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Why does coffee taste like it does?

An often misunderstood aspect of coffee is describing how it tastes. That's because so much goes into it. People turn up their noses at coffee snobs and say 'coffee just tastes like coffee'. Or something vague like 'I like my lattes smooth, and not bitter.'

These are fine. But there's four steps to separate out when you think about how coffee tastes. Let's assume your'e drinking it black.

Some common views that can be improved upon:

"I like my coffee strong" 

"I like my lattes smooth, and not bitter."

"This tastes like tea, not like coffee. It's good but I like coffee that tastes like coffee."

A coffee farm near Pereira, Colombia

1. The Green Bean: What does the underlying bean taste like?

This is what a coffee buyer does. It's kind of a dream job. The buyer goes from farm to farm (stunning places, high up in the mountains in tropical climates with even temperatures of 24-28 all year around and acceptable humidity), testing coffees. Tasting coffee is a meticulous, scientific process that follows a standardised methodology and allows a taster to compare different lots, crops, farms, varietals, seasons and many other variables. It's complicated. But a good buyer can see through the noise and through many cuppings to find those rare gems that when brewed well can really shine, either alone or with milk.

A unique 25kg fluid air bed roaster in Brisbane, Australia

2. The Roast: How was it done?

How a bean has been roasted can greatly impact its flavour. You think roasting is just putting the beans in an oven and waiting? Think again. It's a complicated dance of temperatures, and air movement over time. Batch size matters. You can roast in small batches 100g a time at home, or in 15KG huge gas-fired roasting machines. Time matters too. You can roast something fast, slowly, or some variable in between (or more usually, a graduated curve that moves up and down temperature over time). You can roast something light, medium or dark (or many other gradations along the way, described using the final temperature, the suitability for different styles of coffee or to what 'crack' it was roasted). Another thing that impacts is what machine was used to roast. There are many kinds of roasters on the market, with different grades of gas roaster and an emerging trend to use large-scale fluid air-bed roasters. 

The most complex part: The roast process has to take into account the green bean and what it's best suited to, as well as how it's going to be brewed. In other words, this middle step is intrinsically linked to the first and last. Separate them and you'll get an imperfect drink.

A Clever coffee dripper and a V60 in the background

3. How has the coffee been brewed, and what can you expect from this brew process?

There's many ways to brew coffee. Most of us are familiar with traditional 'drip' or with espresso drinks (lattes and so on). There are a few master categories of coffee extraction, including immersion, pour-through and pressurised. Under these categories there are MANY sub-categories of brew. Pressurised includes of course espresso, as well as Aeropress and some mechanised processes like machines made by Bunn, Alpha Dominche and others. Pour-through includes v60s, Melitta brewers and many other similar devices. Immersion brews include the french press, the Able Clever Coffee Dripper and many others. All of these produce a unique flavour profile that isn't easily replicated using other methods.

A second thing to consider is what exact recipe was used. You can alter many variables including water:coffee ratios, water temperature, dwell time, grind distribution, agitation methods and many other variables. All of these distinctly impact a cup and are the subject of much study.

4. Has the coffee been extracted correctly?

This is where the magic happens and where the rubber hits the road. Matt Perger did a terrific post on this on his new blog Barista Hustle. Extraction can be quantified in two main ways: total dissolved solids (TDS) and brew strength. The TDS measures the proportion of the coffee solids that have been dissolved in the water. The rough target is 18-22%. If you get less than this you'll end up with underextraction: sour, lacking in sweetness and with too quick a finish. Extract too much and you get (surprise) over-extraction: a bitter, hollow and astringent flavour that unfortunately many associate with coffee. The sweet spot, naturally, is somewhere in the middle. Over time, you will learn to appreciate what properly extracted coffee can be: basically, you'll be able to taste the coffee

As to what leads to good extraction - great question, and basically the subject of many posts in this blog. Stay tuned.