Digestibility of glycated milk proteins and the peptidomics of their in vitro digests

Abstract

BACKGROUND Milk proteins are widely used in food production and are often glycated by reducing sugar. Although many studies have reported the digestibility of glycated milk protein, most have focused on measuring degree of hydrolysis (DH), showing sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE) image of digests. Detailed information on the changes in peptide composition of digests has seldom been revealed. Therefore, in addition to measuring the DH and showing the SGS‐PAGE images of digests, we also analyzed the peptidomics in digests using liquid chromatography–electrospray ionization–tandem mass spectrometry (LC‐ESI‐MS/MS) and Mascot database in this work to further reveal the influence of glycation on protein nutrition. RESULTS Compared with β‐lactoglobulin and bovine serum albumin (BSA), DH of β‐casein was suppressed to a lesser extent by glycation in both gastric and intestinal stages. Aggregates of glycated BSA were less sensitive to the action of digestive enzymes throughout gastrointestinal digestion according to SDS‐PAGE images. Changes in the peptide composition of digests induced by glycation were distinctly displayed, showing both absence of peptides and occurrence of new peptides, based on the results obtained from LC‐ESI‐MS/MS. CONCLUSIONS Glycation can greatly change the peptide composition in digests of milk protein. The nutritional impact of the change in the peptide composition requires further investigation, and the impact of MRPs in unabsorbed digests on the gut flora should be an interesting field for further studies. © 2018 Society of Chemical Industry

Interplay between Residual Protease Activity in Commercial Lactases and the Subsequent Digestibility of β-Casein in a Model System

“…The MS and MS/MS masses were scanned in the range of 300–1800 m / z and 150–1800 m / z , respectively (small peptides (smaller than 5 amino acids) are not considered). The obtained tandem mass data were searched using Mascot v2.4 (Matrix Science, London, UK) against a custom-made database, as described earlier [5,28]. The following parameters were applied: protease, unspecified; mass tolerance for the precursor iron was set as 15 ppm and 0.6 Da for the product irons; variable modification: phosphorylation for Ser and hexose for Lys.…”

Myoglobin diet affected the colonic mucus layer and barrier by increasing the abundance of several beneficial gut bacteria

“…The digestibility of β-casein was 83.10%, 24 while the degree of hydrolysis of myoglobin was much lower than that of other food proteins. In previous in vitro digestion experiments, the pepsin digestibility and pancreatin digestibility of myoglobin were 7.03% and 33.00%, respectively.…”

“…23 Arginine and lysine in myoglobin are exposed to hydrophilic surfaces and expected to bind well to pancreatin, while phenylalanine with high content in myoglobin can be cleaved by chymotrypsin. 9 The digestibility of β-casein was 83.10%, 24 while the degree of hydrolysis of myoglobin was much lower than that of other food proteins. In previous in vitro digestion experiments, the pepsin digestibility and pancreatin digestibility of myoglobin were 7.03% and 33.00%, respectively.…”

A comparative study of the modulation of the gut microbiota in rats by dietary intervention with different sources of egg‐white proteins

“…The proteins in egg are degraded and glycated during the processing . Previous research on the digestibility of glycated milk proteins and the peptidomics of their in vitro digests suggested its impact on gut microbiota structures . The composition in digestion products of hen egg white, duck egg white, and preserved egg white could be different due to the differences in protein member and its glycation, and the undigested peptide composition in unabsorbed digests may alter intestinal bacteria.…”