The Effect of Transglutaminase and Whey Protein Concentrate on Some Physicochemical, Sensory and Microbial Properties of Probiotic Drink Made from Mixture of Cow Milk and Soy Milk

Acidified milk drinks have low pH with healthy properties. These properties might be expanded and improved by fortification of these products with soy milk, probiotics and Whey Protein Concentrate. The aim of this study is to investigate the impact of transglutaminase (TG) and Whey Protein Concentrate (WPC) on physicochemical, sensory and microbial properties of functional drink from mixture of cow's milk and soya milk.
Cow's milk and soya milk with equal proportion were used for producing probiotic drink containing Lactobacillus casei. Different concentrations of transglutaminase (150, 200 and 250 ppm) and WPC (0.5, 1 and 1.5 % w/w) were added and the viability of probiotic bacteria and physicochemical and sensory properties of the drink samples were studied during three weeks of cold storage.
The results showed that the addition of enzyme and WPC increased the viscosity significantly (p˂0.05). Samples containing 1.5% WPC and 200 ppm enzyme and 1.5% WPC and 250 ppm enzyme had the highest acidity and the lowest pH. The highest number of L. casei belonged to the sample containing 0.5% WPC and 150 ppm enzyme. Moreover, this sample had the highest score of overall acceptability during storage. During the storage time, the viability of L. casei and pH decreased significantly (p˂0.05) whereas acidity and viscosity increased significantly (p˂0.05). The population of probiotic bacteria of the samples during storage was more than 106 CFU/ml.
The addition of 0.5% WPC and 150 ppm transglutaminase resulted in production of a functional drink with the highest viability of probiotic bacteria and sensory quality.