What is the Difference Between HTST and LTLT

The key difference between HTST and LTLT is that HTST method uses a high temperature and a short time for the pasteurization, whereas LTLT method uses a low temperature and a long time for pasteurization.

Pasteurization is a thermal process that is useful in killing harmful bacterial species in packaged food such as milk and fruit juice. This process involves the treatment of these foods with mild heat, which can reduce or eliminate pathogens in the food, thereby it can extend the shelf life. Therefore, pasteurization is important in deactivating organisms and enzymes that can lead to the spoilage of food and reduce the risk of diseases. However, the process does not remove any bacterial spores.

CONTENTS

1. Overview and Key Difference
2. What is HTST  
3. What is LTLT
4. HTST vs LTLT in Tabular Form
5. Summary – HTST vs LTLT

What is HTST?

HTST stands for high temperature short-time pasteurization. It is also known as flash pasteurization. This is a method of heat pasteurization in which perishable beverages such as fruit and vegetable juices, beer, wine, and milk undergo a thermal process where their color and flavor are maintained. However, some types of cheese respond to this process differently.

This method is important in killing spoilage microorganisms before filling the food into the container. This makes the food safe and extends the shelf life. However, we need to use aseptic processing in order to prevent post-pasteurization contaminations.

Figure 01: The Step by Step Process of HTST Pasteurization

In the flash pasteurization of milk or other juice, we need to use a controlled and continuous flow of liquid that is subject to high temperatures around  71.5 Celsius degrees (maximum is at 74 Celsius degrees). This thermal treatment is performed for about 15 to 30 seconds. This also requires a rapid cooling step, which occurs at a range of 4 °C to 5.5 °C range.

According to the standard US protocol for the HTST pasteurization of milk, we need to use 71.7 °C for 15 seconds. Then it kills Coxiella burnetiid, which is the most heat-resistant pathogenic germ we can find in raw milk. This pasteurization condition was introduced in 1933. This method can reduce the harmful bacterial content by 99.9 %.

What is LTLT?

LTLT stands for low temperature long-time pasteurization. This process involves heating the food to a temperature around 62.5 °C for 20-30 minutes. It is a very important method for milk banks, which use the Holder method for pasteurization or for the Vat method.

Figure 02: Pasteurized Milk

LTLT does not change the structure and the taste of the milk. It is also known as batch pasteurization. However, if we use an extended holding time in this process, it can cause an alteration in the milk protein structure and taste.

What is the Difference Between HTST and LTLT?

HTST and LTLT are two types of pasteurization methods. HTST stands for high-temperature short-time pasteurization while LTLT stands for long temperature long-time pasteurization. Therefore, the key difference between HTST and LTLT is that HTST method uses a high temperature and a short time for the pasteurization, whereas LTLT method uses a low temperature and a long time for the pasteurization.

The below infographic presents the differences between HTST and LTLT in tabular form for side by side comparison.

Summary – HTST vs LTLT

Pasteurization is a thermal process that is useful in killing harmful bacterial species in packaged foods such as milk and fruit juice. There are two types of pasteurization known as HTST and LTLT. The key difference between HTST and LTLT is that HTST method uses a high temperature and a short time for the pasteurization, whereas LTLT method uses a low temperature and a long time for the pasteurization.