Allergenic protein behavior, parvalbumin (PA) contained in skipjack tuna ( <i>Katsuwonus pelamis</i> ) during the fish sauce processing stage

Parvalbumin (PA) is a major muscle allergen in fish capable of triggering immunoglobulin E-mediated hypersensitivity reactions in fish-allergic individuals. This study investigated the degradation and allergenic behavior of PA in skipjack tuna ( Katsuwonus pelamis ) sauce during a 60-day fermentation process, sampled at 20-day intervals. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis and immunoblotting were used to monitor PA profiles and immunoglobulin G (IgG)-binding ability, which revealed a thin, undetectable band of PA and low IgG-binding ability by immunoblotting with the progress of fish sauce manufacturing. Additionally, because skipjack tuna belongs to the Scombridae family, histamine levels, pH, total acidity, and total soluble peptides were analyzed to ensure food safety and monitor proteolysis. The results demonstrated that PA bands became progressively thinner and undetectable by day 60, which strongly correlated with a marked decrease in IgG-binding ability. Fermentation also triggered significant peptide solubilization, while histamine content showed a strong correlation with changes in pH and total acidity. These findings demonstrate that traditional fish sauce processing effectively degrades the allergenic protein PA, highlighting fermentation as a viable method to reduce allergenicity in scombroid fish products while maintaining standard quality markers.