Effects of Different Storage Temperatures on the Quality of Sweet Potato “Kenroku”

Abstract

The effect of storage temperature on the quality of the sweet potato (Ipomoea batatas (L.) Lam.) cultivar “Kenroku” was investigated. In general, sweet potato storage roots are stored at 13°C to avoid chilling injury. Although flesh decay was not observed at this temperature, the sucrose content and sweetness index of “Kenroku” storage roots did not change during 12 weeks of storage at 13°C. Storage at 16°C induced sprouting within 4 weeks, suggesting that this temperature is inappropriate for longer storage durations. In contrast, cold storage at 6 or 9°C increased the sucrose content and sweetness index for the first 6 and 10 weeks, respectively, after the start of storage; subsequently, the flesh started decaying. With unheated storage, the sucrose content and sweetness index began increasing 4 weeks after the start of storage, when the daily average temperature fell below 10°C, and continued to increase 12 weeks after the start of storage, when the flesh began decaying. Because “Kenroku” has been cultivated to produce steamed and dried slices and is harvested at the end of October, our results suggest that cold storage at temperatures of 6 to 9°C is suitable if the storage roots will be processed by the end of the year, whereas unheated storage is available if processing will occur early in the next year.