Types of Milk Pasteurization

January 25, 2023 9 mins to read
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The pasteurization process was initially developed by Louis (yes you guessed it) Pasteur, a French scientist, in the 19th century (well developed in 1862 but applied commercially in the 19th century). Up until then and since humans first began domesticating animals, people consumed raw milk directly from the cow, sheep or goat. Pasteurization was developed as a method to kill harmful bacteria in milk, which can lead to serious health issues such as food poisoning (even though only a handful of deaths have been recorded). In fact it wasn’t until the 20th century, following the formation of US and European milk industry regulation, that it became mandatory to pasteurize milk for commercial distribution. In this article I take a look at the three most common types of milk pasteurization HTST, UHT and LTLT.

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High-Temperature Short-Time (HTST) Pasteurization

For types of milk pasteurization – HTST pasteurization involves heating the milk to at least 161°F (72°C) for at least 15 seconds and is the most commonly used method today, not just for milk but other beverages as well like juice and beer. The process is not intended to pasteurize the milk, but instead reduce the level of harmful bacteria to acceptable levels. Therefore HTST milk must still be refrigerated. Let’s detail HTST pasteurization process further:

HTST Step 1

The HTST pasteurization process begins with the milk being pre-heated to a temp of approx. 104-122°F (40-50°C) which helps prep the milk and reduce the overall time required for pasteurization.

HTST Step 2

Once the milk has been pre-heated, it’s pumped into the pasteurizer – a series of stainless steel plates or tubes heated by steam. The milk is then heated to a minimum temp of 161°F (72°C) for at least 15 seconds. This high temperature is sufficient to kill any harmful bacteria potentially present in the milk.

HTST Step 3

Following pasteurization, the milk is rapidly cooled to a temp of about 39°F (4°C) in order to stop any further bacterial growth. The cooled milk is then packaged and transported to retail outlets, where it’s sold to consumers.

Overall HTST pasteurization is a fast and effective method for removing harmful bacteria from milk products. Proponents of the method will state it preserves the nutritional value of milk, which is only partially true…many enzymes, heat-sensitive vitamins, beneficial bacteria and proteins are damaged during the HTST process, all of which can: positively impact our health, protect the milk and make digestion of lactose easier (More Info). Let’s detail UHT pasteurization process further:

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Ultra-high-Temperature (UHT) pasteurization

For types of milk pasteurization – UHT pasteurization involves heating the milk to at least 280°F (138°C) for at least 2 seconds. The higher temperatures in this method kill more bacteria and are intended to sterilize the milk, which means the milk does not require refrigeration, and has a shelf life of several months. Therefore UHT more commonly used to produce long shelf-life milk and other dairy products.

UHT Step 1

The UHT pasteurization process begins with the milk being pre-heated to a temp of approx. 176°F (80°C) which helps prep the milk and reduce the overall time required for pasteurization.

UHT Step 2

Once the milk has been pre-heated, it is then pumped into a sterile holding tube, where it is heated to a min temp of 280°F (138°C) for 2 seconds or less. The higher temp kills any harmful bacteria potentially in the milk and is designed to sterilize it.

UHT Step 3

Following pasteurization, the milk is rapidly cooled to a temp of about 39°F (4°C) in order to stop any further bacterial growth. The cooled milk is then packaged and transported to retail outlets, where it’s sold to consumers.

As with HTST, UHT pasteurization is also a fast and effective way to remove harmful bacterial and sterilize milk. UHT is common in the milk industry because by sterilizing milk, it can be transported over long-distances and last longer on store shelves. The higher temperatures remove more bacteria, and consequently also remove or destroy more of the many enzymes, heat-sensitive vitamins, beneficial bacteria and especially proteins present in raw milk (More Info). Unlike HTST, the UHT process does affect the taste and nutrient value of milk, making many prefer either HTST or raw milk.

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Low Temperature Long Time (LTLT) Pasteurization

For types of milk pasteurization – LTLT pasteurization aka “Batch Pasteurization” heats milk to 145°F (63°C) for at least 30 minutes. Like HTST, LT pasteurization is designed to kill harmful bacteria potentially present in milk, while preserving it’s nutrient quality, possibly more-so than HTST. LTLT pasteurization is more commonly used by small-scale dairy producers as it requires less of the costly equipment used in HTST or UHT pasteurization.

LTLT Step 1

The UHT pasteurization process begins with the milk being pre-heated to a temp of approx. 104-122°F (40-50°C) which helps prep the milk and reduce the overall time required for pasteurization.

LTLT Step 2

Once the milk has been pre-heated, it is then placed into a large tank or vat, where it’s heated to a temp of 145°F (63°C) for at least 30 minutes. The higher temp kills any harmful bacteria potentially in the milk and is designed to sterilize it.

