Comparative performance of milk proteins and their emulsions under dynamic in vitro adult and infant gastric digestion

There is an increasing interest in the development of functional foods and bioactive ingredients to fully exhaust foodʹs potential to promote human health and prevent disease. The wish to rationally design such foods based on their gastrointestinal behavior has led to an upsurge in studies looking into the physicochemical basis of digestion and application of various in vitro methods. In light of advances in physiology and bioreactor technologies, this study aimed to develop and apply a dynamic yet simple in vitro method mirroring gastric pH alterations in the adult and infant stomach. These models were used to examine the digestive fate of β-lactoglobulin and lactoferrin as well as the behavior of their corresponding emulsions. In respect to proteolysis, SDS-PAGE of digesta collected revealed retarded protein breakdown and altered peptide profiles compared to common in vitro gastric models held at a constant pH. Regarding emulsion behavior, laser based droplet sizing and fluorescence microscopy showed altered times for emulsion destabilization, flocculation and coalescence occurring during the dynamic gastric digestions. Moreover, proteolysis and emulsion stability during digestion were found to differ between adults and infants. To the best of our understanding, the results of this study indicate that application of documented physiological gastric pH changes provides an opportunity to better understand the physicochemical basis of colloid digestion. Application of such models could help facilitate the development and screening of foods for health and well-being.