A Method for Identification of Exogenous Formaldehyde in Bombay Duck (Harpodon nehereus)
2015
Shen, Yu | Wang, Wei Feng | Wu, Yan Yan
Bombay duck (Harpodon nehereus) is a highly perishable fish species due to its unusually high moisture content. This has contributed to the use of formalin (water solution of formaldehyde) to extend aquatic products’ shelf life, which has brought great harm to consumers’ health. What’s more, the fish itself generates minute amount of formaldehyde through metabolism making it very difficult for the inspection authorities to distinguish the source of formaldehyde detected during quality inspection. Against such background, this paper established a reliable method to identify whether the fish has been artificially adulterated with formalin, by observing changes of formaldehyde and dimethylamine content in the flesh and the viscera of Bombay duck, along with sensory analysis. The results showed that the variation trend of endogenous formaldehyde resembled that of dimethylamine in the flesh and viscera during ice and fresh storage. The endogenous formaldehyde content in the viscera was always twice higher than that in the flesh. As to the formalin immersed samples, formaldehyde detected in the viscera and the flesh were very approximate to each other, additionally, formaldehyde content is much higher than dimethylamine content in the flesh and/or viscera with a ratio larger than five. Sensory analysis also exhibited attributes like stiff flesh, gray gill, and mouth corresponding to the presence of exogenous formaldehyde.
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