Bioaccessibility of four calcium sources in different whey-based dairy matrices assessed by in vitro digestion

Abstract Numerous calciumsources are available to enrich food, but their behavior during digestion is still unknown. This study focused on the influence of the gastro-intestinal pH, the food structure and the calciumsource on the bioaccessibility of the nutrient. Four calciumsources were studied: calciumcarbonate, calciumcitrate malate, calciumphosphate and calciumbisglycinate. These were added to dairy matrices, containing cream and whey proteins, of different forms (liquid or gel). The kinetics of solubility and ionic calciumconcentration during in vitro digestion were studied, as function of gastro-intestinal pH. All calciumsources were almost fully soluble in the gastric compartment, and then became insoluble in the intestinal phase. The level of calciuminsolubilisation in the intestinal phase was not significantly influenced by the matrix structure (liquid or gel), but was more dependent on the calciumsource, this effect leading to different final calciumbioaccessibility from 36% to 20%.