Fermented soy sauce was dehydrated by spray drying in powder form. The moisture sorption properties of powered soy sauce were discussed. The equilibrium moisture contents were determined by using concentrated salt solutions and sulphuric acid solutions in the bottom section ofdesiccators stored at 20°C, 30°C, and 40°C.
The following results were observed.
The equilibrium moisture contents capacity decreased especially at low relative humidity, on the other hand increased especially at high relative humidity. The equilibrium moisture contents at 20°C were more higher than at 40°C. A monomolecular layer according to the Brunauer- Emmett-Teller theory was not gained. The heat of sorption according to the Clausius-Clapeyron-equation showed 10-12 Kcal/mole at low equilibrium moisture contents. Powdered miso employed for comparison showed the similar equilibrium moisture sorption with that of powdered soy sauce, but adsorbed more moisture for long period to reach the equilibrium moisture content.

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The purpose of this experiment was to determine the changes of o-diphenol, ascorbic acid and activities of polyphenol oxidase and peroxidase, accompanied with the browning by the low dose of gamma ray, in three parts of tuber tissue (cortex, vascular bundle and pith), and to observe the relation between the browning and the changes of those compounds and enzyme activities.
1. The o-diphenol content increased in irradiated tubers and the increasing rate was greater in cortex and vascular bundle than in pith. The ascorbic acid content decreased with higher doses, and the decreasing rate was greater in cortex and vascular bundle than in pith.
2. The activities of polyphenol oxidase and peroxidase also increased in irradiated tubers. The activity of polyphenol oxidase increased more in cortex than in vascular bundle and pith and the activity of peroxidase increased more in vascular bundle than in cortex and pith.
3. In the potato tubers which irradiation was conducted immediately after harvest, the browing was induced within several days after irradiation. However, in the potato tubers which irradiation was conducted about 3 months, the browning did not occur after irradiation. The former showed the increase of o-diphenol content and the activities of these enzymes and the decrease of ascorbic acid content, the latter did not show the changes of o-diphenol and ascorbic acid and activities of the enzymes.

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Six trypsin inhibitors (F₁, F₂, F₃-I, F₃-II, F₄ and F₅) and three α-chymotrypsin inhibitors (F₃-II, F₄ and F₅) were fractionated from crude soybean acetone insoluble inhibitor by gel filtration with Sephadex G-100 and DEAE-Sephadex A-25 chromatography.
The F₄ inhibitor was found to be homogeneous by electrophoretic and ultracentrifugic analyses, and strongly inhibited both trypsin and α-chymotrypsin, and had separate binding sites for trypsin and α-chymotrypsin, and was stable at temperature in an acidic pH. Molecular weight and sedimentation constant of the F₄ inhibitor were determined to be 8000 and 1.85, respectively. NH₂- and COOH-terminal amino acids of the F₄ inhibitor were aspartic acid and glutamic acid-asparagine, respectively. The reaction between trypsin and the F₄ inhibitor consisted in formation of a dissociable complex.
The chemical and physicochemical properties of the F₄ inhibitor were in good agreement with those of Bowman-Birk inhibitor and 1.95 inhibitor.

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The chemical reactivity of the disulfide bonds toward 0.1 M sodium borohydride and heat denaturation of the F4 inhibitor (Bowman-Birk inhibitor) were studied.
The disulfide bonds were completely reduced at 25°C for 1-2 hours, and the remaining inhibitory activities toward trypsin and α-chymotrypsin were 0-5% and 10-20%, respectively. At 0°C, most of the disulfide bonds were reduced for 5-7 hours, and the remaining inhibitory activities toward trypsin and α-chymotrypsin were 15% and 20%, respectively.
One disulfide bond could be reduced at 0°C for 75 minutes without loss of inhibitory activity toward both trypsin and α-chymotrypsin.
The solutions of the F4 inhibitor in 0.001 M HCl were heated at 100-200°C for 20 minutes. Depression of the inhibitory activity occurred at 135-140°C. At 200°C, the remaining inhibitory activity toward trypsin was 30-40%, whereas α-chymotrypsin inhibitory activity hardly remained.
The disulfide bonds were more or less affected by heat with the rise of temperature, and 1.3 M sulfhydryl groups were formed at 200°C for 20 minutes.

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In order to estimate the quality of citrus fruits an attempt was made to apply the conductometric method to the determination of free acid content in juices.
(1) An intimate correlation between the amount of free acid and the specific conductivity was obtained with the diluted citrus juices.
(2) The correlation coefficient of Citrus unshiu juices was the highest in the diluted sample containing about 0.5% of the juice (r=0.994). The coefficient of Citrus natsudaidai juices was a little lower than that of unshiu.
(3) The regression of free acid upon specific conductivity indicated the highest correlation coefficient in case of the same species and the same dilution. The regressions of Citrus unshiu juices were identical during the period of maturity of fruits.
(4) It was found to be able to determine the free acid content directly from the conductivity by the use of the relationship between the titration value and the specific conductivity of diluted citrus juices without the influence of sugar.

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The astringency of multivalent metallic salts, vegetable tannins, dehydrating solvents and halogenated acetic acids were measured organoleptically to obtain their threshold values which varied from 0.038% to 0.075%. The astringency of these substances were also accompanied by bitter, sour or sweet taste. Dehydrating solvents such as alcohol and acetone were not astringent but gave hot sensation in the mouth.
The astringents formed insoluble complex with water soluble protein. The tannins of high molecule formed the complex more easily than those of low molecule. The metallic salts did not form the insoluble complex at low concentration but formed soluble complex resulting in remarkable astringency.
When the all astringents were taken into consideration, there was no significant relationship between their astringency and the quality of the complex with protein.

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