Studies on the viability of Saccharomyces boulardii within microcapsules in relation to the thermomechanical properties of whey protein

Abstract

Present work investigates the effectiveness of using whey protein isolate as an encapsulant for a biotherapeutic agent (Saccharomyces boulardii) under varying concentrations of protein and CaCl2. Viability of S. boulardii within the matrix of whey protein is highly dependent on the physicochemical properties of the protein network, and its response to various environmental stress factors including processing temperature, moisture content and change in pH. Our interest is to optimise the spray drying conditions of whey protein isolate, through observations from differential scanning calorimetry and small deformation dynamic oscillation on shear, in relation to the denaturation and subsequent aggregation of the globular molecules. It is evident from this work that protein concentration is directly proportional to the strength of the network, but inversely proportional to the denaturation temperature. Increasing concentrations of calcium chloride have a direct influence on electrostatic repulsion between protein molecules thus creating a better protein structure. Development of a cohesive network was used as a basis of manipulating the viability of S. boulardii under given conditions of spray drying. Analysis on spray dried powders suggests that whey protein preparations at the isoelectric point (pH ∼5) and with CaCl2 additions of 50–100 mM act as an efficient encapsulant providing high viability of S. boulardii.