Separating oil from milk at home is extremely difficult, if not practically impossible, using simple household methods. Milk is an emulsion, meaning the fat (which is similar to oil) is dispersed throughout the water-based solution. Unlike a mixture of oil and water where the two liquids readily separate into distinct layers, the fat in milk is stabilized and will not easily separate using common techniques.
Why It's Difficult:
The fat globules in milk are very small and are surrounded by a membrane that prevents them from coalescing and separating out like oil and water would. This stabilization is what gives milk its characteristic creamy texture.
Attempts and Limitations:
While completely separating oil (milk fat) from milk at home is unlikely without specialized equipment, here are a few things you could try, with the understanding that they will not result in pure separation:
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Letting it sit: If you leave raw (unpasteurized and unhomogenized) milk to sit undisturbed for a long period, the fat may rise to the top as a cream layer. You can then skim this cream off. However, this is not pure oil; it's still mostly milk fat mixed with some water and other milk solids. The efficiency of this depends greatly on whether the milk has been homogenized. Homogenization reduces the size of the fat globules, making them less likely to separate.
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Centrifugation (with specialized equipment): If you had access to a centrifuge, you could potentially separate the milk into its components, including the fat. However, centrifuges are not standard household appliances.
Conclusion:
While you can skim some of the cream from the top of raw milk, a true separation of "oil" (milk fat) from milk at home without specialized equipment is practically impossible due to the nature of milk as an emulsion.
