Detection Of Nong-jiang Flavor Liquors Of Different Years And Study Of Their Aroma Compounds

The topic mainly focuses on identification of nong-jiang flavor liquors of different years(3-year(3Y),5-year(5Y),12-year(12Y),15-year(15Y)and 20-year(20Y))and study of their aroma compounds.The contents of this paper are as follows:(1)Nong-jiang flavor liquors of different years were analyzed by electronic nose(E-nose).Through single factor level experiments combined with sensor response values(G/G0)analysis,linear discriminant analysis(LDA)and analysis of variance(ANOVA),the optimal operating conditions are alcohol concentration of 14%vol,heating temperature of 40°C,heating time of 30 min.The RSDs of 10 sensors are small,indicating that the E-nose technology is stable.Nong-jiang flavor liquors of different years are completely dispersed by LDA,and their original information retention more than 96.78%.Combined with the stepwise linear discriminant analysis,the aged liquors stored within 12 years can obtain 100% prediction accuracy and more than 12 years can also obtain a high accuracy.(2)The trace substances of Nong-jiang flavor liquors of different years were analyzed by headspace-gas phase-ion mobility spectroscopy(HS-GC-IMS)for the first time.60 signals detected were used to establish fingerprint and analyze relative content.Among them,the concentration of 15 compounds increase with the cellaring ages,13 compounds decrease with the cellaring ages,and 6 compounds basically keep unchanged.Similarity analysis shows that the differences among five liquors are positively correlated with the differences of cellaring ages,indicating that the cellaring age is of great significance to the quality of nong-jiang flavor liquors of different years.3Y,5Y and 12 Y can be completely separated by PCA,but 15 Y and 20 Y cannot be separated,indicating that the composition of 15 Y and 20 Y are very similar.(3)In the study,quantitative results of five liquors including liquid-liquid extraction(LLE)combined with gas chromatography-mass spectrometry(GC-MS),headspace solid-phase microextraction(HS-SPME)combined with GC-MS and GC were integrated,aim at having a comprehensive and accurate understanding for nong-jiang flavor liquors of different years.A total of 128 compounds were quantified,including 70 esters,18 alcohols,9 acids,5 aromatic compounds,6 pyrazines,2 sulfur compounds,8 furans,4 aldehydes,5 ketones,and 1 acetal.The total concentration of esters,acids,aromatic compounds,and pyrazines increases with the cellaring ages,and alcohols decreases with the cellaring ages.According to heat map,five liquors were clearly grouped into two clusters,3Y and 5Y are grouped into one cluster(I);12Y,15 Y and 20 Y are grouped into another cluster(II),and the cluster II can be divided into 2 sub-clusters: 12 Y and 15 Y,20Y.In the study,a total of 63 aroma compounds were identified,including 23 important aroma compounds(OAV>10)and 16 aroma compounds(OAV>1).Among them,there are 12 compounds,including ethyl butyrate,ethyl 3-methylbutyrate,ethyl valerate,ethyl hexanoate and hexyl hexanoate,ethyl octanoate,n-hexanoic acid,guaiacol,4-methylguaiacol,dimethyl disulfide,3-methylbutanal and 2,3-butanedione,contribute the most to the aroma in nong-jiang flavor liquors of different years.