Pasteurized Vs Unpasteurized Milk: Compounds Removed or Altered

January 24, 2023 10 mins to read

Many people are aware of the fact that pasteurization sterilizes milk, but may not be aware of just how many different nutrients, enzymes and proteins are damaged or removed during the process. If you are having a debate with a devout vegan (yes I was one for 8+ years) who is wholly against milk, print this off and remind them that while pasteurized milk is raped of its nutrients, and provides little to no nutritional value (aside from being fortified with some vitamins), raw milk is a nutrient powerhouse and superfood. Pasteurization (especially ultra high heat pasteurization) can remove heat sensitive vitamins and enzymes, and alter the chemical composition of proteins in a process known as denaturation. Below are the compounds in milk which may be removed or changed during pasteurization:

Pasteurized Vs Unpasteurized Milk: Enzymes Destroyed

Pasteurization can destroy raw milk enzymes including (but not limited too) lipases and phosphatases, which can potentially alter the taste and nutritional quality of the milk. The extent of enzyme destruction is variable and based on pasteurization, while some enzymes more resistant to heat may survive. Here are some of the enzymes that can be destroyed during pasteurization/HST pasteurization:

  • Lipases – catalyze hydrolysis of ester bonds in triglycerides (breaks down fats).
    • By breaking down fats it makes it easier for the body to digest and use them.
    • Also responsible for the development of flavor in fermented dairy products.
  • Phosphatases – catalyze hydrolysis of phosphates –> helps to release calcium and phosphorus from milk.
    • Important in the production of cheese, as they help to release calcium and phosphorus from the milk, which are necessary for the formation of a curd.
    • Calcium is important for the development and maintenance of strong bones, teeth and muscles.
    • Phosphorus is also important for strong bones and teeth and plays a key role in the body’s metabolism.
  • Lactoperoxidase – protects milk from bacterial infection by catalyzing the formation of compounds that are toxic to bacteria, such as hydrogen peroxide and hypothiocyanite.
    • Can help to maintain the freshness of the milk and reduce the risk of food-borne illnesses.
  • Xanthine oxidase – catalyzes oxidation of xanthine to uric acid and hydrogen peroxide. Responsible for the production of flavor compounds in cheese.
    • Palatability (texture and mouthfeel) makes individuals more likely to consume larger amounts of these nutrient dense foods.
  • Phosphatase – breaks down phospholipids, a type of fat found in milk and are important in the production of cheese.
    • By breaking down fats it makes it easier for the body to digest and use them.

Pasteurized Vs Unpasteurized Milk: Heat Sensitive Vitamins Removed

Pasteurization can cause a loss of some heat-sensitive vitamins like vitamin C and B-complex. Again the extent of vitamin loss is variable and can depend on pasteurization conditions and what specific vitamins are present in the milk. A study in the Journal of Dairy Science found that raw milk contains higher levels of certain vitamins and minerals, such as vitamin C and calcium, when compared to pasteurized milk.

Vitamin C

Vitamin C is water-soluble and can be partially or completely destroyed during pasteurization due to being heat sensitive. Vitamin C has numerous benefits to the human body some of which include:

  1. Antioxidant – destroys potentially harmful free radicals, which helps reduce chance of diseases such as cancer or heart disease.
  2. Collagen production – vital for production of collagen, a protein that supports healthy skin, blood vessels and more.
  3. Immune system support – supports a healthy immune system by helping produce white blood cells and antibiotics which can fend off infections, viruses and diseases.
  4. Iron absorption – Iron is essential for red blood cell production and oxygen transport to the body.
  5. Wound healing – helps with the body’s mechanisms for wound healing and formation of scar tissue.
  6. Cardiovascular health – can lower blood pressure and reduce risk of heart disease.
  7. Mental health – can improve mood and cognitive function through various mechanisms.
  8. Skin health – helps protect skin from sun damage, reduces wrinkles and age spots and helps keep skin looking youthful.

B-Complex (multiple B Vitamins which are heat sensitive)

  • B1 (thiamine) – plays a vital role in maintaining the health of the nervous system, heart function and metabolism.
  • B2 (riboflavin) – essential for maintaining healthy skin, eyes, and nervous system, as well as for the metabolism of fats, drugs and other nutrients.
  • B3 (niacin) – helps to maintain healthy skin, nerves, and digestion, as well as being essential for the metabolism of energy and the production of hormones.
  • B6 (pyridoxine) – plays a vital role in protein metabolism, brain development and function, in production of red blood cells and regulation of the immune and nervous system.
  • B12 (cobalamin) – plays a crucial role in the production of red blood cells, the maintenance of a healthy nervous system, the synthesis of DNA and the metabolism of every cell in the body.

Pasteurized Vs Unpasteurized Milk: Bacteria Killed

Pasteurization can reduce the number of both beneficial bacteria (such as lactic acid bacteria and Bifidobacterium) and harmful bacteria (such as E.coli and Salmonella), found in raw milk. Keep in mind that the alleged health benefits of these bacteria can vary depending on the specific strain, and amount present in the milk and total amount of milk consumed.

