Isolation of Thermotolerant, Alcoholtolerant and Osmotolerant Yeast Strains from Dairy Products and Non Dairy Products

摘要

Thermotolerant yeast strains were isolated from dairy products and fruit juices. A total of 200 yeast isolates were selected on the basis of their growth at 40° C. Eighty eight yeast strains were isolated from dahi samples, forty nine strains were isolated from whey, thirty strains from skim milk, twenty from sugarcane juice samples, seven from grape juice and six from orange juice. Further, all the thermo tolerant yeast isolates were subjected to sugar tolerance (10-25%) and alcohol tolerance (5-10%) tests. 55% of yeast strain were able to grow at 10% sugar concentration. 22% of the isolates were able to tolerate up to 15% sugar concentration, whereas, 15% of them showed tolerance to 20% sugar. However, only 7.5 % of the isolates even tolerate upto 25% sugar concentration. 19% of the isolates were able to tolerate up to 7.5% ethanol, whereas, 8.5% of thermo tolerant yeast isolates could even tolerate up to 10% of ethanol. However, no isolate was able to tolerate more than 10% of ethanol. Of allthe isolates tested, twenty two isolates were found to be highly alcoholtolerant and osmotolerant.