Selection of suitable yeast starter for making cheese-like soy protein foods was carried out using Saccharomyces fragilis, Saccharomyces rouxii and Torula aeria. Suitable yeast starters were obtained successfully by shaking method of the cultures in soymilk for 48 hours at 25°C. As a result of the inoculation of yeast cultures with a lactic starter of Streptococcus thermophilus, lactic acid production was increased resulting in the reduction of curdling time of soymilk especially by the inoculation of S. fragilis. Each green curd obtained by fermentation with the mixture of yeasts and lactic acid bacteria was ripened for 40 days at 15° or 20°C. The curd ripened with S. fragilis showed the highest rate of protein hydrolysis (the rate of water soluble nitrogen to total nitrogen) reaching about 30% in 40 day's ripening at 20°C. The curd by S. fragilis also gave mild flavor and small holes on the cut surface like Gouda type cheese.

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When the egg yolk solution was heated at various temperature from 55°C to 100°C for 1.5 min. or 5 min., the viscosity of egg yolk increased by heating. At 100°C for 1.5 min., the viscosity of heated yolk was finally 3 fold of the viscosity of unheated yolk. When separated fractions were heated, the viscosity of LDL(Low Density Lipoprotein)increased at above 80°C. On the contrary, the viscosity of Livetin did not almost increase. The viscosity of HDL(High Density Lipoprotein) rapidly increased at above 80°C, and HDL showed highest viscosity among separated fractions. In the disc gel electrophoresis, main bands of HDL almost disappered at above 90°C. When HDL and LDL were heated at 60°C for 5 min., particles of larger size was found in gel filtration. From the above findings, change of turbidity and viscosity of heated egg yolk was estimated to be mainly due to the coagulation of HDL and LDL.

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In order to stabilize the lipids in chicken bone hydrolyzates, some chemical properties of the lipids and the influence of various components in chicken bone on lipid oxidation were examined. It was found that the lipids obtained in a cooking process of chicken bone had good aroma and contained very low level of phospholipids, and that they were relatively stable to oxidative rancidity. The lipids obtained by the enzymatic proteolysis of bone showed roast chicken like aroma and contained about 3% of phospholipids. In the lipids remained in an insoluble fraction after the protelysis, phospholipids were present in large quantities, and these lipids were very labile to oxidation. It was concluded from these results that it was necessary to separate and remove these lipids in order to produce flavoring substances stable to oxidative rancidity. Both the cooking extract and the enzymatic hydrolyzate showed antioxidative activity for the lipids, on the contrary, both the insoluble fraction and the cold water extract of bone showed prooxidative activity. As the lipid oxidation catalyzed by the prooxidants was effectively prevented by the combined use of polyphosphate and ascorbate, it was assumed that the prooxidative activity was ascribed to the action of hemoprotein and inorganic iron.

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The effects of low-oxygen concentrations on mycerial growth of 17 fungous species isolated from intermediate moisture confectionaries weres tudied. (I)The ratio between the growth rate of the molds in low-oxygen level and that in air was changed depending on its growth stage, even under the condition of acertain level of oxygen. The inhibitory effect of low-oxygen concentration on growth was much more ovious at initial stage than at the later stage of incubation. (II)Most species showed considerable growth in the atmosphere containing 1% oxygen and their growth rate, calculated from colony diameters, decreased linearly with decreasing oxygen concentration below 1%. (III)In the atmosphere containing 0.1% oxygen, more than several % growth of the growth in air, was observed with Asp. oryzae, Asp. awamori, Pen.cyclapium, Pae. varioti, Rhizopus orpyzae and Mucor ambiguus.

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Rheological studies were carried out on two kinds of hydrogels(sample I and II)obtained from seaweeds Gelidium amansii of Izu in order to investigate the relation between the rheological properties and gel strength. A chainomatic balance relaxometer was used for the measurement of the relaxation Young's modulus, in the temperature range of 25°-55°C. Dynamic visco-elasticity of the hydrogels was also measured. The gel strength of the sample I and II was 850g/cmcm², each determined at agar concentrations in the range of 0.8-4.0wt%. The elastic modulus, E₁, which is a Maxwell element with the longest relaxation time, τ₁, and supposed to correspond to the main network structure, was approximately proportional to C^1.7, were C is wt%. The magnitude of E₁ of the sample I was greater than that of the sample II. The magnitude of the storage modulus, E' and the longest relaxation times, τ₁ also took similar tendency to the case of E₁. From the results described above, those two hydrogels were found to be different too greatly from one another in the rheological properties, irrespective of the same gel strength.

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Changes in the flavor of soy milk heated at 95°C for various periods were investigated. The effect of heating time on the flavor of soy milk was estimated by the analyses of the volatile components, gel chromatogram, composition of free amino acids and organoleptic test. The beany flavor could be fairly removed by heating for 15 min. at 95°C. Further heating, brought about the development of volatile off-flavor and degradation of free amino acids.

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The degree of bacterial contamination was evaluated on 108 commercial boiled rice materials, box lunces and rice balls purchased from retail stores from May to September in 1978. Seventy seven samples were contaminated with more than 10⁵/g of aerobic bacteria through survey period. Boiled rice materials were polluted with the highest amount of bacteria in June and July. The degree of bacterial contamination of each lunch varied remarkably among the stores from which the samples were collected, probably depending on the sanitary conditions of the stores. The most predominant flora in boiled rice was gram positive cocci (42.7%)being followed by gram positive rods (27.7%)and spore forming rods (16.9%) among the 799 isolates. Gram positive cocci and bacilli had been related with the spoilage of boiled rice. Although the number was small, S. aureus and B. cereus were also found.

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Calcium ion is used to coagulate the soy-bean milk for the preparation of tofu. The presence of sodium monovalent anion salts in the soy-bean milk or in the heat-denatured protein solution increases the concentration of calcium ion to coagulate the milk or the protein solution. The larger the size of anions in the sodium salts is, the greater the antagonistic effect of the salts becomes.

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The determination method based on conducto-metry was proposed for measuring salt content inworcester sauces and margarine. The equation(1)was set up between the specific conductance for 1, 500 times diluted solution of worcester sauces(x)and the salt content determined byargentometry(y).
y=0.07792x-1.417 (1)
x: specific conductance (μmho·cm^-1)
y= salt content (%)
The salt content could be estimated by the eq. (1)and the measured specific conductance. The esti-mated salt content agreed with that determined by argentometry within 0.1% as salt content. For margarine, the equation(2)was set up between the specific conductance(x)and the salt content deter-mined by argentometry(y).
y=0.01501x-0.040 (2)
x: specific conductance (μmho·cm^-1)
y: salt content (%)
The sample solution for measuring specific conductance was prepared as the following manner: 2.000g margarine was homogenized for 5 min with 50ml boiling H₂O and cooled at 0°C and a 2.5ml portion of the separated water phase was diluted 12 times. The salt content estimated with both the eq. (2)and the measured specific conductance agreed with that determined by argentometry within 0.02% as salt content.

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