Breeding Of Yield Aroma Esters Yeast

China is one of the oldest Liquor birthplaces, which has a long history and profound wine culture. Chinese Liquor is popular in domestic and foreign because of its variety, unique production technology and excellent quality. It is one of the effective technical measures to improve the Liquor quality by adding ester producing yeast properly during Liquor fermentation process. In order to obtain a better aroma ester producing yeast strains, this paper firstly screened ester high-producing yeast strains, and then treated with UV, we also researched on the fermentation properties of the mutagenesis.The results are as follows:In our research, we screened11aroma-producing yeast, and determine their species by studied their physiological and biochemical characteristics. We measured their fermentation total ester to select the high-yield stains. In the selected11strains, the highest ester producing strains is S8, the fermentation broth of total ester reached1.78g/LThe ester high-producing yeast S8was treated by ultraviolet irradiation, after plate cultivation we selected the bigger stains to the tube culture. In the primary screening, we used Durham fermentation tube to determine the carbon dioxide volume. We got a stain named as Y16, which total ester content was up to3.21g/L after the second turn screen. The total ester product of original stain S8is1.78g/L, the ester producing gross increase around75.28%after mutation. The optimal time for t ultraviolet treatment is2min. This strain can be preserved for later optimization experiment and product.We optimized the fermentation conditions of the highest ester producing yeast strain Y16. Ester producing yeast physiological conditions was used as factors, the best ester producing culture medium was determined as pH5, alcohol dosage2%.And we found that the still regularly ventilation cultivation is better than oscillating culture for ester produce. Then we selected three factors: temperature, sugar content and fermentation time for surface analysis, the total ester in fermentation liquid reached4.033g/L when yellow bean sprout juice concentration is100g/L in the culture medium, the culture temperature is28℃and the fermentation time is6days. The results of these studies have certain reference significance for further explore of the physiological and biochemical properties of ester producing yeast.The main flavoring compositions of luzhou-flavor liquor is ethyl hexanoate, but ester producing yeast produce ethyl acetate ester mostly. Through the study of mixed culture of ester producing yeast and caproic acid bacteria which screened from Liquor cellar mud draws the following conclusion:the caproic acid produced by caproic acid bacteria largely and the ethanol produced by yeast transformed into ethyl caproate under the action of esterification enzyme of ester producing yeast. The effect is most pronounced when inoculation ratio of the ester producing yeast and caproic acid bacteria is1:2, the total ester reached4.815g/L, and ethyl caproate achieved the highest as1.72g/L.This conclusion of have certain significance to luzhou-flavor liquor production.