What is HPP?

There’s really nothing nicer than fresh produce to get the maximum enjoyment of flavour and texture but, for most of us, cooking and eating fresh produce every day isn’t always possible.  Many of our eating habits are dictated by time constraints imposed by our busy lifestyles, leaving little opportunity for daily visits to the supermarket for fresh items with which to prepare our meals.

Fresh products will spoil fairly quickly as any bacteria present in food multiplies and makes the food unfit for consumption.  Some bacteria are beneficial to us, such as those present in yoghurts, but others can cause illness and are known as pathogens.  It is these pathogens that pose a threat to our health when they multiply in foods; defiling them and rendering them unsafe to eat.  Other types of bacteria will simply cause the food to spoil and perish, making it inedible.

Therefore, the tendency is often to rely on foods which have been preserved by one method or another that we can keep in our fridge longer than just a few days.  Some of the most common ways of food preservation include adding chemicals to stop the bacteria from growing, high heat or thermo treatments and dehydration.  All these options are effective but can bring with them a depreciation in taste and texture and often a loss of nutrients.

The food industry is always looking for ways to improve and a relatively new method of preserving products called high pressure processing (HPP) is gradually gaining a foothold in the trade as awareness of its benefits increases.  Interestingly, the knowledge of this process has been around since the 19th century, but it has only really been developed to greater potential in the last twenty years.

HPP is a method which uses high pressure to pasteurise foods, making bacteria inactive.  Unlike most other methods, it pasteurises the food once it is sealed and in its final packaging.  It works by passing food items through an industrial container which is then filled with cold water and the pressure increased to about 6000 bars.  This is equivalent to the pressure of being at least five times deeper than the deepest point of the deepest ocean.  ThyssenKrupp, a company which specialises in HPP and high pressure technologies compares this to, ‘the weight of three jumbo jets acting on an area the size of a smartphone’.  This pressure is what makes the microorganisms inactive and the food safe.  However, it is worth mentioning that the degree of microbiological inactivation will be affected by things like the pH, water activity and protein and sugar content of the product itself.

Its trump card is that it requires no heat and no chemicals so the food can retain its flavours, nutrients and texture.  Another big advantage is that as the product is in its final packaging, any risk of recontamination, which is possible with other methods, is massively reduced.  In a progressively more demanding market, this is good news for consumers and for food suppliers who want to ensure their products are as safe as possible.

The process can only be used if the item is vacuum packed and sealed in flexible packaging or in a plastic bottle so it does have its restrictions.  A glass container, for example, would be obliterated under the pressure so, at present, HPP is regarded as an alternative to other thermo methods and companies use it mostly for fruit juices and smoothies but it is developing quickly.

In a world where food waste is an increasingly big issue with millions of tons being thrown away each year, HPP is great news.  Companies claim that the process can extend shelf life by up to 10 times the normal length.  Items are safer for longer whilst still maintaining much of their original freshness, flavour and nutrients, resulting in overall food wastage being reduced.  This can only be a good thing for the food industry and, as HPP continues to be advanced, things can only get better.