In a world where food presentation and safety are more relevant than ever, packaging plays a crucial role, especially in advanced preservation techniques such as high-pressure processing (HPP). This method, which uses extremely high pressures (up to 6,000 bar) to eliminate pathogens and extend the shelf life of products, improves food quality, but at the same time poses unique challenges in terms of packaging selection and design. In this article, we will explore how the right packaging not only protects the food, but also optimises the HPP process, ensuring product integrity and enhancing the consumer experience.
Suitable materials
Certain conditions must be taken into account in the materials to be used, as they must have certain characteristics:
- Flexible: the material must be able to withstand compression at such high bars, therefore a material such as glass wouldn’t be suitable.
- Elastic: the material must be able to recover its shape after compression, so cans would not be a valid option.
- Water resistant: because the medium through which pressure is transmitted is water, the materials used must be able to withstand water.
Therefore, the perfect solution is plastic, which can be found in different types, although some are more common than others. The most commonly used types of plastic are: PET, HDPE, LDPE, PP, APET.
In addition, we have even more interesting options. We are talking about bioplastics such as RPET (from Recycled PET).
The most common is RPET for several reasons:
- Its structure resists HPP processing, without compromising product quality.
- It is a recycled material from PET products, thus promoting a circular economy.
- It is 100% recyclable
Packaging Formats
We will now look at the different types of packaging formats and their main characteristics:
Bottles and caps
The most common material for bottles is PET, due to its good mechanical properties, transparency and gas barrier, while HDPE closures are popular for their compressibility and effective sealing. Bottle design influences pressure resistance, with rounded corners recommended to reduce stresses. Air space (headspace) should be minimised to avoid paneling. As for closures, induction sealing is required prior to fitting, with HDPE plug-type seals being the most recommended. So-called liner seals can leak if the materials are compressed at different rates, and aluminium seals are prone to failure.
Tubes, trays and films
For tubes, trays and films, round or square containers are ideal for various HPP applications, and trays are perfect for ready-to-eat meals. Rigid or semi-rigid containers, usually made of PET or PP, can be used in microwaves. Rounded corners increase rigidity and reduce the risk of puncturing the lidding film. Plastic films are heat-sealed prior to HPP, and microwave and oven compatible films allow venting to prevent explosions during cooking. A low oxygen transmission rate maximises shelf life, yet 10K OTR films help prevent the formation of toxins in seafood products.
Bags and pouches
Bags and pouches are versatile, used for a variety of products, such as guacamole and pet food, optimising the space between packaged units. Multilayer materials are preferred for their mechanical strength and oxygen barrier properties, while single-material bags are easier to recycle.
As for fittings, the heat seal must be optimised to resist compression and decompression. Accessories such as taps and closures are compatible with HPP pouches, although it is recommended to validate their design beforehand. Bag-in-box pouches facilitate the dispensing of products in large presentations, and handles on the top and bottom panels simplify handling and transport.
If you want to know more about what type of packaging is right for your product, do not hesitate to contact our experts in food applications, and they will answer any questions you may have.
Also, here you have the video of the session of the last edition of the HPP Innovation Week, where you can see all these questions.
