.3.2. Determination of total volatile basic nitrogen (TVB-N)
TVB-N content was determined by distillation after the addition
of MgO to the minced sample. The distillate was collected in a flask
containing 3% (w/v) aqueous solution of boric acid and a mixed
indicator produced by dissolving 0.1 g of methyl red and 0.05 g
methylene blue to 100 mL ethanol. The boric acid solution turned
green when the distilled TVB-N made it alkaline. Finally, the boric
acid solution was titrated with a 0.01 mol/L HCl solution until it
turned pink (Goulas & Kontominas, 2005). The quantity of TVB-N
in mg/100 g sample was calculated from the volume (V) of HCl
added and its concentration (C)