During treatment, product and packaging undergo changes; In High Hydrostatic Pressure technology, the pressure is transmitted uniformly and instantly throughout the product, allowing a wide variety of foods to be processed regardless of their shape or size. The geometry of the container affects the filling percentage of HPP equipment, which directly influences productivity. This is why packaging must have specific qualities to withstand these modifications, such as:
- Airtightness: containers must withstand such high pressure without breaking or collapsing, and cannot have pores on their surface.
- Flexibility: they must accommodate the size reduction that occurs during the process, and then return to their original state.
- Impermeability: the oxygen and water permeability parameters are very important for the product to remain intact until the end of its useful life, so it should be as reduced as possible. If water or air enters, the proliferation of undesirable microorganisms could occur sooner than expected.
- Others: although they are not mandatory, the opacity and morphology of the packaging must also be taken into account to optimize the treatment and ensure a perfect product!
Types of materials
- As for types of materials, the one suitable for high pressure processing is plastic, since it is malleable and resistant enough at the same time, capable of meeting the characteristics just mentioned. Flexible packaging is essential. The container must be able to fit the product under pressure without experiencing permanent distortion.
- Glass, metal and cardboard are not suitable. Any material that can permanently break or bend under pressure is not a good HPP packaging material. Recycled and recyclable plastics can be used. This makes HPP an environmentally friendly option, important if promoting a sustainable and ecologically conscious product.
Examples of packaging suitable for HPP
- Bottles. This type of packaging is used for liquids, such as juice, gazpacho or salmorejo. A large percentage of these containers are PET. The peculiarity of this packaging is the cap, which must leave the container perfectly sealed. With double lip stopper bottles, this is achieved perfectly.
- Tubs. Dips are the star product in this type of packaging, mostly guacamole, although we can find other types of products such as grated tomato, pico de gallo, salads or children’s purees. In these containers, filling is important, since, if the headspace is too large, the container may not withstand the treatment and may break.
- Trays. Ideal for treating products with a certain weight and mixtures of solids and liquids such as stews with sauces or prepared dishes. The kg/cycle ratio is greatly optimized, which lowers the final price per kg of product.
- Skin / vacuum. This type of packaging, apart from minimizing waste due to minimal air entry, the appearance is optimal, as it leaves maximum visibility to the product.
- Bag in box. Hermetically closed bag that keeps the product packaged. It wrinkles as we empty the product and prevents air from entering. In this way it avoids contact with oxygen, lengthening its conservation. It is a type of packaging that allows you to have a built-in tap. The kg/cycle ratio is greatly optimized, which lowers the final price per kg of product, making it one of the ideal containers.
- Modified atmosphere packaging (MAP), also called protective or controlled atmosphere packaging (EAP), involves packaging your products in specific blends of food-grade nitrogen, oxygen, and carbon dioxide that reduce spoilage. For this system to be suitable for treating HPP, the volume must not exceed 15% of the volume of the container, to avoid implosion and reduce waste.