Sulfur Dioxide Control In Apple Wine Fermentation And The Effect On Malolactic Fermentation

Sulfur dioxide control in cider wine has become an important research project in food safety. The aim of this research was to decrease the residual of sulfur dioxide and control the release of free sulfur dioxide in malolactic fermentation. This paper studied sulfur dioxide control in alcoholic fermentation and malolactic fermentation of apple wine, and the effect of sulfur dioxide, pH, temperature on malolactic fermentation. The results were as follows:The amounts of binding sulfur dioxide could be decreased by adding ammonium monoacid phosphate , ammonium sulfate separately. The results showed the relation between binding sulfur dioxide(Y) with ammonium monoacid phosphate (X₁ 232-568mg/L) , ammonium sulfate (X₂, 348-852mg/L) is significant. The regressive equation is Y=67.22—3.075X²₁+5.48X₁X₂—4.685X₁— 3.676X²₂, R-square is 0.7543.The degradation abilities of SO2-bound acetaldehyde of five O.oeni was almost accord between rest cell experiments and malolactic fermentation of apple wine. O.oeni MBR, O.oeni SD-2gf, O.oeni SD-2b had high degradation abilities of SO₂-bound acetaldehyde in two systems, while O.oeni ML34, O.oeni 31DH had low degradation abilities of it. When initial SO₂-bound acetaldehyde increased, the degradation time of SO₂-bound acetaldehyde was drop behind and the degradation rate of it was decreased gradually.SO₂ control points of apple wine fermentation: Based on assimilatory nitrogen concentration of apple juice, nitrogen concentration should be adjusted by adding ammonium monoacid phosphate and ammonium sulfate by the regressive equation. The aim of this measure is to get lower comparatively binding sulfur dioxide after alcoholic fermentation; When MLF went, it should select O.oeni that had high ability to degradate SO₂-bound acetaldehyde, in order to control the release of free sulfur dioxide together with the time of degradation ratio and the time of organic acid metablism. Then it controlled organic acid metablism.It was significant that the effect of pH,total sulfur dioxide and alternation function of above two factors on degradation of malic acid in MLF of O.oeni Viniflora. O.oeni 31DH, O.oeni ML34.The best MLF condition of three O.oeni was respectively as follows: pH4.0, total SO_<60mg/L, 23℃; pH4.0, total SO₂<100mg/L, 23℃; pH4.0, total SO₂<60mg/L,23℃.