Hadi Ebrahimnejad, Hamidreza Gheisari and Abdollah Hossein Khan Nazer
Despite the known antihistaminic effects of PSAO, this enzyme remains unrecognized as an antihistamine additive in the food industry. The objective of this study was to ascertain the plausible histamine-degrading effects of a new food-grade additive (pea seedling extract) in tuna fish. PSAO was purified from cultured pea seedlings via ionexchange and size-exclusion chromatography. SDS-PAGE results indicated that the PSAO subunit has an apparent molecular weight of about 95 kDa. To evaluate the optimized conditions for antihistaminic activity of the enzyme, the reaction of PSAO and histamine was carried out in KPi buffer under conditions relevant to the fish processing industry. 1 unit mL-1 of PSAO significantly reduced the histamine content at pH 7.0 but not at pH 5.0. Accordingly, its antihistaminic activity was assessed in homogenized skipjack tuna fish (Katsuwonus pelamis) using an ion-paired HPLC method. The results showed that PSAO can reduce 87.14% of the histamine content of the tuna fish at pH 7.0, 37°C. This study indicates that PSAO - purified or even filtrate of pea seedling homogenate - can degrade histamine, which suggests practical application of this enzyme in fish processing industry.