Microencapsulation of probiotic bacteria and their survival in frozen fermented dairy desserts

Abstract

A procedure was developed to entrap probiotic bacteria (Lactobacillus acidophilus MJLA1 and Bifidobacterium spp. BDBB2) into calcium alginate beads. The effects of sodium lauryl sulfate and Tween 80 on bead sizes and the release of the organisms from the encapsulated beads in the presence of acid and bile were investigated. The external and internal appearances of the bead were observed using scanning electron microscopy. The encapsulated beads were freezedried and incorporated into the mix for making frozen fermented dairy desserts prior to freezing. Two batches of fermented frozen dairy desserts were made with or without encapsulated probiotic bacteria and viable counts of probiotic bacteria were enumerated in fermented frozen dairy desserts at fortnightly intervals for 12 weeks. The mean diameter of the beads without any sodium lauryl sulfate and Tween 80 was 1.17 mm, but the size of the beads decreased as the concentrations of sodium lauryl sulfate and Tween 80 increased. The average diameter of the beads with 1% sodium lauryl sulfate and 0.3% Tween 80 was 0.064 mm. The beads appeared to be ellipsoidal in shape and the microorganisms were located in the matrices formed in the beads. The entrapped bacterial cells were released by shaking in O.1M phosphate buffer for 5 min and in the presence of bile, but not in the presence of acid. In general, the survival of probiotic bacteria in fermented frozen dairy desserts was improved with encapsulation.