Licorice standardisation has a quirk that catches careful buyers: the marker everybody measures is the one compound that cannot tell you what species you bought. Understanding why — and what to measure alongside it — is the difference between a specification that controls your material and one that merely describes it.
The Marker: Glycyrrhizin
Glycyrrhizin, also written glycyrrhizic or glycyrrhizinic acid, is a triterpene saponin: a glycyrrhetinic acid aglycone carrying two glucuronic acid units. Three properties follow from that structure and between them they explain most of how licorice behaves commercially.
- It is intensely sweet — roughly fifty times sucrose — which makes the standard grade a functional sweetener and bitterness-masker as well as an active.
- It is highly water-soluble, because of the sugar units. This is why licorice extract works in beverages and syrups, and also why the powder is hygroscopic and cakes in humid storage.
- It is metabolised to glycyrrhetinic acid, which is the compound behind the mineralocorticoid effects that give licorice its intake ceiling.
How Glycyrrhizin Is Measured
HPLC — the method to specify
Reversed-phase HPLC with UV detection around 250 nm resolves glycyrrhizin as a discrete peak, quantified against a reference standard. It separates glycyrrhizin from the flavonoids and from related saponins, and it is the basis of every SV Botanica licorice CoA.
UV spectrophotometry — why it reads high
A bulk UV method reads absorbance in a region where glycyrrhizin absorbs — and so do the flavonoids, and so does anything else phenolic in the extract. On a material as flavonoid-rich as licorice the overstatement is substantial and inconsistent. For a marker with an intake ceiling, an assay biased upward is the dangerous direction: it makes your material look closer to specification while your actual glycyrrhizin delivery is unknown.
Why this matters more for licorice than for other botanicals: with most markers, an inflated assay means you paid for actives you did not get — a commercial loss. With glycyrrhizin, an inaccurate assay in either direction breaks the dose calculation on which a labelling threshold depends. Specify HPLC by name.
The Inverted Specification: How DGL Works
Deglycyrrhizinated licorice is made by taking a licorice extract and removing the glycyrrhizin, typically by a solvent partition or resin step that exploits glycyrrhizin's solubility profile against that of the flavonoids. The target is not more than 2% residual glycyrrhizin, with the liquiritin, liquiritigenin and isoliquiritigenin fraction retained.
Two things follow that buyers routinely get wrong:
- The DGL specification is a maximum, not a minimum. Every QC habit built around "assay must be at least X" runs backwards here. A DGL batch that assays at 3.5% glycyrrhizin has failed, even though on any other licorice grade that number would be a low-strength pass.
- DGL is not "weak licorice". It is licorice with one fraction removed and another retained. Its purpose is to let you dose the flavonoid fraction well above where the glycyrrhizin ceiling would otherwise stop you. Substituting a low-assay standardised grade for DGL does not achieve the same thing.
A useful QC habit: state the DGL limit in words as well as figures on the purchase specification — "glycyrrhizin not more than 2.0% w/w (maximum limit)" — because a supplier's system that auto-formats specifications may otherwise render it as a minimum.
Glabridin: A Different Marker Entirely
Glabridin is an isoflavan, not a saponin, and it sits in the hydrophobic fraction of the root. It is the marker for cosmetic grades, typically standardised to 40% by HPLC, and it is used in skin-brightening and even-tone formulations.
Three practical differences from the glycyrrhizin grades:
- Solubility is inverted. Glycyrrhizin grades are water-soluble; the glabridin fraction is oil- and glycol-soluble. A formulator who assumes all licorice grades disperse in water will have a bad afternoon.
- Value density is far higher. Concentrating a minor constituent to 40% takes a lot of root, and the price reflects that.
- It is species-diagnostic. Glabridin is characteristic of G. glabra. This makes it useful for identity as well as for cosmetic function.
The Blind Spot: Glycyrrhizin Cannot Identify the Species
This is the point that makes licorice specification genuinely different. On most botanicals, the marker assay doubles as a species check — an extract without the marker is not the plant. Licorice breaks that rule, because G. glabra, G. uralensis and G. inflata all contain glycyrrhizin. A 20% glycyrrhizin assay is fully consistent with any of the three.
To control species you need something else on the certificate:
| Control | What it establishes | Method |
|---|---|---|
| Explicit species declaration | The supplier's documented claim, and their liability for it | Documentation |
| TLC identity vs reference | Correspondence with authentic G. glabra material | TLC |
| Glabridin present | Positive indicator for G. glabra | HPLC |
| Flavonoid profile / fingerprint | Species discrimination on the whole chromatogram | HPLC fingerprint |
| DNA barcoding (raw material) | Definitive species ID before extraction | PCR |
For most buyers the first three are sufficient and cost nothing extra. For a cosmetic buyer, the glabridin figure is doing double duty as function and identity, which is convenient.
Writing a Licorice Specification That Holds
- Name the grade family in the first line. Standardised, DGL, glabridin or native ratio.
- Name the method. "Glycyrrhizin NLT 20.0% w/w on dry basis, by HPLC."
- State DGL limits as maxima explicitly, in words as well as figures.
- Require the species declaration as a separate line, not implied by the product name.
- Require the measured figure, not the nominal grade, so your dose arithmetic runs on reality.
- Set acid-insoluble ash at NMT 2% — a deep-rooted perennial carries soil.
SV Botanica standardises licorice root extract to glycyrrhizin NLT 20% by HPLC with identity confirmed by TLC and species declared per batch, and supplies DGL and glabridin 40% grades to their own specifications. See the licorice extract product specification for the full parameter list, or the buyer's guide for how to approach the purchase.
Source Standardised Licorice Extract from India
Glycyrrhizin NLT 20% by HPLC · DGL, glabridin 40% & full-spectrum grades · CoA-backed · samples for qualified buyers