Milk, cream and butter are all daily foods in life, and they are all foods derived from milk. However, many people do not know the relationship between them and the nutritional differences between them. Whole milk is the source of cream and butter. Natural milk contains 3% to 4% fat and about 87% water. These fats are the "oil in milk." It stands to reason that oil and water do not mix, but the fats in milk do not stratify, because they exist in the milk as tiny fat globules. There is a protein film on the outside of the fat globules that is "affinity" with water, helping The fat globules are evenly suspended in the whey. These pellets are very small, the larger ones are only a few microns in diameter, and the smaller ones can pass directly through the mucosa of the small intestine, so the body can easily digest and absorb the fat in milk. According to the laws of physics, these tiny fat globules scatter light, giving milk its milky white color. The terms "emulsification" and "emulsion" actually come from the white liquid produced by the fat globules of milk. If whole milk is centrifuged, the fat microspheres in the milk will float on the upper layer depending on the specific gravity. Separate them directly and the product is called cream. Cream contains only 20% to 30% fat, and the fat still exists in the form of fat globules, so the cream is still white. Cream, also commonly known as butter, can be added to coffee and tea, and used to make desserts and candies. If it is fermented, "sour cream" can be produced. If the milk or cream is stirred vigorously, as Tibetans and Mongolians do when "making butter", the protein membrane of the milk fat globules will rupture and the milk fat will flow out of the globules. After losing the protection of protein, fat and water cannot melt together and inevitably separate. As a result, the fat in the milk slowly floats up and clumps together. At the same time, due to the loss of the original "emulsion" structure, the milk loses its milky white color, and the milk fat shows its original color - light yellow. At this time, the upper layer of fat is separated, salted and pressed to remove the moisture, and it becomes butter for daily consumption. Butter is also called "butter", but many people also call it "cream", which sounds the same as cream, causing some confusion. The milk after the fat has been removed is called skim milk, and the fat contained in it is reduced to about 0.5%. The fat-soluble nutrients in milk are found in milk fat, including vitamin A, vitamin D, vitamin K and carotene. Therefore, butter is an excellent source of vitamin AD. The yellow color of butter comes from carotene, because the grass and carrots that cows eat contain a lot of carotene. However, because butter contains more than 85% fat, various water-soluble components in milk are basically separated and remain in skim milk. Therefore, the content of protein, lactose, B vitamins and calcium in butter is very low. Therefore, butter cannot be used to supplement calcium, it is just a large piece of fat. Anyone who has used butter knows that butter is solid and harder than lard. This means that the fat in milk is highly saturated, with very little unsaturated fatty acids and very little essential fatty acids. Therefore, the nutritional value of butter is not high and is basically the same as butter. At the same time, butter also contains a small amount of cholesterol. If you drink a cup of milk, the amount of saturated fat and cholesterol is very small, so you don’t need to consider it; if you want to eat foods made with butter regularly, you should consider it appropriately. For example, cakes, cookies, pastries, butter bread, etc. may bring a lot of saturated fat. It can be seen that whole milk contains the most comprehensive nutrients. The vitamin AD of skimmed milk is basically lost, while the skimmed butter contains a lot of saturated fat, contains cholesterol, is rich in vitamin AD, but is not a good source of calcium and protein. The nutritional value of cream is somewhere in between. As for the so-called "fresh cream" used to make cakes, it has nothing to do with cream. Their main ingredient is plant creamer, which is actually a mixture of hydrogenated vegetable oil, starch hydrolyzate, some protein ingredients and other food additives. It contains "trans fatty acids", which have worse nutritional value than butter and can easily induce cardiovascular disease, so it should be used as little as possible.