Journal of Food Processing & Technology

The growth and interaction of yeasts and lactic acid bacteria in milk fermentation

International Conference and Exhibition on Food Processing & Technology

November 22-24, 2012 Hyderabad International Convention Centre, India

Xue Han, Lanwei Zhang, Huaxi Yi, Yi Qu, Wei Gao and Ming Du

Accepted Abstracts: J Food Process Techno

Abstract:

Yeasts affect the quality of fermented milk through the production of flavor compounds and other metabolites. As a specialty product, yeast and lactic acid bacteria combined fermented milk has its own niche in the special places in China. In present study, five yeasts were screened and isolated from traditional dairy products throughout the northwestern China according to their fermented milk characteristics. The yeasts which have higher production of CO2 and acid rate were selected to combine with the yoghurt starter culture to fermented milk. The fermented temperature, inoculate and the ratio of yeast and LAB were optimized. Then the changes of viable count of yeast and LAB, the content of CO2, ethanol and pH were also detected during 100C storage for 4 weeks. The results showed the total inoculate rate of starter was 4%, the ratio of yeast and LAB were 1:4, fermented temperature was 370C . The storage test manifest the pH of fermented milk were decreased from 4.21 to 3.83. The count of LAB were increased from 5.5?108 to 8.3?108 CFU/ml during the first week storage at 100C . Then the count were decreased to the 7.3 ?107 CFU/ml. The viable count of yeast were increased from 6.8 ?105 to 9.6?106 CFU/ml. The content of CO2 and ethanol produced by yeast was 22.9 mmol/l and 14.57 mg/ml respectively. For the texture of product were better than LAB fermented milk (yoghurt). However the apparent viscosity of product was lower than yoghurt. For the sensory evaluation, the product has the little milk taste and with the little fresh flavor. These results manifested that the yeast possesses stability enhancing effects on LAB and yeast combined yoghurt could provide the new products to the Chinese dairy marketplaces.