Detection of Illegal Addition of Formaldehyde to Fresh Fish

Bremner and Snell (1978) later extended these observa-The formaldehyde content of fresh fish in Bangkok markets tions to the Macruridae and Saurida species. The reac-was very low in chub mackerel, rake-gilled mackerel (ReM) tion causes textural toughness in fish muscle due to the and Indo-Pacific king mackerel (below 1.0 mg/kg) but higher denaturation of proteins by formaldehyde (Ang and in silver pomfret (1.5 mg/kg). It was concluded that the Hultin, 1989). The objectives of this work were to formaldehyde content depended on the species of fish (P < survey the formaldehyde content of fresh fish sold in 0.01). Formaldehyde increased from 0.50 to 1.4 mg/kg dur- Bangkhen and Chatuchak areas and to determine ingfrozen storage of ReM at-20"C whilst in lizard fish (LF) whether the detected and analysed formaldehyde was it increased from 16.8 to 42.5 mg/kg after six months. In added or naturally formed. ReM and LF, dipped in differentconcentrationsofformalde-hyde solution for 10 minutes, the analysed concentrations correlated well with the concentrations used (r = 0.9955for MATERIALS AND METHODS ReM and 0.9904 for LF). Sampling and data analysi