Infrared imaging and multivariate analysis of structure, bioactive compounds, and starch digestibility of dough and mature stages rice

Infrared Imaging combined with multivariate data analysis provides a powerful tool for the qualitative and quantitative assessment of biochemical changes in rice varieties. Rice varieties at two ripening stages—the dough and mature stages—were analyzed at high spatial resolution, focusing on the pericarp and aleurone regions. Structural features, physicochemical properties, starch digestibility, and bioactive compounds were examined. In the endosperm and aleurone, the α-helix content and α-helix/β-sheet ratio in dough-stage rice were significantly lower than in mature-stage rice, indicating lower protein digestibility and allergenic potential. Furthermore, the dough stages of Khao Dawk Mali (KDML), Riceberry (RB), and JHN02313 variety exhibited higher proportions of β-sheet and β-turn structures within the Amide I region, which were associated with higher slowly available glucose and lower rapidly available glucose. The dough stage of pigmented rice varieties (JHN02313 and RB) showed the highest levels of anthocyanins, total phenolics, total flavonoids, and DPPH activity. These findings provide insights into the nutritional quality of dough-stage rice, particularly pigmented varieties, which offer significant benefits for dietary management.