Comparison Of Compounds Between Traditional And Mechanical RAW Baijiu (Chinese Liquor) Of Laobaigan And Roasted-sesame-like Aroma Type Baijiu

Traditional Chinese liquor(baijiu)is mainly handmade,but in recent years,this way has been turning to mechanization again.Mechanical equipments have been used instead of manual operations,such as in the raw material processing,pit entry,pit export,liquor distillation and other production chains.The production of laobaigan,and roasted-sesame-like aroma type baijius have high level of mechanization at present,but due to the lack of a scientific summary of the traditional brewing and the difficulty to simulate the manual operation with the mechanized devices leads to being difficult to ensure the key parameters.Finally,flavor and quality differences of the two may exist.However,there are few reports on the differences of the components between traditional baijiu and mechanical baijiu currently.And it is unclear what their differences are.Besides,the difference researches of baijius are most about volatile compounds,seldom refer to non-volatile compounds,which will cause the incomplete comprehension on the study.Therefore,it is of great practical importance for exploring the differences of the compositions between the traditional baijiu and the mechanical baijiu,and providing theoretical and practical guidance for improving the quality of mechanical baijius.So in this paper,a comprehensive study on the volatile and non-volatile compounds in traditional/mechanical raw baijius of roasted-sesame-like aroma type,and laobaigan aroma type were separately carried out.The details are as follows:(1)By gas chromatography with flame ionization detector(GC-FID),ultra performance liquid chromatography(UPLC),and liquid-liquid microextraction(LLME)and hexamethyldisilazane(HMDS)derivatization coupled with gas chromatography-mass spectrometry(GC-MS),and other methods,a total of 99 compounds in roasted-sesame-like aroma type and laobaigan aroma type raw baijius were quantified,including 27 acids,8 alcohols,24 esters,15 aromatic compounds,3 phenols,6 furans,5 sugar alcohols,4 sugars,2 sulfides,2 terpenes,1 pyrazine,1 acetal and 1 lactone.(2)The total concentrations of compounds in roasted-sesame-like aroma type traditional raw baijiu were higher than mechanical raw baijiu.Except acids,phenols,sulfides and lactones,the concentrations of other compounds in traditional raw baijiu were higher than mechanical raw baijiu.And through discriminant analysis(DA),the two raw liquors could be classified by lactic acid,2-hydroxybutyric acid,2-hydroxyisopentoic acid,succinic acid,2-methylpropionic acid,benzoic acid,4-hydroxybenzoic acid,4-hydroxyphenethyl alcohol,ethyl 4-ketovalerate,2-furfuryl butyrate and ethyl pentadecanoate.(3)The total concentrations of compounds in laobaigan aroma type traditional raw baijiu were higher than mechanical raw baijiu from the first and second runs.In mechanical raw baijiu from the first run,compared with traditional raw baijiu from the first run,the concentrations of esters,alcohols,furans and aromatic compounds were relatively lower,and the concentrations of phenols,acetal,sugars and sulfides were relatively higher.However in mechanical raw baijiu from the second run,compared with traditional raw baijiu from the second run,the concentrations of esters,furans and terpenes were relatively lower,and the concentrations of phenols,acetal,lactone,sugars,sugar alcohols and aromatic compounds were relatively higher.The two raw liquors from the first run could be classified by 2-furoic acid,3-hydroxybutyric acid,2,3-dihydroxypropanoic acid,malic acid,lactic acid,pentanoic acid,3-methylbutanol,diethyl succinate,ethyl butyrate and ethyl decanoate by using DA.And also through DA,the two raw liquors from the second run could be classified by succinic acid,dodecanoic acid,myristic acid,pentadecanoic acid,pyruvic acid,ethyl octanoate,isoamyl acetate,diethyl malonate and 2,3,4,5-tetramethylpyrazine.(4)After the mechanized production of the two raw baijius,the concentrations of phenols increased,while the concentrations of total compounds,furans and esters decreased.Besides,the concentrations of 4-ethylphenol and 4-ethylguaiacol in the mechanical raw baijiu increased obviously,while the concentrations of 1-butanol decreased obviously.Besides,the concentrations of ethyl lactate,ethyl butyrate,ethyl hexanoate,1-octanol,propionic acid,butyric acid,dodecanoic acid,oleic acid,pyruvic acid,furfural and ethyl 3-phenylpropionate also decreased in raw baijius,while the concentration of benzyl alcohol also increased.(5)To get a preliminary exploration of the volatile and non-volatile organic acid content and composition from different aroma type raw baijius,UPLC,LLME-GC-MS and HMDS derivatization coupled with GC-MS were employed.A total of 40 organic acids were identified and quantitated in baijius.The total concentration of organic acids in raw baijius were: herblike > soy sauce > sweet and honey > miscellaneous > texiang > chixiang > fenxiang > strong > roasted-sesame-like > light > laobaigan aroma types.