Shiitake is the second most cultivated edible mushroom in the world, which is precisely why its extract market is crowded with numbers that do not mean the same thing. A buyer comparing two Shiitake Extract quotes is usually comparing a polysaccharide figure against a beta-glucan figure, and those differ by a wide margin. Sorting that out starts with the chemistry, not the price.
Two marker compounds, two very different molecules
Shiitake carries two chemically distinct actives that suppliers routinely conflate. The first is the polysaccharide fraction, dominated by the beta-glucan lentinan — a beta-(1,3)-D-glucan with beta-(1,6) branches, registered under CAS 37339-90-5. The second is a small, fully characterisable molecule: eritadenine, CAS 23918-98-1, molecular formula C9H11N5O4, molecular weight 253.22 g/mol, PubChem CID 159961, IUPAC name (2R,3R)-4-(6-aminopurin-9-yl)-2,3-dihydroxybutanoic acid. One is a polymer you assay by a colorimetric method; the other is a defined compound you assay by HPLC. They should never appear in the same column of a specification sheet.
Identification data worth putting on the enquiry form
| Botanical source | Lentinula edodes (Berk.) Pegler |
|---|---|
| Polysaccharide marker | Lentinan, CAS 37339-90-5 |
| Lentinan backbone | beta-(1,3)-D-glucan with beta-(1,6) branching |
| Small-molecule marker | Eritadenine, CAS 23918-98-1 |
| Eritadenine formula | C9H11N5O4 |
| Eritadenine molecular weight | 253.22 g/mol |
| Eritadenine PubChem CID | 159961 |
| Aroma marker | Lenthionine, CAS 292-46-6 |
| Lenthionine formula | C2H4S5 |
| Lenthionine molecular weight | 188.4 g/mol |
| Lenthionine PubChem CID | 67521 |
| Generic beta-glucan repeat unit | C18H32O16, 504.4 g/mol, CID 439262 |
Where the polysaccharide number goes wrong
The phenol-sulfuric acid method measures total carbohydrate, not beta-glucan. It responds to any reducing sugar, including the alpha-glucan starch-like material that mushroom tissue also contains. A dedicated beta-glucan assay — the enzymatic kits built on this principle, or a specific glucan-binding measurement — is the only defensible number for a beta-glucan claim. Reported literature values for Lentinula edodes beta-glucan content vary widely with strain, substrate and extraction, which is exactly why a buyer should ask for the method alongside the value rather than the value alone.
Extraction decides which fraction you receive. Hot-water extraction pulls the water-soluble glucans. Alkaline extraction reaches a different, often higher-molecular-weight population. Ethanol precipitation then selects by solubility. Two extracts from the same lot of dried fruiting bodies can legitimately carry different glucan figures because they were never measuring the same fraction.
Procurement checklist
- Name the assay method, not just the percentage. Total polysaccharide and beta-glucan are different measurements with different numbers.
- Confirm the plant part. Fruiting body and mycelial biomass produce different compositional profiles and different buyer expectations.
- Ask for the extraction solvent sequence. Water versus alkaline versus ethanol-water changes the glucan population you receive.
- Specify the marker you actually need. If the product concept rests on eritadenine at 253.22 g/mol, say so and get an HPLC method attached.
- Request batch-specific data. Assay, moisture, particle size, packaging and shelf life belong on the COA.
Frequently asked questions
Why is one quote 30% polysaccharide and another 20% beta-glucan?
They are different measurements. The polysaccharide figure includes non-glucan carbohydrates; the beta-glucan figure does not. Compare like with like before comparing price.
Is mycelium-on-grain acceptable?
It depends entirely on your label and target market. The compositional profile differs from fruiting-body material, and some markets require the distinction to be declared.
What is lenthionine and why is it listed?
It is the cyclic sulfur compound responsible for much of shiitake aroma, C2H4S5 at 188.4 g/mol. It matters for flavour applications, not for a glucan claim.
Facts in this article are taken from PubChem (US National Library of Medicine) records for the compounds listed above and from published compositional literature on Lentinula edodes. Grade-specific data — assay, moisture, particle size, packaging, shelf life — is issued per batch on the COA and is not published here.