Microencapsulation of Lactobacillus casei BNCC 134415 under lyophilization enhances cell viability during cold storage and pasteurization, and in simulated gastrointestinal fluids

Lactobacillus casei BNCC 134415 cells were micro-encapsulated in whey protein isolate (WPI), WPI + Gellan gum (GG), WPI+ cellulose acetate phthalate (CAP) or WPI+GG+CAP as capsule matrixes under lyophilization. Physical and chemical properties of the microcapsules and viability of the probiotic cells in simulated gastrointestinal fluids (SGJ) and under heating and refrigeration stresses were determined. The results showed that no free cell survived in SGJ for 120 min, or heating at 68 °C for 25 min, whereas the microencapsulated cell counts decreased by 0.27–0.885 log CFU mL−1 in SGJ and 0.725–1.245 log CFU mL−1 after the heat treatment. And the viability of encapsulated cells decreased from 7.725 to 8.255 log CFU/g in the first week to 6.775–7.590 log CFU/g in the last week of storage. Combinations of WPI with GG and CAP resulted in chemical interactions between them and the formation of hydrogen bonding in the mixed materials as shown by Fourier transform infra-red spectroscopy analysis. Results support the feasibility of using a mixture of WPI, CAP and GG for microencapsulation of probiotics under lyophilization for food process.