Inosine 5-monophosphate (IMP) and guanosine 5-monophosphate (GMP) appear in white crystalline powder. They are ribonucleoside monophosphate that can be interconverted by various reductases and hydrogenases in the body. GMP is indispensable in IMP’s primary role of synthesizing purine. Thus, the 2 ribonucleosides are usually categorized together. Besides playing important roles biologically, IMP and GMP are synthesized into salts which are then used often in the food industry as food additives in sauces and meat.
Since both IMP and GMP are biological molecules, they are naturally occurring in the body. Biologically, IMP is synthesized from hypoxanthine in the process of nucleotide salvage. GMP is mainly produced from the conversion of IMP to GMP.
Commercially, IMP is obtained from chicken byproduct in the meat industry. The process involves deamination of another monophosphate, namely, adenosine monophosphate. This is followed by hydrolysis into inosine. Synthesized IMP is usually made into disodium inosinate. GMP can be produced from microbial fermentation and is usually made into disodium guanylate and dipotassium guanylate salts.
Comparing the synthesis of IMP and GMP, GMP has a more costly manufacturing process thus it makes a more expensive additive.
When incorporated as food additives, IMP salts and GMP salts exhibit an umami taste. Thus, it is widely utilized in the food industry as flavor enhancers in meat sauces and seasonings.
Since GMP is more expensive than IMP, GMP salts like disodium guanylate is often used in conjunction with monosodium glutamate (MSG). In contrast, IMP salts can be used as food additives independently.