Combination of alginate and yeast cell-wall as a dual carrier to improve the storage stability and colonic delivery of probiotic yeasts

Protection of probiotics (PRO) during cold storage period of food matrices and their colon delivery using efficient carriers has received considerable attentions. In the present study, in vivo biosafety of the selected yeast isolated from acorn sourdough was verified. Phylogenetic evolutionary analysis led to the identification of the isolate as Wickerhamomyces anomalus . The yeast isolate also showed proper survivability under simulated gastrointestinal (SGI) conditions, antibacterial and adhesion capabilities. Moreover, DPPH radical-scavenging and antifungal activities of the isolate were approved. Besides, anti-ochratoxigenic activity of the yeast heat-killed cells was significantly ( p <0.05) higher than that of the viable cells and the yeast cell-free supernatant according to the HPLC-based analysis. Microencapsulation of the isolate with alginate (Alg)-yeast cell-wall (YCW) not only significantly improved its viability during cold storage period of the whey-pistachio drink (with potent antibacterial and DPPH radical-scavenging activity) and under SGI conditions but also enhanced in vivo colonic recovery of the entrapped yeast (about 3 Log CFU/mL viability higher than the free cells). Scanning electron microscopy and Fourier-transform infrared spectroscopy verified coating of the Alg with YCW and also intermolecular interactions between the functional groups of the mono-layer Alg and double-layer Alg-YCW microcapsules. Accordingly, YCW of the isolate can be used in colonic delivery of PRO in a cost-effective, sustainable and food-grade encapsulation platform.