Abstract：The physicochemical properties of most food allergens confer stability to the proteolytic in the digestive tract. Stability of simulated gastric fluid (SGF) is an important parameter for the estimation of food allergenicity. To study the digestive stabilities of a major fish allergen — parvalbumin (PV) and non-allergenic proteins from the muscle of carp (Cyprinus carpio) and silver carp (Hypophthalmichthys molitrix) in SGF and simulated intestinal fluid (SIF), three kinds of proteinases including pepsin, trypsin, and chymotrypsin from porcine (Sus scrofa) were used to simulate digestive proteinases from humans (Homo sapiens). Two runs of trichloroacetic acid precipitation and gel filtration chromatography were used to purify the fish PV. Results were evaluated via Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Tricine-SDS-PAGE) and Western blot. The results showed that PVs of carp and silver carp with molecular weight of approximate 10 kD was obtained. Similar results were obtained in SGF assays of purified PVs of carp and silver carp. The original PV band with pepsin was almost completely degraded within 60 min, and some stable peptide fragments were observed. Both trypsin and chymotrypsin could not effectively degrade PV in 240 min. In the SGF digestion on non-allergenic fish sarcoplasmic proteins were rapidly degraded within a short period of time, whereas the digestion time of PV was prolonged. Western blot analysis indicated that the polyclonal antibody against silver carp PV could specifically detect the PV and its degraded products. In conclusion, results indicated that fish PV was more resistant to proteinase digestion than non-allergenic proteins, and pepsin treatment was more effective than trypsin and chymotrypsin in reducing hypersensitivity. This study provides a theoretical reference for the development of hypoallergenic fish products in the future.
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