Effect of co-encapsulation of Lactobacillus acidophilus LA5 and selenium in hydrogelated matrix of basil seed mucilage/sodium caseinate on properties of set yogurt

Abstract

This study aims to prepare and optimize basil seed mucilage and sodium caseinate as a biocomposite wall to co-encapsulate Lactobacillus acidophilus LA5 and selenium. The efficacy of this biocomposite wall in improving the viability of L. acidophilus LA5 under in vitro acidic conditions was investigated. The mixture design method was applied to find optimal ratio of basil seed mucilage/sodium caseinate as components of the capsule wall. The maximum encapsulation efficiency of the selenium and L. acidophilus LA5 and the minimum zeta potential led to the selection of the optimal ratio of basil seed mucilage/sodium caseinate (basil seed mucilage 58.27% and sodium caseinate 41.73%). Possible cross-linking of basil seed mucilage and sodium caseinate, thermal properties, crystal structure, and morphology of the capsule were investigated using FTIR, DSC, XRD, and SEM tests, respectively. The composite wall of basil seed mucilage/sodium caseinate significantly enhanced the viability of encapsulated L. acidophilus LA5 in comparison to the control sample (free L. acidophilus LA5) (p < 0.05). Five yogurt samples were produced, including samples with free probiotic, free probiotic bacterium and selenium, free selenium, control (no probiotic bacterium and selenium), and probiotic yogurt with encapsulated selenium and probiotic bacterium. The physical, chemical, sensorial, and microbial characteristics of yogurt samples were investigated during storage for 21 days at 4 °C. Yoghurt enriched with free selenium and microcapsules (co-encapsulated probiotic and selenium) had minimum and maximum viscosities, respectively (p < 0.05). In addition, the probiotic yogurt sample with encapsulated L. acidophilus LA5 and selenium received a higher overall acceptance score than the other treatments (p < 0.05). As a result, basil seed mucilage and sodium caseinate based composite wall was demonstrated great potential to encapsulate probiotics and selenium for application in yogurt formulation.