Which Milk Has More Protein: Raw vs. Boiled?

November 28, 2025 •

3 min read

A study found that boiling milk significantly reduces its whey protein levels, a key factor in determining which milk has more protein, raw or boiled. This heating process, though essential for safety, creates structural changes that affect milk's overall nutritional profile and digestibility. Understanding this difference is crucial for informed dietary choices.

Quick Summary

Boiling affects milk's protein composition, denaturing sensitive whey protein while leaving casein largely intact. While the total protein quantity remains similar, its bioavailability changes, with raw milk containing more readily available whey protein. This comes with significant food safety risks, making boiling or pasteurization crucial for eliminating harmful bacteria.

Key Points

Raw vs. Boiled Protein: Raw milk contains more undenatured whey protein, while boiling denatures this sensitive protein, though total protein amounts remain similar.
Safety First: The critical reason to boil raw milk is to kill harmful bacteria, an absolute necessity outweighing the minor nutritional losses.
Whey vs. Casein: Boiling significantly affects whey protein structure, while the dominant casein protein remains relatively stable during heating.
Nutrient Loss: Boiling can reduce levels of water-soluble vitamins like B2 and B12, but heat-stable minerals such as calcium are unaffected.
Better Digestibility: For individuals with mild milk protein allergies, the denaturation of protein in boiled milk may make it easier to digest.
Pasteurization is Key: For safety and nutritional balance, commercially pasteurized milk is the recommended option, as it is heated sufficiently to kill pathogens without drastic nutritional changes.

The Science of Milk Protein

Milk is a complex substance composed of two primary protein types: casein and whey. Casein makes up about 80% of the total protein, forming micelles that are relatively stable under heat. Whey protein, comprising the remaining 20%, is more sensitive to temperature and prone to denaturation, or structural change, when heated.

Raw Milk Protein

Raw milk, fresh from the source and unheated, retains its native protein structure, including the full complement of undenatured whey protein. It is important to note that the protein content in raw milk can vary based on the animal's breed, diet, and overall health. While some proponents claim raw milk is more nutritious due to these intact enzymes and proteins, it is crucial to recognize the significant health risks involved with unpasteurized dairy. Raw milk can harbor harmful bacteria like E. coli, Salmonella, and Listeria, which can cause serious illness.

Boiled Milk Protein

When milk is boiled, its protein structure is altered. The high heat causes whey proteins to denature and lose their original shape. This change is why a film or 'skin' forms on the surface of boiled milk. The denaturation of whey protein is the primary reason why boiled milk is considered to have a different protein quality, even if the total amount of protein is not drastically reduced. The casein protein, being more heat-stable, is less affected by boiling.

Impact on Nutritional Value and Digestibility

Beyond protein, boiling milk affects other nutrients as well. Heat-sensitive vitamins, particularly water-soluble B vitamins like B12 and B2, and vitamin C, can be significantly reduced. Some studies have shown a reduction of B vitamins by at least 24% after boiling. Minerals like calcium, however, are largely heat-stable and remain mostly unaffected by boiling.

Conversely, the denaturation of proteins in boiled milk can offer some benefits. Some individuals with mild milk protein allergies or lactose intolerance find boiled milk easier to digest because the heat modifies the protein and lactose structures. The boiling process also converts some lactose into other compounds, which may aid digestibility. For the general population, however, these changes result in a slightly less bioavailable protein profile compared to raw milk.

Raw vs. Boiled Milk: A Comparison

To highlight the key differences, here is a comparison of raw versus boiled milk.


Feature	Raw Milk	Boiled Milk
Whey Protein	Intact, native structure	Denatured, less bioavailable
Casein Protein	Intact, native structure	Largely stable
Food Safety	High risk of bacterial contamination	Pathogens are eliminated, safe for consumption
Vitamins (B/C)	Full, native levels	Reduced levels due to heat sensitivity
Minerals (Calcium)	Stable, unaffected by boiling	Stable, largely unaffected by boiling
Digestibility	Potential issues for sensitive individuals	Potentially easier for those with mild sensitivities
Enzymes	Contains naturally occurring enzymes	Enzymes are destroyed by heat

The Crucial Role of Safety

While this article examines the protein content and other nutritional differences, food safety is the paramount concern. Health organizations worldwide, including the FDA, advise against consuming raw milk due to the risk of serious foodborne illnesses. Boiling effectively kills these harmful pathogens, making it a necessary step for raw milk from unverified sources. Commercial milk is already pasteurized, a heating process designed to kill bacteria while preserving most of the nutritional value, including protein integrity, better than boiling.

For consumers, especially those in regions without strict regulations, boiling is the safest option. The minor reduction in whey protein or vitamins is a small price to pay for eliminating the risk of life-threatening infections. Pasteurized milk, which is readily available in grocery stores, offers the best of both worlds: a safe product with most of its nutritional content intact. You can find more information on food safety and raw milk misconceptions from the FDA.

Conclusion

In summary, while raw milk contains more of the readily available, undenatured whey protein, the difference in total protein is not significant. The boiling process denatures sensitive whey protein and reduces some heat-sensitive vitamins, but its primary benefit is eliminating dangerous bacteria. For safety, pasteurized milk from a commercial source is the best option as it balances nutritional retention with pathogen elimination. For raw milk from unverified sources, boiling is a critical safety step, even if it slightly alters the protein profile.

Frequently Asked Questions

No, boiling milk does not destroy its protein entirely. While the sensitive whey protein is denatured and its structure changes, the more abundant casein protein is largely unaffected, and the total amount of protein remains relatively stable.

Raw milk contains more of the original, undenatured whey protein. However, studies show that the overall protein content, including casein, does not differ significantly between raw and boiled milk. The primary difference is in the protein structure and digestibility.

When milk is heated, the whey protein is denatured, meaning it changes its structure and becomes less bioavailable. Casein protein is more heat-stable and remains mostly intact throughout the boiling process.

Boiling milk is recommended for raw, unpasteurized milk to kill harmful bacteria, such as E. coli and Listeria, that can cause severe foodborne illnesses. It is a critical step to ensure microbiological safety before consumption.

Pasteurized milk, which is heated to a lower temperature for a shorter time, retains more of its original whey protein structure compared to milk that is brought to a full boil. Ultra-high-temperature (UHT) pasteurization, however, can also denature some protein.

Yes, even raw milk from healthy, well-cared-for animals can harbor dangerous pathogens. Contamination can occur during milking or processing, and there is no way to know for sure without proper testing.

For individuals with mild milk protein allergies or lactose sensitivities, the heat-induced changes in protein and lactose structure can sometimes improve digestibility. However, it does not significantly reduce the overall lactose content and is not a guaranteed solution for those with severe allergies or intolerance.