ABSTRACT
Histamine consumed with food gives rise to allergic reactions. Dark muscle fish, for example skipjack (Katsuwonus pelamis) has been shown to contain histamine. Studies using TLC (acetone: NH4OH, 80:20.5) on silica gel G60 plates and densitometry after spraying with ninhydrin, using a computerized densitometer, showed that freshly harvested skipjack has no detectable histamine (detection limit, 50 micrograms.g-1 fish). However, with time histamine (Rf 0.84) is formed > 1.5 mg.g-1 probably through microbial action. Skipjack contains high levels of free histidine at levels of > 10 mg.g-1 (Rf 0.41) but fish like seer (Scomberamous spp.), which are not reported to be allergenic, contain < 4 mg.g-1 histidine. Addition of exogenous histidine (50 mg.g-1) results in histamine formation in seer 2.2-fold that of skipjack under the same conditions. A type of herring (Amblygaster spp., sinhala-hurulla) is not a histamine former, but had been shown to cause allergenic reactions, resulting in a ninhydrin positive spot (Rf 0.79) on incubating for 24 hours. Addition of arginine and lysine to blended skipjack results in their loss probably by decarboxylation. Addition of the spice Garcinia cambogia (extracts 0.2 g ml-1) known as 'goraka' in Sri Lanka (sinhala) and 'kukum' in India (hindhi), to fresh skipjack incubates prevents histamine formation as a results of lowering pH to 3.2-3.6 whereas Avverhoea bilimbi (bilin) and Tamarindus indica (tamarind) extracts did not prevent histamine formation.
