How to Make Cold Brew

What exactly is cold brew coffee?
Not to be confused with iced coffee, cold brew coffee is a type of brewing method that significantly alters the taste of coffee when compared to its usual flavours when brewed with heat. Iced coffee often has connotations of added sweeteners and extravagant toppings, but cold brew coffee couldn’t be further from this. Although it has only just become a popular choice in cafes, it’s a method that has been around for a long time. The Japanese were even using cold brew methods in the 17th Century!
Cold brew coffee tends to be brewed using room temperature water, but can be brewed using colder temperature water too. The science behind cold brew coffee is to avoid higher concentrations of certain flavours and compounds that are released during high temperature brewing. This completely alters the balance of flavours in the final product. Keeping everything controlled, in a blind taste test side-by-side of the hot brew and cold brew of the same coffee, (using the same recipe, same water, same dose, brewing to the exact same strength and using the same filtration etc) it is difficult to even recognise that the two products are made with the same ingredients, let alone the same recipe.
Heat in chemical reactions and processes is often used as a catalyst to speed things up. That is precisely what it does in coffee brewing, allowing water to ‘do its work’ quicker than it would at room temperature or lower. You can look at coffee brewing as a process of dissolving flavours into water, the same process that occurs when you brew with a teabag or loose leaf tea. The process can be done without heat aiding it, but it simply takes much, much longer. The slow version of the process without heat is what is going on with cold brew. A good starting point for anyone keen to try it out is outlined below.
Essentially the basic process can be as simple as making a cafetiere, but without heat. All you do is leave it for 12-18 hours then filter it using your preferred paper coffee filters! We certainly urge any consumer to do this using any glass carafe / Chemex / French Press (cafetiere) that they have at home. It is so simple yet can be a delicious way to try coffee you already have, without the need to buy any more equipment!
Depending on what you want to get out of the coffee you are brewing (for example more or less flavour in a trial and error kind of process), the cold brewing process could end up taking you up to 24 hours to ensure your brewing extracts all the desirable flavour, while hopefully leaving behind unwanted compounds. Usually, cold brewed coffees taste a little less acidic, or at least less sharp than their hot brewed counterpart would. It certainly seems that cold brewing yields a typically less intense, wild flavour than is found with hot brewed coffee.
In cold brew you will typically find lower bitterness too, given that it would take a very long time to extract as many bitter compounds as can easily be drawn from beans when heat is used. It simply takes longer to get to all flavours, which already come out in a ‘queue’ so to speak. Bitter compounds will consequently not be drawn from the coffee used until brewing time extends past your likely ‘desirable’ range (which may of course be subjective according to taste preferences). Some may enjoy a slightly bitter brew, even using the cold brew method. If so, brew longer than those who enjoy either ‘fruitier’ or ‘weaker’ coffee usually. The same goes for hot brews too actually. If you like bitterness, brew for longer. If you don’t, brew for less time than those who prefer more bitterness.