WU Lin, CHEN Zhiqiang, JIANG Wei, LIU Wei, ZHANG Yiji, ZHU Jiajian
To ensure liquor quality and improve the brewing process, this study employed headspace solid-phase microextraction combined with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (HS-SPME-GC×GC-TOF-MS) to analyze Maotai-flavor Baijiu of various qualities.It was determined that Maotai-flavor Baijiu contains 1 063-1 347 components, including esters, acids, alcohols, aldehydes, ketones, and sulfur-containing substances.The percentages of esters in high-quality Baijiu A1 and A2, as well as mixed-flavor Baijiu B1 and B2, were 58.75%, 55.47%, 42.05%, and 41.55%, relative contents of alcohols were 17.14%, 16.15%, 26.77%, and 26.92%, respectively.The percentages of acids present were 1.47%, 2.05%, 6.71%, and 7%.69%.High-quality Baijiu exhibited high levels of ester, low alcohol, and moderate acid, while mixed-flavor Baijiu had low ester, high alcohol, and high acid.Sulfur-containing components such as sulfur ethers, sulfones, thioesters, and thiophenes were more prevalent in mixed-flavor Baijiu, whereas they were either negligible or undetectable in high-quality Baijiu.The use of principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) revealed significant variations in flavor between high-quality Baijiu and mixed-flavor Baijiu.A total of 85 potential flavor components were identified, each with a variable importance in the projection (VIP) value >1.Notably, components with VIP>1 and P<0.05 were mapped using a heatmap.The study identified that high-quality Baijiu was characterized by high levels of ethyl butyrate, ethyl caproate, nonanal, and octanal, while mixed-flavor Baijiu had high levels of caproic acid, acetic acid, isobutanol, isoamyl alcohol, etc.The sensory evaluation revealed that the mixed-flavor Baijiu had a lower intensity of ester aroma, a stronger advanced alcohol flavor, a slightly acidic flavor, a slightly unusual aroma, and a lack of crispness, which was consistent with the result of low ester, high alcohol, high acid, and the presence of more sulfur-containing substances.The results of this study indicate that HS-SPME-GC×GC-TOF-MS technology can be used to investigate the Maotai-flavor high-quality Baijiu at the molecular level.This provides effective technical support for the subsequent quality improvement and process control of Maotai mixed-flavor Baijiu.