Hexose-derived glycation sites in processed bovine milk

Area of Science:

• Food Chemistry
• Proteomics
• Analytical Chemistry

Background:

• Milk processing, including pasteurization and UHT treatment, aims to ensure safety and retain nutritional value.
• Heating triggers chemical reactions like protein glycation, where sugars react with amino groups on proteins.
• While lactose glycation is studied, the role of other hexoses in milk protein glycation remains less understood.

Purpose of the Study:

• To identify and quantify hexose-derived glycation sites in various milk products.
• To investigate the influence of processing methods (pasteurization, UHT) and product types (infant formula, lactose-free milk) on protein glycation levels.
• To establish a proteomics strategy for analyzing protein glycation in milk.

Main Methods:

• Utilized tandem mass spectrometry and electron transfer dissociation for glycation site identification.
• Employed boronate affinity chromatography to enrich glycated peptides.
• Conducted a bottom-up proteomics approach to analyze 17 bovine milk proteins across diverse milk products.

Main Results:

• Identified 124 hexosylated tryptic peptides, corresponding to 86 glycation sites in 17 milk proteins.
• Quantitatively, glycation increased from raw milk to pasteurized, UHT milk, and infant formula.
• Lactose-free milk showed significantly higher hexosylation than regular milk; infant formula and lactose-free UHT milk had the highest levels.

Conclusions:

• The developed proteomics strategy effectively identifies and quantifies protein glycation in milk products.
• This analytical approach allows for in vitro studies on the health impacts of consuming differently processed milk, including lactose-free varieties.
• Findings highlight the potential to optimize production processes to reduce glycation, with particular attention to high levels in infant formula.