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.

Heat markers and quality indexes of industrially heat-treated [15N] milk protein measured in rats.

To determine the bioavailability of industrially heat-treated milk proteins, male Wistar rats were given [15N]-labeled meals containing either nonheated-micellar casein (CAS), milk soluble protein isolate (MSPI), and microfiltered milk (MF)-or heated products-"high temperature short time" pasteurized (HTST), "higher temperature, shorter time" pasteurized (HHST), ultrahigh temperature-treated (UHT), and spray-dried (SPRAY) milks. The postprandial distribution of dietary nitrogen was measured in the splanchnic area and urea. Digestibility was around 96% except for SPRAY (94%) and MSPI (98%). Ingested nitrogen recovered in the splanchnic bed was 19.3% for SPRAY, 16.7% for MF, and around 14-15% for other products. Deamination of dietary nitrogen reached 21.2, 20.6, and 18.2% of ingested nitrogen for MSPI, SPRAY, and CAS, respectively, and around 14-16% for other products. In our model, only spray drying led to a significant increase of splanchnic extraction. Moreover, the biological value of purified protein fractions appeared to be lower than that seen in products containing total milk protein.