Effect of Different Concentrations of Inulin and Whey on the Qualitative and Rheological Properties of Aloe vera Doogh Containing Microencapsulated probiotic bacteria

The aim of this study was to investigate the effect of microencapsulation of probiotic bacteria with sodium alginate/resistant starch and sodium alginate/chitosan by extrusion method on qualitative and rheological properties and viability of bifidobactrium animalis subs lactis in Aloe vera doogh. 10% of aloe vera gel with different concentrations of whey (5, 10 and 15%) and inulin (0.5, 1 and 1.5%) added to probiotic doogh and their effect on the protection of Probiotic bacteria and qualitative properties were evaluated. The results showed that increasing the level of inulin had no significant effect on pH. Increasing the percentage of whey up to 5% had no significant effect on the pH, but increasing more than 5% significantly decreased the pH of the doogh samples during storage period. In terms of sensory properties samples containing 1% inulin and microencapsulated bacteria with sodium alginate/chitosan had highest scores in flavour while lowest score was observed in control treatment (without inulin and whey) and free bacteria. Doogh samples containing 1.5% inulin had the lowest serum separation and the control sample (without inulin and whey) showed the highest serum separation at the end of storage period. In general, samples containing microcapsules had a lower serum separation than samples containing free bacteria. The highest viscosity and consistency coefficients were observed in the doogh samples containing 1.5% inulin. The microencapsulation process increased the apparent viscosity, consistency index and loss modulus and decreased the flow behavior index of the doogh samples. Microencapsulation of probiotic bacteria by sodium alginate / resistant starch and chitosan and use of whey and inulin in doogh samples increased their viability during storage period.