Studies on the utilization of persimmons (Diospyros Kaki L. fil). III

Effect of storage temperature on persimmons

Abstract

The experiment was made to investigate the effect of storage temperature on keeping period and dessert quality of persimmon fruits, and to determine more desirable storage temperature and the maximum length of time for the fruit to be stored advantageously. At the same time, the effect of packing in polyethylene bags was also studied. Two varieties, Hiratanenashi (astringent variety, harvested on October, 17, 1955) and Fuyu (non-astringent variety, harvested on November, 13, 1955), were tested. One half of these fruits were packed in polyethylene bags of 0.02mm in thickness with dimensions of 12×30cm, three persimmons in each bag. Samples were stored at room temperature, 5°, 0°, and -15°C. The results are as follows.
1. The rate of softening, loss of weight and shriveling, and damages were much more rapid at room temperature than at the lower temperature. The contents of sugar, acid and ascorbic acid in the fruit also decreased rapidly with the increase of the storage temperature, but, when the fruit was kept at -15°C, it showed their gradual but slight decrease over a long period of time. It was noted that the content of soluble tannin was decreased during storage at room temperature, 5 and -15°C, while at 0°C the decrease was very slight.
2. Fruits in polyethylene bags were still in good condition with negligible shriveling and lost only about 1 per cent in weight during five months storage. The concentrations of oxygen and carbon dioxide gas in polyethylene bags were not so different as to compared with the atmosphere because the polyethylene bags used in this experiment was gas permiable. Therefore, they seem to be not so effective so far as the after ripening was concerned.
3. Maximum length of time that the fruits may keep their marketable quality was judged from the texture and the condition of decay. Those were approximately as follows. Hiratanenashi; one month at room temperature, one to two months at 5°C, two to three months at 0°C and throughtout the year at -15°C. Fuyu; two months at room temperature, two to three months at 5°C, three to four months at 0°C and throughtout the year at -15°C.
4. Judging through this experiment, the most desirable storage temperature for Hiratanenashi was found to be about -15°C, because of its fine texture, higher content of sugar, seedless character and the removal of astringency during freezing. For Fuyu, 0°C was found to be favourable.