Microencapsulation of Lactobacillus rhamnosus ATCC 7469 in whey protein isolate-crystalline nanocellulose-inulin composite enhanced gastrointestinal survivability

Microencapsulation, as one of the most modern methods, has a significant effect on the survival of probiotic bacteria. The present study aimed to determine an optimal formulation for Lactobacillus rhamnosus ATCC 7469 microencapsulation by freeze-drying and using Whey protein isolate, (WPI) crystalline nanocellulose (CNC) and inulin (INU) as wall materials, which can improve the survival of probiotic bacteria against the gastrointestinal condition. For this purpose, WPI, CNC, and INU were used as wall components for the encapsulation of L. rhamnosus ATCC 7469 by mixture design. Then the optimal formulation (WPI: 57.22%, CNC: 25.00%, INU: 17.78%) was determined for minimization of Z-average and zeta potential, as well as maximization of encapsulation efficiency and viability after 60 min at simulated gastrointestinal condition using numerical optimization. FTIR and SEM tests were performed to investigate the interaction between the wall compounds and the surface morphology of the capsules. The selected optimum capsule significantly improved the survivability of probiotic bacteria in simulated gastrointestinal conditions (p < 0.05).