Raw milk pasteurisation

The Complete Guide to Raw Milk: Good or Bad for Food Safety

Reading Time: 14 minutes

Raw milk consumption, meaning milk that has not be pasteurised and sold commercially, has been a growing trend for those that are health conscious.

There are strong arguments for and against the use of raw milk and in this article, we review both the benefits and dangers of raw milk in terms of food safety. 

Let’s first start by talking about what pasteurisation is:

First off, milk is an excellent source for microbial growth. Thus, by its very nature milk is a high-risk product. As milk is a good nutrient source for us as humans, so it is for bacteria. Milk also has a very short natural shelf-life and expires quickly. When stored at ambient temperature bacteria and other pathogens soon proliferate.

The US Centers for Disease Control (CDC) says improperly handled raw milk is responsible for nearly three times more hospitalisations than any other food-borne disease source. Diseases prevented by pasteurisation can include tuberculosis, brucellosis, diphtheriascarlet fever.

Pasteurisation also kills the harmful bacteria:

  1.  Salmonella
  2. Listeria monocytogenes
  3. Campylobacter
  4. Staphylococcus aureus
  5. Escherichia coli O157:H7 among others.

How Pasteurisation Works

Pasteurisation is the process of heating milk to a certain temperature for a set amount of time in order to kill pathogenic bacteria to make the milk safe to drink.

It is important to note that foods can become contaminated even after they have been pasteurised. Through cross-contamination during the food production chain.

High Temperature Short Time Treatment (HTST)

This process uses higher heat for less time to kill pathogenic bacteria. Milk can be pasteurised at 75°C (167°F) for 15 seconds.

Low Temperature Long Time Treatment (LTLT) 

This method uses lower heat for a longer period of time to kill pathogenic bacteria. Milk can be pasteurized at 65° C (149° F) for 30 minutes. 


This process involves the heating of milk and cream to at least 135° C (275° F) for at least 2 seconds, but because of less stringent packaging, they must be refrigerated. 

The shelf life of milk is extended 60 to 90 days. After opening, spoilage times for ultra-pasteurised products are similar to those of conventionally pasteurised products.

Ultra High Temperature (UHT) Pasteurisation

This method involves heating milk or cream to 138° to 150°C (280° to 302°F) for 1 or 2 seconds. The milk is then packaged in sterile, hermetically-sealed (airtight) containers and can be stored without refrigeration for up to 90 days. 

After opening, spoilage times for UHT products are similar to those of conventionally pasteurised products.

Times and the temperatures for pasteurisation depend on 2 elements:

  1. The type of food. In this case milk.
  2. The need to retain nutrients, colour, texture, and flavour

The Effect of Pasteurisation on Nutrients and Flavour 

Pasteurisation can affect the nutrient composition and flavour of the milk. There is a distinct taste difference between ‘fresh’ low temperature pasteurised milk and UHT milk.

Milk as a Vitamin source

Milk is a source of vitamins B12 and E, but we no longer consider this a significant contributor for our diet. 

In milk, the colour difference between pasteurised and raw milk is related to the homogenisation (separating milk and cream) step that takes place prior to pasteurisation. Before pasteurisation, milk is homogenised to separate the solids (fat) from the liquid, which results in the pasteurised milk having a whiter appearance compared to raw milk.

In summary, there seems to be very little lost in milk during pasteurisation. In areas where there is loss, milk is not the primary source in our diet.

Why is There Such a Big Debate Over Raw Milk? 

We know that because milk is a good nutrient source. Because of this, the debate begins from the presence of pathogens versus the loss of beneficial bacteria, which assist in gut health.

What Are We Being Told About The Benefits of Raw Milk?

  • Organic, raw milk is a complete food.
  • Loaded with minerals, protein, and vitamins. Raw milk contains an amazing selection of minerals ranging from calcium and phosphorus to trace elements.
  • Raw milk has 20 of the standard amino acids.
  • Up to 80% of the proteins in raw milk are easy to digest (This is a false statement about Lactose intolerance) 
  • Raw milk is abundant in calcium
  • It is also loaded with enzymes that have an array of health benefiting functions.
  • Raw milk is alive with beneficial bacteria that aid digestion and protect against disease-carrying organisms. (Here, we want to add, that raw should never be confused with yoghurt! Milk is not a fermented product and does not contain probiotic bacteria that out compete pathogens.) 

