Effects Of Maceration Enzyme And Polysaccharide On Condensed Tannin Properties And Sensory Qualities Of Blueberry Wine

High-quality blueberry wine has a pleasing complex taste,and condensed tannins are an important factor on tastes of blueberry wine.Deficiency of condensed tannin contents can make blueberry wine bland,poorly flavored and uncoordinated.Optimization of the maceration enzyme and exogenous polysaccharide addition process can increase the contents of condensed tannin in blueberry wine and improve the qualities of blueberry wine.In this study,blueberries were used as materials to carry out the following aspects: In the simulated system,the addition method of maceration enzyme was optimized according to the decomposition effect of blueberry cell wall and the adsorption rate of condensed tannins.Effects of enzymolysis methods on the content of condensed tannins and volatile components were analyzed in blueberry juice to determine the optimal enzymatic hydrolysis process.Chitosan and yeast mannan were added to blueberry juice after enzymolysis to analyze the dynamic changes of physicochemical indexes and condensed tannin components in the alcoholic fermentation stage of blueberry wine.The effect of chitosan and yeast mannan on tastes and qualities of blueberry wine was investigated.The main research results are as follows:1.Preliminary screening of enzymatic treatments in the simulated systemEffects of five enzymatic treatments of pectinase and cellulase(individually,sequentially,and simultaneously)on condensed tannin contents,condensed tannin components,galacturonic acid contents,total sugars contents and cell wall structure in the simulated system containing blueberry condensed tannins and blueberry cell walls were investigated.Results showed that the content of condensed tannins(1.26 mg/m L),the mean degree of polymerization(4.03),the percentage of galloylation(13.32%),the content of galacturonic acid(16.52 mg/g)and the content of total sugar(2.93 mg/g)were the highest in the simulated system with the simultaneous addition of pectinase and cellulase,which were significantly higher than the other treatments(p<0.05).Combined with infrared spectroscopy and scanning electron microscopy analysis showed that three enzymatic treatments,pectinase individually,pectinase followed by cellulase,and simultaneous addition of pectinase and cellulase,could effectively break down the polysaccharide network structure of blueberry cell wall and reduce the adsorption rate of cell walls to condensed tannins.2.Effects of enzymatic treatments on qualities of blueberry juiceEffects of three enzymatic treatments(pectinase individually,pectinase followed by cellulase,and simultaneous addition of pectinase and cellulase)on the content of condensed tannins,the mean degree of polymerization,volatile components and the content of organic acids in blueberry juice were analyzed in the preliminary screening.Results showed that the content of condensed tannins in blueberry juice with simultaneous addition of pectinase and cellulase was 326.93 mg/L,and the mean degree of polymerization was 7.27,which was significantly higher than the other treatments(p<0.05).The results of volatile components showed that compared with the control group,the number of volatile components in blueberry juice increased by 44.44%,61.11% and 66.67% in the group with pectinase individually,the group with pectinase followed by cellulase,and the group with simultaneous addition of pectinase and cellulase,respectively.There were 26 aromatic substances in blueberry juice of the enzymic treatment group,three new alcohols(phenylethanol,1-hexanol,citronellol),three new esters(Isopentyl acetate,methyl benzoate,ethyl benzoate),three new aldehydes(2-hexenal,E-(2)-heptenal,decanal),two new terpenes(β-damascenone,pineolene),and the disappearance of nonanoic acid.A total of four organic acids,oxalic acid,tartaric acid,citric acid and malic acid,were detected in blueberry juice.Combining with the content of condensed tannins and the type of volatile components in blueberry juice,it was found that the simultaneous addition of pectinase and cellulase treatment was the best adding method.3.Effects of chitosan and yeast mannan on contents and components of condensed tannins in blueberry wine at the alcoholic fermentation stageIn order to further reduce the loss of condensed tannins,the effect of adding chitosan and yeast mannan before alcoholic fermentation on contents and components of condensed tannins in blueberry wine at the end of alcoholic fermentation were investigated.The results showed that the content of condensed tannins,the mean degree of polymerization of condensed tannins and the content of anthocyanins in the yeast mannan group were significantly higher than those in the chitosan and control groups,which were 215.59 mg/L,5.93 and 543.89 mg/L,respectively.Seven subunit monomers of condensed tannins were detected in three groups of blueberry wine samples,with the highest percentage of terminal(-)-epicatechin(11.25%)and the lowest percentage of galloylation(11.55%)in the yeast mannan group.4.Analysis of condensed tannin properties and sensory qualities of blueberry wineWhen the post-fermentation was ended,the yeast mannan group had the highest condensed tannin contents,percentage of terminal(-)-epicatechin,suppleness index and anthocyanin/tannin ratio of 205.28 mg/L,13.08%,5.86 and 2.58,respectively.Compared to the control group,the addition of yeast mannan reduced the amount of malic acid in blueberry wine(0.45 g/L to 0.38 g/L)and increased its lactic acid content(0.92 g/L to 1.21g/L),while the addition of chitosan reduced the amount of lactic acid in blueberry wine(0.92 g/L to 0.66 g/L)and increased its malic acid content(0.45 g/L to 0.53 g/L).The type and mass concentration of volatile components in blueberry wine were increased by adding chitosan and yeast mannan,and the addition of yeast mannan was the most significant.Types of aroma component with odor activity values(OAV)>1 were 20 and 22 in the chitosan group and yeast mannan group,respectively,which were higher than the control group(16).The electronic tongue analysis and sensory evaluation showed that the addition of yeast mannan made blueberry wine had the least sour and astringency,the highest roundness and aroma intensity,and had the best taste and flavor.