Effects of Extrusion Conditions on the Physical and Functional Properties of Instant Cereal Beverage Powders Admixed with Mulberry (Morus alba L.) Leaves

On account of studying the feasibility of the production instant cereal beverage powders admixed with mulberry leaves by extrusion process, a box-behnken design of the response surface methodology (RSM) was employed to investigate the interaction of operating conditions at varying screw speed (300, 350 and 400 rpm), mulberry content (5, 10 and 15%) and feed moisture (15, 17 and 19%) on the physical and antioxidant property of product. Data were modelled by multiple regression analysis and the coefficient indicating for best fit model. The results showed that the effect of mulberry content and feed moisture had significant on bulk density, color, viscosity, water absorption index, antioxidant activity and total phenolic compound. Increasing of mulberry content resulted in finished product with higher bulk density, less lightness, less viscosity, less water absorption index, higher antioxidant activity and total phenolic compounds as a result of materials in green foods. Whereas increasing of feed moisture resulted in finished product with higher bulk density, less viscosity and less water absorption index also, but tended to lower antioxidant activity and total phenolic compounds. In addition, the optimum condition should be operated at 350 rpm screw speed, 10% mulberry content and 17% feed moisture to obtain finished product of high antioxidant activity and total phenolic compounds with good characteristics of moderate color green, easy to dissolve in hot water, palatability, and acceptability.