Does loose leaf tea go off?
Short answer: dry tea does not go off in the way that makes you ill, it goes stale. The leaf is dried to a few percent moisture, which is why it has been shipped round the world for centuries without a fridge. What happens over time is that it loses aroma and gets flat. Here is what that means for the pouch in your cupboard.
What the best before date means
Our pouches carry a best before date two years from the day they were packed. That is a quality date, not a safety date. Tea drunk after it will not harm you, it just may not taste as lively as it did. Compare that with a use by date on fresh food, which is about safety and should be respected.
How long each type keeps its best
Black teas keep best. A sealed pouch of Scottish Breakfast, Assam or Earl Grey will be in good shape for two years and drinkable well beyond that. Oolong and pu-erh are the same, and pu-erh is often said to improve with age.
Green and white teas fade fastest. Sencha, Jasmine, Gunpowder and Pai Mu Tan are at their brightest in the first six to twelve months. After that they are still fine, just softer.
Herbals and fruit teas sit in the middle. Rooibos, honeybush and nettle keep well for a year or two. Peppermint, chamomile and lavender rely on volatile oils for their flavour, so they are best within a year of opening.
Flavoured teas like Caramel and Chocolate Mint lose the added flavour before the base tea fades, so drink those within a year of opening for the full effect.
How to tell if tea is past its best
Open the pouch and smell it. Fresh tea smells of something. Stale tea smells of very little. If the leaf smells musty or damp, it has been stored wet and should go in the compost, but that is rare and usually means the pouch was left open somewhere steamy. The brewed cup from stale leaf is thin and dull rather than nasty.
If a tea is a bit tired, use a little more leaf and brew a minute longer. It will not bring back what is gone, but it gets a better cup out of what is left.
Opened pouch versus sealed
The clock really starts when you open the pouch. Once air gets in, the leaf starts to lose aroma. Reseal the pouch properly after each use, keep it out of the light and away from the kettle, and a 100g pouch drunk over two or three months will stay fresh all the way through. If you buy a 500g bag, decant a small amount into a caddy for daily use and keep the big bag sealed.
Can old tea make you ill
Dry tea that has been kept dry, no. The only tea to avoid is tea that has got wet and grown mould, and you will see and smell that. Brewed tea left in a cup or a pot is a different matter. Drink it within the day.