Golden flowers are the tiny yellow specks you see when you break open a Fu brick. They are a fungus called Eurotium cristatum, known in Chinese as jin hua, and Fu bricks are made so that it grows inside them on purpose. They are not spoilage mould. A brick full of evenly spread golden flowers is a well-made brick, and in Hunan a Fu brick without them has long been considered a lesser tea.
What are golden flowers, exactly?
Golden flowers are the fruiting bodies of Eurotium cristatum, a fungus that thrives in warm, humid, low-oxygen conditions. Each yellow dot is smaller than a pinhead and is packed with spores. Together they look like fine yellow pollen dusted through the leaf, thickest in the middle of the brick.
The name is literal. Jin hua means golden flowers, and when the dots are dense the broken face of a brick does look as if it has bloomed. The fungus works on the tea as it grows, changing its colour, aroma and flavour. Fu brick drinkers describe the result as mellow, sweet and rounded, with a clean woody note that is easy to recognise once you have tasted it.
Is it mould?
It is a fungus, and biologists do group Eurotium with the moulds. It is not mould in the sense most people mean: the fuzzy growth that appears when food or tea has gone off. Golden flowers are cultivated deliberately, under controlled conditions, as a normal stage of making the tea. Brick tea carrying them has been drunk across China, Tibet and Mongolia for centuries.
That long record is tradition, not science, and we present it that way. You will also read health claims about golden flowers online, some of them drawn from studies in China. We make none. If you have a mould allergy, talk to your doctor before drinking any fermented tea.
How do you tell golden flowers from bad mould?
Look at colour, shape, where it is, and smell. Golden flowers are bright yellow to yellow-orange, evenly spread, and mostly inside the brick. Spoilage mould is fuzzy, patchy and usually on the surface.
- Colour. Golden flowers are yellow. White fluff, green, blue-grey or black patches are not golden flowers.
- Shape. Golden flowers are separate tiny dots, like grains of pollen. Bad mould forms hairy or cottony threads and spreading patches.
- Where it is. Golden flowers run through the brick and are easiest to see on a freshly broken face. Spoilage usually starts on the outside, often on the side that touched a damp wall or floor.
- Smell. A good Fu brick smells clean, woody and slightly sweet. Spoilage smells sour, musty or of wet cardboard.
If a brick shows fuzzy coloured patches or smells sour, do not drink it. If you cannot tell, send us a clear photo of the broken face and we will tell you what we see.
Why do Fu bricks have golden flowers?
Because the bricks are made to grow them. Fu brick is a Hunan hei cha, a dark tea fermented after it is made. Unlike tightly pressed puerh cakes, a Fu brick is pressed fairly loosely, so there is air and moisture inside for the fungus. The pressed bricks then go through a flowering stage, called fa hua, in warm, humid rooms for several weeks while the golden flowers grow and the brick slowly dries.
This was the brick tea of the border trade. For centuries Hunan dark tea was carried north and west to Tibet, Mongolia and Central Asia, where it was boiled with salt and mixed with butter or milk. The bricks travelled for months, and the golden flowers kept working inside them.
The history is layered. Fu tea is closely tied to Jingyang in Shaanxi, where Hunan leaf was pressed into bricks for the northwest trade. Hunan's own first Fu brick came out of a factory in Anhua founded in 1939. The name is usually explained as coming from the fu days, the hottest stretch of summer, when the bricks were traditionally made. Accounts vary, and we would not stake much on any one of them.
Our Fu brick with golden flowers comes in 780g bricks from 2010 and 2014. The Gao Ma Ming Zhu jin hua hei cha is a smaller everyday Hunan tea with golden flowers.
Does liu bao have golden flowers?
Sometimes, and sources disagree on what that means. One view holds that liu bao was never judged by golden flowers the way Hunan bricks are, though they occasionally appear on it. Another, from researchers at the Wuzhou Tea Factory, treats golden flowers on well-aged liu bao as an established mark of quality. Some newer liu bao is now fermented to encourage them.
Our view: judge liu bao by its aroma, taste and storage, not by yellow specks. A liu bao with golden flowers can be very good. So can one with none. The fungus rarely grows on puerh, sheng or shou. For more on liu bao itself, see what is liu bao tea?
How do you brew and store a Fu brick?
Break off a piece with a tea pick or blunt knife, working along the edge of the brick rather than stabbing the middle. Use water at a full boil. For gong fu, start with about 5g per 100ml, rinse once, and brew short infusions that lengthen as you go. Fu brick is a hardy tea and also boils well: a few grams simmered in a litre of water makes a thick, sweet pot.
Store the brick in its paper, somewhere dark and away from strong smells, at ordinary room humidity. It does not need a sealed bag. The flowers keep working slowly for years, which is why older bricks taste rounder and deeper. Keep it away from damp walls and floors, where unwanted mould can start. Our guide to storing puerh and liu bao at home covers dry and humid climates.
Break a brick open and look before you brew. Even yellow dots through the leaf mean it is doing what it should.