Effect of microencapsulation in whey protein and water-soluble chitosan derivative on the viability of the probiotic Kluyveromyces marxianus VM004 during storage and in simulated gastrointestinal conditions

The aim of this study was to evaluate the effect of the microencapsulation (by spray drying) of the whey-native probiotic yeast Kluyveromyces marxianus VM004 in matrices of whey protein concentrate (WPC) and water-soluble chitosan (WSCh) on the viability of the yeast during drying and storage and in simulated gastrointestinal conditions. The optimized outlet drying temperature was 68 degrees C. This temperature allowed obtaining an encapsulation efficiency of 91% for a suspension of 10% (w/v) WPC. Yeasts microencapsulated in WSCh showed a significantly improved tolerance to simulated gastrointestinal conditions in comparison to free yeasts and yeasts microencapsulated in WPC. Besides, the solids content showed a significant influence on the probiotic viability during storage, with a suspension with 30% (w/v) solids (29:1 WPC:WSCh) showing 95% of viability after passing through gastrointestinal conditions. The results allow expanding the development of mixtures of encapsulating materials to improve the probiotic aptitude of a food ingredient powder.