Study On Polyphenol Oxidase From Nanguo Pear And Fermentation Technology Of Nanguoli Wine

Nanguo pear obains the fame of “The King of the pear” for its appealing color, soft fresh, full of juice and strong fragrance. It is very popular because of its mature aromas smell which is produced by natural fermentation.Nowadays, with the growing of wine market, it is quite meaningful to do the research of nanguo pear wine to fill the gap.But nanguo pear is apt to brown. Browning affects not only the product color, sales, also caused the loss of some nutrients which lead Nanguo pear deep-processing products hard to be accepted by market.The content discussed in this paper is how to control the nanguo pear PPO activity and its fruit wine brewing. It will provide the basis for Nanguo pear wine production.Acetone method used for Nanguo pear polyphenol oxidase crude extract, and then study its properties.The results of Nanguo pear PPO activity showed that:the optimum pH of fresh nanguo pear PPO is 6.8, the optimal temperature is 30℃. The kinetics of enzymatic reaction is fit to Michaelis-Menten equation. The maximum rate of fresh nanguo pear PPO enzymatic reaction is 52.632 U/min, the Km value is 0.105 mol/L.Metal ions which have no influence on nanguo pear PPO activity are as follows: Na+, K+, Fe3+, Ca2+, Al3+, Pb2+, Mg2+ have no influence with PPO. Hg2+, Cd2+, Mn2+, and Cu2+ can markedly activatethe activity of Nanguo pear PPO; Cr2+ has inhibition action on Nanguo pear. Inhibition sequenceis as follows: Sodium bisulfate, Ascorbic acid, Citric acid, EDTA-2 Na, L-cysteine. Sodium bisulfate has the most markedly inhibit effect.The results of nanguo pear wine research showed that, in natural temperature sweet wine added 10 mmol/L sodium bisulfite, the Diboshi 2% pectinase adding amount was 0.03%, the initial sugar content is 16%, stop fermentation on 16 days, alcohol 6%, sugar 4.5%. Dry wine added 10 mmol/L sodium bisulfite, the Diboshi 2% pectinase adding amount was 0.03%, the initial sugar content is 22%, in the end, alcohol 10.7%, sugar 0.32%. Use of Diboshi brewing yeast wine was good color, luster are remarkably bright and clear, no obvious turbidity, swing without bubble, strong fragrance, fruit and wine coordination, soft and mellow, the structural integrity of the wine, no smell has the unique flavor of Nanguo pear.