Research On Selection Of Yeasts And Fermentation Technology Of Mead

In order to improve alcohol and flavor of mead, in this paper, selection of yeasts strains, nutrients, honey types and parameters were studied for mead brewing. The main results were as follows:(1)Five yeast strains, which were named strains A1, A2, A3, A4, and A5, were selected from Litchi honey by enrichment culture and the dilution plate method. A1and A3had high fermentation speed, strong producing ethanol capability and high producing ester capacity, measured by gas production, TTC plate screening method and ester capacity training. Temperature-resisting, acid and alcohol-resistant ability and glucose tolerance of Al and A3were measured. The results showed that the highest temperature strain A1can withstand was35℃, and it can grow and reproduce well in the higher acidity environment (pH3.0-6.0). The tolerance of upper alcohol and the highest sugar content for A1were18%and40separately.Under the same conditions, fermentation rate of strain A1was higher than strain A3, and both in ethanol production and sensory of mead, strain A1was better than strain A3. At the same time, the optimum growth temperature of strain Al was28℃, the optimum growth pH value was4.5, and the optimum inoculation was10%.(2)Comparing fermentation capacity of four yeasts in this experiment, which were Al, Saccharomyces ellipsoideus, Angel temperature resistant active dry yeast and rice wine dedicated active dry yeast, showed that Saccharomyces ellipsodeus was the most suitable for mead fermentation. The most suitable inoculation of Saccharomyces ellipsoideus for the fermentation was5%, the optimum temperature was25℃and the optimum initial sugar content was25%.(3)The organic nitrogen and inorganic nitrogen sources were tested in single factor experiments, and the optimal concentration was selected. For orthogonal test, the optimal nitrogen combination:ammonium phosphate (APP) dosage was1.6g/L, beef extract0.3g/L and yeast extract for the0.3g/L(4)The optimal ratio obtained after fermentation of8kinds of honey mixed at different ratios was X1:X2:X3:X4:X5:X6:X7:X8=1:1:1:1:1:1:1:1by uniform analysis. The alcohol yield was12.6%, sensory experience score was89.9, which was higher than the other group.(5)Chitosan was the best clarificant and it’s optimal dosage was0.15%, which dosage had certain effect on the soluble solids in mead.