Milk Pasteurization- Methods, Steps, Significance

Pasteurization : Definition

The act or process of heating a beverage or other food, such as milk or beer, to a specific temperature for a specific period of time in order to kill microorganisms that could cause disease, spoilage.

What Is Pasteurized Milk?

Pasteurization was first introduced in the late 1800s, and was pioneered by Louis Pasteur after his study on the fermentation process of both wine and vinegar. After discovering the difference in the microbes in both substances, he developed the process, determining the exact time and temperature microbes die.

Pasteurization was first applied to dairy products after the spread of numerous milk-borne infections in the population. It refers to the heating of milk to a temperature higher than the boiling point, and then rapidly cooling it.

This process supposedly removes the bacteria and other harmful particles found in conventionally produced milk. However, what government health agencies have left out is that pasteurization renders essential enzymes and nutrients inactive.

Conventional Milk May Also Be ‘Ultra-Pasteurized’

In addition to this, milk producers have also devised another process for milk production, a process called ultra-heat treatment (UHT), which produces ultra-pasteurized milk. Nowadays, you’ll notice that most milk, including organic milk, bear the label “UHT.”

Milk that is labeled as such is thermally processed at or above 280 degrees Fahrenheit, in contrast to pasteurization, which heats the milk at about 161 degrees Fahrenheit. This prolongs its shelf life under refrigerated conditions.

While a small amount of bacteria can survive the process of pasteurization, ultra-pasteurization produces a nearly sterile milk product. This means that ultra-pasteurized milk can last from 30 to 90 days when unopened, which is good news for milk producers because they can ship to a larger population without the risk of spoilage.

But is ultra-pasteurized milk good for you? No, it isn’t. Because of the extreme process, ultra-pasteurized milk contains fewer nutrients than pasteurized milk, and even fewer when compared to raw milk. Researchers and microbiologists have also said that ultra-pasteurization is extremely harmful to milk, as it was found to flatten milk molecules and cause immune responses in the body when digested.

Raw Milk Versus Pasteurized Milk: Which Is Safer and Healthier?

The debate between raw milk and pasteurized milk has plagued the public for numerous years because of both safety and health issues on both sides. Processed milk advocates claim that the pasteurization is essential to avoid the recurrence of milk-borne diseases such as brucellosis, listeriosis and typhoid fever. They also claim that aside from preventing bacterial infections, pasteurization can lengthen the shelf life of milk.

But although pasteurized milk is highly recommended and advertised by both the CDC and FDA, the talks of its safety are questionable. While raw milk enthusiasts are commonly lambasted because they supposedly “expose themselves to a higher risk of milk-borne bacteria,” pasteurized milk consumers actually have a higher chance of ingesting chemicals and other toxins from conventional dairy factories.

Because of pasteurization and other filtering processes, factory milk producers are allowed to raise cows in unhealthy, cramped environments, where they are fed an unnatural diet of grains and corn. This is mainly because they are dependent on pasteurization’s ability to kill off pathogens or filter antibiotics that may have leaked into their milk products.

But while they claim that this is entirely safe, the nutrient content and the overall quality of these milk products may be compromised.6 Pasteurization removes the essential nutrients and compounds that are beneficial to the human body. Studies show that this process deactivates the enzymes that are necessary for the human digestion of milk, kills off the good bacteria that may be beneficial to the human body, alters the calcium content and removes most of the vitamin C in raw milk.

By switching to raw milk, you ensure that you get a whole food filled with minerals, proteins, vitamins and beneficial bacteria that assist digestion and metabolism.

The only issue that is often held against raw milk is that it supposedly increases your risk of ingesting pathogens or harmful bacteria, but this can easily be dealt with by locating and sourcing your raw milk from trustworthy producers. Organic, pasture-raised dairy cattle guarantee that you get safe and high-quality raw milk, in contrast to the antibiotic-treated cattle used in concentrated animal feeding operations (CAFOs).

