The physicochemical properties of most food allergens confer stability to the proteolytic in the digestive tract,which increases the probability of reaching the intestinal mucosa,where absorption and interaction with the immune system can occur.Stability in simulated gastric fluid is supposed to be an important parameter for the estimation of food allergenicity.The digestive stability of a major fish allergen(parvalbumin,PV) and nonallergenic proteins from the muscle of crucian carp (Carassius auratus cuvieri) and silver carp(Hypophthalmichthys molitrix) in a standard simulated gastric fluid(SGF) and simulated intestinal fluid(SIF) digestion assay system was compared.Proteinases including pepsin,trypsin and chymotrypsin from porcine were used to simulate digestive proteinases from human.The results were evaluated by means of Tricine-sodium dodecyl sulfatepolyacrylamide gel electrophoresis(Tricine-SDS-PAGE) and Western-blot.Fish PV was purified to homogeneity by 70%-100%ammonium sulfate fractionation and DEAESepharose following heat treatment and a protein with molecular weight of approximately 10 ku was finally obtained.In SGF assay of purified crucian carp PV and silver carp PV,similar results were obtained,the original PV band was almost completely degraded within 60 min and some stable peptide fragments were observed.In SIF assay of purified PV,both trypsin and chymotrypsin could not degrade PV effectively in 4 h.In SGF digestion on fish sarcoplasmi proteins,nonallergenic proteins were rapidly degraded within a short period of time,while the digestion of PV was prolonged to some degree.Western-blot analysis indicated that the polyclonal antibody against silver carp PV can specifically detect the PV and it degraded products.In conclusion,our present results indicate that fish PV is more resistant to proteinase digestion than nonallergenic proteins and pepsin treatment is more effective than trypsin and chymotrypsin in reducing the hypersensitivity.It should be remembered that our present study only measured the antigenicity which may not completely equate to allergenicity.Thus,to further evaluate the allergenicity alteration of PV after proteinase treatment,experiments such as the release of histamine from basophiles and skin prick test are required.In addition,the amount of undigested PVs that has to persist in gastrointestinal digestion to induce food allergy is also needed to be studied.