Transglutaminase-induced caseinate gelation for the microencapsulation of probiotic cells

A novel method for the encapsulation of probiotic cells in foodgrade casein microcapsules was developed. The process is based on a transglutaminase-catalysed gelation of casein suspensions containing probiotic cells. Water insoluble, spherical capsules with a volume-based median diameter of 165 +/- 23 mu m resulted from the process. Encapsulation yields of 70 +/- 15% and 93 +/- 22% were achieved for Lactobacillus paracasei ssp. paracasei F19 and Bifidobacterium lactis Bb12, respectively. Analysis of living cell numbers after incubation of free and encapsulated probiotics in simulated gastric juice without pepsin at pH 2.5 and pH 3.6 (37 degrees C, 90 min) showed a protective effect due to microencapsulation under all conditions tested. The study indicates that transglutaminase-induced caseinate gelation can be applied to the microencapsulation of probiotics. Furthermore, it could be shown that an entrapment in a dense casein matrix can protect these microorganisms from damage due to pH-levels similar to those in the human stomach. (C) 2008 Elsevier Ltd. All rights reserved.