Milk Pasteurization- Methods, Steps, Significance

There is a general and urgent need for rapid procedures, applicable to process control, to monitor food safety and quality.
Pasteurization is a process in which certain packaged and non-packaged foods (such as milk and fruit juice) are treated with mild heat, usually less than 100 °C (212 °F), to eliminate pathogens and extend shelf life.
The process safeguards foods by destroying or inactivating organisms that contribute to spoilage, including vegetative bacteria but not bacterial spores.
The process was named after the French scientist Louis Pasteur, whose research in the 1880s demonstrated that thermal processing would inactivate unwanted microorganisms in wine.
Today, pasteurization is used widely in the dairy industry and other food processing industries to achieve food preservation and food safety.

Different Types of Thermal Processing Methods

Thermization: Heat the milk to between 57°C to 68°C and hold for 15 minutes. Thermization targets pathogenic bacteria while leaving the good bacteria in the product. The low temperatures do not alter the structure and taste of the milk.
Batch pasteurization: Also known as low-temperature long time (LTLT) pasteurization. Heat the milk to 63°C for 30 minutes. The extended holding time causes the alteration in the milk protein structure and taste.
Flash pasteurization: Also known as high-temperature short time (HTST) pasteurization. Heat the milk to between 72°C to 74°C for 15 to 20 seconds. Targets resistant pathogenic bacteria spores (Clostridium botulinum spores).
Ultra-high temperature (UHT) pasteurization: Heat the milk to between 135°C to 140°C for 2 to 4 seconds. The extreme heat targets Coxiella burnetii, which causes Q-fever. The heat kills all the vegetative forms of bacteria and the milk can survive for 9 months.
Canned sterilization: This is a wet treatment of canned milk products in an autoclave/specialized treatment chambers. Heat to between 115°C to 121°C for 10 to 20 minutes.

Milk Pasteurization

Milk pasteurization is the process of heating milk (or milk product) to a predetermined temperature for a specified period without re-contamination during the entire process.
The predetermined temperature usually depends on the heat resistance of spoilage microorganism that the pasteurization program is targeting to destroy.

Methods Used in Milk Pasteurization

High-Temperature Short Time (HTST) Pasteurization

This type of pasteurization is also known as flash pasteurization.
Flash pasteurization involves heating milk to 71.7°C for 15 seconds to kill Coxiella burnetii, which is the most heat resistant pathogen in raw milk.
Since it is technically impossible to bring the milk to that exact temperature, it is always safe to work with a range of temperatures. To be safe, you can heat the milk to between 72°C to 74°C for 15 to 20 seconds.
This will ensure that the milk is heated uniformly to the required temperature.
This method is most suitable in continuous pasteurization systems.
Flash pasteurized milk will keep for between 16 and 21 days. For commercial reasons, some manufacturers intentionally reduce the number of days to push the products out of the shelves.

Low-Temperature Long Time (LTLT) pasteurization

Here, the temperatures used for pasteurization are reduced to 63°C and held for 30 minutes.
The prolonged holding period alters the structure of the milk proteins making it better suited for making yogurt.
This method is best for batch pasteurization where the milk is held in a jacketed vat for effective pasteurization.
There are many designs of batch pasteurizers in the market that are suitable for both domestic and commercial use.

Ultra High Temperature (UHT) Pasteurization

This is a completely closed pasteurization method. The product is never exposed even for a fraction of a second during the entire process.
It involves heating milk or cream to between 135°C to 150°C for one to two seconds, then chilling it immediately and aseptically packaging it in a hermetic (air-tight) container for storage.
Despite the risk of Millard browning, UHT pasteurization remains the most popular milk preservation method for safe and stable milk.

Steps of Pasteurization

1. Milk chilling

Chilling is not a pasteurization process but it is a necessary step when dealing with large volumes of milk.
Milk leaves the cow’s udder at temperatures above the ambient, which encourages rapid bacterial multiplication that speeds up spoilage.
However, reducing the temperatures to between 2° C to 5° C arrests bacterial growth and metabolism.
This provides a head start at keeping the quality before proper pasteurization commences.

