physicochemical, sensory and rheological properties (creep behavior) of sour cherry jam based on stevia and optimization of formulation by response surface methodology

The response surface methodology was used to produce cherry jam containing stevia sweetener with desirable physicochemical, sensory and rheological properties. These experiments were planned using a central composite design (CCD) with three independent variables including sugar, pectin and stevia. The production process of samples was done in five levels of sucrose (50-10%), pectin (0.5-1%) and stevia (0.6-0.2%) in a constant amount of 300 g of fruit. To evaluate the jam, the physicochemical, sensory and rheological properties of the jam were determined and optimized. Concentrations of sucrose, pectin and stevia had a significant effect on the color, sensory and rheological properties of the jam. The results showed that none of the linear and interaction effects of the studied factors on the pH of cherry jam were significant. The values ​​of L * (brightness) and b * (yellowness) increased with increasing concentrations of sucrose and stevia, also increasing pectin increased a * (redness) of the jam. The evaluation results of sensory tests showed that the sugar variable plays an important role in improving the sensory parameters of the jam. Examination of the tests resulting from the creep test showed that the sugar factor plays an important role in the value of the parameters G0 and η0. The results show that the viscosity shown by Dashpot Maxwell (η0) can be a good indicator of the effect of sucrose concentration in the jam. Also, G1 and η1 parameters can not be clear indicators for understanding the structural changes in the jam with changes in the concentration of sugar, pectin and stevia. In general, the results of the study showed that using pectin and stevia sweetener can reduce the amount of sucrose in the jam and produce a low-calorie product with optimal quality and desirability index of 0.69 on a commercial scale.