Novel strategies for exploitation of milk glycoproteins for food ingredient applications

Abstract

This thesis sets out to explore the potential bioactivities associated with the bovine milk proteome with a view to improving our understanding of the roles bovine milk proteins may play in human health promotion. The bovine milk proteome is a rich source of numerous biological and nutritionally relevant components including proteins, oligosaccharides and calcium.The thesis aims to contribute towards further discovery and development of functional ingredients which can be potentially used for supplementation in infant formula and products for elderly or immune-compromised individuals. Here we investigate the entire milk proteome in early lactation and individual milk proteins including glycomacropeptide (GMP) and immunoglobulin G (IgG) which, in recent years, have been shown to be highly bioactive glycoproteins that are commercially viable to produce. In order to better understand the potential effects of bovine milk proteins on immune function and gastrointestinal development, the transcriptional response of HT-29 cells exposed to the proteome of raw milk at Day 1 and 10 of lactation were compared. Similarly, the response of the HT-29 cells to a commercial GMP ingredient isolated from bovine mature milk was also investigated using microarray analysis. Bovine colostrum is an excellent source of IgG with a distinct glycosylation profile. IgG was isolated from milk samples (3 cows at 4 time-points over lactation) and alterations in glycosylation were profiled using lectin microarrays and monosaccharide analysis. Finally, the anti-infective properties associated with bovine GMP towards Escherichia coli (E.coli) strains were investigated using human colonic adenocarcinoma, HT-29 and Caco-2 cell line models. Furthermore, GMP was shown to help in preventing the destruction of cellular tight junctions and subsequent translocation of E.coli across Caco-2 cell monolayers. It further highlights the importance of these complex molecules as bio-active ingredients for use in the pharmaceutical and food industry. Future research should focus on in vivo trials, in order to fully access the ability of these ingredients in maintaining and preserving human health.