Effect of Casein Hydrolysates on Yogurt Fermentation and Texture Properties during Storage

Qiang-Zhong Zhao¹, Jin-Shui Wang¹*, Mou-Ming Zhao¹, Yue-Ming Jiang² and Cui Chun<sup>1

1</sup>College of Light Industry and Food Science, South China University of Technology, Guangzhou 510640, PR China
²South China Institute of Botany, The Chinese Academy of Sciences, Guangzhou Leyiju 510650, PR China

Article history:
Received November 9, 2005
Accepted March 6, 2006

Key words:
yogurt, casein hydrolysates, probiotic count, acidification, viability, texture properties, sensory evaluation

Summary:
Effects of casein hydrolysates by papain on acidification of the yogurts and growth of probiotic bacteria during yogurt fermentation have been investigated. The viability of probiotic bacteria and texture characteristics of the yogurts during storage at 4 °C have been evaluated. The hydrolysates strongly decreased the fermentation and coagulation time of the yogurts. The post-fermentation acidification was retarded by the hydrolysates. The hydrolysates increased the probiotic counts during initial fermentation stage. The growth of the probiotic organisms decreased at the final stage. Survival of probiotic bacteria was improved by the hydrolysates. The hydrolysates significantly (p<0.05) increased the adhesiveness of the yogurts except for 0.5 % of hydrolysate with degree of hydrolysis of 8.5 %. The sensory evaluation scores of the yogurts were significantly (p<0.05) improved by the hydrolysates after the storage. The effect of casein hydrolysates on fermentation and texture properties was related to the molecular mass of the hydrolysates.

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