Effects of Roasting Conditions on Physicochemical Properties of the Watermelon Seed

Roasted watermelon seeds are consumed as snack foods. In this research, the Response Surface Methodology (RSM) was used in order to examine the effect of roasting on some physicochemical properties of watermelon seeds. The Central Composite Design (CCD) was applied to investigate the effects of two independent variables, i.e. temperature (180-260 °C) and time (5-15 min), on moisture content, texture, color, total phenol, and antioxidant activity. According to the results, increasing the temperature and prolonging the duration of roasting caused reductions in the moisture content, DE and texture hardness. Meanwhile, the total phenol content and antioxidant activity increased. The linear, quadratic, and interactive effects between the independent variables (temperature and time) were significant on moisture content and texture hardness (p <0.05). All variables, except the quadratic effect of time and the quadratic effect of the two independent variables, caused significant changes to the antioxidant activity and total phenol content. However, the total difference in color was only significantly affected by the linear effect of the two variables. Finally, roasting conditions (i.e. roasting temperature and time) were optimized in a manner that the acquired model-generated results akin to the experimental data (desirability=0.74).