We’ve all heard the saying “the cream rises to the top” in reference to the idea that something good won’t go unnoticed for long. It is interesting that this saying is still used because it is referencing the way cream performs in non-homogenized milk — something many people have never seen first-hand due to today’s widespread practice of homogenization. In the past, higher fat milk meant healthier and happier cows. Consumers would actually look for the cream at the top of the milk jug to know they were getting a quality product. Nowadays, homogenized milk is the norm and many people have no idea that milk naturally separates.
Whole milk naturally separates into two portions — the watery milk portion which is a mixture of water, lactose, and milk proteins such as casein, and the cream portion which is mostly fat and rises to the top because fat is less dense than water. Homogenization forces whole milk through a high-pressure, high-temperature system that shreds the normally large fat globules into much smaller globules. Due to the laws of chemical attraction, the fat globules in milk naturally attract protein molecules to their surface. Smaller globules have more surface area than larger globules, which gives more space for protein to attach to. This allows more protein to attach to the small globules of fat, which makes them heavier and allows the globs to blend or “homogenize” into the watery portion of the milk. This causes the processed milk to retain a uniform texture, unlike fresh milk which will have a cream portion that rises to the top.
So what’s all the fuss? Homogenization may be useful for presenting a product that is uniform in appearance, but it is not without its side effects. Casein makes up approximately 87% of the protein found in milk, with the remainder attributed to whey protein. Casein is one of the more allergenic molecules in milk and the fact that smaller fat globules in homogenized milk expose the consumer to more milk protein (namely casein) may be part of why modern day milk allergies are so widespread. It may also be why makers of non-homogenized dairy products receive calls from customer after customer reporting with surprise that they do not experience an allergic response after drinking non-homogenized milk.
When non-homogenized milk is ingested the large fat globules are processed in the digestive system and the small amounts of casein attached to their surface are broken down by digestive enzymes and stomach acid. When milk fat is homogenized, the small globules become “delivery capsules” which allow allergenic milk proteins such as casein to be absorbed directly into the blood stream without being broken down prior. This absorption of undigested protein is strongly linked to increased allergies, because the immune system will attack undigested foreign proteins. In conventionally produced milk, this delivery system may be of even more concern because it allows compounds such as hormones and antibiotics to pass into the body with greater ease.
Modern dairy processing practices have turned whole natural milk, one of nature’s most healthy foods, into a processed and allergenic food. Fortunately there are still a few traditional dairies who stick to a standard of producing milk that is true to what nature intended. If the saying holds true, it won’t be long until this superior way of creating milk products “rises to the top.”