Changes in Scomberotoxin (Histamine) and VolatileAmine (TVB-N) Formation in Longtail Tuna (Thunnustonggol) Stored at Different Temperatures

Changes in histamine and volatile amine (TVB-N) formation was studied in longtail tuna (Thunnus tonggol) captured in theSea of Oman and stored at different temperatures. Based on sensory analysis, longtail tuna maintained shelf life for 1, 4, 15 and 300 daysat 0, 8, 25 and -18 oC, respectively. Histamine and TVB-N increased with time, but the rate of change varied with storage temperature.Histamine formation was suppressed significantly at lower than the FDA limit of 5 mg/100 g at 0 and -18 oC but not at 8 or 25 oC. TVB-N didnot reflect the quality index at 0 or 8 oC even though the samples were rejected by sensory evaluation. No correlation was observed betweenhistamine and TVB-N values except at 25 oC and assessment of TVB-N was not sufficient for estimating the degree of histamine-relatedhealth hazard. Poor correlation was found between sensory score and pooled TVB-N value compared to histamine, and the correlation wascloser at 8 and 25 oC than at the lower temperatures.