From Stevia Leaves to High-Purity Sweeteners: Understanding Stevia Extract

What the leaf contains sets the ceiling

Dried stevia leaves carry highly variable loads of sweet compounds, roughly 6% to 15% of dry weight, which puts a dried leaf anywhere between 18 and 45 times sweeter than sugar. Glycosides accumulate as leaf tissue ages, so older lower leaves hold more than younger upper leaves, and once flowering begins, glycoside concentration starts to decline. Two lots of leaf from the same growing area can differ substantially before processing starts.

Published composition figures vary just as widely. A peer-reviewed survey of the plant reports stevioside at 22% to 62% of total glycosides and Rebaudioside A at 5% to 65%, because cultivar and growing conditions move the profile. Huacheng Bio publishes its stevia material as Rebaudioside A 50% to 99% and Rebaudioside M 95%, and does not publish a native leaf profile behind those grades. Ask for a measured glycoside profile with the grade you are quoted, since a range this wide does not transfer from one supplier's leaf to another.

The glycosides that decide taste and cost

Sweetness and aftertaste come from different molecules, and the leaf does not hold them in the proportions most buyers assume. The current monograph prepared by the Joint FAO/WHO Expert Committee on Food Additives defines steviol glycosides broadly, as any compound carrying a steviol backbone conjugated to sugars in orientations found in the leaf. The published sensory and abundance data below comes from a peer-reviewed survey of steviol glycosides.

The practical consequence is that two powders can clear the same 95% purity line and taste nothing alike. One may reach the total mostly through stevioside, the other through Reb A or Reb M. The total tells you what is pure. It does not tell you what is sweet.

Hot water extraction pulls the good out with the bad

The current JECFA monograph for steviol glycosides from Stevia rebaudiana Bertoni states the first step plainly: the leaves are extracted with hot water. Water does two jobs at once. It dissolves the glycosides you want, and it also dissolves pigments, polysaccharides, proteins and tannins from the leaf. Push extraction harder to lift recovery and you carry more coloured, bitter material into purification, which then has to strip it out at the cost of capacity and yield. Extract more gently and recovery falls.

Huacheng Bio's stevia production uses advanced methods, including supercritical fluid extraction and enzyme-assisted extraction to maximise steviol glycoside yield, and has the independently developed organic membrane separation among the technologies that are shown on industry chain page.

Resin, alcohol and recrystallization create high purity

Everything that turns a leaf infusion into a high-purity sweetener happens after extraction. Per the same monograph, the aqueous extract is passed through an adsorption resin that traps and concentrates the steviol glycosides while much of the rest passes through. The resin is washed with a solvent alcohol to release the glycosides, and the product is recrystallized from methanol or aqueous ethanol. Ion exchange resins may be used during purification, and the final product may be spray-dried.

Keep that sentence in mind when you write your certificate of analysis requirements. Methanol is named in the process, and the monograph caps residual solvents at 200 mg/kg of methanol and 5,000 mg/kg of ethanol. Request both solvent figures with the test method, and state the limit your own market imposes.

High purity means 95% total steviol glycosides

Three regimes draw the line at the same number. The JECFA monograph requires an assay of not less than 95% of total steviol glycosides on the dried basis. EU specifications for E 960 require not less than 95%, held today across eleven named steviol glycosides. In the United States, Import Alert 45-06 exempts highly purified steviol glycosides from detention when they reach at least 95% steviol glycosides on a dried weight basis, with stevioside, Rebaudioside A, Rebaudioside D, Rebaudioside M, enzyme-modified steviol glycosides or comparable steviol glycosides as principal components.

Below that line the rules change completely. Since 1991 the FDA has treated stevia leaf and crude stevia extracts as unapproved food additives rather than GRAS substances, and their import for use as a sweetener is not permitted. The alert was revised again in 2025. Purity total therefore decides which side of that line a shipment lands on, which is why it matters more than any grade name.

H2-Via stevia is offered at Rebaudioside A 50% to 99% tested by HPLC, and at Rebaudioside M 95%. Those are single-molecule figures. The total steviol glycosides sum is a different calculation, and it is the one all three regimes above apply. Ask for it explicitly, on the dried basis, together with the method. Current JECFA specifications use HPLC with UV or mass detection against external reference standards.

Read the powder against the numbers your market uses

Once purity is settled, the rest is arithmetic against permitted use levels. Commission Regulation (EU) No 1131/2011 authorises E 960 steviol glycosides category by category, with maximum levels expressed as steviol equivalents: 80 mg/l in energy-reduced flavoured drinks, 100 mg/kg in energy-reduced flavoured fermented milk products, 200 mg/kg in energy-reduced jam and jelly, 350 mg/kg in confectionery with no added sugar, 3,300 mg/kg in chewing gum, and quantum satis for tabletop sweeteners in liquid, powder or tablet form. Because the limits are expressed as steviol equivalents, glycoside mass has to be converted before you can tell whether a formulation fits.

Request each of these for the grade you intend to buy:

• Total steviol glycosides on the dried basis, with the HPLC method and reference standards.
• Loss on drying, capped at 6% at 105 °C for 2 hours.
• Total ash, capped at 1%.
• Lead reported individually at not more than 1 mg/kg, alongside the total heavy metals figure.
• Methanol and ethanol residues, with the test method used.
• Salmonella reported as negative in 25 g and E. coli as negative in 1 g. The published table records conformance without stating a limit, which leaves nothing to audit against.
• pH of a 1 in 100 solution, expected between 4.5 and 7.0, and water solubility, both of which shape dispersion and stability in a beverage base.

Huacheng Bio runs sensory, physical and chemical, microbiological and precision-instrument laboratories equipped with HPLC, GC, AA and UV-VIS, and sends material to third-party laboratories including NSF, SGS and Eurofins on a scheduled basis. Ask which tests were run in-house and which were sent out for your lot, because that determines how fast a disputed result can be reproduced.

FAQ: reading a stevia extract specification