Study On The Construction Of Cider Yeast And Fermentation Kinetics

Recently, with the people life level improving and readjustment of industrial structure, cider development has a wide market prospect. Because of lack of excellent cider yeast and aroma controlment technology, the industry developing of cider has serious imbalance with market demand, which has been the main bottleneck of rapid internationalization of cider industrial.22 yeast strains were selected as experimental material in this study. According to the synthetic analysis of physico-chemical characteristics and organoleptic evaluation on ciders, WF1 had better fermentation ability. PF14 was a strain had the best ability of aroma- generation, which had been identified by the predecessor. So WF1 and PF14 were the parent strains. It was optimized that the condition of preparation, inactivation, fusion of Protoplast. The fusion experiment was completed in the optimal condition. The results obtained from analysis of different ciders by gas chromatography-mass spectrometry and sensory taste suggested that four fusants had better fermentation ability. Fermentation kinetics of one strain which was best in fuzzy comprehensive evaluation was studied, The main results in this study showed:(1) In the experiment of the parent strains screening, WF1 which was regarded as the parent Y had the better ability in ferment-stability, alcohol production and sensory taste. PF14 which was regarded as the parent X had the best ability of aroma-generation.(2) The optimal condition of getting rid of cell wall for the parent X was: cell age 8h, power of ultrasonic 240W, temperature 35℃, treating time 60min and the formation rate of protoplast was 90.15%, the regeneration rate of protoplast was 44.32%. The optimal condition of getting rid of cell wall for the parent Y was: cell age 8h, power of ultrasonic 240W, temperature 30℃, treating time 30min and the formation rate of protoplast was 95.21%, the regeneration rate of protoplast was 30.03%.(3) In the condition that power of ultraviolet 30W, irradiation distance 30cm, treating time 25min, the protoplast inactivation rate of the parent X was 100%. In the condition that temperature 60℃, treating time 15min, the protoplast inactivation rate of the parent Y was 100%.(4) The result of range analysis of orthogonal experiments showed that the impact sequences of factors for fusion rate was pulse field strength>Pulse intervals>Pulse number>Pulse time. The optical condition was pulse field strength 2200v/cm, Pulse intervals 1s, Pulse number 2, Pulse time 20μs. The result of variance analysis of orthogonal experiments showed that the impact of pulse field strength for fusion rate was extremely remarkable, the impact of Pulse number and Pulse intervals for fusion rate was remarkable.(5) Identificate the different ciders by gas chromatography-mass spectrometry, quantitative analysis 35 components, including esters, alcohols, acids, evaluate the sensory taste, the results of fuzzy comprehensive evaluation showed that 38#, 21#, 35#, 46# were the Superior cider yeasts.(6) Research on the kinetics of 38#, establishing the kinetics model of biomass growth, the kinetics model of alcohol-producing, the kinetics model of sugar-consumption. The results indicated that relative coefficients of 3 models were high, the models could explain and predict the dynamic change of fermentation process well.