Harmful bacteria killed during pasteurization

  • Escherichia coli (E. coli)
  • Salmonella
  • Listeria monocytogenes – listeriosis infection
  • Campylobacter – Campylobacteriosis (food poisoning)
  • Staphylococcus aureus – can cause a range of illnesses, including skin infections such as boils and impetigo, as well as more serious infections such as sepsis, pneumonia and food poisoning.
  • Mycobacterium tuberculosis – can cause a serious lung infection called tuberculosis

Beneficial bacteria killed during pasteurization

  • Lactic acid bacteria (LAB) – Includes Lactobacillus and Streptococcus, which are what ferments the milk and production of lactic acid (preserves milk & gives it it’s distinct flavor). These bacteria also improve our digestion of lactose and boost the immune system by stimulating creation of some immune cells. Also have anti-inflammatory properties that may reduce gut inflammation.
    • Some studies show LAB may help with Irritable Bowel Syndrome (IBS) and other gut-related disorders.
    • Other studies show LAB benefits mental health by reducing symptoms of anxiety and depression
    • Recent studies have also shown that certain strains of LAB can also have potential benefits in reducing the risk of certain diseases such as allergies, obesity, and type 2 diabetes.
  • Bifidobacterium – plays a role in maintaining a healthy gut and boost the immune system and may have anti-inflammatory properties. Some studies suggest this bacteria may benefit mental health, by reducing symptoms of anxiety and depression.
  • Propionibacterium – also known as the bacteria that is responsible for making swiss-type cheese (such as Emmental, Gruyère and Jarlsberg.) This bacteria produces propionic acid (short-chain fatty acid) that benefits the gut flora / microbiome by promoting growth of other beneficial bacteria. They also can help boost the immune system by promoting production of specific immune cells. Some studies also suggest they may have anti-inflammatory properties.

Other killed during pasteurization

  • Yeasts and molds – most yeasts are heat-sensitive and are killed during pasteurization.
    • Yeasts that are used in the production of fermented dairy products such as cheese or yogurt, like Saccharomyces cerevisiae, are inactivated by pasteurization.
    • Some yeasts are able to survive pasteurization temperatures, such as Saccharomyces boulardii, a probiotic yeast which can be used in fermented dairy products like yogurt to provide beneficial effects for the gut microbiome.
  • Spores of thermophilic bacteria – encompasses many different bacteria known for their ability to grow and thrive in hot temps from 45-120°C. They can potentially degrade various organic pollutants, which is why they are a prospect for industrial applications.

Pasteurized Vs Unpasteurized Milk: Proteins Altered (Damaged)

Pasteurization can cause denaturation of certain proteins in milk, which can affect the functional properties and nutritional value of the milk. Milk is primarily comprised of Casein (80%) and Whey (20%). Whey proteins that can be damaged/removed during pasteurization:

  • Alpha-lactalbumin – a good source of essential amino acid tryptophan and rich in sulfur containing compounds.
  • Beta-lactoglobulin – a good source of amino acids and minerals.
  • Immunoglobulins – a vital component in immune system function.
  • Lactoglobulin – contains a high volume of branched-chain amino acids (BCAA’s) in particular, leucine, isoleucine, and valine which are vital for muscle protein synthesis, recovery, and repair. It’ is’s also a good source of the amino acid cysteine; a precursor to the antioxidant glutathione.
    • Some studies suggest lactoglobulin may have a number of potential health benefits including: build+maintain muscle mass, improve post-exercise recovery, support immune system and improve lactose digestion.

Removal of lactoperoxidase and other beneficial proteins or enzymes which keep harmful microorganisms in check, also makes milk more susceptible to re-infection post-pasteurization; they are no longer there to kill the harmful bacteria if it is somehow reintroduced into the milk through contamination or other means.

Pasteurized Vs Unpasteurized Milk: Conclusion

In the comparison of Pasteurized vs Unpasteurized milk, it’s clear that unpasteurized in the winner! While pasteurization does remove some potentially harmful bacteria such as E.coli and salmonella it also damages, alters or destroys numerous enzymes, vitamins, bacteria and proteins which have a wide range of potential health benefits for the body; and together may interact to support health in ways that aren’t yet fully understood. Pasteurization even removes Lactoperoxidase, an enzyme responsible for helping protect milk from bacterial infection, making post-pasteurized milk susceptible to unimpeded re-infection, due to cross contamination or any failure of the pasteurization process.

So just how dangerous are the harmful microorganisms in milk? Well since 1987 there have been only a handful of deaths attributed to the consumption of raw milk (1, 2, 3). Statistically you have a better chance of winning the lottery (more than once) than dying from consuming harmful bacteria that may be present in raw milk. Obviously if you have a digestive disorder, an immunological disorder or are otherwise immune compromise, you may want to consult with a naturopath or holistic doctor (or your physician), before buying a cow. And ide also say infants shouldn’t due to an undeveloped immune system. However compromised individuals aside…you must ask yourself if the pros of pasteurization killing potentially harmful bacteria, outweigh the cons of destroying it’s nutrient profile.

Personally I consumed plenty of raw milk as a child and I was pretty darn healthy then, I’ve turned out pretty alright now as well…my mother and grandparents were in the same boat. But again each person is unique, and ultimately you have to make the decision yourself. Hopefully this gives you some required information so you can make an informed decision for yourself on whether or not unpasteurized milk is right for you.



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