Disodium guanylate (GMP) and disodium inosinate (IMP) are discussed together on this page because you will often find them used together in the same food product. They are part of a family of food additives that are vary similar to monosodium glutamate (MSG), the well-known flavor enhancer. As such, they are often used together with MSG, as the three ingredients can have a synergistic effect to enhance the flavor of a product.
Umami
Both GMP and IMP, along with MSG, are part of the natural taste of animal and vegetable foods and impart what we generally know as a savory, meaty, or broth-like taste but what has more recently been described as a kind of fundamental fifth taste perception called umami. GMP and IMP are known as 5’-nucleotides which have been known shown to contribute strongly to umami.
Disodium Inosinate and Disodium Guanylate Presence in Foods
The natural occurrence of MSG, GMP and IMP in different foods has long influenced they way ingredients are combined and cooked, whether cooks realized this or not. For example, animal meats are rich in IMP, some mushrooms are rich in GMP, and many vegetables contain glutamate. Combining these different ingredients in a stock or soup provides a similar synergistic effect on flavor to the effect that food manufacturers achieve using these enhancers as additives.
It is less expensive to add these ingredients to foods than it is to use combinations of other foods to achieve similar results, therefore you will tend to see these ingredients in cheaper products, or in products where a concentrated flavor is desired. They are found in dried bouillon cubes, powdered soup mixes, sauces, ham and chicken salad spreads, and some canned vegetables. They may also contribute to mouthfeel in canned soups, sauces, meats, or tomato juice, causing a sensation of higher viscosity which gives the products more “body” and even a perception of freshness.
Umami, and therefore the addition of these ingredients, can help make foods more palatable, but only certain foods. It may help meat, fish, and vegetable products, but will not improve cereals, milk, and dairy products, or sweet flavored products. A certain level of salt is necessary, in combination with umami enhancing substances, so that many products may contain more salt than would normally be present, or needed in the diet. Therefore, food researchers have worked to find the minimum level of salt necessary to obtain the desired taste effects.
Both GMP and IMP are supplied as odorless, colorless or white crystals, or as a white powder. They are soluble in water. They are considered safe for use in foods as long as they are purified to a proper degree and are only used as flavor enhancers.
Foods that Contain Naturally Occurring Disodium Guanylate
Disodium Guanylate occurs naturally in mushrooms such as shiitake, enokidake, matsutake, syoro, hatsutake, pork, chicken, and whale meat.
Foods that Contain Naturally Occurring Disodium Inosinate
Disodium inosinate is found naturally in beef, pork, chicken, and many common fish including sea bass, tuna, and others.
Autolyzed Yeast Extract, high in MSG, is a similar food additive, along with hydrolyzed vegetable protein.