| The red wine from the east Helan mountain area in Ningxia has an elegant and rich aroma,a balanced and rich taste,and has been widely praised in the industry and abroad.However,some studies have found that most red wines in the production area have a relatively obvious green flavor,which makes red wines from the east Helan mountain area in Ningxia rejected by some consumers,affecting the stable and healthy development of the production area.This research takes the green flavor of red wine from the east Helan mountain area as the research object,and launches an indepth study of its compounds basis and source.First,the research combined sensory analysis and GC-MS instrumental analysis to trace the base of green flavor compounds in red wine from the east Helan mountain area in Ningxia.Next,four red wine grape varieties,Cabernet Sauvignon,Cabernet Gernischet,Cabernet Franc and Merlot,were selected to compare the variation rules of free and bound aroma during berry ripening,and the variation rules of methoxypyrazines and their distribution in various parts of grape were studied.The main research results are as follows:(1)The compounds basis of the green flavor in red wine:The results of sensory evaluation showed that 75%of the 12 red wine samples in this production area had a perceptible green flavor(4-7 points),and 41.7%of the wine samples had a heavier green flavor(7-10 points).The main descriptive words for the green flavor of red wine in this production area are green pepper and grassy smell.Combined with volatile components GC-MS analysis,the study found that three compounds that may cause green flavor were detected in the red wine samples of this production area,namely IBMP,IPMP and 1-hexanol.Among them,IBMP has a significant positive correlation with the green flavor in red wines of this production area.(2)Variation of free volatile compounds for different varieties wine grape during ripening:A total of 43 free volatile compounds were detected in the four varieties of wine grapes,Cabernet Sauvignon,Cabernet Gernischet,Cabernet Franc,and Merlot,which can be classified into 7 types of compounds,the content of carbonyl compounds continues to decrease during the maturation process;alcohols,esters,and terpenes generally increase in the maturation stage,and slightly decrease in the later stage of maturity;benzene series,acids and other compounds are in the maturation process Fluctuates;through principal component analysis,it is found that berries of different maturity can be distinguished by 1-hexanal and E-2-octenal.Found 9 free volatile compounds that may cause green flavor,all of which are C6 alcohols/aldehydes,of which C6 aldehydes are negatively correlated with berry ripeness,while C6 alcohols are positively correlated with berry ripeness.The free volatile compounds of different varieties of grapes can be well separated by principal component analysis.Compounds such as β-Damascenone and Benzyl alcohol contribute more significantly to the free aroma of Cabernet Sauvignon;naphthalene,Toluene,OXylene,2-Pentylfuran contributions to the free aroma of Cabernet Gernischet and Cabernet Franc are more prominent;compounds such as P-Isopropyl toluene and Methylheptenone contribute more to the free aroma of Merlot.(3)Variation of bound volatile compounds for different varieties wine grape during ripening:A total of 41 bound volatile compounds were detected in the four varieties of wine grapes,Cabernet Sauvignon,Cabernet Gernischet,Cabernet Franc,and Merlot,which can be classified into 7 types of compounds,the content of carbonyl compounds fluctuates during the maturation process;alcohols,esters,and terpenoids show an overall upward trend during the maturation process;benzene compounds and other compounds fluctuate during the maturation and over-maturation process;pass Principal component analysis found that berries of different maturity levels can be distinguished well by 1-Hexanol and Decanal.This research found that there are 6 kinds of bound volatile compounds in the grape berry that may cause the green flavor,all of which are C6 alcohols/aldehydes,and the changes of C6 alcohols/aldehydes in different varieties grape are inconsistent.The bound volatile compounds of different varieties of grapes can be well separated by principal component analysis,and the results show that Geranyl acetone,α-Cedrene and other compounds contribute more significantly to the bound aroma of Cabernet Sauvignon;2,4-Di-tertbutylphenol,E-2-hexenal and other compounds contribute more significantly to the bound aroma of Cabernet Franc;2,4-Dimethylbenzaldehyde,2-Ethyl hexanol and other compounds contribute more significantly to the bound aroma of Cabernet Gernischet;E-Ocimene,D-Limonene and other compounds contribute more significantly to the bound aroma of Merlot.(4)Variation of methoxypyrazines for different varieties wine grape during ripening:IBMP is inversely proportional to maturity in the four varieties of Cabernet Sauvignon,Cabernet Gernischet,Cabernet Franc,and Merlot wine grapes,and IBMP is in the berty of Cabernet Franc and Cabernet Gernischet the higher the concentration,the lowest content in the Merlot berry.In the comparison of different parts,the concentration of IBMP,IPMP and SBMP in the stem of Cabernet Sauvignon is the highest compared to other varieties,the concentration of IBMP in the skin,pulp,and seeds of Cabernet Franc is the highest compared to other varieties in the same part,the IBMP concentration in the stem,skin,pulp,and seeds of Merlot is the lowest among the four varieties.About the proportion of the total amount of IBMP in different parts of a bunch of grapes to the total amount of IBMP in the whole bunch,in Cabernet Sauvignon,the proportion of IBMP in the stem and skin is the highest,and it is significantly higher than the pulp and seeds;among Cabernet Gernischet and Cabernet Franc,the skin accounted for the largest proportion,and it was significantly higher than other parts;in Merlot,the pulp has the largest proportion and is significantly higher than other parts. |
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