Qualitative Characterization of Neu5Gc-Containing N-Glycans in Commercial Cheddar Cheese Products Using Nano-UHPLC–ESI–MS/MS—A Pilot Study

N-Glycolylneuraminic acid (Neu5Gc) is a non-human sialic acid present in mammalian tissues and certain dairy products. Although humans cannot synthesize Neu5Gc, it can be metabolically incorporated from dietary sources, potentially leading to the generation of anti-Neu5Gc antibodies, and has been associated with chronic inflammatory responses. While Neu5Gc distribution has been extensively studied in red meat, its presence in processed dairy products remains insufficiently characterized. In this pilot study, nano ultra-high-performance liquid chromatography coupled with electrospray ionization–tandem mass spectrometry (nano-UHPLC–ESI–MS/MS) was used for qualitative characterization of Neu5Gc-containing N-glycans in two commercially available cheese products. Neu5Gc-positive N-glycans were identified in reduced-fat sharp cheddar cheese (CHE), whereas such structures were not observed in processed cheddar cheese slices (SLI). These findings suggest that dairy processing and formulation parameters may influence glycan composition and Neu5Gc identification in cheddar cheese. Further studies using quantitative approaches and a broader range of dairy matrices are warranted to elucidate how processing-related factors affect Neu5Gc availability and its potential implications for diet-associated inflammation.