Re: what is exactly disodium guanylate and disodium inosinate
No. MSG (monosodium glutamate) is the sodium salt of glutamic acid. The two that you mention can be mixed together and are called collectively as disodium-5-ribonucleotides.
Here's the problem. Some foods naturally contain glutamic acid. So when the manufacturer adds MSG, since in food labeling rules you can list salts as the same name of their corresponding acids, instead of listing MSG, they can just say glutamic acid.