Edinburgh's independent student newspaper

Barista at home: how science can fuel your caffeine addiction

Sunday 21st February 10.12

We are all going to have to become better baristas in our own homes. Changes to Edinburgh lockdown restrictions from the 16th January have dealt another blow to our finest coffee shops. No longer will you be able to pick up your coffee in the shop – now it must be delivered to your home. For lots of us, that is a stretch too far. My coffee is important, but the idea of it arriving to me on the back of a moped is silly.


Don’t get me wrong: instant coffee is great. It does what it says on the jar and does not pretend to be something more special than it is. However, it is not going to cut it for achieving our desired coffee shop vibe. With some science to guide us, we’re going to get as close as possible with a home brew. The first big toss up is between light and dark roasts. Want a flavourful, mild coffee which smells lovely? A light roast is for you. Want something that tastes stronger and more bitter? A dark roast is what you should be looking for.

A common misconception is that because dark roasts taste stronger they are stronger. This is incorrect. The roasting process breaks down some of the caffeine, meaning that it isn’t going to give you the same kick. Good for drinking in the mid-afternoon, worse for keeping you awake for your third hour of zoom tutorials.


The next step is to grind those beans. Beware: science ahead. The fineness of your bean powder dictates how strong your final brew will be, especially if you are making filter coffee or brewing by a similar method. Fine powder imparts more flavour (and caffeine). Not only does it have a larger surface area for coffee-water diffusion, but its sand-like nature forms something like an impenetrable wall of coffee sediment, increasing the amount of time that it takes for water to pass through. More time interacting with the grounds means stronger coffee.

Want a tip that will make your coffee game even better? Never use boiling water straight out of the kettle. Too hot and the water will be too good at extracting the oils and flavours of the coffee and you’ll be left with a bitter mess. Let it cool and then brew your mug of brain juice (don’t leave it too long though, otherwise the only thing that you will accomplish is gently washing your grounds, and nobody wants that). The science says that the ideal temperature range is between 90oC-95oC.


Once you’ve brewed your coffee, the real creativity comes in. What kind of coffee are you going to concoct? A latte, with plentiful milk and a light taste? Or an Americano with only a splash? Check out the graph for a rough idea of the ratios behind some of our favourites. You’re on your own from here on out - becoming a barista takes practice and patience. Science can’t help you with that.

Image: Nicholas Bush