KEYNOTE: Milk glycoproteomics: Preserving, enhancing, and delivering bioactivity

Daniela Barile, Dept. of Food Science and Technology, University of California, Davis, USA

Daniela Barile1,2, Jaime Salcedo1,2, Annabelle Le Parc3, Adam Sun3, Sercan Karav1,2, Joshua Cohen1,2, Juliana DeMoura Bell1,2
1. Department of Food Science and Technology, University of California, Davis;
2. Foods for Health Institute, University of California, Davis;
3. Prolacta Bioscience®, City of Industry, CA

Human milk is the ideal food in terms of nutrition for newborns as it provides a myriad of bioactive functions that influence infant’s healthy growth, before they are able to digest any other food. Much importance has been given to the free glycans known as human milk oligosaccharides (HMO), as they may enhance the development of the gastrointestinal and immune systems of human milk-fed infants. Remarkably, the very complex pool of oligosaccharides found in human milk are indigestible: they do not nourish the infant in any direct sense but rather they nourish a few select strains of commensal bacteria. Studies show that exclusive human milk feeding during the first few months of life decreases the risk of developing necrotizing enterocolitis (NEC) compared to commercial infant formula feeding. When mother’s milk is not available, pasteurized donor milk can be used. While heat treatment is conventionally used to improve milk safety, it remains unknown whether such treatment could damage potentially heat sensitive components of human milk (oligosaccharides, glycoproteins, glycolipids). The transformative analytical, computational, and biological toolsets capable of answering this question are only now becoming available. Proteomics and glycomics are being applied to investigate the stability of human milk components to industrial processes: initial results reveal fluctuations in abundance of glycosylated milk bioactive compounds at various thermal treatments and storage conditions.

Despite the important role of HMO for human health, a particular difficulty with research in this area is the lack of sufficient material for performing large functional and in vivo studies. In the search of HMO-mimics, bovine milk oligosaccharides (BMO) were discovered a few years ago. However, bovine milk contains a much lower concentration of these oligosaccharides than human milk. To this extent our group has explored the viability of dairy streams as sources and identified a multitude of BMO in cheese whey permeate. Considering that over 50 million pounds of cheese whey is produced daily just in the state of California (mostly deriving from whey protein extraction) the quantities of whey permeate available for massive extraction of bioactive oligosaccharides make it an attractive source. The concurrent application of mass spectrometry methods with novel purification techniques enable gaining valuable information about the structures of the bioactive milk oligosaccharides and guide their separation process from dairy streams. This work has also been generating valuable bioinformatic libraries containing the experimentally determined information (accurate masses measurements, tandem spectra and retention times) of human and bovine glycans to facilitate their identification in both donor human milk and dairy streams.

Additionally, the ability to use novel processing enzymes to harvest bioactive HMO-mimics (glycans from proteins) using an abundant and inexpensive substrate such as cheese whey, will enable development of new food products with health guiding capabilities for infants, immuno-compromised elderly, and the population at large as well as add value to an existing agricultural co-product.

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