Why is coffee not steeped in tea bags?

Question

Brewing coffee and steeping tea seem to be the same process: soluble molecules of coffee/tea are dissolved into hot water and the solid insoluble parts are filtered out by my understanding. So why can’t coffee come in tea bags so that it would be easier to make a singular cup? Or inversely, why is hot water not percolated over tea like making a pot of coffee?

In: Chemistry

Answer 1

The process is similar, but the actual flavours are very different, chemically speaking.

First thing to consider is unpleasant flavour. Black Tea (the most common tea in European / Anglo) cultures is fermented as part of the processing. This fermentation removes most of the unpleasant flavours from tea. Coffee is not fermented, and the unpleasant flavours remain in the beans. This means coffee needs carefully controlled brewing to avoid getting the unpleasant flavours in the cup.

Second thing to consider is volatile flavours. These are flavours that evaporate out of the tea/coffee while it is being stored. These flavours are typically sweet, floral or chocolatey. The fermentation of tea removes a lot of the volatiles during processing. Super fresh and high quality tea will have some volatiles contributing to the flavour, but even then, they aren’t the main flavour. The main desirable flavour of tea is the much less volatile tannins (ie woody, vegetable flavours). As tannins don’t evaporate so quickly, you can store tea in a ready to brew state for a long time, and while you lose some minor flavours, the main flavour sticks around.

For coffee, virtually all the desirable flavours are volatile. Meaning that once the coffee is prepared for brewing (by grinding) you have a very short shot of time before all the desirable flavours have simply evaporated away. For this reason, coffee is transported unroasted, and stored unground.

Put together, a tea bag works because you can store prepared tea a long time and brew it carelessly and still get a drink that is 90%. Store ground coffee then brew it carelessly and you’ll lose 90% of what it is supposed to be.