Study on the breeding of high alcohol tolerance yeast by enthanol shock treatment

• Main Authors: Meng-Yu Tsai, 蔡孟佑
• Other Authors: Wu Ph.D
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/97315148838700782552

碩士 === 國立屏東科技大學 === 食品科學系所 === 97 === Abstract Student ID :N9636002 Title of thesis: Study on the breeding of high alcohol tolerance years by ethanol shock treatment Total Page: 61 Name of Institute: National Ping-tung University of Science and Technology,Department of Food Science Graduat Date: June,2009. Degree Conferred: Master Name of Student: Meng-Yu Tsai Adviser: Ming-chang Wu Ph.D. The Content of Abstract in This Thesis: Alcohol is a metabolite from yeast during fermentation. It is an important commercial product as wine in the brewing industry. However, it is also toxic for the yeast during cell growth or brewing. There two type of commercial alcohol products, one of them is brewing alcohol contains 3.5 %-14 % alcohol, and the other one is distilled liquor contains 28 %-65 % alcohol. This study investigated the effect of alcohol shock treatment on the alcohol production of yeast Saccharomyces pastorianus. The yeast was shocked with alcohol for 0 to 5 times. The results showed that the growth of yeast is slow down at 3rd and 4th stage after a 20% alcohol shock. However, the growth rate of yeast returns to normal at the 5th stage shock treatment. The experiment was divided into 3 groups in the wine making (brewing) test. One of them was directly adjusted the initial soluble solids content by adding sugar to 40 0Brix in pressed grape juice. Another group was directly adjusted the initial soluble solids content of pressed grape juice to 25 0Brix, while adding the remained sugar to 40 0Brix in the mash at the first 3 days and keeps fermenting. The results showed the osmotic tolerance of yeast significantly increase after the alcohol 5 times shock treatment. The shocked yeast grows well and companies with alcohol fermentation in 40 0Brix sugar fortified grape juice. The alcohol production rate of alcohol shocked yeast reduced during the fermentation. The yeast with non-alcohol shock stopped fermentation at 12th days during brewing and the alcohol concentration was 12% in wine. The yeast shocked 5 times and cultured in the 25 0Brix and 40 0Brix sugar fortified grape juice. The alcohol content of the mashes at 12th day during the brewing are 9 % and 8 %, respectively, and increasing to 19 % and 17 %, respectively at the 35th days. The results of SDS-PAGE analysis showed that the protein profiles, e.g. molecular weight 95 KDa, of extracts from the yeast shocked 5 times with 20% alcohol is significantly different to that of non-alcohol shock treatment. Keywords: Ethanol, Yeast, SDS-PAGE