Dextrin: Starch Moistened with Dilute Nitric Acid and Heated at 110-120 °C (Payen, in Thorpe 1912)

Dextrin, also called British gum, is starch broken down by heat into a powder that dissolves in water to a sticky gum. A trace of nitric acid lets it form at a lower heat, 110 to 120 °C, so it comes out paler. The lower the heat and the drier the starch, the whiter the dextrin. Source: Thorpe, Dictionary of Applied Chemistry, vol. 2 (1912), Dextrins, giving Payen's recipe. Ours: potato starch (Payen names no starch) and the scaling to 1 kg. Not given: how long to dry and to heat. Picture drawn by Youblob.