Matrix effect on food allergen detection - A case study of fish parvalbumin

Two fish parvalbumin models were established to study relationships among matrix effect, extractability, and thermostability during in vitro immunodetection using two parvalbumin-specific monoclonal antibodies (3E1 and PARV19). Our results illustrated that matrix-induced thermal instability of parvalbumin was due mainly to physical (hydrophobic effect) and chemical (thiol-disulfide interchange) interactions. The addition of sodium dodecyl sulfate (SDS, surfactant), β-mercaptoethanol (reducing agent) or ethylenediaminetetraacetic acid (EDTA, metal chelator) during sample preparation could not only increase the extractability of parvalbumin but also enhanced its immunodetection. Our findings demonstrated excess EDTA completely chelated Ca²⁺ in parvalbumin and rendered it undetectable using PARV19 (a Ca²⁺-dependent antibody). Overall, our resulted showed that matrix effect on in vitro analyte quantification cannot be underestimated. Any false negative or positive results could lead to severe or life-threatening allergic reactions.