Biogenic amines and potential histamine - Forming bacteria in Rihaakuru (a cooked fish paste).

The biogenic amine concentration in Rihaakuru (a fish paste) (n=28), obtained from different parts of the Maldives (North, South, and Central), was determined by HPLC. Ten biogenic amines were detected; agmatine, not detected (ND) - 161ppm; cadaverine, ND - 387ppm; histamine, ND - 5487ppm; putrescine, ND - 290ppm; phenylethylamine, ND - 23ppm; serotonin, ND - 91ppm; spermine, ND - 329ppm; spermidine, ND - 79ppm; tryptamine, ND - <5ppm; and tyramine, ND - 50ppm. Nine biogenic amines were found in 3 samples, 8 in 10 samples, 7 in 6 samples, 6 in 3 samples, 4 in 5 samples, and 1 was found in 1 sample. Histamine was detected at levels that are regarded as a risk to human health. Fourteen isolates were selected from two randomly selected samples out of the 28 samples of Rihaakuru and screened for histamine production. Twelve of the 14 isolates produced histamine, with the highest histamine producers being Bacillus massiliensis Nai5 (6.65ppm) and Bacillus polyfermenticus (5.58ppm); while Bacillus malacitensis produced the least (<0.5ppm).