Research Of Nonvolatile Compounds In Fermented Grains In Chinese Roasted-sesame-like Aroma Type Liquor

Fermented grains are mixture of cooked sorghum,barley,corn and other grains and qu.The Qu is the saccharifying ferment.In the process of fermentation,the microorganisms decompose and use the raw materials.The starch is decomposed into glucose and other reducing sugars by the microorganisms.The reducing sugar can be further transformed into various small molecular substances by microorganisms.Sugar,amino acids,fat acids can react with each other during the fermentation process and some flavor substances are produced.Nowadays,most studies on fermented grains are focused on volatile compounds.However,there are few studies on non-volatile compounds in fermented grains.The types of sugars,organic acids and amino acids,and the changes of these compounds in the fermentation process are not studied.Therefore,the research and analysis on nonvolatile compounds in fermented grains are helpful to get a full understanding of the fermented grains.In this paper,the free amino acids,organic acids and carbohydrates in the fermented grains of Chinese roasted-sesame-like aroma type liquor were identified by derivatization combined with gas chromatography-mass spectrometry(GC-MS).In order to understand the difference between fermented grains by mechanical and traditional production,this study measured and analyzed the content of nonvolatile compounds during the fermentation process.Moreover,the changes of nonvolatile compouds during the distillation process were studied.The study mainly includes the following research contents:(1)For the first time,N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide(MTBSTFA)and hexamethylsilazane(HMDS)combined with GC-MS were used to analyze the nonvolatile components such as free amino acids,organic acids and carbohydrates in fermented grains.16 carbohydrates(7 sugars,8 alditols and 1 glycoside),14 amino acids and 8 nonvolatile organic acids were indentified.Futhermore,one glucoside was temporality identified.(2)Quantitative analysis of nonvolatile compounds in fermented grains was carried out.The results showed that the four amino acid with highest content in the fermented grains were proline,alanine,and glutamic acid.The higher content of free sugars and alditols were glucose,meso-erythritol,arabitol,ribitol,xylitol.Nonvolatile organic acids are lactic acid,3-hydroxyisobutyric acid,3-hydroxy-3-methyl glutaric acid,malic acid,citric acid and succinic acid,in which lactic acid had the highest content.(3)Quantitative analysis of nonvolatile compounds in fermented grains by mechanical and traditional production during fermentation was carried out and their changes were studied.Then,the changes of nonvolatile compounds in the two craft were compared and analyzed.The content of proline in the fermented grains by traditional production was higher than that in the fermented grains by mechanical production.The content of lactic acid among the nonvolatile acids was the highest and the content of lactic acid in the fermented grains by traditional production was higher than that in the fermented grains by mechanical production.The content of glucose rised before reduction.The content of glucose in the fermented grains by traditional production was higher than that in fermented grains by mechanical production.The content of glucose rised before reduction.The content of glucose in the fermented grains by traditional production was higher than that in fermented grains by mechanical production.The content of alditols in the fermented grains by traditional production was higher than that in fermented grains by mechanical production.During the fermentation process,the change of disaccharides in fermented grains by mechanical and traditional production was similar and not obvious.The content of methyl-?-D-glucoside and glycerylglucoside in fermented grains by traditional production changed faster than that in fermented grains by mechanical production.(4)The contents of nonvolatile compounds in fermented grains before and after distillation were analyzed.The total contents of free amino acids were increased by 8.21% and the change was not obvious.The highest free amino acids were alanine and proline after distillation.The content of ornithine and lysine changed much more.The total content of non volatile organic acids decreased.Lactic acid had the highest content after distillation,which was 29.65% lower than that before distillation.The total content of sugar decreased by 15.30% after distillation.The sugar with the highest content was arabinose after distillation.Glucose had the most significant change and its content increased by 155.22%.