The amount of basic, nitrogen-containing chemicals distilled from an alkalized extract or suspension of a fishery product. The bases, amines, in the distillate are determined by titration with standard acid. The amines all have one basic nitrogen atom in the molecule and TVB is expressed on a nitrogen basis, typically mg nitrogen/100g of sample. The main component of TVB from very fresh fish is ammonia and, as fish spoils, increasing amounts of trimethylamine (TMA) are present. Small amounts of dimethylamine (DMA) are often present in TVB from spoiled fish.