Maltogenic amylase and glucosyltransferase synergistically control the chain structure of rice starch and their effects on rheological properties and functional characteristics of rice milk

Maltogenic amylase (MA) and glucosyltransferase (TG) were used synergistically for the development of rice milk products with low glycemic index (GI), and its storage properties and nutritional functions were evaluated. The structural results showed that MA and TG treatment could effectively reduce the molecular weight of rice starch and increases its overall branching degree, which further affected the storage and nutritional properties of rice milk products. Compared with gelatinized rice milk and rice milk treated with MA or TG, MTRM (treated with MA and TG) had lower paste viscosity, stable storage modulus, and stronger ability to bind water during storage period, indicating that the dual-enzyme treatment significantly improved the retrogradation properties of rice milk and the anti-retrogradation rate reached 76.12%. In vitro studies showed that dual-enzyme treatment significantly increased the resistant starch content of rice milk to 39.46%, thereby reducing its predicted glycemic index to 53.85, improving its antioxidant properties and contributing to the proliferation of short-chain fatty acids produced bacteria. Notably, MTRM significantly elevated butyrate content which showed a better prebiotic effect. This research provides new approaches for the preparation of low-GI rice-based beverages.