The improvement of pre-loading technology on the gastrointestinal tolerance and storage stability of probiotic microcapsules

• A novel delivery system induced by pre-loading technology. • An encapsulation method combined the advantages of both heat and cold-gelation. • Enhanced gastrointestinal tolerance and storage stability of SA-pre-loaded microcapsules. Aims to obtain highly resistant and stable microcapsules, we introduced the concept of sodium alginate (SA) pre-loading for L. amylolyticus L6 and P. freudenreichii subsp. Shermanii CGMCC 1.2231 and combined the advantages of heat and cold gelation of SA and whey protein isolate (WPI). By evaluating the appearance, structural characteristics, flowability, gastrointestinal tolerance, and storage stability of several microcapsules after spray drying, it was concluded that the viable probiotics for all microcapsules reached 0.43-3.40 × 10 10 CFU/g and the bacterial viability of encapsulated probiotics exhibited a more robust resistance, maintaining levels at 8.18-9.33 lg CFU/mL after digesting in simulate gastric fluid for 2 h, whereas 6.09-8.21 lg CFU/mL after digestion in simulate intestinal fluid for 4 h continuously. Pre-loading with SA can effectively reduce the damaging effect of simulated gastrointestinal environments on probiotic cells of microcapsules. In addition, SA pre-loading had more significant and protective effect on storage stability of L. amylolyticus L6 and P. freudenreichii subsp. Shermanii CGMCC 1.2231.