Ascorbic acid (AsA) is oxidized as an electron donor by ascorbate peroxidase (APX) that is an H₂O₂-scavenging enzyme, and then reduced by monodehydroascorbate reductase (MDR) and dehydroascorbate reductase (DHR). The AsA content and enzyme activities related to the metabolism of AsA have been investigated for spinach stored in air at different temperatures and under controlled atmospheric conditions at 10°C. As the results, a low temperature (2°C) prevented AsA content and APX activity in spinach leaves from decreasing, on the contrary both decreased remarkably just as yellowing in air at 25°C. In gas control storage at normal air temperature of 10°C, 3% and 10% of carbon dioxide in 2% of oxygen maintained AsA content and APX activity to high levels at harvesting, indicating the CA-effect at normal temperature was accepted. The MDR and DHR activities were independent of carbon dioxide and oxygen concentrations. A high correlation found between AsA content and APX activitiy in spinach leaves apparently showed the AsA content depended not on those reductases but on APX activity. Since APX acts as a scavenger of oxygen radical and AsA activates APX as an electron donor to APX, both existence is indispensable to quality preservation and meaningful as an index of the quality of spinach. CA gas conditions control the enzyme activity and contribute to preservation of the AsA content, which will be applicable to other same leafy vegetables.

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The yolks, taken out of salted duck eggs, are widely used in the Chinese cooking as a main ingredient for producing the sweet called Geppei, or the leave-rolled rice called Chimaki. Under the conventional practice, cooks have used their sense and experience todecide how many days the eggs should be salted in water. In order to find out an appropriate time of salting in water, we employed in this test more scientific methods on the two types of eggs, namely ducks and chickens. When put into salted water, the white of both duck and chicken eggs increased in weight while both yolks decreased. During the salting, it was found the salt content in the whites increased more than that of the yolks. The change was more remarkable in ducks than in chickens. The yolks became ball-like and solid, easily able to be taken out, in 5 weeks for ducks and in 6 weeks for chickens.
The following conclusion can be drawn from the experiment, 1) Pores of duck egg shell are large in size then help the passage of the salt, producing rather higher concentration of salt in the whites. 2) The above causes dehydration of the yolks, solidifying the yolks. The duck egg yolks were solidified in a shorter time compared with the chicken egg yolks, because the pore size of duck egg shell is larger than that of chicken egg shell.

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We evaluated the effects of various enzymes on the taste of soymilk. Sensory evaluation and evaluation of soybean isoflavone involved in taste were performed using soymilk treated with various enzymes. Soybean-derived isoflavone and soymilk were treated with various enzymes. After treatment with CGTase and pullulanase, increases in components suggesting addition of sugar to the isoflavone skeleton were observed. After treatment with α-glucosidase, β-glucosidase, pectinase, naringinase, hesperidinase, and β-glucuronidase, aglycone of isoflavone formed. Taste preference assessment was performed using soymilk treated with CGTase. The CGTase-treated soymilk showed a higher taste preference than the control soymilk. In the treatment of soymilk with CGTase, the association between the types of added sugars and the conversion rate was evaluated. Addition of sugar to the isoflavone skeleton was observed for α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, and soluble starch. Evaluation of the sugar concentration in CGTase treatment of soymilk showed an increase in sugar addition efficiency after CGTase treatment using a reaction solution containing 12% α-cyclodextrin.

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The authors investigated optinal conditions for the hot water treatment of domestic eggs, which is known as a way of keeping egg quality. Eggs immerdiately after laying were immersed in hot water kept at 45∼55°C for 5∼30 minutes and air-dried. The eggs treated under the above conditions kept more or less better quality in their freshness compared with non-treated ones during storage at 20°C. The most suitable conditions for the treatment were at 50°C for 15 minutes. The results of storage tests for the eggs treated under the most suitable conditions were as follows. The freshness keeping period of the treated eggs was extended about twice compared with the non-treated ones at 20°C. Both treated and non-treated eggs kept their freshness for a long-term storage at 4°C, but the quality of treated eggs was better when compared. When stored at 25°C after storage at 4°C for 4 weeks, the freshness keeping period of the treated eggs was also extended. A similar result was obtained when using three varieties of eggs. In conclusion, the effect by the hot water treatment is observed regardless of the storage temperature and the variety of egg.

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Pathogenic mold contaminating bean sprout seeds (mung bean, black mappe) cause putrefaction to bean sprouts. We previously reported the use of allylisothiocyanate to inhibit pathogenic mold growth on sprout seeds. It is reported that ammonia vapor can reduce contaminating bacteria on sprout. So, we tried disinfections of mold on sprout seeds using ammonia vapor. The following results were obtained: (1) Ammonia vapor has antimicrobial effect on bacteria and mold. Minimum inhibitory concentration (MIC) against Aspergillus niger was less than 1/2 of MIC against Escherichia coli. (2) Ammonia vapor exposure of 11.3mg/l reduced ratio of molding with no influence on bean sprouts germination.

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The amylographic characteristics of non-glutinous rices using copper sulfate water solution which lose the enzyme activity were compared with the amylographic characteristics using distilled water. The viscosity differences of amylographic characteristics with copper sulfate water solution and with distilled water were small in the temperature from 70°C to 80°C. On the other hand, the viscosity differences were large at the maximum viscosity. There was a positive correlation between the viscosity differences of amylographic characteristics at the maximum viscosity and the balance degrees (-H/H) in the textural characteristics. The negative and positive correlations were also recognized between the viscosity differences at the maximum viscosity and the amylose contents or the enzyme activity in each.

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The contents of flavonoid compounds and anthocyanin in buckwheat (Fagopyrum esculentum Moench) seedlings were investigated. At two days after germination, seedlings were divided into two groups, and grown under etiolated and continuous illuminated conditions. All flavonoid compounds have increased until 4 days under etiolated condition and 24 hours of illuminated condition (3 days after germination). In etiolated condition, C-glycosylflavon compounds have increased more than illuminated condition, whereas more rutin has accumulated in illuminated condition. Anthocyanin content has increased with illumination during 72 hours investigated.

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