Improving the eating quality of cooked rice with rice bran oil: Effects of starch and protein structures and leached components on water migration and microstructure.

Lipids play a crucial role in determining the edible quality of cooked rice (CR), but their regulatory mechanisms on starch and protein structural changes, dissolved component composition, and final rice quality remain unclear. This study investigated the effects of adding rice bran oil (RBO, 0-2.0%) before cooking on the quality characteristics of rice. Results showed that appropriate amounts of RBO promoted the formation of starch-lipid complexes, improving the ordered structure and gelatinization properties of starch. Simultaneously, RBO induced protein conformation unfolding, promoted disulfide bond cross-linking, and the aggregation of hydrophobic cores of rice proteins. These structural modifications promoted the dissolution of amylopectin and proteins, forming a uniform surface layer, and improved water flowability and distribution uniformity by increasing the ratio of immobilized and bound water. Creep-recovery and SEM results indicated that RBO enhanced the structural support and resistance to deformation of rice by limiting excessive starch granule swelling and promoting the formation of a continuous, uniform starch-protein interaction network. Notably, rice treated with 0.5% RBO exhibited a glossy surface, balanced chewiness and resilience, achieving the highest sensory acceptability. In contrast, excessive RBO leads to an overly dense gel network and excessive hardness, impairing the texture. This study provides a theoretical basis and practical strategies for lipid regulation of rice quality.