Determination of histamine levels in commonly consumed fish in the region of Fez: The effect of heating and enzymatic treatments

The purpose of this paper is, first, to evaluate the quality of commonly consumed fish species in Fez region (Morocco) by quantifying the levels of histamine in fresh fish samples using competitive enzyme-linked immune sorbent assay (ELISA), and then to study the effect of heating and enzymatic digestion on the level of fish-histamine.

Histamine content was tested on 80 fresh fish samples of 11 species collected from various local stores in Fez region, from February to March 2016. The analyses were performed using a competitive ELISA assay to measure histamine in fish samples.

ELISA results showed that 80 percent of 80 fish samples analyzed was found to contain much lower levels of histamine (<1 mg/kg) and can be considered to be safe for human consumption. However, 20 percent of the samples (16/80) had histamine level higher than the tolerance limit of 200 mg/kg established by Moroccan and International regulations, which the maximum level reached up to 7,331 mg/kg in horse mackerel. Concerning the effect of heating and enzymatic treatments on fish-histamine levels, results have shown a low reduction in histamine contents in the majority of fish samples under these treatments.

In conclusion, good quality of the fish product, demonstrated by histamine levels, was found in the most of fish samples analyzed, while 20 percent of the samples are non-compliant and exceed the tolerance limit established by the national and international regulatory limit.