Discrimination Of Wine Aged With Different Toasted Oak Chips By Electronic Nose And GC-MS

Three toasted degrees of oak chips (light, medium, and heavy) andheavy toasted oak powders were employed to age wine for30days at aconstant temperature (25°C) and relative humidity (60%). Electronic nose(e-nose) and SPME-GC-MS (Solid phase microextraction-gaschromatography-mass spectrum) were employed to study the effect oftoasting degree of oak chips and aging time on the oak related aromas inwine.Main research contents and results:(1) Discrimination of wine aged with different toasted oak chips anddifferent aging times by e-noseAccording to the aroma information collected by e-nose, PCA(principal component analysis) and LDA (linear discrimination analysis) ofe-nose were used to discriminate wines aged with different toasted oak chipsand different aging times. Results showed that LDA-DI (differential index) was over80%during the30days of aging, so wines aged with differenttoasted oak chips and times were well discriminated by LDA. Since LDA-DI (differential index) was bigger than PCA-DI, LDA was better than PCAfor discriminating wines aged with different toasted oak chips and times.(2) Discrimination of wine aged for different times by e-noseAccording to the aroma information collected by e-nose, PCA andLDA of e-nose were used to discriminate wines aged for different time (0,2,3,5,9,18,26,30d). Results showed that, for wine aged with the sametoasted oak chips, LDA of e-nose can well discriminated wine aged fordifferent time. At the same time, LDA-DI was still bigger than PCA-DI. Itshowed that LDA was better than PCA for discriminating wines aged fordifferent time.(3) Quantification of oak related aromatic compounds in wine by SPME-GC-MSGuaiacol, eugenol, vanillin and syringaldehyde were the products fromthe degradation of lignin, and they were the four main oak aromaticcompounds that contribute to the wine aroma. After solid phase micro-extraction, GC-MS were used for quantification of oak aromatic compoundsin wine aged with different toasted oak chips and aged for different times.Results showed that, the concentrations of the four oak aromatic compounds increased to peak quickly before day5, and then decreased after that. Fromday9to day18, their concentrations increased a little, and they keptbasically stable after day18. Results also showed that the concentration ofeach oak aromatic compound differed for wines aged with different toastedoak chips, and both the aging time of wine and the toasted degree of oakchips influenced the concentration of oak aromatic compounds in wine.(4) Comparison of results from e-nose and SPME-GC-MSE-nose could effectively discriminate wines aged with different toasteddegrees of oak chips (or oak powders). It indicated that the wines haddifferent wine aromas. Results from GC-MS indicated that different toasteddegrees of oak chips led to the different concentrations of each oak aromaticcompound in the wine. It showed that the toasting degrees of oak chips (oroak powders) can influence the concentrations of oak aromatic compounds,leading to the difference of wine aromas. E-nose can recognized thedifference.E-nose can clearly discriminate wines aged for0,2,3,5,9days, butthe discrimination results for wines aged for9,18,26,30days were notobviously. These results indicated that there was more difference in winearoma for wine aged for less than9days than those aged for9,18,26, and30days. GC-MS results showed that there were different concentrations inguaiacol for wine aged for less than9days. Eugenol, vanillin andsyringaldehyde also had different concentrations for wine aged less than9days. Wines aged for9,18,26,30days had similar concentrations inguaiacol, vanillin and syringaldehyde, but not in eugenol. Consequently,concentration of each oak aromatic compound showed big difference forwine aged for0,2,3,5,9days, while it showed unconspicuous differencefor wine aged for9,18,26,30days. Hence oak aroma in wine differed forwine aged for0,2,3,5,9days clearly, but not obviously for wine aged for9,18,26,30days.The toasted degree of oak chips and the aging time of wine influencedthe concentrations of guaiacol, eugenol, vanillin and syringaldehyde,leading to different wine aromas. E-nose can recognize the difference ofwine aroms, which were caused by toasting degree of oak chips and theaging time.