In the food industry, pasteurization is one of the most widely used techniques for extending food shelf life. This technique involves heat treatment at a moderate temperature of between 60°C and 100°C maximum, followed by rapid cooling, to reduce the presence of microorganisms likely to develop in food (bacteria, molds, yeasts, etc.). The aim is to make the product fit for consumption and extend its shelf life. The equipment used in the food industry to do this is called a pasteurizer.
Some foods likely to be preserved through pasteurization include:
There are different industrial food pasteurizer models, some of which process pre-packaged products, while others are used for products in raw form, i.e. without packaging.
A. Pasteurizers for packaged products include:
A steam pasteurizer consists of a large chamber in which batches of products can be pasteurized at once. They are easy to use, require little handling, and operate in batches.
The main advantage of this type of pasteurizer is that the steam injected does not damage the packaging, so there is no risk of the packaging contaminating the product, resulting in pasteurized products that are safe to consume.
In contrast to the simplicity of steam pasteurizers, tunnel pasteurizers are more complex, consisting of a series of chambers where the product is heated directly or indirectly. Steam, water sprays, or hot water baths are used to gradually heat a product as it passes through each chamber, ensuring that the appropriate temperatures are reached without damaging the packaging.
This type of pasteurizer is an automated system that can be easily integrated into a continuous production line.
Although different in their construction (number of chambers), these two types of pasteurizers can use steam injection as the heat source for pasteurization. The disadvantage of this heat source is that the temperature rise of the product is slow and uneven due to the poor thermal conductivity of the packaging material. These drawbacks can be overcome by using radio-frequency pasteurizers. Radio frequencies help to generate heat rapidly and volumetrically in the product. The heating process is rapid, uniform, and controlled, minimizing product deterioration.
B. Pasteurizers for unpackaged products include:
As their name suggests, they operate with a tank in which unpackaged products are pasteurized. Tank pasteurization is a batch process, also known as Low-Temperature Long Time (LTLT) pasteurization. The products are heated to 63°C for 30 minutes.
This is the least expensive option for pasteurization. Because of the temperature, time, and cost involved, they are often used in small factories or for small batches.
HTST (High-Temperature Short Time) pasteurizers use flash pasteurization, otherwise known as continuous pasteurization. This has become one of the most common pasteurization methods today. This type of pasteurizer operates continuously, which quickly and efficiently destroys microorganisms in products. Food is heated to 71.7°C in a plate or tube heat exchanger and held at this temperature for 15 seconds in a holding tube, before returning to the exchanger to be cooled to 32°C and then 4°C.
Here are the main points to consider when choosing an industrial pasteurizer:
Temperature is the most important element in a pasteurizer, as it is this that eliminates the bacteria present in food. The pasteurizer must be able to reach a temperature suited to the type of product being pasteurized. To pasteurize a wide range of products, you need an industrial pasteurizer with a temperature range from 60 to 100°C. Temperatures above 100°C are used for sterilization.
Some pasteurizers are dedicated to a single type of solid or liquid product. Examples include juice pasteurizers and milk pasteurizers. The choice of these standard models depends on the products you have to pasteurize.
Small-scale industries tend to opt for tank pasteurization. This type of pasteurizer is the least expensive option. If you work with small batches (< 4000 L), lower temperatures and longer durations are more suitable. For high-volume industries (> 4000 L), on the other hand, HTST pasteurizers would be the most economical and efficient option. HTST systems are designed to work with large quantities at higher yields. HTST pasteurizers are more complex, so they can be more expensive than LTLT pasteurizers.
It’s best to opt for self-cleaning models (CIP – Cleaning In Place), as they save you time and guarantee better hygiene.
In the food industry, several products, whether liquid, semi-solid, or solid, are pasteurized under different conditions while respecting the thermal sensitivity of each product. Below is a non-exhaustive list of pasteurization conditions for some of the most frequently consumed food products.
Pasteurization Processes by Product
|
FOOD |
PASTEURIZATION PROCESS |
| Beer | 20 minutes at 60°C |
| Milk | 15 seconds at 72°C |
| Cream | 15 seconds at 82°C |
| Fruit juice | 10 seconds at 97°C |
| Fruit and vegetable compotes | 90°C to 95°C |
| Egg by-products | 2 to 6 minutes at 57°C to 65°C |
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