Comparative study on key aroma components of Hongqu Huangjiu with different sugar contents through aroma analysis technology.

Hongqu Huangjiu (HQHJ) is a representative traditional Chinese fermented beverage with medicinal and nutritional value. However, composition of aroma-active components in HQHJ with different sugar contents remains unclear. Herein, solid-phase extraction combined with gas chromatography-olfactometry-mass spectrometry revealed 56 aroma-active compounds (20 newly identified) in HQHJ. Difurfuryl sulfide was identified as a odorants in Huangjiu for the first time. After quantification and odour activity value calculation, β-phenethyl alcohol, dimethyl trisulfide, 1,1-diethoxyethane and ethyl isobutyrate were identified as important odorants. Combined with partial least squares regression analysis and addition tests, ethyl 4-oxopentanoate (imparting Chen aroma to HQHJ) and 2-methoxy-4-vinylphenol were validated as key differential odorants in HQHJ with varying sugar contents. Notably, semi-sweet HQHJ promoted contents accumulation of aroma compounds, while semi-dry HQHJ enhanced aroma intensities and diversity of compounds. Conversely, sweet HQHJ, through its brewing process involving adding alcohol, inhibited formation of certain compounds. Therefore, they exhibited distinctive aromatic characteristics.