Licorice Extract Adulteration and How Authenticity Is Proven

Why Licorice Is a Difficult Case

Adulteration follows economics. It appears where raw material has cost, the buyer checks one number, and the seller's chemistry is deeper than the buyer's testing. Licorice adds a fourth condition that makes it unusually exposed: the standard marker assay is species-blind.

Glycyrrhiza glabra, G. uralensis and G. inflata all contain glycyrrhizin. A 20% glycyrrhizin result is equally consistent with all three. On most botanicals, the assay implicitly confirms identity; here it does not, and a buyer relying on assay alone has no species control whatsoever.

Route 1 — Species Substitution

The most common issue, and often not even framed as adulteration by the seller — a supplier sourcing opportunistically may genuinely regard "licorice is licorice". If you are buying for a cosmetic application, or for any market where your registration names G. glabra, it is not.

What catches it: a TLC identity against authentic G. glabra reference material; an HPLC fingerprint read across the whole chromatogram rather than a single peak; and most usefully, a glabridin figure — glabridin is characteristic of G. glabra, so its presence at expected levels is a positive species indicator. A species declaration on the CoA also converts a sourcing shortcut into a documented claim the supplier is answerable for.

Route 2 — Ammonium Glycyrrhizinate Spiking

The licorice-specific route, and the one buyers most often have not considered. Ammonium glycyrrhizinate — a purified salt of glycyrrhizin — is a legitimate, inexpensive, widely traded commodity used as a sweetener and flavour ingredient. It is not an illegal substance and there is nothing wrong with it in its own right.

The abuse is obvious once stated: add it to a weak or spent licorice extract and the glycyrrhizin assay rises to specification without any additional root. The material passes HPLC — because it genuinely does contain more glycyrrhizin — while containing far less real extract than declared.

What catches it: the glycyrrhizin figure alone cannot. What exposes it is the relationship between glycyrrhizin and everything else:

• Flavonoid content out of proportion. A genuine 20% extract carries a characteristic liquiritin and isoliquiritigenin load alongside its glycyrrhizin. Spiked material has the saponin without the matching flavonoid fraction.
• HPLC fingerprint mismatch. One peak elevated against an otherwise unchanged chromatogram is the signature.
• Ammonium content. Where spiking is suspected, testing for ammonium is direct and inexpensive.
• Organoleptic mismatch. Spiked material is often sweeter than its apparent extract strength warrants and lighter in colour.

Route 3 — Spent Root and Exhausted Marc

The classic dilution: extraction residue, dried and milled, blended back into good extract. It still smells and looks like licorice.

What catches it: straightforward HPLC assay, since the actives are absent. Which is exactly why in practice it is rarely done alone — it is combined with route 2, where the spent material provides bulk and the glycyrrhizinate provides the assay. The pairing is the reason a fingerprint check matters more than a single assay.

Route 4 — Undeclared Carriers and Bulking

Maltodextrin, starch, dextrose and rice flour are legitimate when declared — a spray-dried grade may genuinely need a carrier. The adulteration is the undeclared version, sold as pure extract.

Licorice has a specific tell here: the standard grade is a water-soluble, hygroscopic material with characteristic bulk density and colour. Bulked material tends to be paler, flow better than it should, and show a loss-on-drying that does not match its handling behaviour.

What catches it: total ash and acid-insoluble ash for mineral bulking; a declared-carrier line by name and percentage on the CoA; and specifying the assay on a dry, carrier-free basis, which forces the arithmetic into the open.

Route 5 — DGL Specification Abuse

A route unique to licorice, and it exploits the inverted specification. Because DGL requires glycyrrhizin below 2%, a supplier can meet that limit trivially by diluting a standard extract with carrier until the glycyrrhizin falls under the ceiling — producing something that passes the stated DGL test while containing almost none of the flavonoid fraction that DGL is bought for.

What catches it: specifying DGL on both ends. A proper DGL specification carries a glycyrrhizin maximum and a minimum for the flavonoid fraction — total flavonoids, or liquiritin specifically. Without the second limit, "DGL" can legitimately mean "diluted".

The Testing Package That Covers All Five

Practical Steps for a Buyer

1. Never rely on the glycyrrhizin assay for identity. On this botanical it does not do that job. This is the single most important point on the page.
2. Require an HPLC fingerprint, not just a peak. Spiking and species substitution both show up in the whole chromatogram and nowhere else.
3. Add the no-added-glycyrrhizin-salts clause to your purchase specification.
4. Specify DGL on both ends — glycyrrhizin maximum and flavonoid minimum.
5. Ask for glabridin to be reported even on non-cosmetic grades. It is a cheap species check riding on an existing method.
6. Third-party verify the first batch. Nominate Eurofins, SGS or Intertek. One independent report at the start of a relationship outweighs a year of supplier CoAs.

SV Botanica declares species on every licorice batch, confirms identity by TLC against G. glabra reference material, assays glycyrrhizin by HPLC and will report glabridin and the flavonoid fraction on request. Buyers are welcome to nominate an independent laboratory for pre-shipment verification — see the supplier evaluation guide, or the product specification for the full parameter list.