Nisin-coated alginate microbeads loaded with honey-derived probiotic yeast for enhanced shelf-life and functionality in snack bars

• Selected yeast isolated from honey was used in probiotic honey-based snack bars • The yeast isolate had in vitro inhibitory effect on B. cereus and ochratoxin-A • SEM and FTIR findings verified coating of alginate by nisin in dual coating layers • Alginate-nisin encapsulated yeast showed potent in situ antibacterial activity • Microencapsulated yeast had proper survival in SGI conditions and snack bars A selected yeast isolate (YI) from natural honey showed proper inhibitory activity against Bacillus cereus (77.64%). Meanwhile, the YI had low survival under upper simulated gastrointestinal (SGI) conditions. To overcome this, YI (10 8 CFU/g) was encapsulated within dual-layered carriers of 2% (w/v) alginate (Alg) and 4 mg/mL nisin (N). Phylogenetic evolutionary analysis led to the identification of Saccharomyces cerevisiae as the YI. The Fourier transform infrared spectroscopy and field emission scanning electron microscopy also verified the interactions between positively charged amino groups of N and negatively charged carboxylic groups of Alg and presence of N on the surface of the produced double-layer carriers. Microencapsulated yeast in double-layer Alg-N significantly ( p <0.05) showed higher survival under SGI conditions compared to mono-layer Alg carriers (91.92 and 70.32%, respectively), before and after application in the produced snack bar (127.31 and 89.77%, respectively). Higher in situ inhibitory activity of the encapsulated yeast in Alg-N compared to free N against B. cereus also verified the role of N and its release during a week storage period of the product. Accordingly, dual Alg-N coated beads loaded with the YI can be sued as an efficient bio-preservation approach in the production of probiotic honey-based snack bars.