Disodium 5’-inosinate (INS 631, E631) is the sodium salt of inosinic acid, the nucleotide that gives dried bonito flakes, meat and fish much of their savoury depth. It was identified in 1913 by the Japanese chemist Shintaro Kodama, who was studying katsuobushi. Today it is made mostly by bacterial fermentation, but it can also be obtained from meat or fish, so its source is not always vegetarian.
Like guanylate, inosinate works mainly as a booster. On its own it tastes faintly savoury, but together with glutamate it strongly intensifies umami. Seasoning makers therefore use small amounts alongside MSG and guanylate, and the two nucleotides are often sold premixed as disodium 5’-ribonucleotides.
It is permitted under Codex as a flavour enhancer. On SeekSnack it seasons Lay’s Flat Potato Chips Esan Hot Pot Flavor and Fashion Food’s Tomato Flavoured Cracker.
