Survival of entrapped Lactobacillus rhamnosus GG in whey protein micro-beads during simulated ex vivo gastro-intestinal transit

Cell survival of Lactobacillus rhamnosus GG entrapped in gelled whey protein isolate (WPI) micro-beads was elucidated relative to cells suspended in native WPI and free-cell controls during ex vivo porcine gastro-intestinal incubation. Probiotic gastric tolerance was investigated as a function of pH (2.0-3.4) and time with subsequent intestinal incubation (pH 7.2). Free cells showed no survival after 30 min ex vivo stomach incubation (<= pH 3.4), while native WPI enhanced survival by 5.7 +/- 0.1, 5.1 +/- 0.2 and 2.2 +/- 0.2 log(10) cfu mL(-1) following 180 min incubation at pH 3.4, 2.4 and 2.0, respectively. Protein micro-beads augmented ex vivo probiotic acid resistance (8.9 +/- 0.1 log(10) cfu mL(-1)) and demonstrated significant micro-bead adsorption capacity coupled with micro-bead digestion and controlled release of viable, functional probiotics within 30 min intestinal incubation. This technology potentially envisions whey protein micro-beads as efficacious entrapment matrices and binding vehicles for delivery of bioactive ingredients. (C) 2011 Elsevier Ltd. All rights reserved.