Study On The Effect Of Addition Of Nitrogen Source And Environment Temperature On The Quality Of Huangjiu

The factors affecting the quality of Huangjiu are mainly divided into two categories,one is the fermentation raw materials and the other is the fermentation process.This study selected exogenous supplemental yeast assimilable nitrogen in the fermentation raw materials and environment temperature in the fermentation process,and investigated the effects of two factors,additional nitrogen sources and fermentation environment temperatures on the quality of Huangjiu,in order to clarify the effects of different temperature conditions on the quality of Huangjiu and the effects of additional nitrogen sources on yeast growth,fermentation properties,and yeast metabolism during the fermentation of Huangjiu,with the aim of providing technical support for further improvement of in order to provide technical support to further improve the quality of Huangjiu.The main contents and results of the study are as follows:(1)Effects of adding nitrogen sources on Huangjiu fermentation and yeast metabolism.Three types of yeast assimilable nitrogen(YAN)were added to simulate Huangjiu fermentation experiment at 267mg/L(in N)to investigate the effects of different types of YAN on the growth,fermentation properties,yeast metabolites and the effects of YAN on yeast transcriptomics in Huangjiu.The fermentation kinetics,amino acid,esters and higher alcohols changes of Huangjiu were measured and transcriptomic sequencing was performed.It was found that YAN significantly promoted yeast growth and reproduction during fermentation,enhanced yeast sugar metabolism and alcohol metabolism during fermentation;significantly decreased the content of glutamic acid and alanine,and significantly promoted the formation of arginine,valine,phenylalanine,cystine,leucine and lysine;ammonium chloride,arginine and glutathione increased 85.64%,23.64% and 94.38%,and total advanced alcohols decreased by 27.91%,25.31% and 12.05%,respectively.Transcriptome sequencing analysis identified 54 genes related to nine metabolic pathways,including galactose metabolism,starch and sucrose metabolism,glycolysis,amino acid biosynthesis,and pyruvate metabolism,as important factors affecting yeast growth,yeast glucose metabolism and alcohol metabolism,and higher alcohol content.They can provide a technical method for the quality improvement of Huangjiu,and a theoretical reference for clarifying the biological mechanism of brewing yeast growth and metabolism.(2)Effect of environment temperature on the quality of Huangjiu.The traditional Chinese solar terms reflect temperature changes.Huangjiu was brewed in each of the five solar terms and aged for one year to determine the basic physicochemical indicators,volatile components,amino acid content and sensory analysis of the indicators.It was found that the ethanol,total sugar and p H of Huangjiu fermented at different temperature conditions without significant difference,and there were significant differences in total acid and amino nitrogen.The amino acid and essential amino acid contents varied somewhat,with the highest amino acid content of 4184.15 mg/L in T5,followed by 3737.65 mg/L and 3862.71 mg/L in T2 and T3,respectively.43 volatile components were detected by GC-MS,with the highest content of esters and alcohols,and 14 OAV>1 compounds such as phenylethanol,ethyl caprylate and phenylethanal.Ethyl butyrate,isobutanol,acetic acid,nonanal and 19 other substances were important in distinguishing Huangjiu fermented at different temperatures.Sensory analysis showed that Huangjiu fermented in T3 had the highest score of 91.0,followed by T2 and T4 with 83.7 and 85.7,respectively,meaning that Huangjiu brewed around the Winter Solstice(T3)had a better taste,and Huangjiu fermented at the Winter Solstice had the best taste quality.This study will provide a theoretical reference for Huangjiu process improvement and Huangjiu quality enhancementIn this study,to improve the quality of Huangjiu,we investigated the effects of two factors on the quality of Huangjiu: fermentation raw materials-additional nitrogen source and fermentation processenvironment temperature.The results showed that the additional nitrogen source could significantly promote the growth of yeast,improve the fermentation efficiency of Huangjiu,added nitrogen source significantly promoted yeast growth,fermentation efficiency,promoted ester production and reduced the content of higher alcohols,especially arginine and ammonium chloride had the best effect.The transcriptomic results on this basis revealed that nine metabolic pathways related to sugar metabolism,amino acid metabolism and pyruvate metabolism and genes,were the main reasons for the differences in yeast growth,yeast fermentation and metabolism.And appropriate low temperature fermentation could improve the quality of Huangjiu,and Huangjiu fermented in Winter Solstice had the best quality.