This study shows several genes in sweet potatoes, whose expression level changed during low-temperature storage. In addition, the relationship between their expression and occurrence of chilling injury was investigated. The expression levels of phenylalanine ammonia-lyase A (PALA), ACC oxidase, regulatory protein NPR1, 70 kDa heat shock protein, and α-amylase were increased upon storage at 5-10 ℃; however those of β-amylase (BAM) and starch synthase were decreased. The effects of continuous changes in storage temperatures on the expression of PALA and BAM were investigated. The changes in their expression levels during storage at 5 ℃ within 10 days could be recovered by storage at 20 ℃ for 5 days; however, at 5 ℃ for more than 15 days, the recovery phenomenon was not observed. PALA expression level increased at below 10 ℃, but was absent at over 13 ℃. Heat shock treatment at 40 ℃ for 2 days did not affect the expression levels of these genes. These findings indicate the irreversible physiological changes in sweet potatoes according to by low-temperature storage periods and can be used as expression makers of chilling injury.

　The present study analyzed the differences in potatoes harvested during two cropping periods, namely "fall" and "spring", in Nagashima, Kagoshima Prefecture. Specifically, tuber size, weight, hardness, approximate mineral composition, and ascorbic acid content were measured. There were no differences in potato size, weight, ascorbic acid content, and hardness between the two harvest periods. However, moisture, sodium, and calcium content of fall potatoes were higher. Indeed, differences in the quality and taste of the potatoes between the fall and spring potatoes have been widely acknowledged by local consumers since long. The moisture and calcium content of potatoes varied with changes in transpiration. The lower calcium content of spring potatoes than that of fall potatoes led to the development of internal brown spots, hollow heart, and bruising in the former. We hypothesized that the higher moisture and calcium content of fall potatoes is related to their higher water absorption in this period. Additional factors such as mean temperature may also shape the differences between the two cropping periods.

　In this study, a storage method for 'Taishuu' persimmon using a moisture-proof corrugated fiberboard box (MCB) was assessed. Flesh firmness was evaluated using the elasticity index (EI), determined by measuring acoustic resonance. Use of MCB prevented early fruit softening at room temperature. MCB retained EI and shelf-life for approximately 20 days and more than 2 weeks longer, respectively, than when a conventional corrugated fiberboard box was used. Treatment with 1-Methylcyclopropene (1-MCP) was ineffective in preventing softening of fruit stored in MCB. Therefore, fruit quality could be retained in MCB without 1-MCP treatment. This approach retained EI and shelf-life for approximately 30 days. However, conspicuous shallow concentric skin cracks occurred after 14 days of storage, lowering the appearance quality. Therefore, the effectiveness of using MCB at different temperatures in retaining EI and shelf-life was examined. The development of shallow concentric skin cracks could be prevented by storage at 0℃. Moreover, EI and shelf-life were higher at this temperature than at room temperature. The appearance quality and the internal quality could be retained for 39 days after storage. These results indicate that storage of 'Taishuu' persimmon in MCB can preserve the appearance and interior qualities for 14 days at room temperature and for at least 39 days at 0℃.

　We investigated the factors determining color stability and discoloration in camu-camu fruit juice. Heat treatment deepened the red color of the juice, although it faded subsequently. Fading of the red color was also observed when juices were not heated. These findings suggest that the stability of red color is affected by the high concentrations of ascorbic acid in camu-camu juice. Heat treatment at high temperatures and for long durations turned the juice dark yellow. Under conditions of accelerated heating at 50℃, camu-camu juices varied from light pink to yellow and from yellow to brown. Polymerized polyphenols were more abundant in the browning juice than in light pink juice. Polyphenol oxidase activity was not detected, indicating that the browning was non-enzymatic. Regarding preservation conditions using model juices prepared from camu-camu juice containing polyphenol (PP), ascorbic acid (AA), and polyphenol and ascorbic mix (PP+AA), the b^＊ value increased in the order PP < AA < PP+AA. These findings suggest that high concentrations of ascorbic acid greatly influence non-enzymatic browning. Thus, it was clarified that red fading and browning are mainly caused by the presence of ascorbic acid in camu-camu juice.