Comprehensive characterization of nutritional components in sweetpotato ( Ipomoea batatas [L]. Lam.) during long-term post-harvest storage

To uncover the variation patterns of the nutritional components in sweetpotato storage roots during long-term storage comprehensively, the general nutrients, phytochemicals, and starch properties of nine sweetpotato varieties with different flesh colors were quantified and analyzed by chemical and physical techniques. During the storage, the starch content decreased firstly and then increased, with sugar content the opposite. The crude protein content and the total dietary fiber content both increased continuously. The beta-carotene content decreased or kept constant, while the anthocyanin content showed different variation patterns in the three purple-fleshed varieties. The four types of polyphenols and two types of flavonoids showed no obvious content changes during the storage. The amylose contents of all varieties showed various patterns, while the crystallinity was C-type. The proportion of small-sized starch granules reduced, and the combined proportion of medium-sized and large-sized granules increased. New correlations among the nutritional parameters for each variety were revealed for the first time. Principal component analysis indicated that the orange-fleshed varieties were distinguished from other varieties. Finally, the most storage-resistant variety ZZ3 and the suitable variety for each quality trait was selected. This study provides not only theoretical basis for comprehensive understanding of the nutrient's variations in sweetpotato storage roots during long-term storage, but also guidelines for evaluation of nutritional quality of sweetpotato roots during storage and improvement of storage methods.