A recent article by the Huffington post wrote: 10 things you should know about raw milk that the government won’t tell you:

  1. Raw milk is healthier:

Pasteurised milk is accused of causing everything from allergies to heart disease to cancer, but back in the day, these diseases were rare. In fact, clean raw milk from grass-fed cows is chock full of healthy amino acids and beneficial enzymes and was used as a cure

2. Raw milk does not make you sick:

That is, if it is properly collected from cows fed good, clean grass. Grass-fed milk has natural antibiotic properties that help protect it from pathogenic bacteria. But it’s worth noting, if you’ve been using pasteurised dairy products, you might want to eat small amounts of yogurt or kefir for a week or so, for a dose of probiotics, just to be safe. I did, and it helped.

3. Not all raw milk is the same:

The cow’s diet, how and where it’s raised, and how the milk is collected are all factors in the safety and quality of raw milk. Cows pastured on organic green grass produce milk with good health benefits. It’s good to know where your milk is coming from.

4. Pasteurisation was instituted in the 1920s

To combat TB, infant diarrhoea, undulant fever and other diseases caused by poor animal nutrition and dirty production methods. But modern stainless-steel tanks, milking machines, refrigerated trucks, and inspection are enough of a precaution, and pasteurisation has become irrelevant.

5. Pasteurisation destroys enzymes

Diminishes vitamin content, kills beneficial bacteria, promotes pathogens and is associated with allergies, increased tooth decay, colic in infants, growth problems in children, osteoporosis, arthritis, heart disease and cancer.

6. Calves fed pasteurised milk don’t do very well.

And many die before maturity. Scary, considering the milk originally came from their mom.

7. Raw milk sours naturally

But pasteurised milk turns putrid; processors must remove slime and pus from pasteurised milk by a process called centrifugal clarification. Gross.

8. Inspection of dairy herds for disease is not required for pasteurized milk.

This means, pasteurisation is used as a nifty way to wash away all forms of bad bacteria that are allowed to flourish freely before the process. Imagine that for a second.

9. Raw milk has more butterfat.

Which is rich in fatty acids that protect against disease and stimulate the immune system. Skim milk doesn’t necessarily mean it’s better for you, in other words.

10. Pasteurisation laws favour large, industrialised dairy operations

And push out small farmers. When farmers have the right to sell raw milk directly to their consumers, they can make a decent living even with a small number of cows. Support small farmers!

What of the above is true and what is disguised nonsense?

  1. Raw is healthier: Arguably true.

Do you remember high fat, low carb diets? Whatever your stance on banting is. There is a benefit to natural fats.

2. Raw milk does not make you sick. True.

It’s the pathogens in the milk that make you sick.

3. Not all raw milk is the same. True.

We’ll get to this debate later in the article. But, yes. Raw milk food safety is highly dependent on good hygiene.

4. Pasteurisation was instituted in the 1920s. True.

Yet we still have outbreaks related to milk and milk products. (we’ll touch on this later)

5. Pasteurization destroys enzymes. Disguised nonsense

As mentioned in the beginning of this article the vitamins lost in the process are not the key source and are actually often replaced by manufacturers. Casein, the milk protein, is still there. Lactase is destroyed, but if you’re lactose intolerant, you’re not gonna be drinking raw milk anyway! By the way casein is used a nutrient source in agar media used to grow bacteria.

6. Calves fed pasteurised milk don’t do very well.

Goodness me, does that make any sense to anyone? Of course, they wouldn’t do well. Cows have four guts, with very complex internal flora. Meaning their immune systems are totally different to ours. We don’t pasteurize a human mothers’ milk either. In fact, it’s a wonder we are able to consumer another species milk at all! 

7. Raw milk sours naturally. Nonsense.

All milk sours naturally. Rancidification is a natural process. The process they are confused with, is likely the separation of butterfat, that actually happens before pasteurisation.

8. Inspection of dairy herds for disease is not required for pasteurised milk. Nonsense.

There are very strict laws that govern herd health and milk food safety. These are managed by food safety experts, farmers and veterinarians. 

Cows that are ill are separated and quarantined from the herd and the milk is never used in production. Anti-biotics never make it into production milk. But yes, pasteurisation is the final safety net for most problems in the food production chain.

9. Raw milk has more butterfat. Partially true.

Low fat milk has definitely lowered in sales worldwide due to banting and the trend for promoting natural fats is almost a norm these days.

10. Pasteurisation laws favour large, industrialised dairy operations. Partly true.

Milk itself is not the big money maker, and it is not so much the laws, but the industry as a whole that favours large farms, due to the scale of economy. The biggest issue for small farmers is the transport of milk. It is no longer cost effective for a producer to collect small volumes of milk per farm. As you will see later in this article, raw milk production is costlier on the farmers side than it is for the manufacturer. 

