Study On The Impact Odorants Of Wine And The Formation Of Wine Aroma Characteristics

This research focused on the impact volatile compounds in wines and the formation oftypical wine aroma properties. A optimized prefermentative freezing process was proposed totreat the Meili grapes to enhance the intensity of wine aroma. Then the regression modelswere built to explain the relationship of aroma properties and impact odorants. The changes ofvolatile compounds in Cabernet Sauvignon wines of different vintage were also discussed toreveal the chemical bases of aromatic changes.(1) The influence of a prefermentative freezing process on changes of aromaticcharacteristics and volatile compounds in Meili wines was studied to optimize freezingparameters and reveal the mathematical relationship between aromatic characteristics andvolatile compounds. The wines obtained were characterized by sensory evaluation and stir barsorptive extraction (SBSE) followed by a thermal desorption-gas chromatography-massspectrometry analysis. A total of28aromatic descriptors from6categories of wine aromaterminology were identified. In addition,19varietal aroma compounds and36fermentationaroma compounds were quantitated, followed by the determination of odor activity values(OAVs).(2) On the basis of the data obtained, principal component analysis (PCA) was used tofind the relationship between characteristic aroma terms and different freezing conditions, andthen partial least-squares regression (PLSR) was proposed to establish the mathematicalrelationship between the resulting terms and impact odorants. Natural thawing treatment onfrozen must resulted in higher aroma quality with higher extraction of varietal aromacompounds. Lower frozen maceration temperature contributed to higher esters and organicacids. Impact aroma compounds were related to models for floral, sweet fruit, temperate fruit,and vegetal, whereas the model of rose and strawberry contained only varietal volatilecompounds, and temperate fruit could be regressed by impact fermentation aromacompounds.(3) The SBSE-TD-GC-MS method was proposed to analysis the volatile compounds inCabernet Sauvignon wine samples of different vintage from Changli.87volatile compoundswere detected in this experiment, and33of them were regarded as potential active odorants. Some compounds, such as terpenols, ethyl cinnamate were only detected in the young sample,and the esters, high alcohols, fatty acid, volatile phenols were important to the long bottleaged wine samples. However, the concentration of fermentative compounds did not changeregularly in this experiment.(4) The results of PCA analysis showed that the wine samples could be distinguished byimpact odorants satisfactorily according to their distributions in the plot, which revealed theinternal differences of wine samples of different vintage. The most important compounds forlong bottle aged wines are β-damascenone, di-ter-butyl-phenol,4-ethylguaiacol,4-ethylphenol, fatty acid ethyl esters, and esters of isoacids, isopentanol,2-octanone, octanoic acidand (Z)-whiskey lactone. Most of these compounds’ concentrations increase with vintage.