Synbiotic potential of Doogh supplemented with free and encapsulated Lactobacillus plantarum LS5 and Helianthus tuberosus inulin

The survival and effect of free and encapsulated probiotic Lactobacillus plantarum LS5 on acidity, exopolysaccharide production, phase separation and influence on the sensory attributes of probiotic and synbiotic Doogh (typical Iranian drink based on fermented milk) supplemented with Helianthus tuberosus inulin were studied over 22 days storage. Results showed addition of L. plantarum LS5 (free or encapsulated) increased acid development (degrees D) in Doogh during storage. In addition, phase separation in Doogh with encapsulated probiotic bacteria was slower compared to Doogh with free probiotic bacteria. More exopolysaccharides were observed in Doogh with encapsulated culture compared to those without encapsulated culture. The results confirmed that there was an increased survival of L. plantarum LS5 due to protection of cells by microencapsulation. Also addition of inulin improved survival of free or encapsulated cells in Doogh during storage, but effect of inulin on acidity, exoploysaccharide content and phase separation of samples containing free or encapsulated cells was not significant (P>0.05). Moreover, sensory evaluation results indicated addition of free or encapsulated probiotic cells and inulin did not significantly affect appearance and color, acidity, flavor and after taste of the Doogh samples over the storage period. Therefore, probiotic and synbiotic Doogh (supplemented with free or encapsulated L. plantarum LS5 and Helianthus tuberosus inulin) are potentially suitable for using as functional dairy foods.