Studies On Organic Acids And Volatile Sulfid In Grape And Wine

An HPLC method was employed to determine organic acid in wine. By general tests on chromatographic separating conditions, the optimal chromatographic separating condition was established: mobile phase was HC1O4 solution of pH 2.5, mobile rate was 0.6mL/min, column temperature was 55 C, detecting wavelength was 210nm, injecting volume was 10 L.Several kinds of original wine were analyzed. The relative standard deviationg from 1.8% to 4.5%, and the recovery rates were from 94.5% to 103.1%. The accuracy of this method was proved.After being pretreated by centrifugalizing at a high speed 10000 rotation/min, 15 kinds of original wine from The Great Wall and Dynasty wine brewing company were determined for organic acid by HPLC. Results showed that the most component of organic acid in wine was tartaric, L-malic and L-lactic acid, and the contents of citric, succinic and acetic acid was very little; There was seldom L-lactic in dry white wine; There was L-lactic in dry red wine, but the contents of L-malic and citric decrease relevantly, even to zero; Of all samples determined, the contents of total acid in The Great Wall original wine was higher than that in Dynasty original wine, mainly on tartaric acid.Finally, several sorts of organic acid in different grapes were determined during the grapes growing from Shacheng, Jixian, Hangu and Changli in 2003. Results showed that the content variety of several organic acids in grapes during their was that the contents of citric was very little in grapes, less than 0.4g/L, and the content varied little during grape's maturing. The contents of tartaric and L-malic decreased gradually during grape matures. L-malic decreased more quick than tartaric.Wine yeasts C I ,C II, W I ,W II were applied for tests. After comparing their fermentation characteristics, C I was selected as the parent strain for mutation to obtain a fine wine yeast which produced low H2S and high glutathione.After treating the parent strain C I by UV, acetate media plates and different differential medium plates containing Na2S and Na2SO3 as the only sulfur sources were used as primary screening plates, a fine mutant S9 which produced low H2S was gotten. S9 differed little from C I in basic fermentation characteristics, butthe production of H2S decreased by 40.0%.After treating S9 using EMS, a fine mutant M6 was obtained recurring to anti-methionine medium plates. M6 differed little from S9 in basic fermentation characteristics, but the production of GSH increased by 47.7%, and the production of HaS decreased by 30.0% again.Finally, the mutant M6 was compared to the parent strain C I . The basic fermentation characteristics of the two strains differed little, but the production of H2S of M6 decreased by 46.1% than C I , and the production of GSH increased by 39.8%, synchronously. The mutant M6 was just the strain which produceed low H2S and high glutathione we wanted. It can be used for wine producing, and improved the flavor of wine accordingly.