Study On The Processing Technology Of Myrtle Wine

Rhodomyrtus tomentosa is a common wild plant in South China.Its fruits are rich in nutrients such as sugars,proteins,fats,organic acids,amino acids,vitamin C and active ingredients including polysaccharides and flavonoids,which have antioxidant and health-promotingeffects.Wine is the most common processing way of myrtle fruit.Proper drinking of myrtle fruit wine can keep fit,and long-term consumption can alleviate the harm caused by oxidation reaction,environmental pollution,high ultraviolet radiation and other factors,and protect against cancers and aging diseases to some degree.The processing technology of myrtle fruit wine was systematically studied,aiming to obtain myrtle fruit wine rich in antioxidant active ingredients and providing theoretical and technical support for the industrial production of myrtle fruit wine.The main contents and conclusions are as follows:1.Study on the processing technology of myrtle fruit soaked wineThe physical and chemical properties,phenolic contents,antioxidant activity,flavor and sensory evaluation of 5 soaked myrtle wines were studied.The results showed that there were no significant differences in total amino acid contents and total wine sensory evaluation scores among the five soaked wines（P>0.05）,but there were great differences in color,total sugar,total acid,Vc,total phenolics,total flavonoids,anthocyanin and total reducing power among the five soaked wines.On the whole,Vc,total phenolics,total flavonoids,anthocyanins and total reducing power of nitrogen-enriched myrtle fruit wine were higher than those of fruit wines produced by other methods.At this point,The contents of total sugar,total acid,total amino acid,Vc were 16.55±0.35 mg·m L^-1,5.64±0.29 mg·m L^-1,0.01±0.00%,0.48±0.00 mg·100m L^-1and3.65±0.07 mg GAE·m L^-1,total flavonoids content of 74.30±3.48μg CE·m L^-1,anthocyanin content of 0.07±0.01 mg·L^-1,total reducing power of 2.14±0.11 mg TE·m L^-1,DPPH·scavenging ability of 1.18±0.01mg TE·m L^-1and·OH scavenging ability of 9.81±0.19 mg TE·m L^-1and O^2-·scavenging ability of 4.80±0.34 mg TE·m L^-1.2.Screening of yeast strains for myrtle wine fermentationThe strains were separated and screened from myrtle leaves,fruit and orchard soil,secondary screened by TTC color rendering method and Duchenne tube gas production method,and then evaluated in alcohol production capacity.Subsequently,two strains with the best alcohol production capacity,named T2 an T19,were obtained.T2 and T19 were identified as Hanseniaspora opuntiae and Lodderomyces elongisporus,respectively,by colony morphology observation,bacterial strain microscopic morphology observation and 26S r DNA sequencing.The tolerance and growth characteristics of T2 and T19 were studied.The results showed that the growth of T2 and T19 was significantly inhibited in the range of alcohol concentration and temperature in this study（P<0.05）.T2 strain was not inhibited by glucose concentration,T19 strain tolerated up to 30%glucose.The p H tolerance of T2strain was 3,and the p H tolerance of T19 strain was 4.5.The SO₂tolerance concentration of T2 strain was 100 mg·L^-1.The growth of T19 strain was inhibited by 100～350 mg·L^-1SO₂concentration.T2 had better tolerance to glucose,p H,SO₂and has better growth characteristics than T19.3.Optimization of fermentation technology of myrtle wineThe enzymatic hydrolysis of myrtle fruit juice was studied.The results showed that the optimal parameters were listed as follows:pectinase concentration 0.04%,30℃and 80min,the juice yield was 62%,which was 22%higher than that of the untreated myrtle fruit juice.The fermentation process of myrtle fruit wine was studied with alcohol content as the main index and total phenolics and flavonoid content as the reference index.The results showed that the optimal fermentation conditions were as follows:initial sugar concentration 160 g·L^-1,p H 4.0,SO₂concentration 100 mg·L^-1,simultaneously inoculated Angel yeast and T2 with volume ratio of 0.4:1,and fermented at 25℃for 10 days.Under the above conditions,the alcohol level of myrtle fruit wine was 10.5%vol.4.Clarification process optimization and quality evaluation of myrtle fruit fermented wineThe clarification process of myrtle fruit fermented wine was studied.The results showed that the best clarification conditions of myrtle fruit fermentated wine were as follows:combined clarifying process,the concentration of bentonite and chitosan were 1.2g·L^-1and 0.2 g·L^-1,respectively,letting stand for 3 days,centrifuging at 3500 r·min^-1for 15min.Under the above conditions,the light transmitance of myrtle fruit fermentated wine was the best（74.28%）.Compared with the original myrtle fruit wine（0.23%）,the clarification effect of fruit wine was significantly improved.After pasteurization,the aerobic plate count of myrtle fruit fermented wine was 0 cfu·m L^-1,Coliform<3 MPN·m L^-1,which met the national hygienic standards of fruit wine.Myrtle fruit fermentated wine is sweet and sour,with intense myrtle fruit flavors.To sum up,compared with the soaked wine,the sensory scores of the fermented wine had the same sensory score and significantly different color.The total phenolic content of fermented myrtle wine was 1.93±0.03 mg GAE·100 ml^-1,the total flavonoid content was0.42±0.01μg CE·ml^-1,and the total phenolic content of soaked myrtle wine was 3.65±0.07mg GAE·100 ml^-1.The total flavonoid content was 74.30±3.48μg CE·m L^-1.The contents of alcohol,total phenolics and flavonoids in myrtle fruit fermented wine were lower than those in myrtle fruit soaked wine.The former was a medium low alcohol fruit wine,while the latter is a high alcohol fruit wine.Both of them had their own advantages and could meet the needs of different groups of consumers.