So here is what Roland has to say….
Adding coffee to beers has become pretty common among both professional and homebrewers, but it’s also been done in lots of different ways. I’m a homebrewer as well as a Coffee Roaster, so I’ve had the chance to try lots of different ideas and to see how some different professional brewers have approached it. This article is intended to give some tips on the different options available and the benefits of each one.
What kind of coffee flavour do you want?
Coffee doesn’t all taste the same, so you need to decide what flavour elements you’re after. Some of the main ones are – Roasty, Chocolate/sweet, Fruity/acidic, spicy & earthy. Your choice of coffee and how you add it will determine what balance you get of these, so you need to think how it will fit with the beer you want to brew – these days it isn’t just Imperial Stouts with coffee in, there are kettle sours, IPAs, mixed fermentations and many more using coffee.
As a coffee lover I’ll have to deny this later, but if what you want is a light touch of generic “coffee” in the background, Instant might be the best bet. The main advantages are that it’s simple, easy to add as little or much as you want and very consistent. It’s fundamentally coffee artificially flavoured as coffee, so it’s an easy and cheap source compared to using other artificial flavourings.
The most common method of using coffee for professional breweries is “cold beaning” – adding coffee (either whole bean or ground) into the fermenter as you would a dry hop. This type of addition is very efficient – a dose of between 5-10g/L left for a few days will give a distinct coffee flavour. Whole beans are a little easier to deal with in the fermenter, but will extract more slowly than ground coffee. Cold extraction typically favours a more generic “coffee” flavour over fruity, spicy and earthy flavours.
Rarely used by pro-brewers because of the amount of it they’d need to do for each brew, the advantage here is control. Buy a cafetière, brew coffee, let it cool then add to taste to the beer pre-packaging. The biggest downside is that you dilute the beer with potentially a lot of extra water, so you need to plan this into your recipe.
Another rarity among professional brewers, this is halfway between the cafetière and cold beaning – it adds extra water – but not a lot – and it gives more control – but not a lot. It’s also a LOT of hassle for most people.
Ground coffee is brewed in the hot wort before cold crashing. This extracts more of the fruity flavours, but requires a much larger dose as contact time is a lot less (plan for 20-30g/L). This is done before fermentation, so the other downside is that CO2 release during fermentation will blow off more of the coffee flavours too – this is a very inefficient option.
Choice of Beans
Look for the flavours you want and remember they can’t be too bold – if you want fruity, make sure you get the most acidic coffee you can, for example. There are some general rules of good coffee buying – freshly roasted and freshly ground will always give more flavour. For good coffee, the first month or so after roasting will have loads of flavour to give, but after that the bits that aren’t “coffee flavour” will start to drop off.
Naturally Big Flavour
One group of flavours many people may not have come across is “Natural Processed”. Coffee starts it’s journey to our mugs as the fruit of a tree and at some point, the seed – the coffee bean – has to have the fruit flesh removed. It can be done in many ways, but the Natural Processed style is to leave the fruit in the sun until you have something like a raisin around the bean. This is important for us, because it will tend to give the bean flavours like fermented fruit, booziness and dried fruit. Those are bold flavours which will help carry though well into your beer.
Just like hops, coffee flavour (especially the non-generic parts of it) are made up of volatile aromatics, which you’ll loose over time. This is particularly obvious with pale beers where the malts don’t add any coffee-like flavours – try a bottle freshly brewed and one after a year and you’ll see a substantial decrease.