Protection of Lactobacillus acidophilus NRRL-B 4495 under in vitro gastrointestinal conditions with whey protein/pullulan microcapsules

•Effect of pullulan in the encapsulation wall matrix of probiotic L. acidophilus was studied.•WPI-pullulan encapsulation obtained 93.72% encapsulation efficiency.•Presence of pullulan provided formation of smoother surfaced microcapsules.•Release of encapsulated bacteria in SIJ was completed within 7 h.•WP-pullulan microcapsules obtained sufficient a viable number at the end of SGJ and bile exposure.

In this research, whey protein/pullulan (WP/pullulan) microcapsules were developed in order to assess its protective effect on the viability of Lactobacillus acidophilus NRRL-B 4495 under in vitro gastrointestinal conditions. Results demonstrated that WP/pullulan microencapsulated cells exhibited significantly (p ≤ 0.05) higher resistance to simulated gastric acid and bile salt. Pullulan incorporation into protein wall matrix resulted in improved survival as compared to free cells after 3 h incubation in simulated gastric solution. Moreover WP/pullulan microcapsules were found to release over 70% of encapsulated L. acidophilus NRRL-B 4495 cells within 1 h. The effect of encapsulation during refrigerated storage was also studied. Free bacteria exhibited 3.96 log reduction while, WP/pullulan encapsulated bacteria showed 1.64 log reduction after 4 weeks of storage.