2. Pre-heating (regeneration) and Standardization Stage

After bulking, the chilled milk is heated to about 40°C to facilitate easy separation of butterfat during standardization.
The system uses regenerative heating, i.e., it uses the heat of the already pasteurized milk to heat up the incoming chilled milk. The chilled milk, in a counter current flow, cools down the pasteurized milk.
The purpose of standardization is to obtain a product with uniform content of butter fat.

3. Clarification stage

Clarification is essential for removing all foreign matter from the product.
Large solid particles are removed by straining the milk through tubular metallic filters.
A centrifugal clarifier (not the one used for standardization) is used to remove all soil and sediments from milk.
The filters, usually fitted in parallel twins permits continuous processing as one can be cleaned while the other is running.
Clean the filters regularly (between 2 to 10 operational hours depending on the level dirt) to avoid growth of bacteria.

4. Standardization stage

It is important to standardize milk fat to ensure that you end up with a product of consistent quality in the market. Different consumers prefer different products.
There are customers who will consume skim milk only while there are those who will take low fat milk. There are those who will take standardized milk while there are those who prefer high fat milk.
Standardization is necessary to ensure that all the customers are catered for. Again, it is during the process of standardization that you get to separate the butterfat that is used for making cream and other fat based products such as butter and ghee.

5. Homogenization stage

Homogenization is a physical process of breaking down the the milk fat globules into tiny droplets to discourage cream separation.
Tiny droplets of fat do not rise in a milk column since reducing their sizes also increases their density in the milk.
A milk homogenizer working at between 100 to 170 bars splits all the fat globules into very tiny droplets that increases the level of integration of the fat in the milk.
As a result, the milk fat remains uniformly distributed in the milk.

6. Heating section

Utilizes heat from steam to raise the temperatures of the milk from about 60°C to the required 72°C that is effective to kill the Clostridium botulinum spores.
The steam exchanges heat with the milk across the PHE plates in a counter current motion.
At the end if this section, there is a temperature sensor, which controls the flow diversion valve.
Any milk that does not attain the required temperature is diverted back to the heating section until it attains the required temperatures.

7. Holding section

After heating, milk flows into the holding tubes whose lengths have been calibrated with the milk flow rate to ensure that milk takes at least 16 seconds in the tubes. All the milk must maintain the required pasteurization temperatures at the end of the tubes.
In case of a breach, a sensor will trigger the flow diversion valve to take the milk back to the heating section to bring the milk to the required temperature.
Once the milk has attained the required temperatures at the end of the holding tubes, milk flows back to the regeneration section to heat the incoming chilled milk while in itself being cooled down to about 30°C.

8. Cooling/chilling section

After regenerative cooling of pasteurized milk, it moves to the cooling section of the PHE where chilled water/PHE coolant lowers the temperature of pasteurized milk to 4°C.
The chilled milk is then pumped to the packaging machines for aseptic packaging and subsequent storage in the cold room.

Significance of Pasteurization

Proper pasteurization is necessary for the following reasons:

The chief objective of milk pasteurization is to destroy pathogenic bacteria that could have a public health concern. By destroying these microorganisms, the product becomes safe for public consumption.
Secondly, pasteurization eliminates destructive bacteria and enzymes that could cause spoilage of the product. This leads to a prolonged shelf life of the milk.
There is need to ensure that the product can keep for longer periods without expensive storage equipment. Pasteurization will eliminate spoilage bacteria and enzymes and extend the shelf life of the product.

Possible Side Effects and Dangers of Pasteurized Milk

Due to the numerous chemically manipulated components of pasteurized milk, it may pose numerous threats to your health. This includes the hidden exposure to pesticides, drugs and other harmful chemicals that may have seeped into the milk. The other dangers of the consumption of pasteurized milk include:

•Exposure to hormones and antibiotics. A 2011 research tested various milk products for chemicals that may have contaminated the product. It showed that conventionally sourced milk had high amounts of antibiotics, anti-inflammatories, natural hormones, anti-malaria drugs, steroid hormones, and anti-fungal drugs. This is probably because of the exposure of the cattle to these chemicals inside CAFOs.

