Abstract:Skimmed milk and soymilk were fermented with Kluyveromyces marxianus，Streptococcus thermophiles，and Lactobacillus delbeueckii subsp. bulgaricus as the compound starter. With titration acidity and sensory score as indicators，single factor test and Box-Behnken design were employed to optimize the skimmed milk-to-soy milk ratio，the addition of white granulated sugar，the inoculation amount of starter，and fermentation temperature. The texture，water holding capacity，titration acidity，sensory score，and viable bacterial count of the product obtained with the optimal processing conditions were determined. The results showed that the optimal fermentation conditions were skimmed milk-to-soy milk volume ratio of 82 ∶18，white granulated sugar addition of 7.25%，the compound starter inoculation amount of 3.92%，and fermentation at 42 ℃for 4.5 h. The compound fermented milk produced under the optimal conditions had the highest sensory score of 94.85，post maturation period of 12 h，hardness of 99.39 g，acidity of 97.52 °T，and viable bacterial count of 2.7×109 CFU/mL. The fermented milk was milky yellow，sour-sweet，and palatable，with uniform texture，soft and smooth taste，unique bean flavor and rich milk flavor.It demonstrated good flavor，texture，and sensory quality within 14 d of storage.