The investigation of rheological and physicochemical characteristics of new formulation of juice produced by combination of sour cherry and red grape, fortified with inulin dietary fibre as a prebiotic product

Because of desirable nutritional value and good taste of red grape and sour cherry juices, as well as achieving optimum formulation for the production of a new prebiotic fruit juice, in this research the combination of red grape and sour cherry juices with inulin was used. At first, 16 formulation of juices using different ranges of red grape concentrate (185-207g), sour cherry concentrate (35-55g) and inulin (8-12g) were chosen by mixture design. The rheological (apparent viscosity) and physicochemical properties (titratable acidity and pH, turbidity, formalin index, absorption color) has been examined. Based on the results, changing in red grape, sour cherry and inulin of formulations doesn’t have any significant effect on sample brix (brix equal to 16). While with increasing the sour cherry content of formulation, the pH of samples was decreased and the acidity increased. Therefore increasing in red grape concentrate leads to increase of color absorbance while with inulin increasing, the turbidity of samples was increased too. The formalin number of samples was measured in standard range. On the basis of optimization results, the best formulation to achieve sample brix equal to 16, in range pH, acidity and formalin, maximum color absorption in addition to minimum turbidity was: 185 g red grape concentrate, 55 g sour cherry concentrate and 10.3 g of inulin. With regard to of comparision optimized sample results sample control with , it has been found that the juice formulation can be optimized by adding inulin to the samples, while the nutritional value and desirability of samples would be increased, which indicates the intended purpose of producing this juice.