Inosinic acid

Inosinic acid, also known as inosine monophosphate (IMP), is a purine nucleotide found naturally at high concentrations in meat and fish, contributing to the characteristic savoury flavour of freshly cooked animal proteins. As a food additive it functions as a potent umami enhancer, activating flavour receptors through the same nucleotide pathway as guanylic acid (E626). IMP and GMP were identified as the key natural umami compounds in katsuobushi (dried tuna flakes) and dried shiitake mushrooms respectively, foundational ingredients in Japanese dashi broth.

JECFA reviewed inosinic acid in 1987 and classified the ADI as "not specified," consistent with its status as a naturally occurring nucleotide involved in cellular energy metabolism and RNA synthesis. The body generates and metabolises IMP continuously as part of the purine nucleotide cycle. At levels used in food enhancement, no toxicological concern arises.

Inosinic acid is approved in the EU and globally for use in processed foods as a flavour enhancer. The critical consumer note for E630, as for all nucleotide enhancers, is the purine content: inosinic acid and its salts are converted to uric acid during purine metabolism. Individuals with gout, hyperuricaemia, or who are at risk for kidney stones should limit intake of foods containing E630 and the broader E626–E634 nucleotide enhancer family. Inosinic acid is frequently used alongside glutamate (E621) and guanylic acid (E626) to take advantage of their powerful synergistic interaction in umami amplification.