Aging-induced evolution in rice-flavored Baijiu: analysis of non-volatile organic compounds, volatile organic compounds multispectral characteristics, and viscosity

Aging plays a key role in improving the sensory quality of Chinese Baijiu, yet the molecular evolution of rice-flavored Baijiu (RFB) remains insufficiently explored. This study systematically explored the aging-induced evolution of non-volatile and volatile flavor compounds, spectral features, and viscosity in RFB aged for 0–15 years. 855 non-volatile organic compounds (N-VOCs) were identified, among which 118 key differential compounds were screened, mainly including phosphatidylcholines, long-chain fatty acids, amino acid derivatives, and benzenoids. Aging promoted the accumulation of lipid and lipid-like molecules, especially phosphatidylcholines, while most long-chain fatty acids exhibited an overall decreasing trend. A total of 180 volatile organic compounds (VOCs) were identified, and 34 key aroma compounds were selected, primarily esters, higher alcohols, and organic acids. Early aging enhanced ester formation, whereas prolonged storage led to a decline in low-molecular-weight esters and higher alcohols. Spectroscopic and viscosity results revealed a clear inflection point at 6 years. Hydrogen bonding and ethanol-water clusters formation strengthened before this stage, leading to maximum viscosity. After 6 years, hydrogen networks weakened and clusters dissociated, which differs from strong- and sauce-flavor Baijiu. These findings provides a systematic understanding of the aging evolution of RFB and offers scientific guidance for improving its quality during the aging process.