Is it possible to purchase Disodium Ribonucleotides (E635) in consumer/small quantities?

It looks like you can get 500 milligrams of disodium inosinate, USP grade from Sigma: http://www.sigmaaldrich.com/catalog/product/usp/1222002?lang=en&region=US

Disodium guanylate is also available. USP grade means it's pharmaceutical grade, which is one step above food grade, which is why it's so expensive.

Alibaba looks like the place to look for "inosinic acid" "food grade" Amazon India has it, but it looks like no one has bought it yet, and you'd have to figure out their currency system.

If you buy the free acid, you can just take the pH up with sodium hydroxide.

I found Special Ingredients (UK) and their "Flavour Enhancer", which is a 1:1 mix of disodium inosinate and disodium guanylate: Special Ingredients. Available in 100g/250g/500g. They seem to sell worldwide and also sell via Amazon, although I can only find their products by searching for the company name.

In the US there seems to be the Ingredient Store for BBQ-Enthuasiasts that offer 4oz and 16oz packages of a mix.

I looked up the Ajinomoto website for Indonesia, where I live:

Their product line-up for Indonesia consists of:

Retail:

• Pure MSG
• Plus various other cooking products, ranging from mayonnaise to bouillon powder to instant noodles. As far as I can tell ALL of these products contain MSG, IMP and GMP, the disodium ribonucleotides you refer to.

Then the Commercial side:

https://www.ajinomoto.co.id/en/product-recipe/produk-industri

• Aji-Plus, which is a pure blend of MSG , IMP, GMP I found this on sale on a local website, priced at the equivalent of $3 for 1kg, which is quite a lot of MSG, but it's also not very much money. https://www.tokopedia.com/indfoodchem/ajiplus-ajinomoto-1

The dosing is on the website

And is quite interesting.

It reads:

• For 100kg of krupuk (e.g., prawn cracker, or similar) mixture, MSG 900g (0.9%) or Aji-Plus 300g (0.3%)
• For processed chicken or beef, 1.2% MSG, or 0.4% Aji-Plus
• For processed fish, 0.6% MSG, or 0.2% Aji-Plus
• For snack mixtures, 2.4% MSG, or 0.8% Aji-Plus
• For snack seasoning to be sprayed/shaken etc onto snacks, 18% MSG, or 6% Aji-Plus

So the I+G reduces the volume of MSG by 2/3.

From what I can see, regular MSG in the same quantity/brand is only slightly cheaper.

Further, it seems that a small amount of I+G has a large effect on MSG, and the dosing is likely to be 1:19 between I+G and MSG. Substantially increasing to, say, 1:1, seems not to be cost-effective, even if it isn't harmful.

I found a study here: http://europepmc.org/article/PMC/4867766

in Singapore and the authors compared a control of Asian soups with a control with only salt, against reduced salt and 0.2%, 0.4% MSG and 0.2%, 0.4% Ajiplus. This does not match the dosage I list above, in that they do not reduce the Ajiplus dosage relative to MSG. However the Ajiplus had a higher umami score than the MSG alone, which is not surprising.

This product is called Ajiplus Ekicho

and it contains MSG plus IMP, but not GMP

Ajinomoto say ' it can also provide a stable, full "UMAMI" flavor and long-lasting. It is suitable for liquid spices (soy sauce, sauce, pasta [?] and so on) because it is more stable the savory taste because of warming process.'

The listed dosage is also 1/3 of MSG.

There are some other interesting products, namely Ajimate Super. This comes in different variants, but besides MSG, I+G, it contains reduced glutathione (GSH), among other ingredients. GSH is another umami activator.

Ajitide is the specific range of products with IMP, GMP and I+G ranges:

http://www.ajinomoto.com.hk/products/industrial/ajitide

Whereas the Aji-Plus product is sold for home industry/restaurants, the Ajitide range seems to be strictly large industry, and it is not on sale at retail as I could find in Indonesia

I looked on Ebay, and found Ajitide I+G:

https://www.ebay.co.uk/itm/Disodium-Inosinate-Guanylate-5-Ribonucleotides-100g-Ajitide-Enhancer-Additive/233693541755

The seller is selling $20 for 100g, or $10 for 25g. This might be a grossly inflated price - I do not know.

The write-up reads:

For example, Ajinomoto Haimi is a premium-priced Japanese product consisting of 92/8 MSG and E635, Ajinomoto Plus (Thailand) is 98/2, and Korean Miwon seasoning is about 97/3; likewise with 'super salt'.