The study was carried out to produce and characterize a low-calorie orange nectar using response surface methodology (RSM). To optimize the formulation, three different levels of independent variables; sugar, stevioside and pectin and two responses of Brix and viscosity were selected. In the optimum formulation, sugar content reduced to 70 % (compared to control sample) using stevioside and pectin with maximum levels of 0.06 and 0.03 %, respectively. Physicochemical properties of optimal and control samples were determined at refrigerated (4 °C) and ambient (25 °C) temperatures for 2 months. At refrigerator, the reduction rate for stevioside was 5 % while a decrease of 18 % was observed at ambient temperature. The vitamin C content in low-calorie orange nactar was 13.4 % higher than control sample at both temperatures. Thus the production of low-calorie orange nectar using stevioside could be industrially feasible and recommended to people who looking for dietetic foods.

No abstract

The present study aimed to produce polylactic acid (PLA) and ethyl cellulose (EC) biodegradable film using a single screw extruder and a roller mixer machine. This method resulted in better mixing of the polymers, reducing the possibility of burns and easier control of the film thickness. The mechanical properties measurement showed that tensile strength (TS) decreased by about 37.9%, and elongation at break (EAB) increased about 2.6-fold by increasing EC to 75%. The increase in EAB indicated the plasticising effect of EC. Since flexibility is essential in shaping a material without fracture, PLA/EC blend films can be a good candidate for packaging. According to DSC results, glass-transition temperature (T g ) decreased in the blend films, probably due to the increase in the hydrophilicity of the films after EC addition. The water contact angle of pure PLA film was about 83°, whereas it reached 28°in the film containing 75% EC. The water vapour permeability of PLA film was 2.24 9 10 À11 g m.s.Pa À1 and PLA reduction to 25% increased the WVP by about two times. Adding EC into the pure PLA film reduced the transparency, indicating the potential of blend film for the packaging of light-sensitive food products. Besides, EC addition enhanced PLA biodegradability after enzymatic treatment (alcalase) and soil burial.

No abstract