Bitterness is a measure of how bitter a plant or substance is. It is determined by allowing subjects to test various dilutions of an extract. The value is given as the highest amount of water in millilitres in which 1 g of the plant, extract or substance still tastes bitter. The bitterness of the bogbean is around 1,500-9,000, i.e. 1 g. of leaf to between 1.5 and 9 litres water. The root of the yellow gentian has a bitterness of approx. 20,000.
Substances isolated from the root of the yellow gentian have considerably higher values, e.g. amarogentin 58,000,000, which means 1 g of the substance to 58,000 litres of water. Absinth has a bitterness of 15,000.