为了保证白酒质量和提高白酒酿造工艺水平,该研究采用顶空固相微萃取结合全二维气相色谱-飞行时间质谱(headspace solid phase microextraction-comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry, HS-SPME-GC×GC-TOF-MS)技术对不同品质酱香型白酒进行分析。研究发现,酱香型白酒中检出组分1 063种~1 347种,主要为酯类、酸类、醇类、醛类及酮类等。优质酒A1、A2和杂味酒B1、B2的酯类物质相对含量分别为58.75%、55.47%、42.05%和41.55%;醇类物质相对含量分别为17.14%、16.15%、26.77%和26.92%;酸类物质的相对含量分别为1.47%、2.05%、6.71%和7.69%;优质酒呈现酯高、醇低、酸适中,杂味酒呈现酯低、醇高、酸高等特点;且杂味酒中硫醚类、砜类、硫代酯类、噻吩类等含硫类组分较为突出,而优质酒中则含量很低或未检出。结合主成分分析(principal component analysis, PCA)和正交偏最小二乘判别分析(orthogonal partial least-squares discrimination analysis,OPLS-DA),显示优质酒和杂味酒的风味差异显著,其中变量权重值(variable importance in the projection,VIP)＞1的潜在差异风味组分共有85种;筛选出VIP＞1且P＜0.05的物质绘制热图,结果表明优质酒中丁酸乙酯、己酸乙酯、壬醛、辛醛等含量较高,杂味酒中己酸、乙酸、异丁醇、异戊醇等含量较高。通过感官品评发现,杂质酒中酯香强度较低,高级醇味较强,口感略酸,略有异香,缺乏爽净感等,与杂质酒中组分鉴定的酯低、醇高、酸高以及存在的含硫类物质较多等结果具有一致性。该研究结果表明,HS-SPME-GC×GC-TOF-MS技术可在分子水平对酱香型杂味酒进行探究,为后续酱香型杂味酒的品质提升和工艺控制提供有效的技术支撑。
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.
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