Physicochemical properties of starch isolated from eight different varieties of Korean sweet potatoes

Abstract

The physicochemical properties of sweet potato starch (SPS) isolated from different Korean varieties, purple-fleshed Shinjami and Borami, orange-fleshed Juwhangmi and Shinwhangmi, and white/cream-fleshed Shinyulmi, Shinchunmi, Yeowhangmi, and Jeungmi, were investigated. The crude protein contents of Shinwhangmi and Jeungmi SPS were higher, and the crude lipid contents of Shinwhangmi and Shinyulmi SPS were lower than those of others. The amylose (AM) contents ranged from 14.66% (Juwhangmi) to 30.51% (Shinchunmi). The water binding capacity (WBC), swelling powers, and solubilities at 80°C were 95.78–79.32%, 15.69–23.39 g/g, and 3.77–11.01%, respectively. The XRD patterns were A and Cb-types. The granular shapes exhibited polygonal and semi-oval, but the sizes differed among different varieties. The initial pasting temperature ranged from 69.4 (Juwhangmi) to 76.4°C (Shinchunmi). Differences between onset and conclusion temperatures of orange-fleshed SPS were greater than those of others. The molecular weight of AM and amylopectin (AP) were (1.26–1.92) × 106 and (5.37–5.99) × 107, respectively. The gelatinization temperatures, amylose contents, and WBCs of SPS were correlated with unit chains of DP6-12 (negative) and DP13-24 (positive) in their APs.