High Pressure Processing FAQs
There is a lot of science behind High Pressure Processing, but it is really a simple concept: HPP is an all natural food safety and preservation method that uses only water and high pressure.
To answer any questions you have about how the technology works, we have come up with this list of High Pressure Processing FAQs.
Want to know more about High Pressure Processing (HPP)?
Check out the most frequently asked questions below.
Question
What is High Pressure Processing (HPP)?
Response:
HPP is a science-based tool for food safety that uses cold, potable water and high pressure applied to the outside of the food package. Potable water is water that is safe to drink or use for food preparation. This non-thermal food preservation method harnesses the power of pressure to comprehensively inactivate illness-causing, vegetative pathogens (E. coli, Salmonella and Listeria monocytogenes), molds and yeasts without compromising the nutritional value of the food. HPP also maintains the optimum attributes of fresh products over an extended shelf life.
Question
How do regulatory agencies view HPP?
Response:
Both USDA/FSIS & FDA recognize HPP as an effective food safety technology. In the case of USDA/FSIS, HPP is often incorporated in the food producer’s HACCP plan. HPP users need to validate their own application’s effectiveness as part of their HACCP program.
Note: Letter of No Objection for RTE meats
Question
How does HPP work?
Response:
Products (often in their final package) are placed in the HPP vessel. Tap water is pumped into the vessel and held at very high pressures (up to 87,000 psi) for anywhere from one to five minutes. The pressure inactivates illness-causing vegetative bacteria and spoilage organisms without negatively impacting the nutritional value of the food.
Question
What do you mean when you say HPP “inactivates” bacteria?
Response:
HPP inactivates foodborne pathogens by interrupting their cellular function of the bacteria, the cells fail to recover and die off.
Question
What are the benefits of using HPP?
Response:
HPP delivers benefits for the food producer, retailer and the consumer. HPP improves food safety. Longer product shelf life reduces food waste for the manufacturer and all the way through the distribution chain to the consumer. The food appearance, texture and taste remains fresher for a longer time. Cleaner label products can be introduced with more natural/better flavors and with lower sodium.
Question
Which food categories is HPP most effective?
Response:
HPP is most effective on products with high water activity (Aw) i.e. free water. This includes RTE meats and meals, salsa, guacamole, premium juices, smoothies, wet (spoonable) salads, fresh ground poultry, lobsters, oysters, mussels, raw pet food, etc.
Question
How does HPP enable shelf life extension?
Response:
A huge benefit to food processors and their customers is the increased product shelf life HPP delivers. Shelf life is increased because HPP impacts the product spoilage organisms e.g. fungi (mold & yeast) and bacteria that cause spoilage. It is common to realize a 2X or more increase in shelf life without the use of bacteriocins and chemical preservatives. The added shelf life allows the processors to reduce production changeovers, ship full truckloads and reach larger geographical markets – all potentially benefiting their bottom line.
Question
How does HPP provide a clean-label approach to formulating food and beverages?
Response:
HPP eliminates spoilage organisms like fungi (yeast and mold) and LAB, which often determine product shelf life. By eliminating these organisms, HPP enables fresh-like and cleaner label products with longer shelf life, without the addition of preservatives. Food manufacturers are removing common preservatives like sodium benzoate, sodium lactate, sodium diacetate, nitrites and nitrates, while implementing HPP, to achieve cleaner-label products.
Question
What types of product packaging can be used with HPP?
Response:
There are a wide variety of packages that can be used with HPP — flexible plastic containers, plastic bottles and cups, stand-up pouches and pouches with spouts. Package choices are numerous as HPP is effective on virtually all package sizes and shapes. A key characteristic of the packaging is that at least one surface must be able to accommodate the temporary volume change that occurs during the HPP cycle. At HPP pressures, liquids are compressible. During the HPP cycle, any headspace within the package is compressed and then the product is compressed up to 15 percent depending on the HPP recipe. As the isostatic pressure is released, the product and headspace return to pre-HPP volumes. Glass and most metal packages are not appropriate for use with HPP.
Question
How does HPP work without harming the product?
Response:
HPP uses isostatic pressure, a fancy word for equal pressure from all sides. Let’s use the analogy of a grape in a plastic bottle filled with water. If you squeeze the bottle, the water inside the bottle is pressurized exerting pressure on the grape equally from all sides.
Question
Does HPP need to be declared on food labels?
Response:
At this time, HPP does not need to be declared on food or beverage labels as it is considered non-thermal and does not add ingredients to the label. Claims on shelf life need to be substantiated with product testing. There are numerous research studies available in the public domain confirming vitamin and nutrient retention when using HPP. Should validation or shelf life studies be needed, there are a growing number of research organizations with the knowledge and experience to optimize HPP for your product application.
Question
How much is 87,000 psi (660 Mpa) and what is it that generates the pressure?
Response:
This pressure is about five times greater that the pressure exerted at the deepest part of the ocean. The pressure is generated by an electric motor powered intensifier pump, similar to the pumps used in the waterjet industry.
Question
Does HPP heat my product and why or why not?
Response:
Adiabatic/compression temperature increases during pressurization, then decreases during decompression due to the Le Chatlier Principle. The temperature increase varies due to compressibility and specific heat of the food. For water, the temperature change is 3C per 100 Mpa i.e. 18C at 600 Mpa.
Question
Does HPP work on frozen products?
Response:
No, the product needs to be tempered above 32F prior to HPP.
