The Distinct Flavor Of Regional Vidal Icewines And Effects Of Nonvolatile Contents On Aromas

Icewine,as a unique sweet wine,is popular among global consumers.Huanren appellation which located in Liaoning province of China,has a typical climate for icewine production and has become one of the most important production regions in the world.While the flavor profiles of its icewines remain unclear as the research on Chinese icewine has just began.Thus,it is necessary to figure out the typical characteristics of Huanren icewines and make a comparison with icewines in main global icewine producers.This reasearch aims to compare the flavor characteristics of Vidal icewines in Huanren,China and Niagara Penisula,Canada through sensory and chemical analysis and preliminarily study the interactions between a specific icewine matrix and aroma compounds in model solutions by chemosensory analysis.Main conclusions are list as follow:（1）Sensory profiles of different regional Vidal icewines were analyzed with quantitative descriptive analysis and principal component analysis（PCA）.The result of quantitative descriptive analysis shows that nut aroma intensity in Chinese Vidal icewines surpasses it in Canadian Vidal icewines,but rose aroma intensity is higher in Canadian icewines.Principal component analysis indicates that nut and honey aromas are the typical characteristics of Chinese icewines which can differentiate Chinese icewines from Canadian icewines and Canadian icewines are positively correlated with apricot,tropical fruit,rose and caramel aromas.（2）Headspace solid phase microextraction combined with comprehensive two dimensional gas chromatography-time of flight mass spectrometry was uesd to identify the volatile aroma compounds in two regional Vidal icewines.Esters,terpenes,alcohols and phenols account for more than 60% of all the compounds and the number of esters ranked the first.Besides,the number of common compounds in two regional icewines is 64% of all identified compounds,which means the composition of compounds in two regional icewines is quite different.Heat map combined with cluster analysis was conducted to further explore the differences of compounds’ concentration between two regional icewines and the icewines were clusterd to two groups based on region.Therefore,two regional icewines can be differenciate according to the species,concentration and composition of aroma compounds.（3）Four different methodologies were used to quantify the important aroma compounds in Vidal icewines,including 10 esters,5 alcohols,6 terpenes,3 lactones,3 ketones,2 phenols and 1 sulfur compound.Calibration curves are linear during the concentration ranges with R² over 0.99 and recovery ranged between 80%-125%.One-way-ANOVA of aroma compounds shows 15 of them are significant between two regional icewines,including linalool,α-terpineol,1,4-cineole,1-hexanol,γ-undecalactone,furaneol,methional（p < 0.001）;ethyl isobutyrate,ethyl butyrate,1-octen-3-one,vinyl guaiacol（p < 0.01）;rose oxide,β-damascenone,1-heptanol,γ-hexalactone（p < 0.05）.（4）Partial least square-discriminant analysis（PLS-DA）was used to relate sensory descriptors and chemical compositions of Vidal icewines.Result shows that icewines in China were positively correlated with honey and nut aromas,icewines in Canada were positively correlated with apricot,tropical fruit,caramel and rose aromas,which conforms to the PCA result.Meanwhile,honey and nut have a close correlation with 1-hexanol,isoamyl acetate,phenethyl acetate and phenylehyl alcohol according to the angle and distance of variables.Rose aroma is correlated with 1-octen-3-ol,1-octen-3-one,ethyl isobutyrate,ethyl butyrate,ethyl isovalerate,ethyl hexanoate,rose oxide,linalool,α-terpineol,nerol and caramel aroma is correlated with γ-hexalactone,γ-undecalactone,γ-decalactone,ethyl acetate,ethyl 2-methylbuyrate,guaiacol,1-heptanol,vinyl guaiacol,ethyl valerate,furaneol,1,4-cineole,3-（methylthio）-1-propanal,β-damascenone.（5）Interactions of nonvolatile matrix and aroma compounds in icewine were preliminarily studied in this work.Rose oxide and β-damascenone can be affected by the nonvolatile compounds in icewine.Epigallocatechin,fructose and arginine can inhibit the release of those two aroma compounds.Meanwhile,high epigallocatechin at 1000 mg·L^-1 and arginine at 100 mg·L^-1 cause the sensory difference of β-damascenone in control group which was perceptible by panelists,but no difference was perceived in rose oxide group.