Okay, so where does that leave us in terms of real benefits?

  1. Raw milk is healthier in terms of vitamins, nutrient content and natural fats. If you do not eat a number of fruits and vegetables, beans and nuts, then milk could arguably be an essential source of the contents mentioned. As we have seen with high natural fat diets, we would agree that a controlled diet which includes butterfat can be beneficial. 
  2. The raw milk itself doesn’t make you sick. Although high fat and very rich dairy is certainly something to get used to, if you’ve genuinely tried it.
  3. Not all raw milk is created equal. Let’s talk about certified raw milk: 

What is Certified Milk?

Below is an explanation from a raw milk producer: 

Raw milk is unpasteurised and must comply with very strict health conditions in order to be approved as Certified Raw Milk, making it safe and healthy to drink.

It’s best to only drink Certified Raw Milk for safety reasons and not just any raw milk. For raw milk to be classified as Certified Raw Milk, the dairy must comply with the most stringent high standards such as:

The dairy herd must be ‘closed and quarantined’, i.e. we never buy in new cows. The only new animals in the herd are our own calves born on the farm.

The herd must be vaccinated and tested annually for brucellosis and tuberculosis.

The herd must also be vaccinated annually against other diseases such as anthrax.

The milk must be tested frequently and randomly for bacteria, brucellosis and other impurities.

The milking parlour and equipment must be of a superior standard with a rigorous washing, maintenance and replacement schedule. 

Meaning special attention needs to be paid to hygiene and cleaning, herd health has to be immaculate, which unfortunately can only be done in smaller numbers.

In comparison, raw milk can be compared to a salad. There is no final line of defense (heating/cooking) so the risks are critical, and any single slip up could mean food poisoning.  Much like in cities versus large open rural areas, the spread of disease happens quicker in densely populated areas than in low density areas. Same as dairy farms. 

Dairy farming and herd health

Let’s talk about the health of the animal where the milk actually comes from. Dairy farming is already a complex process of the health of the cows, hygiene in the milk parlour and the remainder of the food production chain.

This process requires constant effort from the farmer, veterinarian, food safety experts and constant regular testing of the cows and their milk. To give you an idea of what goes into the daily inspection of the herd see below as provided by dairy councils:

General appearance. It is alert and aware of its surroundings. It stands squarely on all four feet and holds its head high, watching what’s happening around it.

Movement. It walks easily and steadily, with all four feet bearing its weight. Its steps are regular; irregular movement suggests pain in its feet or legs. A healthy animal that is lying down will get up quickly.

Eyes.These should be bright and alert, with no discharge at the corners.

Ears.These should be upright, move to pick up any sound, and flick rapidly to get rid of flies.

Nose and muzzle.The nose of a healthy cow is clean, with no discharge, and the muzzle is moist. The animal should lick its nose frequently.

Mouth. There should be no dribbling saliva. If chewing is slow or incomplete, there could be a problem with the teeth.

Hair/coat. The hair coat of a healthy animal is smooth and shiny.

Breathing.This should be smooth and regular at rest. If the animal is in the shade, it’s difficult to notice the chest moving as it breathes. Activity and hot weather will increase the breathing rate.

Pulse. A cow’s pulse can be felt on the tail a short distance below the base. Measure it by holding the tail lightly with your thumb and forefinger. The normal rate is 40 to 80 beats/minute in the adult animal, and somewhat higher in a young animal.

Dung/urine. The dung pat of a healthy animal is soft. Watery dung (diarrhoea) and difficulty in defecating (constipation) are signs of ill health. The urine should be clear, and the animal will urinate with no sign of pain or difficulty.

Appetite and rumination. The cow should eat and drink normally. If feed is available, it will have a full belly. When a herd of healthy cows are at rest, most of them are ruminating. A poor appetite is an obvious sign of ill health.

Milk. There should be no swelling of the udder and no sign of pain when it’s touched. The teats must not be injured. In the lactating cow, a sudden decrease in milk production could indicate a health problem. Blood in the milk points to an udder infection.

Body temperature. An abnormally high body temperature is a sign of infection (although environmental factors must be taken into consideration).

Finally, remember that a healthy animal tends to behave calmly, so any behaviour not usually seen may be a problem. For example, if a cow keeps looking at its flanks or kicks at its belly, there could be pain in the stomach area.

