Investigating the Texture and Antioxidant Capacity of Papain and Trans-glutaminase Enzyme-treated Yogurt with Different Carbohydrates – Glucose, Sucrose and Maltodextrin
Yogurt is considered as a functional food, which is a complex mixture of different biological components. Functional foods are designed to have physio-logical benefits and reduce the risk of chronic diseases beyond basic nutritional functions, and may be similar in appearance of conventional food. Therefore, the consumption of dairy products is highly recommended. In this study, the average composition milk was purchased in a local supermarket. Subsequently, ultrafiltration of milk was carried out with a tubular membrane, placed in a laboratory-developed cross-flow membrane module. Pore size and active surface area of tubular membrane were 5 nm and 0.005 m2, respectively. A static turbulence promoter was placed inside of membrane tube. Retentate of ultrafiltration membrane was treated with different concentrations of papain at temperature 50 °C for 10 minutes and subsequently, deactivation of enzymatic activity was performed at temperature 70 °C for 20 minutes. After deactivation of catalytic activity of papain, milks were fermented with yogurt starter culture (Thermophilic YoFlex® culture) at temperature 45 °C for 6 hours. During fermentation, transglutaminase and different types of carbohydrates, such as glucose, maltodextrin and sucrose were introduced with the aid of changing texture and antioxidant capacity of yogurt. Antioxidant capacity and hardness of yogurt, prepared with cow's milk were 0.44 mmol eqv. ascorbic acid/L and 0.58 Newton, respectively. It was found that application of enzyme (both papain and transglutaminase) and maltodextrin increased the antioxidant capacity of yogurt. Furthermore, it was found that hardness of yogurt was increased by addition of carbohydrate.