LTLT Step 3

Following pasteurization, the milk is rapidly cooled to a temp of about 39°F (4°C) in order to stop any further bacterial growth. The cooled milk is then packaged and transported to retail outlets, where it’s sold to consumers.

The lower temperatures in LTLT preserve more of the nutrient profile than HTST or UHT pasteurization; doing less damage to milks enzymes, heat-sensitive vitamins, beneficial bacteria and especially proteins (which are denatured more-so by higher temps). LTLT milk is often preferred by consumers over HTST or UHT pasteurized milk due to it’s improved flavor and nutrient profile.

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Raw Milk for Thousands of Years

The domestication of animals occurred roughly 11,000 years ago, during the neolithic period. However domestication of other animals, such as pigs, cattle, and horses, likely occurred later depending on the region. For example, pigs were first domesticated around 9000-8000 years ago in the Near East, while cattle and horses were domesticated around 6000-4000 years ago in several other regions around the world. So one could argue that raw milk was a staple drink for roughly 4,000-10,000 years (allot longer than pasteurized milk has been around.)

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Is Pasteurization Really Necessary?

I’m sure if you’ve experienced salmonella or food poisoning, this is not an event you’d like to re-visit. However statistics show very few reported illnesses directly linked to raw milk, and only a handful of deaths. In other words if you vet your milk producer, ensure it’s fresh and take the necessary precautions, such as keep it refrigerated and use it quickly…your chance of dying from bacteria found in raw milk is less than your chance of winning the lottery:

  • According to a 1987 report there were 1,000 cases of illnesses directly linked to drinking raw milk in the past 20 years, but there were no reported deaths [Source].
  • From 1992-2002 there were 19 outbreaks linked to raw milk or products made with raw milk, involving 229 people, of which 36 were hospitalized. The most outbreaks recorded in one year was three, as seen in 1993, 1994, 1996 and 2000. [Source]
  • There was an 11-year period from 2003 to 2013 where no outbreaks linked to RDM were reported. However, since 2014 there have been 7 outbreaks (2 of which were form cheese): three of E. coli O157:H7 and four of Campylobacter jejuni, caused by contaminated RDM were investigated. Between 2014 and 2017, there were 114 patients, five hospitalizations and one death. [Source] of the 7 outbreaks – 2 were from farms that failed testing but kept selling milk before fixing the issue, and 1 where temperature controls were violated when a farmer sold from a stall on a hot day. Also the one death was from cheese (not raw milk) and could have been an instance where the pathogen went from consumer to cheese, due to cheese being handled before/while being consumed (vs cheese to consumer).

In one of the above periods 12 outbreaks were associated with pasteurized milk, including 10 caused by pasteurization failures and 2 due to post-pasteurization contamination of milk. I point this out because it shows that not only is the chance of dying from milk extremely low, you actually have a chance of getting sick from pasteurized milk as well. And while you may think “well yeah but a much lower change from pasteurized milk” that’s statistically not really true.

It’s also pertinent to point out that while raw milk consumption is banned in some countries and states, it is permitted and is a daily staple for many in the UK, and for people in certain states/provinces within Canada and the US. For example in the UK producers of raw milk are strictly regulated and registered as RDM (Raw Drinking Milk) producers, which increased in 2014 from 107 to 165 by 2018.

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Conclusion

It’s clear that when looking at types of milk pasteurization: HTST, UHT and LTLT all have different benefits, while also being effective at removing the harmful bacteria in milk. UHT completely sterilizes milk to increase shelf life, but changes the taste and nutrient profile. HTST pasteurization preserves more of the nutrients and LTLT is more cost effective for small scale farmers, while also doing less damage to the many: enzymes, heat-sensitive vitamins, beneficial bacteria and proteins that make raw milk a nutritional powerhouse. However regardless of what proponents of pasteurization say, all of these methods do still significantly alter the nutrient profile of milk (to varying degrees).

So vegans will vilify you for consuming “baby calf milk” from another species, while the FDA will tell you raw milk is a dangerous plague to mankind that must be sterilized out of existence; flexing it’s (tax payer funded) regulatory power across north America by sending dozens of agents and police to arrest and fine farmers and impound or even shut down farms that don’t comply with the edicts of our regulatory agent overlords. I’m sure many wouldn’t agree with the use of their tax dollars towards such a purpose, and so we must ask: if our ancestors used raw milk for thousands of years and had statistically lower rates of many cancers, mental disorders, immune disorders and others…then is pasteurized milk everything it’s “heated-up” to be? (pun intended) I’ll let you make that decision for yourself.

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