Matcha catechins: EGCG, ECG, CG and GCG explained

Matcha catechins: EGCG, ECG, CG and GCG explained

Catechins are the main polyphenols in the Camellia sinensis leaf and account for 12% to 16% of dry green tea leaf. Four of them carry a galloyl group: ECG, EGCG, CG and GCG. They are responsible for the bitterness and for the astringency in the finish, and their proportions shift with cultivation and harvest.

What a catechin actually is

A catechin is a flavan-3-ol, a type of plant polyphenol. In tea they appear in two families: the free ones, such as epicatechin or epigallocatechin, and the galloylated ones, which carry an attached molecule of gallic acid. That galloyl group changes their chemical behaviour and their flavour too. The galloylated ones bring most of the astringency to the bowl.

The four galloylated catechins in tea

• EGCG, epigallocatechin gallate. The most abundant in green tea and the most studied.
• ECG, epicatechin gallate. Less abundant than EGCG, with a similar profile.
• CG, catechin gallate. Present in smaller proportion and formed partly by isomerisation during heat processing.
• GCG, gallocatechin gallate. Like CG, it gains weight once the leaf meets heat.

How much catechin matcha contains

Here is the figure that gets misquoted most often. It comes from an analytical paper published in the Journal of Chromatography A in 2003 (Weiss and Anderton, PMID 14518774) at the University of Colorado at Colorado Springs. The authors developed a micellar electrokinetic chromatography method to quantify five catechins and the caffeine content of matcha, and measured, in milligrams per gram of dry leaf, an EGCG concentration 137 times higher than the green tea China Green Tips, and at least three times higher than the highest value published at that point for other green teas.

Read the number for what it is: analytical chemistry on dry leaf against one specific comparison tea. Not a trial in people, and not a comparison against every green tea on the market.

Why matcha concentrates more than an infusion

In a green tea infusion the leaf goes into the water, steeps, and comes out again. Only the soluble fraction reaches the cup, and the rest leaves with the spent leaf. With matcha the whole leaf is milled to powder, whisked with water and drunk entirely: catechins, theanine, caffeine, chlorophyll and fibre. No filter, different arithmetic.

Shading in the weeks before harvest matters too. Less direct light means more chlorophyll and more amino acids such as theanine, and slightly fewer catechins. That is precisely what separates the umami sweetness of a ceremonial grade from the grassier, more astringent profile of a culinary one.

What has been measured in people

These are the published trials that measured something in real participants, with what they measured and in whom:

• A systematic review with meta-analysis of 31 randomised trials and 3,321 subjects published in Nutrition Journal in 2020 (Xu et al., PMID 32434539) compared total cholesterol, LDL, HDL and triglycerides in green tea drinkers against controls.
• A randomised placebo-controlled trial published in Nutrition Research in 2021 (Baba et al., PMID 33744591) gave 2 g of matcha a day for two weeks to 42 adults aged 25 to 34 and recorded their reaction times in the Stroop test after stress induction with the Uchida-Kraepelin test.
• A randomised, double blind, placebo-controlled 12 month trial published in PLoS One in 2024 (Uchida et al., PMID 39213264) followed 99 older adults with subjective or mild cognitive decline, 49 taking 2 g of matcha daily and 50 on placebo. Its primary outcome, the Montreal Cognitive Assessment, did not change significantly.
• A meta-analysis of 13 studies published in the European Journal of Nutrition in 2014 (Khalesi et al., PMID 24861099) measured systolic and diastolic blood pressure in green tea drinkers against controls.

What you notice from all this in the bowl

Catechins are the part of the flavour most people describe as green bitterness. Push the water temperature or the whisking time and that bitterness takes over and buries the umami. With water at 70 to 80 °C and about 2 g of powder per 60 to 70 ml, the balance sorts itself out.

Matcha forgives a great deal, but never boiling water. It is the one mistake you can taste instantly and cannot argue your way out of.

If you want to try that with a high first-harvest grade, our Ceremonial Matcha 100 g comes from shade-grown leaf in Jingshan (China), processed at Zhejiang Camel Transworld in Yuhang (Hangzhou) and slow stone milled. Organic certification CCPAE, code ES-ECO-019-CT, plus USDA Organic. At £19.00 for 100 g it works out at roughly 38p a bowl.

References

1. Weiss DJ, Anderton CR., Determination of catechins in matcha green tea by micellar electrokinetic chromatography. Journal of Chromatography A, 2003. PMID 14518774. https://pubmed.ncbi.nlm.nih.gov/14518774/
2. Xu R, Yang K, Li S, Dai M, Chen G., Effect of green tea consumption on blood lipids: a systematic review and meta-analysis of randomized controlled trials. Nutrition Journal, 2020. PMID 32434539. https://pubmed.ncbi.nlm.nih.gov/32434539/
3. Baba Y, Kaneko T, Takihara T., Matcha consumption maintains attentional function following a mild acute psychological stress without affecting a feeling of fatigue: A randomized placebo-controlled study in young adults. Nutrition Research, 2021. PMID 33744591. https://pubmed.ncbi.nlm.nih.gov/33744591/
4. Uchida K, Meno K, Korenaga T, et al., Effect of matcha green tea on cognitive functions and sleep quality in older adults with cognitive decline: A randomized controlled study over 12 months. PLoS One, 2024. PMID 39213264. https://pubmed.ncbi.nlm.nih.gov/39213264/
5. Khalesi S, Sun J, Buys N, Jamshidi A, Nikbakht-Nasrabadi E, Khosravi-Boroujeni H., Green tea catechins and blood pressure: a systematic review and meta-analysis of randomised controlled trials. European Journal of Nutrition, 2014. PMID 24861099. https://pubmed.ncbi.nlm.nih.gov/24861099/