Every food product that reaches the market has passed through a series of barriers designed to protect the consumer. Some are visible, such as packaging or refrigeration. Others, however, occur within the process and are crucial in reducing microbiological risks without compromising quality. Among these barriers, thermal treatment occupies a central place. Understanding its purpose in practice is key for any professional in the sector, and it all starts with knowing what pasteurisation is.
If you need to develop new food products, understanding what pasteurisation is helps you make better decisions regarding formulation, processing, shelf life, logistics, and risk control. At Cosmos Aromática, we explain what pasteurisation is, how it is applied in the plant, its three most common types, the temperature ranges involved, and the food families preserved with this thermal treatment.
What is pasteurisation and what does it consist of?
Pasteurisation is a controlled thermal treatment, normally below the boiling point, designed to inactivate pathogenic microorganisms and reduce part of the spoilage microbiota, with the aim of improving safety and extending shelf life without reaching commercial sterility.
The key principle: time and temperature
Pasteurisation is based on a time–temperature binomial: reaching a target temperature, maintaining it for the required time, and cooling afterwards to halt microbial growth and avoid further degradation. In food manufacturing, the value lies in the repeatability of the process: the same product must receive the same treatment in every batch or in continuous flow.
What are the 3 types of pasteurisation?
To understand what pasteurisation is, we must clarify that it is usually organised into three classic schemes based on operation method and thermal severity: slow (in a vat), rapid (HTST), and UHT.
Slow pasteurisation or vat pasteurisation (LTLT / vat)
This is a batch process: the product is heated and held in a tank for a relatively long time. A typical parameter often cited in dairy products is 63 °C for 30 minutes. Its current use is more frequent in small-scale production or when batch-by-batch control is preferred.
Common technical points
- Requires good agitation for thermal homogeneity.
- Needs rapid subsequent cooling.
- Hourly productivity is usually lower than in continuous flow.
Rapid pasteurisation (HTST, High Temperature Short Time)
This is the dominant option in many liquid lines due to its efficiency: it is heated in an exchanger (plate or tubular), held in a holding tube, and cooled. For milk, a typical range is 72–75 °C for 15–20 seconds.
What it provides to the industry
- High processing capacity.
- Better sensory preservation than longer treatments.
- Easy integration with heat recovery equipment (energy efficiency).
UHT (Ultra High Temperature)
In UHT, work is carried out above ~138 °C for a few seconds (technical and popular literature usually places it in ranges such as 138–150 °C for a few seconds, depending on the product and system). The idea is to maximise microbial destruction while minimising exposure time.
Operational key
- It is usually associated with aseptic lines to avoid recontamination after treatment.
- It allows for long shelf lives without refrigeration in many cases, provided the packaging and material barrier are suitable.
What is the pasteurisation temperature?
There is no single “pasteurisation temperature” valid for everything. The correct question is: what time–temperature combination achieves the microbiological objective for that food whilst maintaining quality? That said, there are well-established references in the industry:
- HTST in milk: typically 72–75 °C for 15–20 s.
- LTLT in milk: a classic value is 63 °C for 30 min.
- UHT: above 138–150 °C for a few seconds (depending on the system and objective).
Factors that require adjusting the binomial
Temperature is defined by product and process variables:
- pH and acidity: acidic foods often allow for less severe treatments for the same level of safety against certain pathogens, because the pH itself limits growth.
- Fat and solids content: these can protect microorganisms against heat and also change thermal transfer.
- Viscosity: determines the flow regime and heating uniformity.
- Initial microbial load: a high-quality raw material is not the same as one with high contamination.
- Shelf life objective: safety and shelf life are not the same; shelf life also depends on spoilage agents, enzymes, and recontamination.
Did you know that heat defines flavor?
Which foods are preserved with pasteurisation?
Pasteurisation is mainly used for foods where heat transfers well (liquids or semi-liquids) and where safety and shelf life benefit from a reduction in flora without “overcooking” the product.
Dairy
- Drinking milk.
- Dairy mixes for ice cream.
- Bases for yoghurt (with thermal treatment adjusted to the subsequent process).
- Cream and dairy preparations.
In dairy products, in addition to safety, the aim is to control enzymes and prevent spoilage flora from rapidly reducing shelf life.
Juices and beverages
In juices, pasteurisation is applied to control pathogens and spoilage agents and maintain a stable sensory profile. The risk of consuming untreated juices has been reflected in real outbreaks associated with unpasteurised drinks.
How does heat affect acidity?
Beer and fermented beverages
It is used to stabilise microbiologically and avoid flavour deviations due to subsequent contamination. In these products, the objective is often closely linked to stability during distribution.
Liquid eggs and egg products
Pasteurised liquid egg is a standard in many industrial applications (sauces, batters, ready meals) for safety against pathogens.
Sauces, creams, soups, and ready meals
In ready-to-eat or ready-to-heat products, pasteurisation can be combined with appropriate packaging and refrigeration to extend shelf life, always with a focus on avoiding contamination after treatment.
How it is applied in the plant: control points that decide the result
Understanding what pasteurisation is from the plant’s perspective involves looking at the entire process.
1) Heating with homogeneity
In HTST, the exchanger (plate or tubular) defines much of the thermal performance. The goal is for the entire product to reach the target temperature without “cold spots”.
2) Actual retention time
The holding tube must ensure the product remains for the minimum required time at the set temperature. In milk, the typical HTST scheme is formulated as 72–75 °C and 15–20 s, with design requirements so that the entire flow receives the minimum treatment.
3) Cooling and protection against recontamination
After treatment, cooling quickly is as important as heating: it reduces the window for microbial growth. Afterwards, the focus shifts to hygienic design: valves, connections, buffer tanks, fillers, and packaging.
A real case that explains why treatment matters
In 1996, an outbreak of E. coli O157:H7 associated with unpasteurised commercial apple juice was investigated in the USA. The epidemiological report identified cases in ill people who had consumed that juice in the days prior to the onset of symptoms. It is a clear reminder that, in ready-to-consume beverages, thermal treatment (or a validated alternative) is not a detail: it is a safety barrier.
The latest technological advances to maximize food safety:
A thermal decision that protects your product
As we have analysed, understanding what pasteurisation is is essential for reducing risks, giving stability to the product, and improving manufacturing consistency. Choosing between LTLT, HTST, or UHT depends on the food, the shelf life objective, the packaging system, and your line’s capacity.
If you are developing or reformulating products and need the aromatic profile to remain stable after thermal treatment, at Cosmos Aromática we work with customised aromatic solutions and support manufacturers with services throughout the product’s life cycle. Contact our team to review your application and move forward with a proposal adapted to your process.