The Reason Why Your Butter is Yellow!

Have you ever thought to yourself, “Why is my butter yellow?” Well, probably not, because like me you’re simply thinking of eating the butter. Today, I want to take you on a journey that will entice you, surprise you and provide you with a very simple, yet interesting scientific explanation for a very unpopular question.

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Photo by Megumi Nachev on Unsplash

How is butter made?

Imagine a time where nomads would travel long distances with large sacks of milk. Here lie the origins of butter. It is said that during one of these long and tiresome journeys, a thirsty traveller reached for their bag, only to find that the milk inside had churned into butter. Thankfully, in this day and age, we need not suffer a long pilgrimage to obtain this god-gifted, heavenly chunk of fat!

To produce butter at home, heavy whipping cream or double cream can be whipped in a food processor. The cream will change in physical appearance as follows: sloshy, frothy and followed by whipped cream (soft, firm, then course). Suddenly, the cream will lose its smooth shape and collapse. At this stage, the droplets of butter disperse throughout the buttermilk, which can be separated using a cheesecloth or strainer.

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Photo by Eiliv-Sonas Aceron on Unsplash

The industrial method of making butter is a bit more complex and requires several steps, which I won’t dive into for this article. However, some of the standard steps include:

  1. Standardising the cream so that it is 35 to 40% fat.
  2. Pasteurising (heating to 82–110 ˚C for 10–30 seconds) to kill bacteria.
  3. Cooling and ageing 5–10 ˚C for 24 hours.
  4. Churning.
  5. Salting and churning again.
  6. Packaging and storage.

Here is a great visual guide on how butter is made.

So why is butter yellow?

Before this becomes a recipe on “how to successfully make butter at home”, it is time we discuss the colour of butter. After all, that is what you have come here for, right?

Would you believe me if I told you that good old Bessie is the one deciding the colour of your butter? Butter can range from vibrant yellow to pale white depending on the feed and breed of the cow that the milk originated from. The intensity of yellow depends on a special vitamin called Beta-carotene (β-Carotene). β-Carotene is a natural vitamin found in cows milk. Now you must be thinking “well, hey that’s cool, but if butter derives from milk, then why is milk not yellow?” Ah-ha! Now here is where the fun part begins.

According to Sophie Egan, milk is white because its fat is surrounded by a thin membrane which hides the β-Carotene pigment. As a result, when light refracts off the membrane our eyes perceive the milk to be white. A fun and simple experiment to conduct at home is to freeze a bottle of milk overnight. The next day you should notice a change in colour. Milk is an emulsion or in other words a uniform mixture of protein, fats and water. Therefore, freezing milk forms big chunky ice crystals that separate proteins and fats out of the mixture. The yellowness is because you are looking at all the fats in clusters. Once left at room temperature, you will notice it returns to its normal colour. Go ahead, give it a try, I promise that the milk will taste as good as new.

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Photo by Sorin Gheorghita on Unsplash

I hope this read was informative and if nothing else, at least now you know the “why” behind the colour of butter. I guess butter late than never, right?

Written by

Part-time food scientist and full-time foodie — Piecing together the disconnect of food, health and well-being.

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