3 reasons why your pre-ground coffee tastes so bad

It’s common street knowledge that coffee tastes better when the beans are freshly roasted – but did you know coffee tastes better by grinding only what you need, when you need it? 

Before we delve any deeper into why you should avoid pre-ground coffee, lets talk about why we need to grind coffee in the first place. 

In whole bean form, coffee isn’t very soluble. Try this little experiment yourself, put a few whole beans into boiling water. You’ll see there wasn’t much change in the water. It’ll remain fairly clear, an indication that virtually no flavour compounds ended up in the water. Taste it to confirm. 

All of the flavours and aromatics we want is trapped inside the cell walls. To release all the magic, we need to crack these walls open to allow the water to do its thing – and that is to dissolve all of the wonderful flavours inside. However, if you’re buying pre-ground coffee, you’re on the back foot when it comes to quality. 

Here’s three reasons why grinding your coffee fresh is always better. 

1 - grinding coffee releases volatile aromatics

 When you grind a single coffee bean, you turn that one bean into many thousands of small bits of coffee. Cracking open those cell walls releases a lot of volatile aromatics which is why freshly ground coffee smells so darn good! 

If you’re not brewing your coffee within minutes of the coffee being ground, those lovely volatiles float off into the environment, never to be found again. Rather than letting them float off into the environment, you want to capture them during the brewing process. 

Fun fact – the smell of ground coffee before water is introduced is called fragrance in the coffee world! It is only referred to as aroma once the grounds have been wet.

grinding coffee into a paper filter

2 - grinding coffee speeds up staling

Coffee stays fresher in whole bean form – why cut an apple today if you want to eat it 5 days from now? If you did, that apple would have turned brown and lost a lot of its quality. 

The browning is caused by oxidation – the same thing that makes metal rust and what makes your food spoil. Grinding coffee exponentially increases the coffee’s surface area, which gives oxygen more access to the coffee, therefore causing it to stale much faster. 

Oxidation is obviously bad and also makes your coffee taste bad. So if your coffee has lost a lot of its nuance and flavour over time, it’s likely the coffee has gone stale. Even worse is if the oxidation causes the fats in the coffee to go rancid – yuck! 

3 - grinding coffee fresh allows you to control extraction

If you’ve been to one of our barista courses, you’ll know that extraction (how much flavour you pull out from the grinds) and strength are directly correlated to grind size. 

In any percolation method of brewing such as espresso or drip filter, the fineness or coarseness of the grinds is the main culprit behind extraction times – how fast or slow the water can pass through the coffee bed. 

If you are using pre-ground coffee, you have no ability to regulate the flow-rate of water through the coffee and therefore how much flavour you dissolve (or leave behind in the grinds). 

You can think of grind coarseness and fineness like passing water through rocks or sand. 

Water will flow through the rocks at a faster rate due to larger spaces between each rock. Similarly, passing water through the same mass of sand will take longer as the gap size between the grains of sand is much smaller, slowing the water down. This is an overly simplified analogy, but it illustrates the impact of grind size on extraction times, and therefore how much flavour you’re likely to end up with in your cup.

So, those are three reasons why pre-ground coffee makes your coffee taste bad. In the age of countless lockdowns, investing in a good burr grinder for home will allow you to brew the freshest and best tasting coffee possible!

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