Bombay duck (Harpodon nehereus) natural formaldehyde levels and changes during frozen storage

Abstract

Demersal fish, including the Bombay duck (Harpodon nehereus), have relatively high levels of TMAO and hence have the potential for high natural formaldehyde content. This study aimed to determine the natural formaldehyde content of bombay duck and the pattern of the change during frozen storage. Approximately 15 kg bombay duck of 38 – 45g each caught by one-day fishing in Juwata Waters, Tarakan, North Kalimantan Indonesia, was transported in ice to the Laboratory of Marine Biotechnology, Research Center for Marine and Fisheries Product Processing and Biotechnology, Jakarta. Upon arrival, they were split into three groups as replicates and stored frozen for five months. Every month, the levels of formaldehyde, TVB, and sensory properties were monitored, and proximate analysis was performed before storage. The results showed that natural formaldehyde was detected in Bombay duck flesh before storage at a relatively high level of 12.58 + 0.35 ppm, increased to 17.3 ppm after one month of storage, and then decreased afterward. In contrast, TVB levels were low, 12.66 + 2, 54 mg N% before storage, then increased during storage. Based on sensory evaluation, all attributes of the bombay duck were deemed in good condition, with scores ranging from 7-8, except for the eyes, which received a score of less than 6.