Espresso Joe and the Milk in Your Coffee   18 Dec 2010

Milk can make or break your coffee experience. Here’s why.

Joseph Hoye

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Holy Moo Juice, Batman. I never knew it was about the chemistry.

Why does cow’s milk make coffee taste even better than it already does? Like love, it’s all about the chemistry!

A lot of it has to do with lactose, which is not good news for the lactose intolerant.

Lactose is a sugar, in this case a combination of galactose and glucose. For the science geeks out there, it’s C₁₂ H₂₂ O₁₁.

Sugar is soluble - it dissolves in water. More so when it has been heated. Thus, heating milk is going to make it taste sweeter.

• Milk – naturally sweet.
• Hot milk – naturally sweeter.

Milk also contains various levels of fat. And fat is a flavour carrier. It's the troop transporter of the culinary world. If you are truly worried about calorie counting, stick to espresso or non-fat milk. If your coffee drinking is all about having the most pleasurable experience possible, don’t quibble over full fat milk. At 4%, it won’t harm you if you’re eating and exercising well.

Milk also lends itself to foaming – think of a cappuccino style coffee. This foaming is due to the protein in milk. Remember your mother/teacher telling you milk is a food? That’s due to the protein. Basically, when you steam the milk with an espresso wand, hot air is trapped inside coatings of protein. Bubbles, in other words.

Now, the protein and the fat have a tendency to slug things out. Lower fat will give you easier foaming ability while higher fat will give you a rapturous taste experience.

• More fat – less foam – more taste

A good barista will be able to extract foam from just about any cow’s milk. Test your local café and see if the coffee maker can get decent foam from full strength milk.

Always make sure your barista is making your latte, flat white or cappuccino from scratch – with fresh, cold milk.

Why?

As milk is heated up, the proteins change shape. Remember, it was the proteins that allowed the foaming to take place. If the proteins have changed shape once through heating, they won’t change back by leaving the milk to cool. It’s a one-way, one-time process.

If you suspect your coffee professional is reusing warmed milk, ask for the fresh moo juice. It will taste much better and after all, you’re the one paying for it.

So milk is all about converting an already glorious espresso coffee into a sensual delight for your taste buds. Natural sweetness, flavour and tiny explosions of warm air are awaiting you in your next latte, flat white or cappuccino. And now you know why. Enjoy!

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