Use of whey protein isolate and gum Arabic for the co-encapsulation of probiotic Lactobacillus plantarum and phytosterols by complex coacervation: Enhanced viability of probiotic in Iranian white cheese

The use of more than one core component in the encapsulation system, or co-encapsulation, may increase the biological activity of the components compared to the case where they are encapsulated separately. Whey protein isolate (WPI) and Gum Arabic (GA) were utilized as wall materials to encapsulate probiotic bacterium Lactobacillus plantarum ATCC 8014 (P) alone or in combination with phytosterols (Ph) by complex coacervation technique. To produce solid microcapsules, liquid coacervate of WPI-P-GA and WPI-P-Ph-GA were dried using spray drying and freeze drying methods. The obtained data showed that the cell viability of L. plantarum ATCC 8014 in both liquid and dried microcapsules (freeze and spray dried) was improved in the presence of phytosterols compared to that in the absence of them and the survivability of L. plantarum ATCC 8014 in freeze-dried microcapsules was better in comparison to the spray-dried microcapsules during the storage time (60 days). Encapsulation efficiency in the freeze dryer was significantly higher than that in the spray dryer (p < 0.05). The microcapsules were analyzed in terms of size, zeta potential, and polydispersity index. The particle sizes of WPI-GA and WPI-Ph-GA were 196.2 ± 13.72 and 366.5 ± 0.56 nm, respectively. The electrostatic reaction and completion of coacervation phenomenon were proven by fourier transform infra-red spectra. Scanning electron microscopy analysis indicated that the microcapsules dried by freeze dryer had a porous morphology and did not have any particular shape; however, those dried by spray dryer showed the quasi-spherical configuration and had a wrinkled surface. X-ray pattern of co-microcapsules revealed that the microcapsules dried by freeze dryer had an amorphous structure compared to the spray-dried ones. Co-encapsulated L. plantarum with phytosterols had the highest viability in comparison with free and single microencapsulated L. plantarum in ultra-filtered Iranian white cheese.