Cultivated and wild yam ( <i>Dioscorea alata</i> L.) starches: physicochemical properties, <i>in vitro</i> digestibility, and related correlations

Abstract The study aimed to compare cultivated and wild Dioscorea alata resources about the physiochemical properties and in vitro digestibility in South China. The isolated and characterised starches were four cultivated D. alata starches (CZP, CXW, CMM, and CXH) and two wild samples, D. alata and Dioscorea japonica (WXH and WMM). The granules of the starches varied significantly from elliptical/oval/elongated to steamed bun in shape. All these six starches displayed a B-type pattern with crystallinity in the range of 15.49%–42.27%. In vitro digestion kinetics indicated that CXH and CMM have a lower digestibility rate constant and lower rapidly digestible starch content (9.59% and 12.27%). No obvious differences were observed in the hydrolysis parameters between cultivated and wild yam starches. Notably, CMM and CXH starches have high levels of resistant starch + slowly digestible starch and a low digestion rate (k = 0.0151 and 0.0082 min−1). These attributes make them promising candidates for the development of functional foods with controlled digestibility—particularly low-glycaemic index products tailored for metabolic health management. Furthermore, the findings provide valuable insights for crop improvement programmes, supporting the breeding of D. alata cultivars with enhanced nutritional profiles suitable for both food and medicinal applications.