James Hoffmann - How to make the best coffee at home

Youll hear over and over again that a great cup of coffee cant exist without great raw materials. All the technique and equipment in the world cant overcome the limitations of the coffee you are brewing. However, there is no real arbiter of what is good. There are definitions of speciality coffee that exist, but that doesnt mean that people should aspire to all like the same kinds of coffee. The joy of coffee, once you dig into it, is the diversity of flavour.

The speciality coffee industry ran into a bit of a wall in its early years by telling people that they should drink better coffee. People, quite rightly, didnt like the inference that what they had been buying, drinking and enjoying just fine thank you very much was inferior.

Yet here I am, about to make a similar case but with some caveats. I would argue that whatever you enjoy right now, theres probably something out there that youd enjoy even more and that a little exploration will be incredibly rewarding and, frankly, surprisingly fun. This chapter aims to break apart the process of buying coffee so that you can explore risk free. I dont like the idea of someone trying something different to their usual choice and hating it. I think this can be avoided, and we can also remove a few of the myths and misconceptions that exist around the coffee-buying experience.

One of the great successes of coffees marketing has been the idea that fresher is better.

You see fresh ground coffee or freshly brewed coffee everywhere, and actually shifting the mindset for many people so that they see coffee as fresh produce, not a shelf-stable staple, is good news. Coffee degrades relatively slowly compared to other fresh produce, and you could argue that because it is safe to drink at a couple of years old, then it really is a shelf-stable product. If you want the best value for money, then drinking your coffee while fresh is a real win. Before I talk about how long coffee lasts, I should briefly discuss the ways in which coffee goes stale.

Loss of volatiles: By volatiles, Im talking about volatile aromatic compounds, the compounds assessed and enjoyed by your olfactory bulb, experienced as aroma or flavour. As coffee ages, a significant quantity of its flavours literally escape the beans or the grounds, often into the atmosphere. This is possible to slow with better packaging but youll always lose nuance, flavour and delight over time.

Development of new/bad flavours: The compounds in coffee that you taste and enjoy are, sadly, not inert. Over time they react with each other and begin to form new compounds. Not always, but often, these are less enjoyable than the ones you started with.

Rancidification: Coffee contains lipids in the form of fats or oils, and these are susceptible to turning rancid. It might be oxygen causing oxidation or it might be moisture leading to the breakdown of the fats. Either way, this pretty quickly causes some unpleasant and undesirable flavours to appear. Darker roasts have more of the oils pushed to the surface of the coffee bean, meaning theyre more likely to interact with any air or moisture present, so these develop rancid flavours more quickly.

Im going to add one more here, even though this doesnt strongly correlate to negative flavours, because it is worth understanding before continuing the discussion of freshness.

Degassing: During the coffee-roasting process, a host of chemical reactions are going on which result in the coffee turning brown and a lot of the flavours we love being created. A by-product of all this is carbon dioxide (CO2). A lot of it, if were talking volume. One kilogramme of coffee produces about 10 litres of carbon dioxide in the roasting process. Most of this escapes during the roast, and what is retained in the coffee bean at the end of the roast still does a pretty good job of escaping in the first few hours after roasting.

Compared to what you started with, relatively little is retained by the beans by the time theyre packaged but, and this is an important but, theres still enough to have a significant impact on the way that the coffee brews.

For this reason, coffee can be too fresh, especially if you plan to use it in an espresso machine. When you brew coffee, water coming into contact with the ground coffee seems from the grounds. If a lot of CO2 is coming out of the grounds, then it is harder for the water to extract the coffee. A frustrating truth of coffee (and there are several in this book) is that the staler coffee gets, the easier it is to brew and extract. Though, of course, the staler the coffee gets, the worse your resulting cup will taste.

The shift to e-commerce in coffee has set the expectation that a coffee company roasts and ships to order. Coupled with wider e-commerce shortening delivery time expectations, this means that most coffee bought online arrives too fresh. For the best experience, you should wait often termed resting the coffee. How long should you wait? How long is the window of goodness before the stale flavours kick in?