| Biogenic amines are indicators of seafood quality and spoilage and are formed as a result of decarboxylation of free amino acids in fish, lobster, shrimp, meat, cheese, etc. The decarboxylating enzymes are produced as a result of bacterial growth in the presence of free amino acids. Histamine, one of the biogenic amines, is the causative agent of histamine poisoning which results from eating certain economically important fish species. Evidence shows that other biogenic amines potentiate the effects of histamine intoxication. Histamine poisoning is not fatal, but frequently occurs and is a worldwide problem.; Histamine is of importance in mahi-mahi, tuna, and other red muscle fish which typically contain high levels of free histidine. Because free amino acids account, in part, for the rapid spoilage and development of biogenic amines in fish, understanding of amino acid levels could help explain biogenic amine formation during fish quality deterioration. Therefore, this work was conducted to support development of simplified procedures for judging seafood quality. The approach involved quantification of biogenic amines formed during mahi-mahi storage at refrigeration temperature (7°C) and correlation of the amine levels with their precursor free amino acids and other indicators of fish quality changes. To achieve these objectives, it became necessary to develop an HPLC method that enabled quick analysis of free amino acids in fish. Gas chromatography was used to analyze biogenic amines, and steam distillation for volatile base nitrogen (TVB-N). The AOAC fluorometric method was also used for histamine analysis.; The HPLC method used 75% methanol for analyte extraction, o-phthaldialdehyde (OPA) for pre-column derivatization, and solvent gradient elution for analyte determination. Recoveries ranged from 84–91.5% for lysine, ornithine, histidine and glutamine. The limit of detection for these amino acid standards were in the picomole range.; Results showed significant decreases in the levels of free histidine, lysine, ornithine, and glutamine. Poor correlation (r = –0.43, p < 0.001) existed between histamine increase and loss of histidine, and between putrescine and ornithine. Histamine levels over time were greater than those of cadaverine. Increase in cadaverine preceded increases in histamine and putrescine, and cadaverine levels were higher than those of putrescine. Good correlation (r = –0.61) existed between cadaverine increase and loss of lysine, between cadaverine and histamine (r = 0.78), cadaverine and TVB-N (r = 0.74), histamine and putrescine (r = 0.72), histamine and TVB-N (r = 0.74), odor and microbial level (r = –0.93), and between TVB-N and lysine (r = –0.69). The results showed cadaverine, putrescine and TVB-N are good indicators of chilled mahi-mahi quality and spoilage, and that cadaverine is a good indicator of incipient and late spoilage of mahi-mahi. |
