Identification of casein peptides in plasma of subjects after a cheese-enriched diet

Despite several studies support the functionality of casein peptides in vitro, a gap of knowledge still exist about their bioavailability. In this pilot study the bioavailability of phosphopeptides (CPPs) was investigated in four healthy subjects who consumed for one week 100 g/day of Parmigiano Reggiano cheese after one week of a dairy products-free diet. CPPs were detected in plasma samples from fasting subjects after the cheese-enriched diet and peptides were detected variously in almost all the 4 samples. Some alpha(s1)- and alpha(s2)-CN-derived CPPs, such as alpha(s1)-CN (f43-52 and f43-50) and alpha(s2)-CN (f8-12), (f7-12) and (f6-12) as well as four non-phosphorylated peptides belonging to the C-terminal end of beta-CN (f193-209, f194-209, f200-209) were detected in plasma samples submitted to extraction and enrichment by hydroxyapatite (HA) chromatography followed by MALDI-TOF and nano LC-ESI/MS/MS analysis. Data indicated that casein oligopeptides are bioavailable after a continued intake of cheese. Future studies are warranted to ascertain this finding on a wider population and to clarify the mechanisms behind CPPs bioaccessibility and absorption. (C) 2016 Elsevier Ltd. All rights reserved.