Blog BY Staff | 30 March 2020
Why is Milk White?
Have you ever wondered why food is the colour it is? When we think of white food we generally think of milk, sugar or rice. Milk - being a crispy white tone in its original form that provides us with valuable nutrients that help keep us strong and healthy as we grow.
How does light and colour work with food? Visible light is explained as having wavelengths in a range of 400-700 nanometers. Each wavelength is a particular colour and the colours we see are based on the wavelengths reflected back to our eyes. The main source of light on earth is the sun, which helps provide the ultraviolet wavelengths. Generally, items appear white due to the light wavelengths they reflect, and they absorb none. If all wavelengths of light were absorbed by items and not reflected back, they will appear black.
Colour in food is primarily made up of 3 main pigments. Carotenoids which give the orange and yellow hue, flavonoids providing blue, red and cream colours and then chlorophyll which gives us the green variations. These colours help give food not only their pigment but also nutrients.
Milk is primarily made of water and has roughly 3-6% fat in whole milk. Fat globules do generally have a yellow pigment that is created by carotene. But these fat globules are lined with a thin membrane which hides the yellow pigment from coming through. And it is this membrane that blocks light absorption and gives a white colour and appearance. Casein in milk is also known to reflect wide ranges of wavelengths which help give liquid milk its clean white colour.
As we have different types of milk, any adjustments we make will alter the wavelengths of light and therefore alter the colour slightly. This is why skim milk can sometimes have a very slight blue tinge due to certain properties that have been removed. It is even suggested that the diet of the animal can play a role in the colour of the milk. For example, if the cow’s milk is high in carotene foods such as carrots or pumpkins, it can add a slight colour hue to the final product.
So as much as food has colour pigments and undertones light will play a role in the final colour we see and key thing to remember is that those colours generally provide us with loads of nutrients and always best to have a rainbow on your plate to keep you healthy.