Study On Deacidification Of Wild Kiwi Wine By O.oeni

Kiwi fruit, one of the natural and contamination free green food, it’s highnutritive and pharmaceutic value make it a superior crude material for kiwi fruit winefermentation. However, the high content of organic acid such as malicacid, Lcitric acidin kiwi fruit may cause excessive sour flavour and tough liquor body. Malicacid-lacticacid fermentation （MLF） can effectively degrade the organic acid of kiwi fruit makingthe sour and tough new wine moderate and soft, increase the complexity in flavour.Producting of kiwi fruit wine can enlarge market for kiwi fruit and is of importanteconomic significant for promoting the characteristic agricultural by-productsprocessing industry.Firstly, tolerance of O.oeni CICC6066to low pH, SO₂, high alcoholic strength ofthe circumstance during kiwi wine fermenting was investigated. The result showedthat while the growth of the strain6066was inhibited to some degree, growth can bedetected when alcoholic strength was8%¹4%, SO₂density of20⁵0mg L^-1and pHof3.1³.4, which declared that the strain6066has well tolerance to low pH, SO₂, highalcoholic strength in circumstance. We find that the OD600was2times lower when pHdecrease from3.4to3.1; it was3times lower when alcoholic strength increased from8%to14%and4times lower when SO₂density increase from20m g L^-1to50m g L^-1.We can see that the density of SO₂has the most remarkable impact on the growth andmetabolism of O.oeni CICC6066.Secondly, optimizing experiment was conducted to find out most suitablegrowing condition for O.oeni CICC6066, at last, the temperature of26℃, pH for4.6,seed age of60h, inoculum size of8%were chosen as the optimal conditions.Thirdly, growth status of O.oeni CICC6066in different media was recorded toexplore the effect of different compositions to the growth of the strain. Orthogonalexperiment was conducted to find out the optimal content of the medium by referringto other Oenococcus media. The optimal compositions was determined as follows（g·L- 1）:peptone,25; yeast extract,1.0; glucose,10; malicacid,0.5; ammonium citrate dibasic,1.0; cysteine hydrochloride,0.5; MnSO₄H₂O,0.001;MgSO₄7H₂O,0.1; tomato juice,15（v/v%）; Tween-80,1.0. The result of verification test declared that the maximal cellconcentration,1.0×10⁹cfu· mL^-1, was obtained in the optimal medium, then4.1×10⁸cfu·mL^-1in ATB medium and2.5×10⁸cfu·mL^-1in MRS medium.Finally, the physicochemical properties such as total organic acid, total malicacid,total lactic acid, pH value and alcoholic strength of kiwi wine before and after MLFwas recorded to investigate the vinification characteristics of O.oeni CICC6066. Theresult displayed that after MLF, the total organic acid density degraded by5.42g L^-1with degradation rate of37.8%, malicacid degraded by4.3768g L^-1with degradationrate of37.8%, lactic acid increased by4.6165g L^-1.This indicated that the malicacidcan be exhaustively degraded by O.oeni CICC6066. Conclusion can be drew thatthrough MLF process, the alcoholic density and pH of kiwi wine were hardly changedand the wine body becomes clear, aroma was fresh, tasty and mellow and quality ofthe wine were significant improved.