“…Therefore, screening for Study on Streptococcus thermophilus isolated from Qula and associated characteristic of acetaldehyde and diacetyl in their fermented milk (Received March 3, 2014;Accepted January 9, 2015) Musu Zha, 1 Jie Yu, 1 Yong Zhang, 1 Hongmei Wang, 1 Na Bai, 1 Yanting Qin, 1 De Liangliang, the specific strains which produce the typical flavor of the traditional dairy products is of high importance. Various volatile bacterial metabolites produced by lactic acid fermentation or other related reactions contribute to the flavor of fermented milk products (Routray and Mishra, 2011). For starter cultures, one important evaluating parameter is their aroma-producing ability, which can result from the formation of metabolites such as acetaldehyde and diacetyl (Yuguchi et al, 1989).…”