Est. 1956 · The Order The independent guide to oolong: the partly oxidized teas, and how to brew them. Oolong.biz
THE ORDER OF THE SEVENTH STEEP SEMPER PARTIM OXIDATUM The Order of the Seventh Steep
The Order of the Seventh Steep
OOLONG
Semper Partim Oxidatum Always partly oxidized

Tagged: catechin

Article · Health & Science

Oolong Carried the Least of a Compound Class That Should Have Favored Green Tea

A 2026 study measured advanced glycation end-products, the same compounds tied to aging and inflammation, across five tea types. Oolong came out lowest of all five, and the antioxidant story that usually explains oolong's health claims does not explain why.

Jul 19, 2026
Article · Basics

Why one plant makes green, oolong, and black tea

Green, oolong, and black tea are the same leaf from Camellia sinensis. What separates them is processing, above all how much enzymatic oxidation the maker allows before heat arrests it.

Jul 1, 2026
Article · Health & Science

The oolong weight-loss trials measured hours of fat-burning, not pounds

No systematic review of oolong and weight loss exists, only two small human trials. Here is what those trials, and the closest systematic review that does exist (green tea's), actually measured, in kilograms, not adjectives.

Jun 17, 2026
Article · Health & Science

Why a Green Oolong and a Heavy Roast Never Want the Same Water

The brewing guide states the temperature bands by oxidation level. Here is the extraction chemistry, measured in real studies, that makes them true.

Jun 4, 2026
Article · Brewing & Gongfu

What Mineral-Heavy Water Does to Oolong: Less Catechin, a Cloudier Cup

A 2024 study brewed the same Tieguanyin in four different waters and measured what came out. Mineral content moved the chemistry, not just the story a taster tells about it.

May 21, 2026
Article · science

Two Reactions Start When the Leaf Is Bruised, Not One

Shaking bruises the leaf once, but it starts two separate reactions on two different substrates. One reddens the edge. The other, mapped only in the last few years, manufactures the floral scent.

Apr 24, 2026
Article · Health & Science

The Oolong Diabetes Trial Everyone Cites Had One Funder

A 2003 trial found oolong tea cut blood sugar by nearly a third in diabetic patients. It was run by a beverage maker's own research lab, the one independent repeat found nothing, and a large cohort found the opposite. Here is what actually holds up.

Apr 10, 2026
Article · Brewing & Gongfu

The Pot Is Not Neutral: What Six Teapot Materials Do to the Same Oolong

Researchers brewed one oolong in six vessels, zisha and zhuni clay, stainless steel, ceramic, glass, and plastic, then measured what actually left the leaf. Clay changed the chemistry. Here is what the pore structure explains.

Mar 27, 2026
Guide · Health & Science

Oolong and Health

What the published research on oolong tea actually measures, not what the label copy claims. The trial and cohort evidence on the heart, blood sugar, weight, and bone, how partial oxidation changes the chemistry those trials test, and how to read a small positive trial against a large null one.

Guide · Health & Science

Oolong Polyphenols

The compound family behind color, astringency, and every published health claim. What catechins, theaflavins, and thearubigins actually are, structurally, and what partial oxidation does to each before the leaf ever reaches a cup.