The above is a basic inspection to quickly identify problems. This excludes the microbiological and quality tests that are performed before milk is released into the market. Below are the risks that follow from dairy farming that the farmer has to be aware of:

  • Adult Dairy Cow Mortality
  • Body Condition Scoring as a Tool for Dairy Herd Management
  • Bovine Leukosis Virus
  • Calf Diseases and Prevention
  • Cow Comfort and Health
  • Electrolytes for Dairy Calves
  • External Parasites of Dairy Cattle
  • Heat Stress in Dairy Cattle
  • Heat Stress Management of Dry Cows
  • Impact of Milk Fever and Hypocalcemia on Reproductive Performance of the Dairy Cow
  • Inflammation and Transition Cow Disorders
  • Internal Parasites in Beef and Dairy Cattle
  • Lameness in Dairy Cattle
  • Minimizing Subclinical Metabolic Diseases
  • New Developments in Understanding Ruminal Acidosis in Dairy Cows
  • Nutrition and Claw Health
  • Prevention and Control of Foot Problems in Dairy Cows
  • Prevention and Controlof Nitrate Toxicity in Cattle
  • Prevention of Displaced Abomasum
  • Prevention of Udder Edema in Dairy Cows
  • Progress in the Understanding of Hemorrhagic Bowel Syndrome
  • Simplified Scoring System to Identify Respiratory Disease in Dairy Calves
  • Therapeutic Nutrition for Dairy Cattle
  • Understanding Fungal (Mold) Toxins (Mycotoxins)
  • Understanding Metritis in Dairy Cattle

What are the risks associated with drinking raw milk?

Common myths and proven facts about milk and pasteurisation:

  • Pasteurising milk DOES NOT cause lactose intolerance and allergic reactions. Both raw milk and pasteurised milk can cause allergic reactions in people sensitive to milk proteins.
  • Raw milk DOES NOT kill dangerous pathogens by itself.
  • Pasteurisation DOES NOT mean that it is safe to leave milk out of the refrigerator for extended time, particularly after it has been opened.
  • Pasteurisation DOES kill harmful bacteria.

Raw milk for direct consumption is generally considered to be of higher risk due to its potential as a carrier of harmful bacteria not normally associated with pasteurised milk.

The understanding is that while the milk is in the production system of a healthy cow it is considered to be virtually sterile. However, everything changes when the milk is exposed to the teat canal of the cow and the environment.

Dairy cows spend much of their time grazing in pastures where they come into contact with a variety of environmental microbes. In addition, many microbes that are “commensal” organisms (that co-exist with cows without causing a disease) may be considered human pathogens. But also safe for calves to feed. (Refer to benefit argument number 6) Raw milk can be very dangerous if handled incorrectly or unsafely.

If there is no pasteurisation, and pathogens do exist in the milk, there is no way to get rid of them. Making raw milk the riskiest of all.

Getting sick from raw milk can mean at the very least; diarrhoea, stomach cramping, and vomiting.  Severe cases or even life-threatening diseases, including Guillain-Barré syndrome, which can cause paralysis, which can result in kidney failure, stroke, and even death.

From 1993 through 2012, 127 outbreaks reported to CDC were linked to raw milk. These outbreaks sickened 1,909 people and caused 144 people to be hospitalised. Most of the 127 outbreaks were caused by Campylobacter, Shiga toxin-producing Escherichia coli, or Salmonella. Reported outbreaks represent the tip of the iceberg. Most food-borne illnesses are not part of a recognised outbreak, and for every outbreak and every illness reported, many others occur.


Just as in meat production, we expect to have bacteria present, which is why we cook them. 

How Does Milk Get Contaminated?

There are a number of ways that contamination can occur: 

  • Infection of the udder (mastitis)
  • Bovine illness 
  • Animal feces coming into direct contact with the milk, which happens naturally. 
  • Bacteria that live on the skin of animals
  • Environment (for example, feces, dirt, and processing equipment)
  • Insects, rodents, and other animal vectors
  • Unsanitary conditions in milk processing plant
  • Cross-contamination from dairy workers, such as contact with dirty clothing or boots

Pasteurisation is the only way to kill many of the bacteria in milk that can make people very sick.

The presence of bacteria in raw milk is unpredictable. People can drink it for a long time without getting sick, and then suddenly get sick if the milk is contaminated.

Growth of pathogens occurred predominantly during domestic transportation and
storage of raw milk. 

