Abstract

An effective encapsulation system is necessary to protect Lactobacillus casei against harsh conditions during food processing and gastrointestinal passage. In this study, L. casei was encapsulated by double emulsion coated with an outer layer of cross-linked alginate; the effect on its viability after freeze drying, thermal treatment, in vitro digestion, and during storage was evaluated. The interfacial structure of the microcapsules produced by the formation of double emulsion and alginate coating improved the protective function of L. casei under stress conditions, especially when the alginate outer layer was subjected to ionic gelation. Microencapsulated L. casei achieved 97.3% encapsulation efficiency and 98% survival rate after the freeze-drying process, while maintaining counts above 10(7) CFU/g at 50 and 70 degrees C for 20 min. The microcapsules provided high viability in the intestinal phase (10(6) CFU/g) and greater stability during storage at 4 degrees C (10(7) CFU/g, 17 wk). Greater microcapsule protective capacity can be associated with increased glass transition and melting temperatures of the encapsulating matrix and formation of a more compact alginate layer. The proposed encapsulation technology represents an alternative to improve L. casei viability under stress conditions and it could be used to develop functional foods. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.