Keeping the pressure on quality

Consumers are increasingly seeking healthy food choices based on fresh, natural additive-free products and ‘fresh’ (not from concentrate) juices sales have almost doubled in the UK in the last ten years. However, most fruit juices available today are thermally pasteurised, which leads to a significant loss of vitamins and nutrients, whilst taste and texture are also compromised.

Holmach is delighted to represent UHDE, part of engineering giant thyssenkrupp, for its state of the art High Pressure Processing (HPP) systems, which extend shelf-life without a thermal process.

HPP is a safe, clean, gentle and eco-friendly process, that extends the shelf life of fruit juices and purees by up to ten times, without the use of heat or additives, whilst retaining quality and freshness.

The process:

After packaging, the food products are conveyed into a high-pressure vessel which is then filled with water. Capacities of the vessels range from 60 to 750 litres. Pressure reaches up to 6,000Bar and is held under full pressure for a specific time to denature the pathogens. The system is then decompressed at a controlled rate and then the product is conveyed back out of the high-pressure vessel. It is then dried in a compressed-air dryer.

Once processed, HPP treated items need to be refrigerated. Direct processing or processing in bulk bags is also possible, but an additional aseptic packaging process is necessary.

Loading and unloading of the product can either be manual or mechanical and Holmach can advise on the best prodcts in the marketplace to handle this.

The science:

In the high-pressure vessel, molecules are pressed closer together. By modifying process parameters such as pressure, holding time, and temperature, it is possible to control which types of microorganism are reduced. Depending on product properties, a four to five log reduction is possible. The pathogenic bacteria are destroyed by rupturing the cell walls, without damaging the overall organoleptic properties of the foodstuff.

High pressure processing is a cold pasteurisation process, not a sterilisation technique and is most effective with yeasts and moulds.

Not just juices:

With HPP, enzymes can be inactivated to prevent the discoloration of fruit products, making it ideal for products such as guacamole and leafy greens like kelp and kale products. It is also highly effective for use on expensive shellfish. Oysters are pasteurised, while remaining raw, and are ‘shucked’ from shells in the process. Recent installations have been completed in Canada for shellfish such as lobster, in Germany for meats and most recently on fruit purees and juices for an Australian customer.


We will be showcasing HPP technology from UHDE on Stand C30 at PPMA Total 2019 1 – 3 October with a Virtual Reality booth, visualizing the future of this technology. Sounds intriguing? We think so! Come see us in person and find out more.

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