The occurrence and persistence of infection within herds or individual animals is often
intermittent, which proves difficult to detect and routinely monitor

These risks can be managed, just as in any other food production.

Pathogen contamination of raw milk may be reduced by exercising enhanced hygienic control throughout the milk harvesting stage. Practices such as teat washing, dipping, foremilk stripping, and good milking hygiene will reduce the number of organisms (pathogenic and spoilage) that may enter the milk from environmental sources. 

For example, pre-milking udder washing with clean water and drying using hand towels reduces milk contamination by transient bacteria located on the exterior surfaces of the udder. Post-milking teat disinfection reduces the resident teat skin bacterial population, which is the main source of infection for the mammary gland.


The safety of raw cow milk is influenced by a combination of management and control measures along the entire dairy supply chain. Control of animal health, adherence to good milking practices, and control over milking parlour hygiene are important in reducing the microbial load in raw milk. 

The ability to detect pathogens in raw milk depends on the accuracy of testing, skill of personnel and the limit of detection for specific testing methods and specific pathogens. 

In the end you as the consumer have the choice to go raw or pasteurised. The intention of this article to highlight the risks. Inevitably consuming any food product carries a risk.

The intention of food safety is to reduce the risk of causing illness through the consumption of food. When it comes to commercial production, even the highest standards do not always guarantee a safe product. All you have to do is search food poisoning outbreaks to see how common these actually are.

When it comes to commercial production, even the highest standards do not always guarantee a safe product. All you have to do is search food poisoning outbreaks to see how common these actually are.

Considering the manufacturing industry, the natural risk in milk, the food production chain and the reliance on the cow, farmer and veterinarian to detect disease is a complex process. 

The claims of increased nutritional benefits are many, however there isn’t any scientific backing for this. This may be because there is no financial backing for such research. Yet, it remains to be seen whether the risk out ways the nutritional benefit. Especially considering that the ‘lost’ nutrients can be gained elsewhere in other foods. 

It seems to us, that consuming raw milk has a heavy reliance on the hygiene practices of the production process, with so many factors that cause contamination, there are some serious risks here. Not only that, but the relative cost of managing these risks are a lot higher that the cover all pasteurization process.

If you think that certain types of bacteria may be beneficial to your health, consider getting them from foods that don’t involve such a high risk. For example, pasteurised fermented foods, such as yogurt and kefir, contain bacteria that are safe to eat.

Raw Milk-Related FAQ (Data provided by the CDC)

Where do most raw milk-related outbreaks happen?

Raw milk-related outbreaks are more common in states that allow the legal sale of raw milk for people to drink than in states that do not allow its sale. In addition, raw milk sales in one state can lead to outbreaks in neighboring states.

Who is most affected by raw milk outbreaks?

A large number of raw milk outbreaks involves children. At least one child younger than 5 was involved in 59% of the raw milk outbreaks reported to CDC from 2007 through 2012. In these outbreaks, 38% of the illnesses caused by Salmonella and 28% caused by Shiga toxin-producing E. coli, which can cause kidney failure and death, were among children aged 1–4.

Aren’t raw or natural foods better than processed foods?

Many people believe that foods with little to no processing are better for their health. Many people also believe that small, local farms are better sources of healthy food. However, some types of processing are needed to protect health. One type of processing happens when we cook raw meat, poultry, and fish to make them safe to eat. Similarly, when milk is pasteurized, it is made safe by heating it just long enough to kill disease-causing germs. Most nutrients remain in milk after it is pasteurized.

Is raw milk a good source of beneficial bacteria?

Raw milk contains bacteria, and some of them can be harmful. So, if you’re thinking about consuming raw milk because you believe it is a good source of beneficial bacteria, you need to know that you may instead get sick from the harmful bacteria. 

Find out more about food safety and the prevention of food poisoning by reading “Food Safety for the Kitchen” by Adrian Carter

This book covers the basics on bacteria in the food environment. Concepts should as defining bacteria, how bacteria grow, what is needed to prevent the growth of bacteria are discussed. This book also covers the most common food-poisoning bacteria, E.coli, S.aureus, Salmonella, Listeria monocytogenes, Clostridium species as well as Campylobacter. The Listeriosis outbreak in South Africa, the largest in recorded history, is covered in a bonus chapter. Food poisoning, the how’s, why’s and when’s are also covered. This book explains how food gets contaminated and discusses the five pillars of food safety; cleaning and sanitising, personal hygiene, food storage, temperature control and the handling of foods, which covers cooking, cooling and defrosting.


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