Isolation and Characterization of Yeast with Benzenemethanatiol Synthesis Ability Isolated from Baijiu Daqu  
[PERSON]  
1 Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University,  
Ministry of Education, Beijing 100048, China; [EMAIL_ADDRESS] (G.Z.) [PERSON]  
1 Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University,  
Ministry of Education, Beijing 100048, China; [EMAIL_ADDRESS] (G.Z.) [PERSON]  
1 Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University,  
Ministry of Education, Beijing 100048, China; [EMAIL_ADDRESS] (G.Z.) [PERSON]  
1 Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University,  
Ministry of Education, Beijing 100048, China; [EMAIL_ADDRESS] (G.Z.) [PERSON]  
1 Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University,  
Ministry of Education, Beijing 100048, China; [EMAIL_ADDRESS] (G.Z.) [PERSON]  
1 Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University,  
Ministry of Education, Beijing 100048, China; [EMAIL_ADDRESS] (G.Z.) [PERSON]  
1 Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University,  
Ministry of Education, Beijing 100048, China; [EMAIL_ADDRESS] (G.Z.) Footnote 1: email: {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,  
enriched with a plethora of aroma compounds, owing to its intricate and elaborate production process. Ethanol and water account for 98% of the total weight of baijiu, while flavor compounds make up the remaining 2% [5]. Baijiu is known to contain in excess of 2000 aroma odorants, encompassing a diverse range of compounds such as alcohols, esters, aldehydes, acids, and sulfur compounds, which contribute to its distinct aroma [6; 7]. Sulfur-containing compounds are particularly noteworthy as they have an extremely low threshold, low concentration, and distinctive aroma characteristics. They can enhance the overall aroma of baijiu at trace concentrations, high or incongruuous levels can lead to off-odor [8; 9; 10]. Several compounds, such as 2-furfurylthiol and benzenemethanethiol, have been identified in baijiu and are known to promote its sesame, roasted, and overall flavor and quality [11; 12; 13]. Notably, benzenemethanethiol has garnered recognition as a significant aroma compound within the flavor spectrum of baijiu, owing to its profound presence and substantial impact on the sensory experience of baijiu [11; 12; 14]. Despite a trace concentration range of 0.02 \(\upmu\)g/L-90 \(\upmu\)g/L, a conclusion has been substantiated through the implementation of aroma recombination and omission tests [13; 14; 15]. [PERSON] and colleagues have identified benzenemethanethiol as a pivotal contributor to the aroma profile of Chinese sesame-flavored baijiu [12]. Since then, several studies have quantified the levels of benzenemethanethiol in various baijiu samples using different analytical methods, with trace amounts detected at 4.87 \(\pm\) 0.27 \(\upmu\)g/L and an odor activity value (OAV) of 487 signifying its substantial flavor contribution [11; 13; 14; 15]. However, despite these efforts, the mechanism behind the formation of benzenemethanethiol during baijiu fermentation remains enigmatic. Previous studies have suggested that yeast may transform cysteine-benzaldehyde adducts into benzenemethanethiol through the action of \(\upbeta\)-(carbon-sulfur) lyase enzyme [16; 17; 18; 19] (Figure 1). Hence, our hypothesis suggests that yeast may employ L-cysteine and benzaldehyde as substrates, leading to the production of benzenemethanethiol through biochemical reactions. This knowledge gap underscores the urgent need for further exploration and research in this particular area.