We’ve all been doing it wrong: the trick to a perfect cuppa Joe is to make it with *cold* water. Or at least, that’s what the prevailing trend among java junkies would seem to suggest.
Cold brew has been taking the coffee world by storm – but why is it so popular? And is it worth changing the coffee habits of a lifetime for?
The science
The popularity of cold brew coffee stems from the fact that it is less acidic and bitter than a standard cup. This not only makes it delicious: it also makes it an excellent choice for people who find normal stuff upsets their stomach or gives them heartburn.
The difference in flavour profile is due to the way the soluble acids and oils which are extracted from ground coffee beans during the brewing process. When using boiling or near boiling water these molecules undergo much higher rates of oxidation. Chlorogenic acid in the bean degrades into quinic or cafeic acid, which gives standard coffee its sour and bitter notes.
By steeping coffee in cold water over several hours much less oxidation occurs leaving you with a brew that has a much smoother, sweeter taste than the normal cup but still retains all the aromas and caffeine-kick you crave from a mug of the good stuff.
How to make it
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First you will need a container to brew your coffee in – a large glass mason jar like one of these is perfect. Sterilize the jar by boiling it in water for a good ten minutes before you begin. This this removes any bacteria/fungi in the jar and ensures the coffee stays fresh for longer.
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Then you want to grind yourself some coffee beans – you can’t really use pre-ground stuff for this as you need to grind your coffee very coarsely. Grind the beans too fine and the finished product will lend up a bit silty: no matter how much you filter it. You want to end up with a grain size somewhere between sea salt granules and peppercorns.
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Next, mix 2.5 cups of ground coffee with 7.5 cups water inside the mason jar. This will make slightly less than 2 litres of cold coffee concentrate, which is mixed with equal parts water to drink. This ratio will make you around four litres of coffee overall. Use spring water or filtered water to make your coffee. The majority of tap water usually has quite high levels of dissolved solids in it. Unless you live an area with the perfect tap water, it will be is sub-optimal for brewing coffee, especially when using this super slow-brew method.
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Seal the jar and place it in the fridge – leave it to brew for 18-24 hours, then open the jar and drain the coffee through a fine sieve or some muslin cloth into a jug. This will remove the large grounds.
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Now pour the contents of the jug back through a sieve which has been lined with a standard drip filter coffee paper. This will remove any finer powdery bits of coffee that escaped the first filter.
How to drink it
Mix the coffee half and half with water or milk to serve. Add ice to taste if that’s your bag.
The finished product is quite stable and you can serve it hot without it taking on a bitter or acidic flavour. Just warm the coffee concentrate in a pan and add it to a mug with either hot water or warm milk to taste.
Thanks to its low acidity the cold brew will last much longer than normal coffee until it turns. Once made, you can keep it in your fridge for up to 28 days.
Cold filter makers – worth it?
There are a plethora of cold brew coffee makers on the market – although as outlined above you don’t need to own one to make cold brew. However, if you are going to have to buy a mason jar and coffee filters before you can mix up your own, you might decide it is just as convenient to buy your own.
Obviously these machines make the process simpler and cleaner as there is no need to double filter the final product. They also take out some of the leg work by setting the ratio of coffee to water for you.
This means you can have cold brew on the go all the time, and with very little fuss – however it does mean that you no longer have so much control over the ratio of coffee to water in your brew.
Whatever you choose to do, give the cold stuff a try – its sweet, aromatic charm is a must-try for any coffee fanatic.