Processing Shapes Architecture, Cultivar Dictates Chemistry: A Structural and Functional Paradigm for Yam Polysaccharides

Yam polysaccharides are promising functional food ingredients, but the systematic understanding of how cultivar and processing synergistically determine their structure and functionality is still lacking. This study systematically investigated how hot water extraction, enzymatic hydrolysis, and extrusion puffing affect the structural and functional properties of polysaccharides from two major cultivars (Dioscorea opposite cv. Tiegun and Dioscorea esculenta cv. Gaozhou). Enzymatic extraction increased yield (1.39–1.77-fold) and solubility, while hot water extraction favored purity. The monosaccharide composition was strongly cultivar-dependent, with Tiegun polysaccharides containing higher mannose levels. Extrusion puffing of Gaozhou polysaccharide improved solubility by 33.3% but induced depolymerization and aggregation, modifying colloidal and functional behaviors. Multivariate analysis revealed that processing methods primarily governed macromolecular architecture and colloidal properties, whereas cultivar determined chemical composition. These findings establish a processing–structure–property framework, enabling the tailored production of yam polysaccharides: Tiegun yam with enzymatic extraction for high bioactivity, and Gaozhou yam with extrusion puffing for superior solubility.