| Pomegranate is rich in nutrition,rich in phenolic compounds and anthocyanins,and has a high value in food and pharmaceutical applications.Xinjiang pomegranate is rich in resources and large production,but the current processing products are mainly pomegranate juice and pomegranate pulp,lacking high value-added products.Pomegranate wine made from fresh pomegranate juice can well retain the flavor and nutrients of the fresh fruit,but the research on pomegranate wine in the industry is still not perfect,and the quality of pomegranate wine needs to be further improved.In this study,pomegranate was used as the main raw material,wolfberry and grape as auxiliary ingredients,and the fermentation process parameters were optimized by single-factor experiment,response surface experiment and BP neural network model to develop a new compound pomegranate wine,and the changes of aroma components,functional components and antioxidant capacity of pomegranate wine before and after compounding and during fermentation were analyzed and compared,and the main conclusions were as follows:(1)By analyzing and comparing the effects of different raw material ratios,initial soluble solids content,initial p H,fermentation time and yeast addition on the quality of the compound pomegranate wine,the best fermentation process parameters of the compound pomegranate wine were determined as follows:pomegranate juice,wolfberry and red grapes 8.5:0.5:1(W/W/W),initial soluble solids content 24°Brix,initial p H 3.7,yeast addition 0.05%,fermentation time of 60 h at 20℃.Under this process condition,the pomegranate wine showed bright pomegranate red,glossy,uniform organization without impurities,sweet and sour,rich and harmonious aroma,and obvious pomegranate flavor,the actual sensory score was 93points,and the alcoholic content was 8%vol,which was in accordance with the national standard.(2)A total of 161 volatile aroma substances were detected by HS-SPME-GC-MS,including 30alcohols,30 esters,12 acids,10 phenols,28 olefins,23 ketones,9 aldehydes and 19 other substances in the pomegranate juice before and after compounding and during the fermentation process.The content of alcohols increased by 103.83 mg/m L after compounding compared with that before compounding,among which the contents of 4-terpinenol,n-octanol,phenylethanol,isobutanol and isoamyl alcohol were significantly increased;the content of esters increased by 47.87 mg/m L,among which the contents of isoamyl acetate and ethyl caproate were significantly increased;the content of acids increased by 29.18mg/m L,and the changes were more obvious for acetic acid,caprylic acid and capric acid.These volatile aroma substances had positive effects on the production of volatile aroma substances in the final grenadine.(3)According to the dynamic changes of volatile aroma substances,the fermentation process of grenadine could be divided into three stages:0 h-24 h as the pre-fermentation period,36 h as the middle fermentation period,and 48 h-60 h as the late fermentation period,of which 36 h was the key point in the fermentation process of grenadine.The total alcohol content in the samples increased from 375.97 mg/m L to 4019.76 mg/m L after fermentation,among which the changes of phenylethanol,isoamyl alcohol and2,3-butanediol were more obvious;the ester content increased from 52.09 mg/m L to 5443.35 mg/m L,among which ethyl acetate and isoamyl acetate reached the peak;the aldehyde content increased from28.46 The content of aldehydes increased from 28.46 mg/m L to 82.61 mg/m L,among which the changes of benzaldehyde and 3,5-dimethylbenzaldehyde were more obvious;the content of ketones increased from33.53 mg/m L to 56.49 mg/m L,among which the contents of 3-hydroxy-2-butanone andβ-pyrosterone reached the peak.Acids and olefins showed similar trends,with the contents increasing from 87.86 mg/m L and 25.64 mg/m L to 790.61 mg/m L and 145.05 mg/m L,respectively.(4)The hydroxyl radical scavenging capacity of pomegranate juice samples after compounding was38.10%,which was 20.41%higher than before compounding,and the absorbance of reducing capacity increased from 0.88 to 2.02.The hydroxyl radical scavenging capacity and total reducing capacity increased significantly(p<0.05),while the scavenging capacity of ABTS~+and DPPH radicals and the content of total phenols,total flavonoids and total anthocyanins remained high and did not change significantly(p>0.05).(5)After fermentation,the hydroxyl radical scavenging capacity of grenadine reached 43.08%,which was 4.98%higher than that of unfermented wine,the absorbance of total reducing capacity increased from2.02 to 2.28(p<0.05),the scavenging rate of ABTS+radicals was 91.49%,the scavenging rate of DPPH radicals was 97.75%,which remained high and stable(p>0.05),total phenols and total flavonoids did not There was no significant change(p>0.05)in total phenols and total flavonoids,the contents were 12.58mg GAE/m L and 260.05 mg GAE/m L,respectively,and the total anthocyanin content showed a certain degree of decrease(p<0.05),the final content was 50.10 mg/L.The fermentation process enhanced the antioxidant capacity of the complex pomegranate wine.(6)By comparing different centrifugal conditions and clarifier addition ratios,it was found that centrifugal clarification and gelatin clarification were not ideal,and the most suitable clarification process for grenadine was saponite addition of 1.4%,at which time the grenadine translucency was 93.57%.The stability experiment proved that the grenadine produced by the optimal process was stable. |
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