The effects of starch molecular weight and chain length distribution on the 0-3 texture levels

The 3-0 texture levels belong to liquids according to International Dysphagia Dietary Standardization Initiative classification. The effects of starch molecular weight and chain length distribution on 3-0 texture levels were not clear. Rice starch (Level 7) was hydrolyzed to Level 3-0 by using α-amylase. When the texture fell from Level 3 to 0, the average molecular weight of rice starch was tumbled from 9.48 × 10⁷ to 1.17 × 10⁴ g/mol, and the Mw/Mn of starch was reduced from 22.0 to 3.3, the chain length distribution of the shortest chain with Dp (6-12) was increased from 41.1 % to 70.5 %, while the longer chain was decreased gradually. Additionally, the height and roughness of starch molecular chains exhibited significant changes, with height decreasing from 1.1 to 0.7 nm and roughness decreasing from 0.332 to 0.208 nm. The amylopectin and amylose were partially hydrolyzed at Levels 3 and 2, and completely hydrolyzed at Levels 1 and 0, converting into smaller molecular weight components. Reducing the molecular weight of rice starch through enzymatic hydrolysis could lower the texture levels from 7 (solid) to 3-0 (liquid). These findings provide a theoretical basis for starch-based liquid food with texture Levels of 3-0.