When you make espresso with beans which are less than two days out of the roaster, they haven’t had time to stabilise properly. The essence of the problem is this – young beans have way too much carbon dioxide gas (CO2) in them to make a truly exceptional espresso. You get a poor extraction as the sheer volume of gas overcomes some of the hot water before it can get to the coffee – you also get as a strange biscuity flavour. It’s just not espresso perfection.

However, it’s not just young beans which can get in the way of the ultimate espresso. With darker roasts, fats (or lipids) are forced to the bean’s surface. These fats don’t like contact with oxygen, so as the beans age, they take on a nasty, fishy taste. Think bitter smokeyness. White-coat types call this process “peroxidation”. We just call it nasty.

Then there’s the crema. As most of the crema-assisting CO2 has
left the beans after 21 days, you’re not going to get the ultimate presentation or mouthfeel either. So fresh (but not too fresh) is good. But it’s not quite as simple as that.

Look at your espresso as it leaves the portafilter. It should look like our cover picture. A rich thick honey like syrup which pulses from the portafilter during extraction. This type of sweet spot perfection can only be achieved in the window of time between Day 2 and 21 of roasting.

We’re now putting our taste panel to the freshness test – plotting the subtle changes in taste as coffee gets older. There are even plans to take a more in-depth look at the chemistry of bean aging – something that’s never been done before.

In the meantime, we’re doing something about the way coffee
is roasted, blended, packaged and delivered. So that you can serve up coffee fresher than a north-westerly in December.

This article originally appeared in Fresh 13