Cloudy Tea, Foam, and Sediment: Is It Normal?
When brewing pu'er, you'll often notice small changes in the liquor: bubbles, cloudiness, fine particles, an oily sheen. It's natural to worry the first time you see them, but most are simply caused by the tea leaves' own components.
Does Cloudy Tea Mean It's Gone Bad?
Usually not. There are several possible causes of cloudiness:
Cream-Down
Hot tea is clear, turns hazy as it cools, and clears again when rewarmed. This is called "cream-down" (冷後渾). It happens because polyphenols, pigments, caffeine, and other components dissolve in the water at high temperatures, then combine and come out of solution at lower temperatures, forming tiny particles that make the liquor look cloudy. Research on cream-down in black tea has observed that at high concentrations and with rapid cooling, theaflavins aggregate into nanoscale particles, with caffeine embedded within them.
Cream-down often appears in teas rich in compounds and brewed fairly strong, and is also commonly seen in cold brew in the refrigerator. The chemistry is explained in Cream-Down and Tea Foam: The Science.
Suspended Particles
Fine bits from prying and tea down (the fine hairs on buds) suspended in the liquor can also make it look less clear. Filtering through a fine-mesh strainer makes the tea much clearer; this is most common with ripe pu'er and raw tea with lots of buds.
Cloudiness Worth Watching
If the liquor is cloudy and dull right from the first pour, and comes with sour, moldy, or stuffy off-flavors, there may be a problem with the raw material, processing, or storage.
What Are the Bubbles on the Tea?
The layer of white foam that forms when you pour water comes mainly from tea saponins in the leaves. Tea saponins are natural components of the tea plant with surfactant-like properties, so they foam as soon as water hits them. Tea down on the buds also adds to the foam.
How much foam you get relates to:
- Pouring from height with a thick stream makes more foam;
- Young tea and bud-rich tea often foam more;
- The first rinse has the most foam, decreasing gradually after that.
If you don't like the foam, pour lower and along the side of the bowl, or gently skim it off with the lid after filling. The foam is part of the tea itself, so there's no need to worry.
Is Fine Sediment at the Bottom of the Cup Normal?
Yes. The fine sediment is mostly:
- Bits from prying;
- Tea down;
- The finer broken leaves in ripe pu'er after pile fermentation.
For cleaner tea, you can put broken tea at the bottom of the gaiwan when adding it, pour so the water avoids the leaves, use a fine-mesh strainer when pouring off, and leave the last bit of tea out of the cup.
What Is the Oily Sheen on Ripe Tea?
After ripe pu'er is brewed, you can sometimes see a faint sheen on the liquor's surface; held to the light, it looks like a thin film. Tea drinkers call it "oil sheen" or "tea oil." The tea world generally believes it's related to pectin, polysaccharides, and other compounds in the leaves dissolving out during pile fermentation and brewing, which also makes the liquor seem thick and silky. It's more common in ripe teas that are rich in compounds and thoroughly fermented.
What to distinguish from this sheen is actual grease: if the teaware isn't clean, your hands are oily, or the kettle has grease buildup, droplets of oil will float on the tea, and it may also smell rancid. In that case, wash the teaware thoroughly. Cleaning methods are in Caring for Teaware.
When to Take a Closer Look
| Observation | Usually | When to watch out |
|---|---|---|
| Turns cloudy as it cools, clears when rewarmed | Cream-down | Never |
| A layer of white foam on the surface | Tea saponins, tea down | Never |
| Fine sediment at the bottom of the cup | Fragments, tea down | Use a strainer if there's a lot |
| A faint sheen on ripe tea | Pectin, polysaccharides, and other compounds | If there are distinct oil droplets or a rancid smell, check the teaware |
| Cloudy and dull right from the first pour | Raw material, processing, or storage problems | Don't drink it if it comes with sour, moldy, or stuffy smells |
| Thick, slimy liquor with a sour, rancid smell | Tea left sitting too long | Don't drink it |
Habits for Clearer Tea
- Peel along the layers when prying to create fewer fine bits;
- Discard the first rinse, which carries away most of the foam and fine bits;
- Pour lower and along the side of the bowl for less foam and clearer tea;
- Put a fine-mesh strainer over the fairness pitcher;
- Drink tea while it's hot, so cream-down is less likely; if you want it cold, cold brew gives clearer tea than hot tea left to cool.
FAQ
Does cloudy tea mean it's gone bad? Usually not. Turning cloudy as it cools and clearing when rewarmed is cream-down; suspended bits can be strained out. Only cloudiness right from the first pour combined with off-flavors deserves attention.
What are the bubbles on the tea? Mainly the tea leaves' own saponins, plus tea down; there's more when pouring from height, and there's nothing to worry about.
Is fine sediment at the bottom of the cup normal? Yes. It's mostly bits from prying, tea down, or the fine broken leaves of ripe pu'er, and a fine-mesh strainer reduces it.
What is the oily sheen on ripe tea? The tea world generally believes it's related to pectin, polysaccharides, and other compounds; if you see distinct oil droplets or a rancid smell, check that your teaware is clean.