[Reading Science] Should Milk Be Shaken Before Drinking?

There are various types of milk sold on the market. Is it true that the way you drink milk varies depending on which nutrients have been added?
[Photo by YouTube screen capture]

[Asia Economy Reporter Kim Jonghwa] How do you drink beverages? When drinking juice or instant coffee in a transparent container, if sediment has settled at the bottom, you must shake it well before drinking to evenly mix the sediment.

How do you usually drink milk that you enjoy daily? Milk in small paper cartons is typically shaken out of habit before drinking. But how about milk in large containers over 1 liter? Generally, people pour it into a cup and drink it without shaking.

Milk contains over 100 nutritional components such as fat, protein, carbohydrates, minerals, and vitamins. Since boiling milk destroys heat-sensitive nutrients like vitamins and minerals, it is usually consumed cold, kept refrigerated.

When you pour milk into a cup and look at it, these nutrients appear to be evenly dissolved. However, in reality, they are not dissolved but surrounded by water molecules.

These nutrients are broken down into very small particles that are evenly dispersed, so visually you cannot see these particles, nor can you distinguish them by taste. This is why some scientists suggest drinking milk as if chewing it. Sometimes, people feel indigestion after drinking milk because of these finely clumped particles. Even though you don’t feel like chewing, breaking down these small particles helps you enjoy a richer flavor.

Because the particles are so small, they cannot be separated even with filter paper. This liquid state is called a colloid. Milk appears white because the fat and protein particles inside reflect light, and the combined wavelengths create the white color.

Among the nutrients in milk, fat, which contains oil, has a lower density than water. On the other hand, proteins and minerals have a higher density than water. Therefore, if milk is left standing, the denser proteins and minerals settle at the bottom, while the less dense fat rises to the top. It’s similar to how oil floats on water.

Nowadays, even if you don’t shake milk before drinking, this sedimentation phenomenon is less noticeable, so the taste between the top and bottom is not significantly different. The secret of milk processing is to prevent fat from rising to the top and proteins or minerals from settling at the bottom.

Milk processing companies use a method called 'homogenization' to ensure nutrients are well mixed. Since milk is an essential daily health drink, no stabilizers or emulsifiers are used. Homogenization involves applying a certain pressure (150 kg/min) to raw milk from the farm, forcing it through very small holes in a homogenizer.

It is recommended to shake milk before drinking as sedimentation may occur.
[Photo by YouTube screenshot]

This process breaks down the fat globules in milk to less than 2 micrometers (μm, one-millionth of a meter), dispersing the fat evenly throughout the milk as fine particles. Even when broken down this finely, milk fat can still slightly rise to the top. Additionally, functional fortified milks with enhanced components like calcium or other unique nutrients may experience sedimentation.

In the past, some companies sold milk without homogenization, where a white cream layer floated on top. The reason was that the rich and savory taste of the cream layer made the milk more delicious. However, while the top layer tasted good, the remaining milk below was too bland or watery, leading to the discontinuation of that milk product.

The conclusion is that milk should be shaken before drinking. Regular white milk can be consumed without much concern, but functional fortified milk, especially calcium-fortified milk, must be shaken before drinking. Calcium particles are large and do not dissolve well in water, causing sedimentation. This is why packaging for functional fortified milk includes instructions to 'shake well before drinking.'

This content was produced with the assistance of AI translation services.