Antibiotics are usually given to cattle to treat mastitis, but this eventually seeps into the milk produced by these cattle. The consumption of this type of milk eventually leads to you to acquire these harmful chemicals that aren’t even supposed to be in milk.

•Ingestion of glyphosate. Glyphosate is a chemical component of Roundup, a pesticide and herbicide that is usually applied to genetically engineered crops, which are then fed to the cattle. Aside from the possibility of glyphosate contamination in the milk that these cattle produce, you are also exposed to the altered composition of the milk because of the unnatural way that these dairy cows are fed.

•May increase asthma risk. Studies show that pasteurization alters the composition of commercially available milk. Instead of preventing the development of asthma by stabilizing mast cells and preventing inflammation, pasteurized milk destabilizes the mast cells and triggers the release of histamines, causing inflammation and eventually, asthma.

•May lead to bone wasting or osteoporosis. Milk has always been packaged as the primary source of calcium, helping preserve bone density and skeletal health. However, pasteurization has been observed to destroy phosphatase in milk, an enzyme that is crucial for the absorption of calcium. This renders the calcium in milk indigestible and basically useless.

While pasteurization was initially done to protect the population, the process has allowed dairy corporations to hide unnatural and chemically-based milk production processes. Instead of providing a healthier and safer choice for people, pasteurized milk has become a lesser version of what milk is supposed to be, endangering the public and simultaneously depriving people of vitamins and minerals that are absolutely essential for your body.

Instead of consuming pasteurized or UHT-labeled milk, consider switching to raw milk to ensure that you get all the nutrients and enzymes that are supposed to be in dairy. This will guarantee that you’re getting whole and healthful milk, in contrast to its sterile counterpart.

Frequently Asked Questions (FAQs) About Pasteurized Milk

Q:Why is Pasteurization important?

A:It is important because pasterurization kills all the germs which cause diseases like diptheria, undulant fever, tuberculosis, typhoid fever, dysentery, food poisoning, septic sore throat, and Q-fever and keeps us safe and healthy.

Q: When did pasteurization of milk start?

A: Before pasteurization was developed by Louis Pasteur, William Dewes proposed the heating of milk before feeding infants during the prevalence of milk-borne diseases. It was only knowingly applied to milk in the late 1880s by dairy producers.

Q: Is organic milk pasteurized?

A: Unfortunately, most brands of organic milk in the United States are still pasteurized. But although most of the organic milk available still undergoes this damaging process, studies show that it is still a better choice compared to conventional homogenized or pasteurized milk.

Q: Is cultured milk pasteurized?

A: Yes. According to the regulations that are enacted by the FDA, the production of cultured milk requires the addition of microbial culture to pasteurized or homogenized milk.

Q: Is pasteurized milk sterile?

A: Not entirely. Pasteurization kills off a significant amount of the pathogens found in milk. There are instances where a small amount can survive this process. UHT, on the other hand, processes the milk to the point that the milk is virtually sterile.

Q: Is pasteurized milk safe to drink?

A: Despite claims of its safety, pasteurized milk can expose you to different harmful toxins that may have seeped into the milk, especially if the pasteurized milk comes from conventional dairy farms. It should be noted that pasteurized milk contains a lower concentration of the beneficial components found in unprocessed and raw milk.

Q: Is pasteurized milk safe during pregnancy?

A: Because of the possible chemical components of pasteurized milk, its consumption may cause different repercussions for both you and your unborn child. Consider drinking raw milk from trustworthy distributors so that you can get the whole array of nutrients and enzymes in milk, without the risk of exposing yourself to possible toxins in conventional milk products.

Q: Is raw milk better than pasteurized milk?

A: Yes raw milk is the highest quality milk you can get. Nutritionally, raw milk contains active enzymes, vitamins and minerals, which are deactivated in pasteurized milk. Consumption of raw milk also ensures that you do not unknowingly expose yourself to possible harmful components found in pasteurized milk.