The relationship between low-oxygen induced injury and respiration rate in four kinds of fruits under air, 0% O₂, 1% O₂, 3% O₂, 5% O₂ and 10% O0₂ atmospheres was investigated. Calyx browning was observed in sweet pepper fruits stored in 0% O₂ for 2 days. The development of off-flavor was perceived in eggplant stored for 3 days, in Japanese pears stored for 4 days and in Japanese persimmons stored for 7 days in 0% O₂ atmosphere condition. The tendency in the suppression of respiration rate under low O₂ conditions was different among four fruits stored in various O₂ concentrations, whereas it did not have a relation with the development of low-oxygen induced injury. The CO₂ production decreased with reducing O₂ concentration up to 1%, and the CO₂ production increased at 0% O₂ level. The minimum CO₂ production was at 1% O₂ level. In an O₂ concentration more than the anaerobic compensation point, which is defined as the oxygen concentration at which CO₂ production is minimum, symptoms of low-oxygen induced injury were not observed in any fruits tested.

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When we separated the purified specimen of Streptomyces chromofuscus phospholipase D (PLase D) by SDS-PAGE, two protein bands were observed. Molecular weights of these proteins were determined to be approximately 57 and 40 kDa, respectively. As a result of N-terminal amino acid sequence analysis of these two proteins, up to 20 residues from the N-terminal amino acid were completely identical. Therefore, to evaluate the intermolecular structure of the 57 kDa protein, we performed limited proteolysis of this protein with Staphylococcus aureus V8 protease. Furthermore, regarding peptide fragments obtained as main products of limited proteolysis of the 57 kDa protein, N-terminal amino acid sequence analysis was performed. As a result, the amino acid sequence of all eight peptide fragments with molecular weights of 10, 14, 16, 18, 20, 30, 42 and 46 kDa, which were obtained by limited proteolysis of the 57 kDa protein, were found in the amino acid sequence of Streptomyces chromofuscus PLase D obtained from DNA analysis. Based on these results, it was suggested that the amino acid sequence of the 57 kDa protein was identical to that of Streptomyces chromofuscus PLase D obtained from DNA analysis.

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The polyphenol oxidase (PPO) activity in water convolvulus was relatively high at 20°C. Whereas that in malabar spinach was not detected at any storage temperatures. The ascorbic acid oxidase activity in malabar spinach was lower than in water convolvulus, and the ascorbic acid peroxidase activity related to ascorbic acid (AsA) oxidation is high with water convolvulus. Some results indicate that the appearance of chilling injury and yellowing were relative to the three enzyme activities.

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In order to elucidate the effect of storage temperature on the changes in activity of softening enzymes, the fruit of the sugar apple in full mature stage was picked and stored at 26°C, 21°C and 16°C. The fruit (Annona squamosa L.) was prepared every day for analysis of soluble solids, force required to deform, activities of pectinmethylesterase, polygalacturonase and β-galactosidase. The activities of those enzymes increased quickly when the fruit was stored at 26°C and reached a maximum in 3-4 days, while the fruit stored at 21°C increased to a maximum around 5-6 days, and that stored at 16°C was 6-8 days. These results showed that low storage temperature suppresses activity for those enzymes above-mentioned and the softening of the fruit.

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The relationship between L-ascorbic acid (AsA) content in cotyledons of Japanese radish and temperature or light intensity during growth was investigated. Japanese radish seedlings were grown in the dark at 15, 20, 25, 30, or 35°C. The maximum rate of hypocotyl elongation occurred at 25°C treatment compared with other temperature treatments. However, lower temperatures led to higher maximum content of AsA in cotyledons on a fresh weight basis. At temperatures below 30°C, AsA content in cotyledons increased rapidly, reaching a maximum 3-5 days after sowing and subsequently declined. Japanese radish seedlings were grown under various light intensity conditions at 25°C. Illumination led to increase of AsA content in cotyledons. A linear relationship was observed between the AsA content and the logarithms of light intensity.

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