Li Ping, Song Wenjun, Wu Shankai, Wang Yumeng, Fan Yicong, Zhang Cuiying
College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin 300134, China.
Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Laboratory of Industrial Microbiology, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China.
Foods. 2024 Oct 4;13(19):3161. doi: 10.3390/foods13193161.
Diacetyl is a flavor compound in wine with a low threshold (1-2 mg/L). It is produced during alcoholic fermentation (AF) and malolactic fermentation (MLF) initiated by lactic acid bacteria (LAB). Whereas, the environment after AF suppresses the normal metabolism of LAB after AF. Researchs have shown the influence on diacetyl mechanisms of the genes , , , , , , and gene from in WY1. While we found that the diacetyl contents produced by mutants after MLF (Co-fermentation and Seq-fermentation) were significantly improved compared to AF alone. Moreover, the genes and from , and gene from exhibited significant effect on deacidification in our previous study, but the diacetyl of the mutants showed obvious improvement in this study. Thus the effects of association mutation of genes (, , , , , , , , and ) on deacidification, diacetyl and other flavors (organic acids, higher alcohols and esters) metabolism in after AF were detected in the study. Among all the mutants, strains V6AmS, V635mS, and V6B12mS showed the most favorable results. Specifically, the L-malic acid contents decreased to 1.26 g/L, 1.18 g/L, and 1.19 g/L, respectively. Concurrently, diacetyl levels were reduced by 52.56%, 61.84%, and 65.31%. The production of n-propanol increased by 18.84%, 20.89%, and 28.12%, whereas isobutanol levels decreased by 37.01%, 42.36%, and 44.04%, and isoamyl alcohol levels decreased by 19.28%, 19.79%, and 16.74%, compared to the parental strain WY1. Additionally, the concentration of lactate ester in the wine increased to 13.162 mg/L, 14.729 mg/L, and 14.236 mg/L, respectively.
双乙酰是葡萄酒中的一种风味化合物，阈值较低（1-2毫克/升）。它在酒精发酵（AF）和乳酸菌（LAB）引发的苹果酸乳酸发酵（MLF）过程中产生。然而，AF后的环境会抑制LAB在AF后的正常代谢。研究表明，来自WY1中的基因、、、、、、和基因对双乙酰机制有影响。而我们发现，与单独的AF相比，MLF（共发酵和顺序发酵）后突变体产生的双乙酰含量显著提高。此外，来自的基因和，以及来自的基因在我们之前的研究中对降酸有显著影响，但在本研究中突变体的双乙酰含量有明显改善。因此，本研究检测了基因（、、、、、、、、和）联合突变对AF后葡萄酒中降酸、双乙酰和其他风味（有机酸、高级醇和酯）代谢的影响。在所有突变体中，菌株V6AmS、V635mS和V6B12mS表现出最有利的结果。具体而言，L-苹果酸含量分别降至1.26克/升、1.18克/升和1.19克/升。同时，双乙酰水平分别降低了52.56%、61.84%和65.31%。与亲本菌株WY1相比，正丙醇产量分别增加了18.84%、20.89%和28.12%，而异丁醇水平分别降低了37.01%、42.36%和44.04%，异戊醇水平分别降低了19.28%、19.79%和16.74%。此外，葡萄酒中乳酸乙酯的浓度分别增加到13.162毫克/升、14.729毫克/升和14.236毫克/升。
