Coffee grinding and why it’s crucial for a perfect pour

As published in BeanScene Magazine

If you are a home barista looking to improve the quality of your brew, you will need to look at every stage of the coffee making process. While sourcing specialty beans from a gourmet roaster will ensure the best raw materials are at your fingertips, the perfect cup of coffee is a result of many different variables. 

Freshness is the key and has a huge impact on the end result, so cannot be compromised. The moment coffee beans are ground, their flavour begins to dissipate - a result of the oils inside the bean oxidising as they are exposed to air. This oxidation process is often referred to as “degassing” and results in flavour loss. Stale coffee grounds will produce a stale taste and affect consistency. They also won’t result in the much-adored crema. 

 So, while grinding of the beans may not sound like the most exciting part of the coffee making process, it is an essential step in producing the best possible cup of coffee. It is also worth mentioning that regardless of whether you use an espresso maker, plunger or percolator, grinding your beans at home as you go will make a big difference to the quality of your home brew.

 

Coffee grinders 101 

The science of coffee grinding has come a long way since the first coffee drinkers used the mortar and pestle, well before the advent of electricity. Thanks to the espresso revolution, today’s range of grinders is vast, with machines to suit a variety of needs and budgets. 

There are two distinct types of grinders: blade grinders that use a metal blade to chop up the beans and burr grinders, which crush the beans between a moving element and a still surface. 

 

Choosing the right grinder 

Blade grinders are more economical than burrs, but produce coffee grounds that are often uneven in size, which leads to an inconsistent brew quality. Blade grinders can also create “dust” which can clog up espresso machines and French presses. 

The other downside to blade grinders is that if you’re grinding finely – for espresso, for example – the friction produces heat, which can give your coffee a burnt taste. 

Burr grinders crush rather than chop the beans, so heating from friction is minimal. Importantly, the burrs produce coffee grinds that are much more uniform in size, which is better for consistency. The crushing action also has the effect of releasing the coffee’s oils which results in a richer and smoother tasting coffee. 

There are two types of burr grinders - flat and conical. Conical grinders will give you a more consistent particle size, plus a particle shape that is more conducive to extracting the flavours from the grounds. On the whole they are superior to flat grinders. Burr grinders come with a heftier price tag than blade grinders, but the extra dollars spent will translate to better coffee. 

So , it really does pay to buy the best you can afford. Ideally, look for a burr grinder that can be adjusted to make the grind very fine, which will enable you to produce a nice espresso, extracted correctly. Several companies make conical burr grinders designed for home use. A specialty coffee outlet will be able to provide guidance on selecting a grinder that suits your needs and budget. 

 

Making the most out of a grinder 

One of the benefits of grinding at home is the precision that can be achieved with grind fineness. Coffee absorbs moisture from the atmosphere, so humidity and temperature can affect the grind. A grind that’s suited to one environment won’t necessarily be ideal in another, so having a grinder at home will allow production of a grind that’s more precise. 

The fineness of grind strongly affects brewing and should match your brewing method for best results. Brewing methods that expose coffee grounds to heated water for longer, such as French press, require a coarser grind than espresso. Beans that are too finely ground for the brewing method in which they are used will expose too much surface area to the heated water, over-extracting the coffee and producing a harsh, bitter taste. 

If you’re using an espresso machine, an overly coarse grind will produce weak coffee. A guide to determine whether the grind is right, when making espresso, is that it should take 25 seconds to extract 25ml of coffee. Adjust the grind accordingly and in no time you’ll be brewing fresh and flavourful coffee at home every time. 

We cover the importance of grind in our Soft Brewing and Principles & Practice course - sign up today.