Effects of cooking methods on starch and sugar composition of sweetpotato storage roots

Authors: WEI, SHUYING - Zhejiang A & F University; LU, GUOQUAN - Zhejiang A & F University; Cao, Heping

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2017
Publication Date: 8/21/2017
Citation: Wei, S., Lu, G., Cao, H. 2017. Effects of cooking methods on starch and sugar composition of sweetpotato storage roots. PLoS One. 12(8):e0182604.
DOI: https://doi.org/10.1371/journal.pone.0182604

Interpretive Summary: Sweet potato (Ipomoea batatas), a dicotyledonous plant, belongs to the Convolvulaceae family. It is a root vegetable due to its large, starchy, sweet-tasting tuberous roots. Sweet potato is native to the tropical regions in America. It is distantly related to potato (Solanum tuberosum). Sweet potato has rich nutrition, good ecological adaptability and high yield. The edible tubers contain high sugar content, beautiful cooking odor, and multiple bioactive compounds with nutritional and health benefits. It was not well-known about the relationship among cooking methods, sugar components and cultivars. The objective of this study was to offer information for quality analysis and cultivar appraisal of sweet potatoes. We determined the relationship among cooking methods, sugar components and cultivars using four sweet potato cultivars under three cooking treatments. Cooking reduced starch content and amylase activity and increased reducing sugar content especially maltose content, but no significant changes in nonreducing sugar content. These effects were different among the four varieties and three cooking methods. This study provides useful information for quality analysis and cultivar appraisal of sweet potatoes.

Technical Abstract: Sweet potato has rich nutrition, good ecological adaptability and high yield. There was a lack of knowledge about the relationship among cooking methods, sugar components and cultivars. The objective of this study was to determine sugar composition of four sweet potato cultivars under three cooking treatments. Sweet potato tubers from cultivars “Xinxiang”, “Hongpihuangxin”, “Zimei” and “Yuzishu 263” were treated by baking, boiling and steaming and subsequently analyzed for starch content, amylase activity and sugar contents including glucose, fructose, sucrose and maltose. Results indicated that cooking reduced starch content and amylase activity and increased reducing sugar content especially maltose content, but did not have significant effects on nonreducing sugar content. These effects were different among the four varieties and three cooking methods. Baking led to the least starch reduction. Tubers from “Hongpihuangxin” contained the highest amount of sugar content and thus sweetest. Sugar composition analysis suggests that “Xinxiang” and “Hongpihuangxin” belong to high-maltose cultivars. This study provides useful information for quality analysis and cultivar appraisal of sweet potatoes.