Green tea extract is sold on its catechins, and catechins are reactive. They hold up well in a dry capsule and less well in a hot, neutral drink. Caffeine and the EU limit on EGCG add two more constraints. Here is how to choose the grade and design the process around them.
Catechin Stability: pH and Heat
Chen and colleagues (Journal of Agricultural and Food Chemistry, 2001) studied green tea catechins in drinks. They were stable in water at room temperature and more stable the lower the pH. Prolonged brewing at 98 °C degraded them by about 20%. Autoclaving at 120 °C converted part of the EGCG into its epimer, GCG.
Two practical points follow. Keep ready-to-drink products acidic where possible. Measure EGCG after your heat treatment, not before it, because the label figure must survive the process.
The same study found that other drink ingredients changed catechin stability even at low pH. Run the stability test in your full recipe, not in water.
Caffeine: Standard or Decaffeinated
Standard grades carry up to 10% caffeine. The decaffeinated grade carries 0.5% or less. Choose decaf for caffeine-free claims, evening products and formulas that already contain caffeine. Our caffeine by grade article gives milligrams per serving for each grade.
The EGCG Limit Sets the Dose Ceiling
EFSA’s 2018 opinion on green tea catechins linked EGCG intakes of 800 mg a day or more from supplements with raised liver enzymes. The EU then restricted green tea extracts containing EGCG under Regulation (EU) 2022/2340. A daily portion must contain less than 800 mg of EGCG, with labelling conditions.
Work back from that figure. At the EGCG 50% grade, 800 mg of EGCG would need 1.6 g of extract, so stay well below it. Write the EGCG per daily portion into your product specification.
Colour, Iron and Proteins
- Colour. Catechins oxidise and darken over time, faster with heat, light, oxygen and higher pH. Brown drift in a drink is usually oxidation.
- Iron. Catechins bind iron. In fortified products this can cause darkening and can reduce iron uptake from the same serving. Test fortified recipes for colour.
- Proteins. Catechins bind milk and plant proteins, which can cause haze or sediment in protein drinks.
Formats and Grades
| Format | Usual grade | Watch-point |
|---|---|---|
| Capsules, tablets | Polyphenols 50% or 90% / catechins 80% | EGCG per daily portion |
| High-EGCG products | EGCG 50% | EU 800 mg cap, label wording |
| Caffeine-free, evening | Decaffeinated (0.5% caffeine or less) | Caffeine declaration |
| Drinks, sachets | Water-soluble grade | pH, heat, haze with proteins |
| Organic lines | Certified organic (on request) | Certificate scope |
All grades are on our green tea extract page. For dosing detail read the EGCG dosage guide, and for assay methods the catechins and EGCG assay explainer.
Green tea extract specified for your format
Tell us the format, the EGCG per serving and whether you need decaf. We send the specification and a reference certificate.