engleski

Endotoxin as the indicator of shellfish freshness

Storage of fish and shellfish at higher temperature may result in high production of endotoxin, biogenic amines (histamine, putrescine, tyramine) and other toxins due to microbial growth. Consumption of sea food with higher histamine level is associated with symptoms of systematic poisoning. Endotoxin, which is a lipopolysaccharide (LPS) component of the cell wall membrane of all Gram-negative bacteria, can be used for the estimation of bacterial contamination in food. The aim of this study was to examine the changes in endotoxin and histamine levels in the muscle of shrimp and mussel from the Croatia Adriatic coast stored at 22º ; C. After 0, 12, and 24h, samples of shellfish were aseptically cut and stored at -20º ; C until assayed. Endotoxin was determined using the end-point Limulus amoebocyte lysate (LAL) test (Charls River Endosafe, USA). Histamine was detected using the thin-layer chromatographic method. The relationship between endotoxin and histamine has not been investigated. Fresh shellfish endotoxin level was very low (<1 EU/mg). The time-course of endotoxin accumulation was found in both shellfish. However, endotoxin load was much higher in mussel than in shrimp. After 12h, endotoxin level in shrimp and mussel increased approximately 15 and 300 times, respectively. After 24h, endotoxin level in shrimp averaged 90.6 EU/mg, and in mussel 4477 EU/mg. During storage at room temperature, histamine levels increased only in mussel. However, histamine level in mussel was lower than the legal limit of 10 mg/100g set by European Community regulations. In this preliminary report, the increase in endotoxin level in shrimp and mussel was not followed with high histamine level. Therefore, the potential use of LAL test can provide additional information about the shellfish fresshness. The role of endotoxin in food poisoning is not well defined and needs further studies.

endotoxin; LAL test; histamine; shellfish

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