Many types of consumable products require sterilization to ensure safety or enhance shelf life. To accomplish this, one of several types of pasteurization is performed to kill bacteria. Vat pasteurization is a common method of treating milk and dairy products. If you’ve ever wondered, “What is pasteurization?” or “How does pasteurization work?” this blog will explain everything you need to know,

What is Vat Pasteurization?

Vat pasteurization — also referred to as batch pasteurization or the holding method — employs specialized equipment to heat milk or cream particles to a specific temperature, effectively eliminating disease-causing bacteria and significantly reducing other bacteria that may impact the quality of the product, ensuring its safety and integrity.

In many situations, vat pasteurization involves heating the milk or cream to 145 °F (63 °C) for 30 minutes. However, if the product contains added sweeteners, a fat content of 10% or more, or 18% or more solid materials, the temperature should be increased by 5 °F (3 °C). Since eliminating harmful bacteria is important for public health and safety, the pasteurization process is the most essential part of a dairy plant.

How Does Vat Pasteurization Work?

During the vat pasteurization process, every particle of a milk product is heated to the minimum temperature required to kill harmful bacteria and held there for at least 30 minutes. To accomplish this, large stainless steel vessels contain and heat the product. These vats feature pipes to deliver water and steam to the vat’s jacket liner, agitators to ensure uniform temperature distribution, and thermometers to monitor temperatures.

It is essential that vat pasteurization equipment and temperature-control instruments be well-designed and accurate. A properly designed vat pasteurizer will feature outlet valves and connections that prevent cold pockets of milk products from being held incompletely pasteurized in the outlet line. It will also be designed and constructed to prevent condensation, leakage, and contamination from water and dust. During pasteurization, vat covers are closed to ensure contaminants don’t enter the milk product.

Methods of Pasteurization

While vat pasteurization is a common method of product sterilization, there are several other techniques to be aware of. The most suitable pasteurization method for a given application depends on product viscosity, heat sensitivity, production speed requirements, and other factors.

  • Vat Pasteurization / Low-Temperature Long Time (LTLT): This method exposes products to a lower temperature over a longer period of time to sterilize them. It is commonly used in the dairy industry for processing milk, ice cream, yogurt, cheese, and other products.
  • Flash Pasteurization / High-Temperature Short Time (HTST): Also called the continuous method, flash pasteurization exposes products to high heat for a short amount of time to kill bacteria without negatively affecting product quality. It is energy efficient and can handle large product volumes at once.
  • Ultra Pasteurization: Ultra-high heat pasteurization uses the highest temperatures of all three methods and takes the shortest amount of time to sterilize food products. In seconds, foods are safe and remain shelf stable for the longest amount of time. However, this method can compromise the taste and quality of certain types of foods, so it isn’t always a suitable option.

Pasteurization Process Systems from Highland Equipment

Whether you’re utilizing vat pasteurization or another method, all sterilization techniques require high-quality process equipment to ensure end-product safety. At Highland Equipment, we develop industry-leading sanitary stainless steel equipment that complies with Dairy 3A and all other relevant standards. To learn more about our pasteurization process systems, contact us or request a quote today.