The food industry is innovating in terms of meeting changing demand and consumer tastes. New products, processes and technologies are increasingly being introduced, indeed one of the most prominent inventions in the sector is the High Pressure Processing or high pressure processing (HPP).
It is a technique that helps to preserve products for longer, improving food safety. It comes as no surprise, therefore, that if you have been to the supermarket lately, you have noticed a number of "cold-pressed" juices, smoothies and soups taking up considerable shelf space.
Well, the technology used in these beverages is HPP, and it is even being used in a variety of products. In the following, we will go into more detail on what HPP is. High Pressure Processinghow it works, its advantages and much more.
High pressure treatment: What is it and how does it work?
HPP is a technology of pasteurisation which extends the shelf life of products by applying pressure to inactivate micro-organisms (yeasts, moulds and bacteria) compared to conventional heat or heat treatment.
This results in food and beverages that more closely resemble their "fresh" or "unprocessed" counterpart. Typical operating pressures are between 400 MPa and 600 MPa (58 000 - 87 000 psi) for a retention time of 2 to 10 minutes, depending on the product application.
How does high-pressure treatment work? Here are some keys to understanding it:
- High Pressure Processing affects the permeability of the plasma membrane of the micro-organism, and the disruption is like the bursting of a balloon.
- When the damage cannot be repaired, it leads to loss of function and ultimately cell death.
- Microorganisms have different degrees of resistance against HPP, due to differences in chemical composition and cell membrane structure.
- Gram-positive bacteria are more resistant to pressure than gram-negative bacteria depending on their membrane fluidity.
- The food matrix, pH and temperature also affect microbial inactivation along with processing parameters such as pressure application and holding time.
Ultimately, high-pressure food processing (HPP) is effective in destroying harmful micro-organisms and poses no more food safety problems than other treatments.
Advantages of the HPP
Like any invention, the High Pressure Processing is being applied in a variety of products because it offers a number of notable advantages, including:
- Food security: HPP inactivates vegetative pathogens (Listeria monocytogenes, Salmonella, Escherichia coli) and spoilage microorganisms (Lactobacillus, Bacillus). It can, in addition, reduce 5 log pathogens necessary for refrigerated products, but does not inactivate spores (Clostridium botulinum spores).
- Improved sensory attributes: Colours, textures and aromas of food and beverages are better preserved by pressure than by heat-based processing.
- Improved Nutritional Composition: Several nutrients are heat-sensitive and degrade with conventional heat treatment techniques, HPP allows the preservation of these heat-sensitive nutrients, improving the functionality of the products.
- Clean label: The ability of this technology to preserve products and increase shelf life eliminates the need for preservatives (natural or chemical).
- Versatile use: The processing equipment required is independent of the sample volume and product type, as the water present in these products allows the pressure to be exerted uniformly regardless of the product geometry. The same HPP machine can therefore be used for different product types.
Products currently using HPP commercially
Currently this technology is mainly used for fruit and vegetable juicessoups and purees, meats, sausages, seafood and sauces (hummus, guacamole).
To a lesser extent, the High Pressure Processing is used to extend the shelf life of salad dressings, fresh garnishes, prepared foods, sliced fruits, pet foods and raw meats.
What are its limits?
Currently, HPP is not specifically regulated by the European Union, in fact, EFSA will inform the possible decisions of risk managers in this area. In the meantime, we will clarify some limitations of the High Pressure Processing:
- Cost and efficiency: It is limited to batch processing or a semi-continuous operation requiring manual assistance to load and unload products, which increases costs and reduces efficiency.
- Type of packaging: HPP packaging is limited to flexible and semi-rigid packaging, as compressibility is required for pressure to be applied to the product and the packaging retains its shape after processing.
- Types of products: High pressure treatment cannot be applied to dry products, highly aerated products, high pH products and non-perishable products.
One of the common problems brands face when bringing their HPP products to market is getting the labelling right. Not long ago, there was much debate on the correct labelling of these products, especially on the use of the words "raw" and "fresh" in cold-pressed juices and smoothies.
Conclusions
As you will see, the High Pressure Processing is being widely applied in the food industry because of the diverse benefits it offers. Not surprisingly, we are talking about a non-thermal food storage technique that kills micro-organisms that often cause illness or damage food.
HPP also excels in using intense pressure for some time and has minimal effects on taste, texture, appearance or nutritional values. Not to mention that it can be used at different stages of the food chain, usually in pre-packaged products.
On the other hand, it can be applied to raw materials such as milk, fruit juices and smoothies, but also to processed products such as cold cuts and ready meals. In the latter case, it reduces contamination of the production environment, such as when cutting and handling products. After all, high-pressure treatment is one of the wonders of the food industry in this day and age.
