A standard cup (8 fluid ounces) of raw whole cow’s milk contains about 7.5 grams of protein. That’s essentially the same amount you’d find listed on a carton of pasteurized whole milk, because heat treatment changes the structure of some milk proteins but doesn’t remove them. What does differ between raw and pasteurized milk is the form those proteins take, which matters if you’re interested in the biological activity of what you’re drinking.
Protein Breakdown: Casein and Whey
Milk protein isn’t a single substance. It’s split into two major groups: casein and whey. In cow’s milk, casein makes up roughly 79% of the total protein (about 2.6 grams per 100 milliliters), while whey accounts for the remaining 21% (about 0.7 grams per 100 milliliters). If you’ve ever seen cheese being made, you’ve watched this split happen physically. Casein is what curdles into solid cheese; whey is the liquid left behind.
Both types are complete proteins, meaning they contain all the essential amino acids your body can’t make on its own. Cow’s milk is particularly rich in leucine, lysine, and valine, three amino acids that play central roles in muscle building and repair. Leucine, which triggers muscle protein synthesis, is present in meaningful amounts in both the casein and whey fractions.
How Pasteurization Changes the Protein
Standard pasteurization heats milk to at least 72°C (161°F) for 15 seconds. This doesn’t reduce the total grams of protein per cup, so from a macronutrient standpoint, raw and pasteurized milk are interchangeable. What heat does change is protein structure, particularly in the whey fraction.
Whey proteins begin to unfold (denature) at temperatures between 55 and 65°C and become irreversibly altered above 65 to 70°C, which means standard pasteurization pushes past that threshold. The percentage of soluble whey protein drops measurably after heat treatment. One class of whey proteins, immunoglobulins (immune molecules like IgG), can decline by anywhere from 13% to 80% depending on the specific pasteurization conditions and the milk source. These immunoglobulins are biologically active in raw milk, functioning as part of the cow’s immune system, but their relevance to human health after digestion is still debated.
Casein, the larger protein fraction, is far more heat-stable and survives pasteurization largely intact. So if your interest in raw milk protein is about total grams for meeting daily protein goals, pasteurization makes no practical difference. If your interest is in preserving the native structure of whey proteins specifically, that’s where raw milk differs.
How Breed and Species Affect Protein Content
Not all raw milk has the same protein concentration. The breed of cow is a significant variable, accounting for up to 36% of the variation in certain protein fractions. Jersey and Brown Swiss cows, for instance, are known for producing milk with higher protein and fat content compared to the more common Holstein-Friesian, which yields a larger volume of somewhat more dilute milk. If you’re buying raw milk from a local farm, the breed of the herd can shift your per-cup protein intake by a gram or more in either direction from the 7.5-gram average.
Species matters even more. Sheep’s milk contains about 4.6% protein (roughly 11 grams per cup), water buffalo milk about 3.8%, and goat’s milk about 3.2%, compared to cow’s milk at 3.3%. The casein-to-whey ratio also shifts between species. Goat’s milk, for example, has the same casein content as cow’s milk (2.6%) but slightly less whey (0.6% versus 0.7%).
Raw Milk Protein in a Dietary Context
At 7.5 grams per cup, raw milk is a moderate protein source. Two cups a day adds 15 grams toward a typical daily target of 50 to 60 grams for a sedentary adult, or higher if you’re active. Milk protein is also highly digestible compared to many plant proteins, with a protein digestibility-corrected amino acid score (PDCAAS) of 1.0, the highest possible rating.
The casein and whey fractions digest at different speeds, which is why dairy protein has long been popular in sports nutrition. Whey is absorbed quickly and spikes amino acid levels in the blood within an hour or so. Casein forms a gel in the stomach and releases amino acids gradually over several hours. Drinking whole raw milk gives you both in their natural ratio, a combination that supports both immediate and sustained amino acid availability.