The fermentation of buttermilk by Lactobacillus debruechii ssp.bulgaricus and Streptococcus thermophilus for Quark cheese production was studied.Based on serum OD500nm,correction yield and sensory quality,the effects of chymosin addition amount,CaCl2 addition amount,starter culture ratio,and cultivation pH on fermentation efficiency were investigated.According to single factor and orthogonal tests,the optimal process parameters of Quark cheese was explored to be chymosin addition amount of 0.015%,CaCl2 addi...