Pasteurization Process - Types, Procedure, Myths, and Facts

What Is the Process of Pasteurization?

Pasteurization is the process of heating liquid food items to high temperatures and then cooling them suddenly to low temperatures before packing them into containers. The process is used worldwide for milk, both by the food industry and at home. This process kills the harmful microorganisms present in the milk, helps to increase its shelf life, and makes it safe to drink, leading to its mass usage worldwide. Hence, the milk can be stored for a long time and used more efficiently, avoiding waste. Another advantage of this method is that the taste and nutritional value of the liquid remain intact.

What Is Raw Milk?

Raw milk is milk that directly comes from the farm animal and becomes available for consumption. There have been claims that raw milk is healthy, but these claims do not have scientific approval. Raw milk contains many pathogens and is risky for health if consumed.

Who Invented the Process of Pasteurization?

Louis Pasteur, a French scientist, discovered pasteurization in 1864. He found this technique to extend the shelf life of alcoholic drinks used for social purposes, like wine and beer. Pasteurization also proved beneficial for milk, and after that, it was widely accepted and used globally. It is the most familiar form of heat treatment used on milk today.

Why and How Was Pasteurization Discovered?

In the nineteenth century, milk production had risen exponentially, but it came with a demerit: an increase in the death rate due to an upsurge in the diseases born from milk. Milk commonly contains bacteria like Mycobacterium tuberculosis, Salmonella, E. coli, Listeria, Campylobacter, and other non-spore-forming microbes that cause food poisoning.

Before discovering the pasteurization process, diseases like tuberculosis (a bacterial infection affecting the lungs and other body parts), Q fever (a bacterial infection that spreads from animals to humans), diphtheria (a bacterial infection of the throat and nose), severe streptococcal infections, typhoid fever (a bacterial infection spreading from contaminated water and food), and other foodborne illnesses were prevalent.

As the revolution gained widespread momentum, the incidence of milk-borne disease outbreaks fell drastically. It came as a life-saving method, which led to less than one percent of reported attacks today.

The milk gets contaminated from a variety of sources, such as:

• Waste products of the animals, like feces and urine. All the three concerned parts are close to one another; contamination is relatively easy.

• Infections and illnesses of the animal udder.

• Skin flora of the animals.

• The surroundings and residing places of the animals have dirt and dust.

• The animal food, equipment, and machines involved in caring for it.

• The animals consume drugs and medicines for their treatment.

• Other neighboring animals on the farm carry disease-causing microbes.

• And the people are dealing with the animals.

• So, to make the milk free from all contaminants, pasteurization is necessary before consumption.

What Are the Different Types of Pasteurization Methods?

1. Vat Pasteurization: This method, also known as batch pasteurization, was originally used by Louis Pasteur. The milk is heated to 145 degrees Fahrenheit for 30 minutes.

2. Continuous-flow Pasteurization: It is of the following types:

• High-Temperature Short Time (HTST): In this method, the temperature of the milk is increased to 161 degrees Fahrenheit (71 degrees Celsius) for at least 15 seconds or 145 degrees Fahrenheit (62 degrees Celsius) for 30 minutes with the help of metal plates and hot water, and then the milk is suddenly cooled.

• Higher Heat Shorter Time (HHST): In this approach, the milk is heated from 191 degrees to 212 degrees Fahrenheit (89 to 100 degrees Celsius) for one second to 0.01 second, depending on the selected temperature. The equipment used here is somewhat non-identical to the HTST technique, and it is called a heat exchanger.

• Ultra-High Temperature (UHT): The milk is heated to 280 degrees Celsius (138 degrees Celsius) for at least two seconds in commercially sterile equipment. It is then filled under aseptic conditions into hermetically sealed packaging. The milk is cooled rapidly after that. This method kills good bacteria as well, besides harmful bacteria, but gives a much longer shelf life to the milk. The milk treated by this technique only needs refrigeration once the pack is opened, and its shelf life is prolonged for at least six months. The product obtained by this technique is known as shelf-stable.

• Ultra-Pasteurized (UP): This process is different from UHT. The milk is again pasteurized using commercially sterile equipment, but it is not considered clean because of its less stringent packaging. The temperature is raised to 280 degrees Celsius (138 degrees Celsius) for at least two seconds, then cooled quickly. The milk served by this method needs refrigeration and remains fresh for 30 to 90 days.

Both UHT- and UP-treated milk need refrigeration, and their expiring times after opening the package are the same as those of other pasteurized products.

The HSTS and UHT techniques involve the compelled flow of raw milk in the hollow pipes and thin plates of the metal. The temperature of the metal increases, consequently raising the milk's temperature. This technique keeps the milk heated for the appropriate time before it gets pushed into the cooling chamber of the pasteurizer. The milk is then suddenly cooled to a temperature below 41 degrees Celsius, which kills the pathogenic microbes that may have become inactive at high temperatures but may get activated at moderate temperatures. This milk is then packed in sealed containers and distributed for consumer use.

What Are the Myths and Facts About Milk and Its Pasteurization?

Like all other famous things, pasteurization also includes a list of myths and facts.

They are as follows:

• Lactose intolerance and allergies are caused by both raw milk and pasteurized milk. The pasteurization process has no role in these reactions, as they are caused by sensitivity to milk proteins.

• The pathogenic microbes are only killed by pasteurization and do not destroy themselves.

• The nutritional content and value of the milk remain unaffected by pasteurization.

• All pasteurization processes do not ensure safety without refrigeration once the package is opened.

• Pasteurization destroys the pathogenic microbes and prevents people from falling ill.

What Is the Difference Between Pasteurization and Sterilization?

Pasteurization and sterilization methods are almost similar in that both use heat to kill the microorganisms in the food in an airtight container. However, both processes differ in their action, as sterilization eliminates or kills the living organism from the food, whereas pasteurization does not kill but only reduces the microbiological load. Also, the temperature used in both the process and the useful life of the final product vary.

Conclusion:

Pasteurization provides many health benefits, particularly wellness, without showing any side effects. Pasteurized milk should be used, which is the key to healthy milk consumption.