| Blueberries are mainly eaten fresh in China.With the increase of planting area and the rapid development of derivative processing industries such as fruit juice and wine,a large amount of fruit residue is generated during the production and processing of blueberries.These fruit residues are usually discarded,and if they can be reasonably reused,it can not only save resources but also avoid environmental pollution.At the same time,the domestic brandy market is dominated by imported alcoholic beverages,with huge development potential.This is a good opportunity for developing fruit residue type brandy products.This article uses blueberry pomace as raw material,obtains a blueberry pomace brandy through fermentation,distillation,and aging,and conducts optimization experiments on its key process points.The main research content of this project is as follows:(1)Blueberry pomace brandy brewing: Based on single factor analysis,sensory evaluation is used as an evaluation indicator to determine the brewing process of blueberry pomace brandy through response surface analysis.The optimal brewing conditions are as follows: the optimal fermentation strain for raw wine is F33,the yeast inoculation amount is 0.3 g/L,concentrated apple juice is the optimal fermentation sugar,the initial sugar addition amount is 217 mg/m L,the fermentation temperature is 28 ℃,and the solid-liquid ratio is 1:1.5.(2)Optimization of blueberry pomace brandy distillation process: The distillation process mainly involves studying the changes in volatile substances during the distillation process and the distillation process for extracting alcohol.This experiment identified a total of 94 volatile compounds,including 24 esters,23 alcohols,7 acids,13 aldehydes and ketones,12 terpenes,2 acetals,3 furans,5benzene and its derivatives,and 5 other compounds.As distillation proceeds,the total amount of aroma compounds in blueberry pomace brandy shows a gradually decreasing trend,with the total content of esters significantly higher than the total content of other substances throughout the entire distillation process.The content of furans gradually increases as distillation proceeds.Among the 9 distillation stages of blueberry pomace brandy,there are 39 substances with OAV>1 and 14 substances with OAV>100.Among them,the OAV value of esters is the highest overall,which is the characteristic aroma substance during the distillation process of blueberry pomace brandy.Substances with OAV>100 are ethyl acetate,ethyl isovalerate,ethyl2-methylbutyrate,isoamyl acetate,isoamyl isovalerate,ethyl caproate,ethyl lauric acid,nonyl alcohol,lauryl alcohol,linalool,citronellol,eugenol,nonanal β-Violet ketone can be considered as a characteristic component of the distilled aroma of blueberry pomace brandy.Except for eugenol,the content of other substances gradually decreases during distillation from 1 to 9.There are significant differences in the products obtained from the three extraction schemes of blueberry pomace brandy.The optimal extraction process based on the comprehensive analysis of alcohol content,extraction volume,total amount of flavor substances,and sensory evaluation is as follows: the distillate obtained during the 0-80 minute cutting period has the highest sensory evaluation,the wine is clear and transparent,the taste is harmonious,and there is no odor,and the blueberry style is obvious.(3)Optimization of the aging process for blueberry pomace brandy: Oak chips from two different sources,the United States and France,with three different degrees of baking,mild,moderate,and severe,were used for artificial aging of blueberry pomace original brandy.The optimal aging conditions for blueberry pomace brandy were determined through physicochemical indicators,sensory evaluation,and flavor substance analysis,and ultimately compared with the quality of blueberry pomace original brandy.The results showed that in the aging experiment of oak chips from different sources,it was found that the geographical indicators,flavor substances,and sensory evaluation of blueberry pomace and brandy aged with French oak chips were better than those aged with American oak chips,and the aging effect was the best.In experiments on the aging of French oak slices with different degrees of baking,it was found that moderate baking of oak slices significantly increased the total ester and total phenolic content of the wine sample.During the aging process,the b * value and total color difference of the wine sample increased significantly with aging time.The aged blueberry pomace brandy was amber in color,with the highest scores in various physical and chemical indicators and sensory evaluation.There were more substances with baking bread aroma and nut aroma,and the aging effect was the best.In the experiment of adding moderate roasted French oak slices,it was found that different amounts of oak slices had a certain aging effect on blueberry pomace brandy,and each had its own advantages and disadvantages.When the amount of oak chips added is 3 g/L,the total ester and total phenol content of the wine sample can be significantly increased.During the aging process,the b * value and total color difference of the wine sample increase significantly with aging time.It is concluded that the aging effect is best when the amount of oak chips added is 3 g/L.Compare the quality of aged blueberry pomace brandy with blueberry pomace original brandy using moderately roasted French oak chips with an addition of 3 g/L.The results showed that aging can enrich the aroma content of blueberry pomace original brandy and significantly improve its quality.(4)Quality comparison between blueberry pomace brandy and other varieties of brandy: There are significant differences in basic physical and chemical indicators and colors among different varieties of brandy,each with its own characteristics.A total of125 aroma compounds were detected in four types of brandy,including 42 esters,25 alcohols,7 acids,11 terpenes,18 aldehydes,ketones,and acetals,3 benzene homologues and their derivatives,3 furans,6 phenols,and 10 other compounds.The total amount of aroma compounds in the four types of brandy is ranked from high to low in the order of blueberry whole fruit>blueberry pomace>ZY1>ZY2.Using OAV,PCA,and PLS-DA statistical methods to explore the differential substances in the volatile aroma components of four different varieties of brandy,the study found that there are a total of 73 aroma compounds with VIP values greater than 1 in the four different varieties of brandy.These compounds can be considered representative compounds to distinguish the same variety of brandy.Combined with OAV analysis,there are 33 substances,including ethyl acetate,isoamyl acetate,ethyl isovalerate Isoamyl isovalerate,ethyl hexanoate,ethyl octanoate,ethyl nonanoate,methyl caproate,ethyl benzoate,ethyl myristate,ethyl palmitate,methyl octanoate,ethyl decanoate,ethyl phenylacetate,ethyl cinnamate,isobutanol,isopentyl alcohol,nonanol,2-heptanol,octanol,linalool,citronellol,lauryl alcohol,octanoic acid,nonanoic acid,phenylethanol,eugenol,benzaldehyde,vanillin,acetal β-Damadone,furfural,and naphthalene are key differential substances.Sensory evaluations ranged from low to high,including blueberry whole fruit brandy(85.58±0.19 points),blueberry pomace brandy(83.65±0.22 points),ZY1(82.50±0.46 points),and ZY2(82.5±0.32 points).The flavor profiles of ZY1 and ZY2 were similar.The flavor profiles of blueberry whole fruit brandy and blueberry pomace brandy were similar,while the flavors of ZY1 and ZY2 were creamy,mushroom,smoked,grassy,toasted bread,caramel,and so on Almond aroma is more prominent,while blueberry whole fruit brandy and blueberry pomace brandy have more prominent floral,ester,mellow,and honey aromas.PLSR was used to analyze the correlation between volatile components and sensory indicators of different varieties of brandy,and to explore the degree of correlation between volatile components and sensory indicators of different varieties of brandy.The PLSR model screened 65 key aroma characteristic contributing compounds with VIP>1. |
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