Journal of Taiwan Agricultural Research

Author:Hsin-Chen Li

Abstract:

    Quality of sweet potato is affected by the change of temperature during storage period. The objectives of the present study were to study how temperature affects quality of tuberous roots of three different sweet potato cultivars (‘TNG 57’, ‘TNG 66’ and ‘TNG 73’) during storage. Tuberous roots were stored at three temperatures (10, 15 or 20℃) and were sampled for physical traits investigation and chemical analysis at 2, 4, 6 and 8 weeks after storage. Results showed that the sprouting of tuberous roots (TR) was inhibited when stored at 15℃ or lower. Fresh weight of TR of all cultivars was signifcantly declined at eight wk after storage in these three temperatures, relative to those untreated ones, particularly ‘TNG 66’ and ‘TNG 73’. The symptoms of chilling injury occurred at 10℃ treatment; roots skin of ‘TNG 57’ and ‘TNG 66’ appeared sunken lesions and browning while translucent lesions occurred inside the core of roots in ‘TNG 73’ making the loss of market and eating value. To cultivar ‘TNG 73’, storage temperature of 20℃ and extended period of storage would decrease anthocyanin content. The chemical components of tuberous roots varied during storage. After storing 2 weeks at these three temperatures, contents of soluble sugar, crude fat and protein were signifcantly higher than those of untreated checks up to 8 weeks of storage. Cultivar ‘TNG 66’ had the lowest dry matter but was the highest in respiration rate relative to the other two. Moreover, ‘TNG 66’ also had lower starch with higher soluble sugar during storage period. By the analysis of variance on factors of cultivar, storage temperature and storage period with chemical components of tuberous roots, results showed that chemical components were affected by all these three factors and their interactions. Accordingly, results suggest that each sweet potato cultivar should have its specifc temperature range to maintain proper tuberous roots storage.

Key words:Ipomoea batatas (L.) Lam, Storage, Sprouting, Chilling injury, Physiological deterioration

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