Brewing Technology And Non-bio-stability Of Kiwifruit Wine

Facing on the Kiwi-fruit wine practices in China, brewing technology and non-bio-stability of dessert kiwi-fruit wine were studied. The experimental results primarily solved the technical and stabile problems. Contents of the dissertation are selection of yeast, making and clarification of kiwi-fruit juice, optimization fermentation parameters, reducing total acid content, clarification technique of raw kiwi-fruit wine after fermentation and applying of ultra -filtration. The results are listed as follows:The yeast for kiwi-fruit wine can be selected from ripe kiwi-fruit. It's endurance of SO: is about 3()mg/L~40mg/L, the lower pH value is, the fermentation speed is faster and the yield of acid is up to 4g/L. The alcohol production is about 9.4%(v/v).The kiwi-fruit juice was clarified by adding 60mg/kg SO2, 100mg/kg pectinase to fragmented kiwi-fruit and squeezing it after 4 hours at 40 ℃, then adding another 20mg/kg SOi, 4()mg/kg pectinase, 0.7g/kg bcnotonite and clarifying for 4 hours. Transmittance of clarified juice in 680nm is above 85% and the vitamin C (Vc) content is high. The time of getting clarified kiwi-fruit juice is short.Adding wine yeast to this clarified juice, you can brew out the best flavor and high clarity kiwi-fruit wine. Clarified juice is better than turbid juice or smashed kiwi-fruit as raw material for brewing. Influence of the content o f total acid reduction before or after brewing to wine is not significant, but the former procedure is better.The absorbance in 520nm and transmittance in 680nm can denote the chroma and clarity of kiwi-fruit wine.The optimal fermentation parameters arc adding 6()mg/kg SO2, 0.1% wine yeast, fermentation temperature is 12℃- 15℃. In this condition, the colour, flavor, stability of wine are the best.Adding 60mg/kg SO2 to clarified juice before brewing can improve the colour of wine.K2C4H4O6 is the best one in the three material used to reduce total acid.Every 2.4 gram K.2C4H.4O(, can reduce 1 gram acid in 1 litre.An ideal method to improve the stability of wine is keeping the wine at 0.5℃~ 1.0℃ above it's freezing temperature for 6 days.The stability,colour and flavor are improved. Warming is not a good method.In the studies on the effect of clarificant, agar, glutosan, casein, activated charcoal, benotonite, polyvinylpyrrolidone(PVP) and chitosan are tested. The results showed that the proper adding quantity of each clarificant is separately that agar 0.15g/L, glutin 0.75g/L, benotonite 3.5g/L, activated charcoal 1.0g/L, casein 1.5g/L, PVP 1.4g/L, chitosan 0.4g/L.When the adding dosage is 0.4g/L, chitosan can remove the solubility protein, phenolic compounds in wine effectively and the clarifing rate is high, thereby, the kiwi-fruit wine' s stability can be improved and the colour and luster are good. The wine treated with chitosan can reach 98% degree of clarity.A study on kiwi-fruit wine clarification by ultra-filtration (UF) with domestic hollow fibers is presented. Used in the kiwi-fruit wine, UF has the advantage of reducing energy consume, having no phase change, reducing processing time, improving product quality. UF can remove most of the material that cau se haze and sediment in wine, and retain wine nutrition elements and flavor bascically. The optimal parameters of UF are pressure 0.04MPa, the temperature 20℃~25℃, the remove speed of wine is 6L/h, after 17 minutes the rate of flow maintains the balance.The new view of the studies showed as follows: The yeast of kiwi-fruit was selected from ripe kiwi-fruit. Adding pectinase 140mg/kg, benotonite 0.7g/kg and SO2 8()mg/kg, the time of getting the clarified kiwi-fruit juice was shortened 1/3 at least. Fermentation at lower temperature and store it at 0.5 ℃~1.0℃ above it' s freezing temperature, the wine is the best. The PVP and chitosan was used as clarificant first and the chitosan is the best. We applied the UF to clarify the kiwi-fruit wine frist, the chlarified wine is no need to kill germs, the effect is very good.