Selection of mozzarella cheese whey native yeasts with ethanol and glucose tolerance ability

Abstract

The research aimed to determine the native yeast on mozzarella cheese whey that has glucose and ethanol tolerance ability. The research did experimentally and the data analyzed descriptively. Native yeasts isolated from 1 ml mozzarella cheese whey with using a modification of Potato Dextrose Agar/PDA (Oxoid Ltd.) with the addition of 3% Yeasts Extract/YE (Kraft Foods) and 10 ppm amoxicillin. The yeasts identified for macroscopic and microscopic characteristics then tested with RapID Yeast Plus System. The ability in tolerate ethanol and glucose contents tested by grown the yeasts on modified Nutrient Broth/NB (Oxoid Ltd.) with 3% Yeasts Extract/YE (Kraft Foods) and 10 ppm amoxicillin then added with glucose monohydrates (10%, 20%, 30%) or ethanol (10%, 20%, 30%) and incubated for 72h at room temperature (23-28°C). Optical density (OD) read for UV absorbance at 600 nm using UVVis spectrophotometer every 24h until 72h. Results showed that six native yeasts isolated and identified as C. tropicalis three isolate, Tri. beigelii two isolates and Blast. capitatus is one isolate. The best isolates with highest OD at 30% glucose concentration (2.215) gained by C.tropicalis (a), while the highest OD at 30% ethanol concentration (0.508) shown by C.tropicalis (f).