Study On Inflencing Factors Of Megranate Wine Brewing

Megranate wine is one of the most nutritional low alcohol beverages which is fermentative and healthy.In this research,SO₂,wine yeasts and organic acids were studied to understand the rclatation between them and fermented megranate wine.The main research results were as follows:1 Effects of Sulfur dioxide(SO₂) on the brewing of megranate juices from three varieties were studied,respectively.The results showed that:adding 60mg/L SO₂ did not affect pH value and acidity significantly during fermentation.The SO₂ could promote the fermentation of megranate juices whose fermentation speeds were influenced by megranate components.The finished wines with lower volatile acid had higher alcohol content and dry extract.And the results also indicated that the wine yeast(Saccharomyces cerevisiae sp.) used in this research possessed good brewing performance in higher acid circumstances.2 A reverse phase HPLC method for simultaneous determination of organic acids in megranate juices and wines was developed.Chromatogram columniations:Waters Atlantis dC18(4.6mm×250mm,5μm);mobile phase: 0.02mol/L K₂HPO₄(adjusted to pH2.80 with phosphoric acid);UV detector at 215nm;column temperature:30℃;flow-velocity:0.7 mL/min;sample size:15μL.There was a linear relationship between the contents of the standards organic acids and the peak area of the chromatogram chart with the R² value 0.9954～0.9999.The lowest detection level was 0.0030～0.83mg/L and the lowest quantity level 0.01～2.78mg/L,recovery was 86.88～100.78%and coefficients of variation 0.7～6.6%under the condition above.3 Oxalic,lactic,citric,malic,ketoglutaric,acetic,succinic,fumaric,tartaric and glueonic acids were found in megranate juices.The main organic acids were lactic acid(about 51.2～53.9%),oxalic acid(about 26.8～28.8%),and citric acid(about 11.8～16.8%) in sweet megranate juices,while citric acid (about 84.4%) and lactic acid(about 14%) were the main organic acids in acid megranate juices. 4 The composition and content of organic acids changed after inoculation of activity dry yeast into megranate juices.Oxalic,lactic,citric,malic and acetic acid originating from megranate juices participated in yeast metabolism and the level of their metabolism was influenced by content of organic acids in juices. Pyruvic,tartaric,fumaric and succinic acid were mainly produced by yeast during the fermentation.5 3 Saccharomyces cerevisiae(WY-1,WY-2,WY-3) and 1 Zygosaccharomyces bailii(WY-4) were selected as fermentation strains to study their effect on the brewing of acid megranate juices and flavor and their ability in metabolism of organic acids.The results showed that wine yeast WY-1,WY-2,WY-3 had the similar fermentation performance and they had rapid and steady fermentation speed,while WY-4 had longer lag phase and slower fermentation speed.3 Saccharomyces cerevisiae possessed good brewing performance in higher acid circumstances comparing to 1 Zygosaccharomyces bailii.In finished wine fermented by 4 wine yeast, titration acid,total sugar,residual sugar and volatile acid content had almost no difference,while alcohol content had significantly difference,which is Saccharomyces cerevisiae had higher alcohol yield than Zygosaccharomyces bailii.Dry extract content increased in wine fermented by WY-1,WY-3,WY-4 and that decreased by WY-2.Sensory evaluations showed that finished acid megranate wine with 1# had best flavor characteristic.The ability of degrade citric acid,which is mainly component in sour megranate juice,for 4 wine yeast has no significant difference(P＞0.05).The total organic acid content decreased by 8.1～12.8%coinciding with citric acid decreasing by 8.7～13.3%.