Is Pasteurization similar to boiling any liquid? I think this is the most common question that comes into the minds of most people. Are you on the list of such people? If yes, then read this complete to know thoroughly about pasteurization.

Pasteurization is a process during which a substance normally a liquid (milk or juice) is heated to a particular temperature for a definite time. This method kills the harmful bacteria and germs in the liquid. Most commonly milk is pasteurized to get rid of dangerous bacteria.



Some foods are heat sensitive and if we heat them, their nutritional contents may be lost. In that condition, such foods will not be worth eating. Then what is the alternate solution to this problem? Don’t you overburden your mind? There exist many alternative methods of pasteurization in which heat is not involved. So, if heat is not involved, it means the nutritional value of food will not be lost.

  • High-Pressure Processing (HPP)
  • Pulsed Electric Field (PEF)
  • Ultraviolet (UV) Light
  • Microwave Heating
  • High-power ultrasound pasteurization
  • Oscillating magnetic field pasteurization

Here is a complete description of pasteurization methods that do not involve heat (non-thermal pasteurization process).

1. High-Pressure Processing (HPP): 

High-pressure processing is a special type of pasteurization technique in which food is preserved. A high level of pressure is applied to the food to destroy the bacteria and other germs.  This method has another name high-pressure pasteurization.

In this method, in a high-pressure vessel food products are placed and water is filled in the vessel. Then pressure inside the vessel is enhanced to 87000 pounds per square inch (psi). This pressure may vary depending on the type of food being pasteurized. This pressure is applied for a few minutes. After release of pressure pasteurized food is removed. 

This so high pressure used in the method is enough to kill the bacteria, viruses, and other microbes that can deteriorate the food products. 

high pressure pasteurization

Benefits of High- pressure pasteurization:

Traditional thermal pasteurization may change the taste and texture of the food. But high-pressure pasteurization does not alter the texture or taste of food products. It also keeps the nutritional contents of food safe. Preservatives are also not required in this process. Those people who have concerns about food preservatives in products can use high-pressure processed food. Now this process is gaining popularity to prepare ready to eat food products.

2. Pulsed Electric Field (PEF) Pasteurization: 

In this process, food products are subjected to short high-voltage electricity bursts.  This technique also destroys pathogens and bacteria without using heat. Pulsed electric field pasteurization is preferred to pasteurize liquid substances like juices and milk.  This PEF pasteurization is also a good substitute for traditional thermal pasteurization. 

In this method, electrical pulses are given to food for a short duration. The time of pulses is typically milliseconds or microseconds. Electric field destroy the cell membranes of microbes present in the food. This results in the death of microorganisms. Due to this treatment flavor, texture or nutritional content of the food does not change significantly. The quality of food also does not alter in this process. 

Pulse Electric Field pasteurization is now significantly applied to a variety of food products. These products include liquid eggs, juices, milk, and meat products. This is considered the secure technology to preserve food products because it enhances the shelf life of products. To apply this food to a vast range of food products, more research is required in this field. 

3. Ultraviolet (UV) Light Pasteurization: 

In UV light pasteurization, food products are exposed to ultraviolet light to destroy bacteria and other microorganisms. UV pasteurization is applied most commonly in water treatment. It is also applied to preserve milk and juices.

This ultraviolet light pasteurization kills pathogens and other harmful microorganisms in beverages and food. A light wavelength of about 200 to 280 nanometers is used in U-V light pasteurization. This wavelength is enough to damage the DNA and RNA or microbes and thus they cannot reproduce. This causes the ultimate death of microorganisms.

In this method, beverages and food products are exposed for a definite period of time to UV-C light. The time can be varied from a few seconds to a few minutes depending on the type of food. In this process, heat is not used and so the texture, taste, and nutritional contents of food are not affected. 

It is proposed as an effective and safe method of non-thermal pasteurization. But it may not be suitable to kill all types of microbes and is not able to eliminate physical contaminants of food or beverages.

4. Microwave Pasteurization:

Microwaves are used in this method to heat a substance up to a particular temperature. These waves are able to inactivate the harmful pathogens and bacteria in food. It is not a common method of pasteurization but is an effective method of preserving some food products.

In this method, the food products are heated by using microwave radiation to get the desired temperature. The temperature limit depends on the level of microbial reduction in the food.  For example, milk is heated to about 72 degrees Celsius for a5 seconds to pasteurize it. While pasteurizing the juices, a comparatively higher temperature for a longer time is required.

There are several advantages of microwave pasteurization over thermal pasteurization.  It is efficient in energy consumption and faster method. We can use it to pasteurize small batches of products.  The products pasteurized by microwave pasteurization have better sensory qualities. These are brighter in color and have a fresher taste relative to other types of pasteurization.

There are also some drawbacks of microwave pasteurization. It is not as suitable relative to thermal pasteurization to destroy microbes to a high level.  Some areas of products may be unevenly heated in this pasteurization method. This can result in overcooking or underheating of food.  Specialized food products having unique sensory qualities can be prepared in this method. Carefully monitoring the process to get safe products is very necessary for this method.

5. High-power Ultrasound Pasteurization:

High-power ultrasound pasteurization is another method of pasteurization in which het is not used.  Sound waves of high frequency are used to kill harmful bacteria and microbes in food products. This technique is becoming most popular these days due to its unique qualities. It can produce high-quality and safe food products and also maintain their nutritional value and sensory properties exactly.

During this method, the food is exposed to sound waves of high frequency resulting in the production of pressure waves. As a result of this in the liquid or semi-solid matrix of food microscopic bubbles are produced.  These bubbles rapidly expand and contract and produce intense localized heat, shear force, and pressure. These cause the death of microorganisms in food products. 

microwave pasteurization

This high-power ultrasound pasteurization can be used to pasteurize a wide range of food products which include, liquids, solids, and semi-solid food.  It is also a fast process and takes just a few seconds or minutes. The time duration depends on the processing conditions and the type of food. It is also a cost-effective technology due to the non-requirement of any chemical.

However high-power ultrasound pasteurization is a new technology and further inquiry and research are required to determine the safety and effectiveness of this method. Several food regulatory authorities like US FDA have provided guidelines and principles to use the of high-power ultrasound pasteurization.

6. Oscillating Magnetic Field Pasteurization:

Electromagnetic energy is used to eliminate harmful bacteria and microorganisms in this pasteurization method. Food is exposed to high frequency alternating magnetic field in this method of food preservation. This causes the rise in temperature due to the generation of eddy currents in food. This high temperature destroys the microbes of products. 

This method can be efficiently used to pasteurize heat-sensitive products. This technique enhances the quality and safety and quality of food.  Fruits and vegetables can also be pasteurized in this method and their flavor and texture remain the same.  It also takes less time in food preservation. 

To increase the efficiency and effectiveness of a variety of food products, more research is required. 

Although these methods are effective in killing harmful bacteria and microorganisms, are not as reliable as the traditional pasteurization method. In different conditions, all these methods are not suitable. Before implementation of any non-thermal pasteurization method, it is necessary to consult with a food safety expert.