyase and actitase were generally effective in softening the cooked rice. In some cases, severer conditions fortreatment with a mixture of actinase and collagenase was necessary to develop stickiness of cooked rice. Addition of glyceryl monooleate was effective in keeping stickiness and hardness of cooked rice unchanged.

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Changes of phytate contents in manufacturing and ripening processes of soybean cheese were studied. Phytase productivity of P.caseicolum used as a starter was ascertained and some characteristics of phytase of mold were investigated. (1) Soymilk added with 10 times of water contained 82% of phytate in soybean. Forty-eight % of phytate in soymilk equivalent to 40% of phytate in soybean moved to curd coagulated by lactic fermentation. (2) During ripening, 50% of phytate in unripened curd decreased in a week's ripened curd. On the other hand, free inorganic phosphorus contents in a week's ripened curd increased to 10 times of that in unripened curd. (3) Phytase activity were ascertained in an extract from wheat bran medium inoculated with P.caseicolum and in ammonium sulfate treatment fraction (saturated 30 to 80%) of the extract. (4) Using the ammonium sulfate treatment fraction, effects of pH on phytase activity were investigated. Two peaks of phytase activities were found at pH 3.0-3.6 and at near pH 4.8, respectively. (5) The effects of temperature on phytase activity showed that optimum temperature was near 45°C under reaction at pH 3.6 and that it ranged from 30°C to 40°C at pH 4.8. (6) In the experiment using sodium phytate from rice as a substrate, the optimum substrate concentrations under reaction at pH 3.6 and at pH 4.8 were 0.375mM and 2.5mM, respectively.

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The wet process, a conventional method for mungbean starch preparation may cause about 80% protein loss in wastewater. In this study, ultrafiltration (UF) was used to recover the protein from the simulated wastewater of mungbean starch processing. The performance and process engineering characteristics of spiral-wound modules and the functional properties of the recovered protein were investigated. The permeate flux of the ultrafiltration increased with an increase in operating pressure, and inlet temperature also enhanced it by aratio of 3%/°C. The conditions of 40°Cand 4kg/cm² were found to beappropriate for recovering proteins from the simulated was tewater. Recovery of total solids was 67.5% and 50.8% and that of protein was 87.8% and 50.3% for MWCO 30000 and 500000 membranes, respectively. Proteinremaining in the wastewater could almost be separated by UF with the MWCO 30000 membrane. The dried products from both membranes were no significantly different in their functional properties. It seems feasible to recover the protein by UF. This would not only prevent contamination but also improve the utilization of mungbeans.

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Physico-chemical components, characteristic properties and maintenance in hardness of brined" ume" fruits by dried egg shells (DES) were compared with those of ashed egg shells (AES) under various ashing temperatures. Calcium (Ca) content of the main inorganic ingredients from DES was about 38%, and its content of AES increased to 70-71% in AES-800 (ignited at 800°C) and AES-900. Observation of particle surfaces of AES-750, AES-800 by scanning electron microscopy (SEM) revealed the acceleration of the growth of pores and projections. At this temperature, fine particles in a size range from 750°C to 800°C were formed and then the phase change of morphological construction occurred. The weight loss of DES measured by thermogravimetry (TG) trailed a shoulder at about 670°C gradually and then paralleled at about 820-835°C (weight loss ratio 44.0%). Also, differential thermal analysis (DTA) of DES showed a weak exothermic reaction with a peak at about 330°C, and a large endothermic reaction with a peak temperature at about 805-810°C. By X-ray diffraction analysis, the main inorganic compound of DES was 93.96% of CaCO3 (m.p.825°C), and the formation of fine particles after the phase change of morphological construction at about 820-835°C concluded 99.48% CaO. The experimental results of the changes of egg shells under various ashing temperatures are shown in a reaction formula (CaCO₃→CaO+CO₂) at about 820-830°C, and it was concluded from the experiment obtained by X-ray diffraction, TG and DTA, atomic absorption spectrometry (AAS) and observation with SEM. Also, it was found that the brined "ume" fruits increased in yield and hardness maintained was with the addition of AES ashed at over 700°C. Especially in the case of using AES above 800°C, the effect was remarkable.

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Various physicochemical events taking place at subzero temperatures in aqueous systems were explained in this review. They are undercooling, ice nucleation, ice crystal growth, freeze-concentration and vitrification. Organisms which survive seasonal exposure to subzero temperatures, or live under the subzero-temperature environment, cope with freezing by various means making most use of the characteristic of water.

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