Physiological changes in carrot [Daucus carota] roots during long-term storage

The purpose of this study was undertaken to improve a method for long-term storage and to detect a quality index or a degree of freshness monitoring periodically the gas exchange and analyzing the internal chemical constituent of carrot roots packed in open polyethylene bag in a cold room. Carrots were sowed on early June and harvested on late September or mid October at open field from 1992 to 1994. Investigation on storage continued from October to May. In respiration rate, the varietal difference between Kyaroshi and Koyo-2-gou was observed at 0 and 5 degrees C during storage. Kyaroshi variety for table use showed approximately the same low respiration rate at both temperatures. On the other hand, Koyo-2-gou variety for processing exhibited a higher respiration rate at 5 degrees C than that at 0 degrees C. However, there was no apparent difference in ethylene production rate between two varieties. The variation in content of total phenol compounds during storage differed among 3 years. The reason for this suggested to be derived from the different climate condition before harvest or/and the pre-treatment before storage. The changes in sugar content of Koyo-2-gou demonstrated that the content of sucrose increased but those of glucose and fructose decreased. In case of Kyaroshi, the change in sugar content was very small. Kyaroshi was well-suited to store a prolonged duration because of less respiration and keep of sugar. The phloem part of carrot roots contained beta-carotene more than the xylem one. The content of beta-carotene in the xylem decreased gradually with time larger than the phloem during storage. We suggest that the content of alanine may indicate a status of quality or freshness in the stored carrot. In case of storage, their combination of pre-treatment, suitable variety, and proper wrapping and temperature will make extend a longer storage of carrot until May