Characterization Of Potent Odorants Causing A "Pickle-Like" Off-Odor In Soy Sauce-Aroma Type Baijiu

"Pickle-like" off-odor is the most frequent detrimental off-odor in soy sauce-aroma type Baijiu.At present,the chemical essence of "pickle-like" off-odor is not clear,and it is difficult to control effectively in the brewing process.The occurrence of "pickle-like" off-odor decreases the quality of the soy sauce-aroma type Baijiu,resulting in economic losses for the Baijiu company.Based on the academic thought of molecular sensory science,this study is attempts to analyze the flavor chemical essence of the "pickle-like" off-odor in soy sauce-aroma type Baijiu via the application of several research strategies.Besides,establish a technical method for quickly determining the quality defect of "pickle-like" off-odor of soy sauce-aroma type Baijiu by using multivariate statistical analysis.The main research contents and conclusions are as follows:(1)In this study,the normal phase chromatography combined with GC-O/MS and GC×GC-TOF/MS were adopted to analyze the volatile flavor compounds in soy sauce-aroma type Baijiu,which eliciting the characteristics of "pickle-like" off-odor.However,no any odor compound smelled like "pickle-like" off-odor was detected.Thus,we speculate that the "picklelike" off-odor is a complicated characteristic off-odor,which produced by several compounds work together.Further,through a series of compound screening and accurate judgment,a total of 1086 volatile flavor compounds were identified at last.It lays a foundation for the analysis of the aroma characteristics of soy sauce-aroma type Baijiu.(2)This study draws on the molecular sensory science concept,conducted the method of comparative aroma extract dilution(cADEA)to analysis the difference of flavor between typical control(TC)and "pickle-like" off-odor(OF)soy sauce-aroma type Baijiu samples.Results showed that the concentrations of 23 odor compounds present significant difference between TC and OF.Further,the 23 compounds in 30 soy sauce-aroma type Baijiu samples which present different intensity of "pickle-like" off-odor were quantified.Statistical analysis showed that the contents of 12 compounds were increased with increasing intensity of the "pickle-like" off-odor in soy sauce-aroma type Baijiu.To verify the obtained analytical data,the 12 compounds present at higher concentrations in OF sample were spiked in the corresponding amounts to the original TC sample.Finally,a triangle test involving omission of the aroma compounds from spiked TC proved that 2-methyl-3-furanthiol,methional,methyl 2-methyl-3-furyl disulfide,dimethyl trisulfide,2-furfurylthiol,methanethiol,dimethyl disulfide,and bis(2-methyl-3-furyl)disulfide with higher concentrations were generally responsible for the "pickle-like" off-odor in soy sauce-aroma type Baijiu.(3)A rapid and convenient judgement method was established to identify the quality defect of "pickle-like" off-odor in soy sauce-aroma type Baijiu based on GC-PFPD and multivariate statistical analysis.The sulfur compounds in 20 soy sauce-aroma type Baijiu samples with different intensity of "pickle-like" off-odor were analyzed by GC-PFPD.Quantitative results combined with the intensity of "pickle-like off-odor" were statistically analyzed to find 6 marker compounds that caused the flavor quality difference on soy saucearoma type Baijiu.Last,a quick and convenient judgement PLS-DA model was constructed,the result of model verification shows that the judgment accuracy reaches 100%.