Fish size matters - Variable food allergen profiles in farmed and wild Malabar red snapper (Lutjanus malabaricus)

Allergic reactions to fish pose complex food safety challenges, driven by species diversity and underexplored intraspecies variability. This study comparatively examines allergen profiles in Malabar red snappers (Lutjanus malabaricus, n = 39) across body sizes, anatomical regions and production origins using SDS-PAGE, immunoblotting and quantitative mass spectrometry. Protein profiles varied greatly by fish size and muscle region, but not by origin. Smaller fish contained higher levels of major allergen parvalbumin and creatine kinase, while larger fish exhibited elevated levels of heat-labile allergens enolase, aldolase, and glyceraldehyde-3-phosphate dehydrogenase. Parvalbumin levels were highest in head, followed by belly, dorsal, and tail. Greatest variation was observed for the three heat-stable allergens - parvalbumin, tropomyosin, and collagen. Minimal origin-dependent differences affected 2 of 11 registered fish allergens. We established an integrated proteomics workflow for systematic allergenicity assessments to uncover intraspecies variability and provide foundational knowledge for understanding intraspecies variability to improve food safety strategies.