ASSESSMENT OF POTENTIAL BIOLOGICAL ACTIVITIES OF CASEINOPHOSPHOPEPTIDES FROM A COMMERCIAL PURIFIED MIXTURE AND FROM GRANA PADANO AND TRENTIN GRANA, AFTER IN VITRO DIGESTION.

Milk and dairy products are an excellent source of bioavailable calcium thanks to the presence of casein phosphopeptides (CPPs), that with their phosporylated serines, bind calcium ions, keeping them in a soluble and bio-absorbable state. Digestion and absorption are limiting steps for the peptide bioavailability; thus the in vitro digestion procedures combined with the use of intestinal cell models allowed to mimic the physiological milieu, where digestion occurs and the interactions between peptides and intestine determine their fate. The purpose of this PhD thesis was to identify the biological potential of casein phosphopeptides after in vitro digestion. The first step was about the bio accessibility property of a CPP purified mixture using a culture of intestinal human cells. Next step was about the bioactivity study of a complete food containing CPPs, represented by Grana Padano (GP) and Trentin Grana (TN) at 13, 19 and 26 months of ripening. Present data show that after in vitro digestion, preformed aggregates (CPP + Ca) in a commercially mixture still maintain their conformation and retain their bioactivity as promoters of
calcium uptake in intestinal cells, regardless of calcium mechanism transport (TRPV6 in Caco2 cells and depolarizing L-type calcium channels in HT-29 cells). GP and TN digestates, were also able to induce a calcium uptake in a co-culture of Caco2 and HT-29, a model of human intestinal epithelium more complete and useful. Moreover, they shown the capacity to induce the bone mineralization in human osteoblast-like cells. Since the biological potential after digestion was verified, CPPs could be considered as a nutraceutical and GP and TN cheeses as potential functional foods.