Abstract/Summary

Cow’s milk is an important part of the human diet, primarily due to its high nutritional content, particularly proteins and fats. Milk processing enhances safety while modifying composition and structure, influencing bioactive peptide release, which impacts protein quality, digestion, and allergenicity. Recently, filtered milk, which undergoes pasteurisation and microfiltration, offering a longer shelf life than pasteurised milk has become available in UK supermarkets. This study aimed to evaluate the effect of microfiltration on the protein structure of cow’s milk compared to pasteurisation and analysis of the peptide profile released after the in vitro gastrointestinal digestion of commercially available semi-skimmed filtered and pasteurised cow’s milk. Dynamic Light Scattering analysis revealed that the Z-average particle size of filtered milk was significantly (p < 0.05) larger than that of pasteurised milk across all brands. Additionally, filtered milk exhibited a significantly (p < 0.05) lower free thiol concentration compared to pasteurised milk, indicating structural modifications in proteins. Confocal Laser Scanning Microscopy (CLSM) further highlighted heterogeneities in fat and protein distribution, with filtered milk samples showing increased interactions between fat globules and proteins. After gastrointestinal digestion, the number of peptides released from filtered milk exceeded, by an average of 5 %, that of peptides released from pasteurised milk. The results provide new in-sights into the potential impact of microfiltration on milk microstructure. Further investigations using advanced analytical techniques are needed to assess the implications of these changes on protein bioavailability and human health.