Milk can make or break your coffee. Good milk gives your coffee that velvety texture and takes the edge off any residual bitterness. Bad milk makes the coffee appear thermonuclear – have you ever had one of those takeaway coffees that seems to get hotter rather than colder in your hand?
The key to a great milk based coffee (and to latte art) is steaming the milk properly, or if you’re heating milk for your plunger coffee or stovetop – not overheating it.
When you’re steaming milk using an espresso machine there are a couple of things to watch out for. Firstly, you don’t want to boil or overheat your milk. Milk is best at somewhere between 55 and 65 degrees. After 65 degrees the sugars and proteins in the milk start to break down and you end up with sour, burnt tasting flavours. A good rule of thumb (literally) is to put your thumb against the side of the jug as you steam the milk. When it gets too hot to hold your hand against for more than a second or two (and this obviously depends on how tough your hands are – so you might need to experiment) it’s just right. You can buy a milk thermometer, which is a worthwhile investment until you get a feel for what temperature you’re after. It’s also worth remembering that your milk will actually continue to heat up for a little while after you stop frothing it (before it begins to cool down). So stop a little bit below your target if you’re using a thermometer.
The other factor in good milk is texture. Good milk is like silk. It moves as a cohesive unit and has a nice glossy finish. Silky milk, also called microfoam, is what separates good coffee from bad. To get microfoam you need to manage the way air is injected into your milk by your steam wand. Your goal is to merge the milk and the air seamlessly. If you stick the wand too deep or two shallow it’ll blow air into your milk in a disruptive way – giving big bubbles. What you want is a whirlpool effect in your jug (some home machines can’t get a whirlpool – you might need a smaller jug, or just to focus on motion in the jug not just stagnant milk with bubbles forming). Tipping the jug on an angle towards the steam wand and holding the tip of the wand just below the surface of the milk is a good way to get a whirlpool happening. If your milk screams like you’re killing it you probably are.
Mastering milk will dramatically improve your coffee.
Some tips for getting your milk right:
- Practice getting the motion in your jug right using water – it’s cheaper than milk and moves in the same way.
- Don’t overfill your jug – you want your milk’s volume to expand by about 50% and you want enough room in the jug to manoeuvre its position to get the motion right.
- Get a feel for the temperature you’re aiming for – the thermometer is handy to begin with, but it will interfere slightly in your attempt to get a whirlpool motion happening.
- Don’t burn your milk – smell a batch of burnt milk to know what it is you’re trying to avoid.