Elution profile of sodium caseinate in simulated gastric fluids using an in vitro stomach model from semi-solidified enteral nutrition

Elution profile of sodium caseinate from semi-solidified enteral nutrition was investigated in simulated gastric fluids using an in vitro stomach model developed. Semi-solidified enteral nutrition was prepared by thickening two systems of sodium caseinate with xanthan gum; aqueous solutions and O/W emulsions. These systems were subjected to the in vitro stomach model that mimicked the peristaltic motion of human stomach in the presence or absence of pepsin in simulated gastric fluids. Elution rate constant of the proteinaceous probe was lowered by increasing viscosity of each system or addition level of the gum, particularly for the bolus (i.e., the mixture of semi-solidified enteral nutrition sample and simulated gastric fluids) formulation at higher solid content. The equilibrium elution concentration was, on the other hand, independent of either the addition level of the gum or the bolus formulation. The elution rate constant also depended on pepsin in the gastric fluids, and its absence retarded markedly the elution of the proteinaceous probe from each system, particularly from the emulsions. Elution kinetics of sodium caseinate from semi-solidified enteral nutrition was well represented by the in vitro stomach model, showing an advantage over a conventional test procedure using vigorous paddle mixing. [Display omitted]