Disodium inosinate

Disodium inosinate (E631), chemical formula C10H11N2Na2O8P, is the disodium salt of inosinic acid. It is a food additive often found in instant noodles, potato chips, and a variety of other snacks. It is used as a flavor enhancer, in synergy with monosodium glutamate (also known as MSG; the sodium salt of glutamic acid) to provide the umami taste.

As it is a fairly expensive additive, it is not used independently of glutamic acid; if disodium inosinate is present in a list of ingredients but MSG does not appear to be, it is possible that glutamic acid is provided as part of another ingredient or is naturally occurring in another ingredient like tomatoes, parmesan cheese or yeast extract. It is often added to foods in conjunction with disodium guanylate; the combination is known as disodium 5'-ribonucleotides.