This study was conducted to understand the regulatory mechanism of ethylene biosynthesis in developing and ripening tomato fruit. The ethylene biosynthetic pathway in immature and ripening tomato fruit treated with ethylene was observed by analyzing the intermediate and enzyme activities. Internal ethylene concentration was low in developing stages of tomato fruit, began to increase in the mature green, and increased sharply in the ripening stage. Carbon dioxide production in immature and mature green fruit was stimulated with 100, μl·l^-1 of ethylene treatment for 22 hr, but ethylene production was not enhanced. Activities of ACC oxidase and ACC malonyltransferase were stimulated with ethylene treatment and the ACC oxidase activity of immature fruit was similar to that at the ripening stage, whereas ACC malonyltransferase activity of immature fruit was substantially greater than in the ripening stage. In mature green tomato fruit, ACC oxidase and ACC malonyltransferase reached maximum rate after one day of ethylene treatment and remained at about the same rate with continual treatment. However, the rate dropped sharply when the fruit were transferred to air. ACC synthase activity and ACC content of immature green fruit did not change during the two days of ethylene treatment but increased when transferred to air for two days.

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The viscosity of four varieties of yam, Tsukuneimo, Ichoimo, Sagamiwase and Nagaimo prepared by freeze dried method, vacuum dried and hot air dried was investigated. The tissues of yam were observed using scanning electron microscope, and the relationship between tissue and viscosity in each sample was also investigated. (1) The viscosity of dried yam decreased, while this changes of hot air dried yam was remarkable. The freeze dried sample decreased a little. (2) Little particles were observed around starch granules in the cell tissue of fresh yam. These particles changed or disappeared in dried yam tissue. (3) The particles were stained using Coomassie Brilliant Blue R-250, so it was confirmed as glycoprotein of yam mucilage. (4) The changes of cell form and mucilage particles during the drying process was one of the sources of changes in viscosity. The cell form and mucilage particles of freeze dried yam were not so changed, so it is suggested that freeze drying is the suitable method for drying yam.

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The rates of C₂H₄ production in peach and banana fruits stored under 3 % O₂ decreased by approximately 60% and 50% respectively compared to those stored in air. 1-aminocyclo-propane-1-carboxylic acid (ACC) oxidase activity in both fruits did not change during low O₂ and subsequent air storage, when measured in the disks incubated under air condition. Low O₂ treatment increased slightly ACC contents in both fruits. However, the increase in ACC content in peaches was much less compared to the calculated increase based on the result of the inhibition in C₂H₄ production, on the assumption that low O₂ atmosphere would not affect the conversion of s-adenosylmethionine (SAM) to ACC. When ACC oxidase activity in excised flesh tissues from peach, banana, cucumber, and eggplant was measured under various O₂ concentrations, the activity was distinctly O₂-dependent. Our results suggest that inhibition of C₂H₄ production by shortterm low O₂ treatment is mainly due to inhibition of ACC oxidase activity, not due to decrease in amount of the enzyme. The inhibitory effect of low O₂ on C₂H₄ production in peach fruit might be partly due to inhibition of the conversion of SAM to ACC.

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Tangor 'Kiyomi' (Citrus sinensis × C. tangerina) fruits were stored at 5°C for 3 months and subsequently transferred to 8°C or 20°Cwith/without polyethylene film packaging (LDPE-20 μm), respectively. The fruits transferred to 20°C showed more severe rind-oil spot injury than those to 8°C, and the packaging with LDPE reduced the injury both fruits stored at 20°C and 8°C. The rate of K ion leakage from the fruits showed the increasing and sharp peak at 2 days for 8°Cand 5 days for 20°C after transferring. The peak of leakage for 20°C was higher than that of 8°C and the rate of leakage of packed fruit was lower than that of non-packed fruit both at 20°C and 8°C. The flavedo tissues were prepared for observation by scanning electron microscopy (SEM). The surface of sound fruit was covered by a thick, waxy, highly patterned cuticles and the stomata scattered over the surface. The SEM showed that the epidermis cells, parenchyma cells, and oil glands remained intact in the cross section of sound fruit. The pit between oil gland and partially ruptured cuticles on the surface were observed for the injured fruit showing rind-oil spot and slight discolor. The destructed parenchyma cells were observed but the epidermis cells remained intact in the cross section of the slight injured fruit. The SEM showed the severely ruptured cuticles on the surface and severely destructed parenchyma cells of the severely injured fruit. The epidermis cells remained intact in the severely injured fruit and the pit in rind-oil spot injury commenced with the destruction of parenchyma cells locating several layers inside the surface.

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We examined the possibility of the sweetness control by the short treatment of low temperature (0--2°C) storage, and investigated consumer taste for sweet chestnuts and the standard of sweetness of chestnut. 1) By the treatment of low temperature, the starch content in chestnut was decreased, and the total sugar and the sucrose contents were increased. These contents were increased by the treatment of low temperature during one week. After the treatment of low temperature, the sucrose content didn't change during 2 weeks at room temperature. 2) By the test of consumer taste for sweet chestnuts, it was defined that consumer preferred sweet chestnuts very much. By the organic test of 4 items, it was seen that the taste was correlated with the sucrose content extremely. 3) At room temperature we can distribute the chestnuts that the sugar content was increased by the short treatment of low temperature. According to the sucrose content we could assumed the standard of sweetness that under 4.5% was 'Ordinary', 4.5-8.0% was 'Sweet', and over 8.0% was 'Fairy sweet'.

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