Variation of the odor-active compounds of cooked fragrant Simiao rice with degrees of milling

This study identified 20 key odor-active compounds in cooked brown rice (CBR), cooked medium-milled rice (CMMR), and cooked well-milled rice (CWMR) of fragrant Simiao rice by gas chromatography-olfactometry-mass spectrometry and odor activity value (OAV). Based on the metabolomics analysis method, aroma fingerprints for CBR, CMMR, and CWMR were established, and 10 differential odor-active compounds contributing to their odor differences were identified, including hexanal, nonanal, heptanal, octanal, decanal, (E)-2-decenal, (E,E)-2,4-decadienal, tetradecanal, acetoin, and 2-pentylfuran. An analysis of the source, OAV, and correlation with lipid content of differential odor-active compounds confirmed that variations in raw rice lipid content led to odor differences of cooked rice with different degrees of milling. Upon the comprehensive evaluation of bran degree and ratio of germ-remained kernels of the samples, it was established that monitoring the ratio of germ-remained kernels during milling was crucial to ensure odor quality of CMMR. This research had significant implications for guiding the medium milling and advancing in the flavor and breeding of rice.