Whey-based cheese provides more postprandial plasma leucine than casein-based cheese: A pig study.

With a long-term nutrition goal for healthy aging, the aim of this study was to compare the bioavailability of amino acids, in particular the leucine, after the ingestion of two solid and isocaloric dairy products (cheese) based either on whey or on caseins, by using pig as an in vivo digestion model. The whey-based cheese contained 25% more leucine than Mozzarella, however its digestion by pigs resulted in a concentration of postprandial plasma leucine between 2 h and 5 h30 twice higher than that produced during the digestion of Mozzarella. Noting that the dry matter of the duodenal effluents were similar after each of the two cheese meals, differences in gastric emptying would not explain the difference in leucine bioavailability. These results suggest the possibility of stimulating more efficiently the muscle synthesis in elderly people with cheese based on whey proteins rather than those based on caseins.

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

Numerous calcium sources 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 calcium source on the bioaccessibility of the nutrient. Four calcium sources were studied: calcium carbonate, calcium citrate malate, calcium phosphate and calcium bisglycinate. These were added to dairy matrices, containing cream and whey proteins, of different forms (liquid or gel). The kinetics of solubility and ionic calcium concentration during in vitro digestion were studied, as function of gastro-intestinal pH. All calcium sources were almost fully soluble in the gastric compartment, and then became insoluble in the intestinal phase. The level of calcium insolubilisation in the intestinal phase was not significantly influenced by the matrix structure (liquid or gel), but was more dependent on the calcium source, this effect leading to different final calcium bioaccessibility from 36% to 20%.