Abstract
This paper reports the relationship between storage period at various low temperatures and chilling injury of pepper fruits.
(1) Peppers (cv. SAKIGAKE MIDORI), used in this study were selected from freshly harvested fruits. After treatment with 0.5% dehydroacetate, they were stored at 1°C, 6°C and 18°C under darkness. Unexpectedly, the typical surface pitting did not appear during low temperature storage. However, in those stored at 1°C for 7 days, there was a loss of greenness of the calyxes and browning of the seeds occurred. Also, a similar symptom appeared on the calyxes of peppers after 14 days at 6°C, while those stored at 18°C were ripening normally. The quality of the fruits stored at 1°C for 2 weeks or 6°C for 3 weeks or longer deteriorated rapidly when they were transfered to 18°C.
(2) The chlorophyll content of the peels decreased during storage in all plots. The decrease of chlorophyll content was the greatest at 18°C, and much less at 1°C and 6°C.
(3) The keto acid content, (α-ketoglutaric acid, pyruvic acid), of the peel of the fruits stored at 1°C and 6°C increased gradually during storage. The longer peppers were stored at low temperatures, the more keto acid content was found after transferring to 18°C from 1°C or 6°C.
(4) Fumaric, succinic, oxalic, citric and malic acids were detected in the pepper fruits. In those organic acids, there was a large amount of malic acid, which increased during low temperature storage.
(5) Phenylalanine, leucine, valine, tyrosine, γ-aminobutylic acid, serine, arginine, glutamic acid, aspartic acid and other several unidentified ninhydrine-positive substances were detected in peppers and their content did not change significantly during the storage.
(6) The CO2 production of the fruits stored at 1°C for 2 weeks or 6°C for 3 weeks increased abnormally after transfer to 18°C.
(7) The respiratory rate of the tissue slices from the peels decreased slightly during storage at 18°C. The tissue slices from the peels of fruits stored at 6°C showed a constant respiratory rate during storage. Those stored at 1°C gave a marked increase of the rate of O2 uptake at the end of storage period (8 weeks) and the RQ values decreased. The abnormal changes of respiration in tissue slices from the peel were not observed until 7 weeks at 1°C. The O2 uptake of the calyxes of the fruits stored at 1°C increased remarkably at the end of storage period, and the time of the increase in O2 uptake corresponded exactly with the time of browning of the calyxes.
