Study on Streptococcus thermophilus isolated from Qula and associated characteristic of acetaldehyde and diacetyl in their fermented milk

The Journal of General and Applied Microbiology

De Liangliang¹  Menghe Bilige¹  Wenjun Liu¹  Hongmei Wang¹  Jie Yu¹  Heping Zhang¹  Musu Zha¹  Yong Zhang¹  Na Bai¹  Yanting Qin¹ 

[1] Key Laboratory of Dairy Biotechnology and Engineering, Ministry Education of China

关键词: acetaldehyde and diacetyl;    isolation and identification;    Qula cheese;    Streptococcus thermophilus;   

DOI  :  10.2323/jgam.61.50

学科分类：微生物学和免疫学

来源: Applied Microbiology, Molecular and Cellulrar Biosciences Research Foundation

【 摘 要 】

In this study, the lactic acid bacterial population of Qula cheese from the Gansu and Sichuan provinces of China were isolated and identified. Eight strains of Streptococcus thermophilus were isolated, of which five strains were selected for further characterization based on their fermentation properties. The changes in a number of parameters, including titration acidity, pH, viable counts, PrtS protease activity and the production of acetaldehyde, diacetyl and organic acid, were monitored during fermentation and the storage of fermented milks produced by the respective strain. All of the strains displaying acidifying capacity and all five fermented milks maintained high viable counts of S. thermophilus from fermentation to storage. Our study found that the changes in the monitored parameters were strain-specific and varied considerably among the five tested strains. Fermented milks produced by strain IMAU80809 had the highest concentration of acetaldehyde and were most favorable in the sensory evaluation. This study confirms that Qula cheese is a good source for isolating novel lactic acid bacterial strains with different fermentation properties, which will be very useful for further development and industrialization of traditionally fermented dairy products.

【 授权许可】

Unknown