POST MORTEM VARIATION OF TOTAL VOLATILE BASE NITROGEN (TVB-N) AND TRIMETHYLAMINE NITROGEN (TMA-N) IN VETKI (Lates calcarifer)

Abstract

Total Volatile Base Nitrogen (TVB-N) and Trimethylamine Nitrogen (TMA-N) contents of Vetki (Lates calcarifer) were investigated following Conway’s Microdiffusion technique at 4 hour interval in Fish Quality Control Laboratory, Fisheries and Marine Resource Technology Discipline, Khulna University. Observed TVB-N and TMA-N value did not vary significantly among different size classes. At fresh condition, TVB-N content was observed as 11.106±0.8 mg, 11.162±0.8 mg, and 11.162±0.8 mg in small, medium and large size classes of fish respectively and it increased to 59.087±0.8 mg, 68.417±1.5 mg and 75.967±2.7 mg for 100 g-1 respectively at complete spoilage stage (after 28 hrs). At fresh condition, TMA–N content was 6.7±0.016 mg, 11.069±1.79 mg and 11.172±1.01 mg for 100 g-1 in small, medium and large size classes of fish respectively and it increased to 48.893±3.01 mg, 52.492±.089 mg and 57.717±1.95 mg for 100 g-1 respectively at complete spoilage stage. TVB-N and TMA-N values started to increase gradually in all size groups with the passage of time but the rate of increase became faster after 20th hour and continued till the final stage was reached.