Revelation for the Influence Mechanism of Long-Chain Fatty Acid Ethyl Esters on the Baijiu Quality by Multicomponent Chemometrics Combined with Modern Flavor Sensomics

Abstract

Long-chain fatty acid ethyl ester (LCFAEEs) is colorless and has a weak wax and cream aroma. It can be used as an intermediate for the synthesis of emulsifiers, and stabilizers and be applied in the production of flavor essence. It is also an important trace component in Baijiu and is attributed to making a contribution to the quality of Baijiu, but its distribution in Baijiu has not been clear, and its influence mechanisms on Baijiu quality have not been systematically studied. Therefore, the distribution of LCFAEEs for Baijiu in different years (2014, 2015, 2018, and 2022), different grades (premium, excellent, and level 1; note: here Baijiu grade classification was based on Chinese standard (GB/T 10781) and enterprise classification standard), and different sun exposure times (0, 6, 12, 20, 30, and 50 days) was uncovered. Thus, in this study, the effect of LCFAEEs on the quality of Baijiu was comprehensively and objectively proven by combining modern flavor sensomics and multicomponent chemometrics. The results showed that with the increase in Baijiu storage time, the concentration of LCFAEEs increased significantly in Baijiu (4.38–196.95 mg/L, p < 0.05). The concentration of LCFAEEs in level 1 Baijiu was significantly higher than that in excellent and premium Baijiu (the concentration ranges of ET, EP, EO, E9, E912, and E91215 were: 0.27–2.31 mg/L, 0.75–47.41 mg/L, 0.93–1.80 mg/L, 0.98–12.87 mg/L, 1.01–27.08 mg/L, and 1.00–1.75 mg/L, respectively, p < 0.05). With the increase in sun exposure time, the concentration of LCFAEEs in the Baijiu first increased significantly and then decreased significantly (4.38–5.95 mg/L, p < 0.05). As the flavor sensomics showed, the concentrations of LCFAEEs in Baijiu bodies were significantly correlated with the Baijiu taste sense (inlet taste, aroma sensation in the mouth), as well as with the evaluation after drinking (maintaining taste) (p < 0.05, r > 0.7). Based on the above, LCFAEEs are critical factors for Baijiu flavor thus, it is essential to explore a suitable concentration of LCFAEEs in Baijiu to make Baijiu’s quality more ideal.

Identification of regionalmarkers based on the flavor molecular matrix analysis of sauce‐aroma style baijiu

“…In detail, propyl hexanoate was the most important regional marker identified by all methods, and the other potential regional markers were ethyl octanoate, ethyl 2‐methylpropanoate, propyl acetate, ethyl heptanoate, ethyl trans ‐4‐decenoate, 2‐nonanone, heptanoic acid and butyl hexanoate. Among them, four esters ((i) produced by bacteria converting acetic acid into butyric acid or caproic acid through metabolism and then reacting with ethanol; (ii) produced by yeast directly using grain) 38 played an important role in distinguishing baijiu production regions and the fact is that Saccharomyces mainly produced ethanol which served as the precursor for synthesizing the ethyl esters during fermentation 39 . The great differences in microorganisms are mainly related to the geographical environment in various production regions, which fully confirmed their reliability as regional markers.…”

Integration of Chemometrics and Sensory Metabolomics to Validate Quality Factors of Aged Baijiu (Nianfen Baijiu) with Emphasis on Long-Chain Fatty Acid Ethyl Esters

“…The esters may act as sensory modulators by inhibiting the activation of certain receptors that perceive spiciness, resulting in a milder and less intense spicy sensation. Although the addition of LCFAEEs offers benefits like flavor improvement and reduced spiciness, it is important to acknowledge that it also results in a decrease in the intensity of aroma release in the oral cavity [ 11 , 25 , 27 , 54 , 59 , 60 , 61 ]. This can be attributed to the physical properties of the esters, which may impede the diffusion of aroma compounds and their interaction with receptors in the mouth.…”

“…Research findings indicated that the pronounced influence of LCFAEEs on the quality of aged Baijiu was verified by combining the distribution of LCFAEEs and sensory evaluation for different years of Baijiu. However, due to the limited number of experimental samples and the years typically spanning 3–5 years, it was not possible to comprehensively reflect the influence of LCFAEEs on the quality of aged Baijiu [ 11 , 12 , 13 ].…”