Foam mat drying of orange juice using cress seed gum and egg albumin

In this research, cress seed gum in three concentrations (0.1, 0.2 and 0.3%) as a stabilizer and egg white powder in four levels (1, 2, 3 and 4%) was used to produce orange juice foam and then the optimal foam sample (minimum density, maximum stability and overrun) was selected. Next, the optimal sample for drying by foam mat drying method was dried at three different temperatures (40, 55 and 70 C) by hot air dryer. The results showed that by decreasing the concentration of cress seed gum and increasing the concentration of egg white protein, the overrun increased significantly and the density decreased (p<0.05). Also, by increasing the concentration of cress seed gum and egg white protein, the stability of the foam improved. Among all the treatments, the sample containing 4% egg white powder and 0.1% cress seed gum, in addition to low drainage (drainage volume 0.5 ml), has low density (0.321 gr/cm) and high overrun (308 percent) which was selected as the best treatment for the production of orange powder. The drying time of orange pulp at temperatures of 40, 55 and 70 degrees Celsius was 100, 150 and 280 minutes, respectively. The effective diffusion coefficient in the temperature range of 40 to 70 degrees Celsius was in the range of 1.38 x 10-7 to 2.938 x 10-7 m2/s. The results showed that by increasing the temperature from 40 to 70 degrees Celsius, the solubility of the powder increased, while the water activity of the powder, density and reabsorption of water decreased significantly (p˂0.05). Also, the results of color analysis showed that with increasing drying temperature, color indices (L*) and (a*) increased significantly and color index (b*) decreased. Our results showed that food powders with good properties can be gained by foam mat drying.