Degree of milling-oriented framework for aroma regulation in Daohuaxiang rice

Rice aroma, a critical determinant of consumer acceptance, is influenced by the degree of milling (DOM). In this work, the volatile fingerprints of 11 Daohuaxiang rice samples across a DOM gradient were characterized using gas chromatography-olfactometry-mass spectrometry, chemometrics, and quantitative aroma structural metrics. Of 50 identified volatiles, 24 differentiated DOM levels, and 12 were key odor-active compounds. As DOM increased, 2-acetyl-1-pyrroline supplanted nonanal and 2-pentylfuran as the dominant aroma contributor. The dominant odor index (DOI) increased from 0.26 to 0.39, whereas Shannon diversity (H') and Pielou's evenness (J') decreased from 1.718 and 0.883 to 1.522 and 0.782, indicating a simplified aroma profile. The 3.40% bran degree sample achieved the highest sensory score, characterized by the dominance (DOI = 0.39) of 2-acetyl-1-pyrroline and moderate diversity (H' = 1.537) and evenness (J' = 0.790) of key odor-active compounds. A DOM-oriented aroma-quality framework was established, linking DOM-induced changes in proximate composition to key odor-active compound profiles and aroma quality.