Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China; National Engineering Research Center of Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, PR China.
National Engineering Research Center of Solid-State Brewing, Luzhou 646000, PR China.
Food Res Int. 2023 May;167:112594. doi: 10.1016/j.foodres.2023.112594. Epub 2023 Feb 17.
The aged Chinese liquor, Baijiu, is highly valued for its superior organoleptic qualities. However, since age-authentication method and aging-mechanism elucidation of Baijiu is still in the exploratory stage, high-quality aged Baijiu is often replaced by lower-quality, less-aged product with fraudulent mislabeling. Authentic high-quality strong-flavor Baijiu was analyzed by gas chromatography-mass spectrometry. Total esters decreased with aging, while acids, alcohols, aldehydes, ketones, terpenes, pyrazines increased. Although concentrations of partial compounds showed non-monotonic profiling during aging, a close positive linear correlation (R = 0.7012) of Baijiu Evenness index (0.55-0.59) with aging time was observed, indicating a more balanced composition in aged Baijiu. The reaction quotient (Qc) of each esterification, calculated by the corresponding reactant and product concentration, approached to the corresponding thermodynamic equilibrium constant Kc. This result demonstrated that the spontaneous transformation driven by thermodynamics explained part of the aging compositional profiling. Furthermore, an aging-related feature selection and an age-authentication method were established based on three models combined with five ranking algorithms. Forty-one key features, including thirty-six compound concentrations, four esterification Qc values and the Evenness index were selected out. The age-authentication based on neural network using forty-one input features accurately predicted the age group of Baijiu samples (F1 = 100 %). These findings have deepened understanding of the Baijiu aging mechanism and provided a novel, effective approach for age-authentication of Baijiu and other liquors.
中国陈年老酒白酒，因其卓越的感官品质而备受推崇。然而，由于白酒的年份鉴定方法和陈酿机理仍处于探索阶段，高质量的陈年老酒往往被低质量、低年份、假冒标签的产品所取代。本研究采用气相色谱-质谱联用技术对正宗优质浓香型白酒进行了分析。随着陈酿时间的延长，总酯含量逐渐降低，而酸、醇、醛、酮、萜烯、吡嗪类化合物的含量逐渐增加。虽然部分化合物的浓度在陈酿过程中呈现出非单调分布，但白酒均匀度指数（0.55-0.59）与陈酿时间之间存在紧密的正线性相关（R=0.7012），表明陈年老酒的成分更加平衡。通过相应反应物和产物浓度计算出每个酯化反应的反应商（Qc），并接近相应的热力学平衡常数（Kc）。这一结果表明，热力学驱动的自发转化解释了部分陈酿成分分布的原因。此外，基于三个模型结合五种排序算法，建立了一种与陈酿相关的特征选择和年份鉴定方法。从三十六个化合物浓度、四个酯化 Qc 值和均匀度指数中筛选出了四十一个关键特征。基于神经网络的年龄鉴定方法使用四十一个输入特征能够准确预测白酒样品的年龄组（F1=100%）。这些发现加深了对白酒陈酿机理的理解，并为白酒及其他酒类的年份鉴定提供了一种新颖、有效的方法。
