Vikram Fotedar (VF): The food industry is increasingly moving toward new product development and propositions like never before. Food processing is one of them. What is high pressure processing of food?
David Flores Corrochano (DFC): High pressure processing (HPP) is a cold pasteurization technique which consists of subjecting food, previously sealed in flexible and water-resistant packaging, to a high level of hydrostatic pressure (pressure transmitted by water). What HPP does is keep the food safe, extend the product’s shelf life, reduce the need for food preservatives and products, which cannot be subjected to thermal treatment can easily processed using this technique.
VF: What pressure ranges do you deal with?
DFC: The maximum working pressure applied on foods is 6000 Bar.
VF: What do you mean by safe food?
DFC: It has the ability to destroy pathogens like listeria, salmonella, vibrio, and norovirus, among others. It can shuck molluscs or extract crustacean meat without boiling giving higher yields and fresh flavour with minimum hand labour. Above all, it’s an environment-friendly process because the water is recycled, and uses electricity.
VF: It looks like a complex machine, and perhaps involves certain safety aspects?
DFC: Yes, it is very complex and very important. The security aspect of the machine is also very important. We have to explain to our customers about the security issues for such a high pressure of 6000 bars.
The machines are safe.
There are three different ways of controlling the safety of their machines. Firstly they have two pressure transducers with auto-verification checking system to check the pressure inside of the machine. The machine is stopped as soon as there is a difference in either of the transducer. The vessel is made with a technology that would create a crack rather than exploding.
VF: How do you get the pasteurisation effect?
DFC: Well, we don’t like to call this pasteurisation because pasteurisation involves temperature and we deal with pressure, we get the same effect of pasteurization by applying high pressure.
The processing product in our machines is always hydrostatic pressure, i.e. pressure made by water. The temperature of the water is controlled all the time and is always cold. So this does not affect the nutrient value of the foods. So we deactivate the microbe activity without affecting the flavour or the texture of the food contents or any other organic attributes of the food.
VF: What are the ranges of machines?
DFC: We have two different ranges of machines. We have, what we call, the traditional HPP, also called the In-Pack technology. We first produce the food and then it’s packed in our flexible packaging. We allow it to pass under water so that it must be water-proof and flexible enough to withstand the pressure thereafter. The packaging and its contents are shrunk 15% inside our HPP processing chamber. Everything will be recovered then without losses.
We have also developed a special line to process liquids in bulk. There is a bladder inside the machine. Bulks of liquids are pumped inside the bladder and the liquid inside the vessel is then compressed. When the process is complete, we pump the liquid out to the filling line. We don’t have any problem in filling in cans or glass or anything that is not flexible because the HPP is done before packaging.
VF: Is there a need for aseptic filling after HPP?
DFC: No, there is no need for an aseptic filling but we provide it. These lines are targeted for high productivity. We provide a throughput of five tonnes per hour.
VF: Can HPP be applied to any kind of liquid?
DFC: The bulk technology is targeted for liquids and beverages and the In-Pack technology is targeted for foods packed in flexible packaging.
VF: Key industry for HPP?
DFC: Our most important industry is meat – dry-cured or cooked. Sliced ham, turkey or chicken cuts, ready-to-eat products, whole pieces of cured ham are our popular applications. Sausages and Burritos are also one of our main applications.
Besides meat products, ready-to-eat products are also one of our main segments right now. This is the new consumer trend where consumers have less and less time to cook at home and ready-to-eat meals that are tasty, healthy and of premium quality has come to the market. These need a shelf life of 15 to 30 days to store at home. Many of our customers are developing ready-to-eat meals without any preservatives with a home-made flavour and that lasts 60 days.
VF: What impact does it have on food texture?
DFC: Protein content in a cooked product already gets stable and is not affected by the pressure but there are some applications where there is a change in the texture. For instance, some of the cooked meat products, depending on the different additives they put for the production process. Different additives have different water retention capacity. So sometimes during compression, there is some water release. But if the additive is replaced by one with better water retention, the product is not affected by water.
So there can be some changes in the texture and even in flavour in some particular foods. Citruses like oranges have mild flavour changes. For such products, we need to keep the pressure much lower than 6000 Bars but it shortens the shelf life.
VF: From a packaging stand point, considerations are imperative for HPP technology?
DFC: The first requirement for the packaging material is that it needs to be waterproof. It needs to be very well sealed because sometimes the sealing may not be as strong as it should be.
VF: Can HPP be a secondary proof for leaks in packaging?
DFC: Yes, even if there is a very minute leak the water under pressure can get inside of the product.
VF: Any specific material requirements?
DFC:: We work a lot on PET bottles for liquids and current plastic bags for vacuum packs are good to use. We are not very restrictive on that because as long as they are sealed well it is fine.
The problem comes for Doy packs that are made of very different layers and the glues between those layers sometimes react differently to high pressures. In some cases, there could be bubble formation between different layers or the lamination. As long as the glue quality is good, the technology works fine, even if there are layers of aluminium in the packaging.
For bottles, it is very important that the screw and the cap are well adapted to high pressures and well-sealed otherwise the water will get inside the product.
VF: How scalable is this machine?
DFC: We have a portfolio of five different machines. We can have from 250 kilos/hr. to 3000kilos/hr.
VF: If a packaging already has air inside it, there are chances air to escape and there-by burst?
DFC: That’s why we advise having the less volume of gas per sealed volume. So vacuum pack is perfect for this technology, and for trays lately, we recommend having skin packaging. It works perfectly because the look is very good. It doesn’t look like a top film at all. When under pressure, the air inside the packaging and in contact with the food will try to escape first. Simultaneously, other air inside the packaging also tries to escape. So this can damage the look. It might take some components out, like grease or protein or water. So we advise having least air inside the packaging.
VF: How many HPP systems has Hyperbaric installed in the MEA?
DFC: In the region, we have some customers. Many of them are confidential. A Dubai-based company called Smart Food Solutions gives this service for third parties. So any company in Dubai or in the region that wants to process their products with this technology need not invest in the machine itself. They can pay for the service from this company – something similar to a contract packager. This business model works well in the USA, in Europe and in other parts of the world because this technology needs investments starting from Euros 0.5-million to 3-million. So this is a big investment but with this business model, customers can save on this investment.
VF: What food products use HPP process here?
DFC: In the region, we are processing dairy products, juices. Smart Food Solutions process dates, salsas like guacamoles, hummus and similar spreads. Those kinds of spreads are also one of our biggest applications. These are healthy snacks. Any food products with good nutritional quality or organic in nature, or has good flavour or natural or no preservatives are products for HPP. We can extend the shelf life of any natural and fresh products by three to ten times depending on the water content in the products and air inside the packaging.