High pressure processing (HPP) is a non-thermal food preservation technology that uses extremely high levels of isostatic pressure, typically up to 87,000 pounds per square inch (psi), to inactivate harmful microorganisms and extend the shelf life of food products, including pet food.
According to Daniela Soto-Castro, HPP food applications specialist for Doral, Fla.-based Hiperbaric, baskets are loaded with packaged raw pet food products, placed into the high-pressure chamber, filled with water and sealed. High-pressure intensifiers then pump water inside the vessel, injecting up to another 15% water volume to increase the pressure to 87,000 psi. Bacterial inactivation occurs once the maximum pressure level is reached and held during a specific holding time. Finally, the pressure is released with the already processed products.
“After HPP, the product can be sold refrigerated or frozen or sent to a clean room to be further processed into bite-size shapes such as nuggets or patties,” she said. “The processed products can then be sold refrigerated or frozen or further dehydrated by heat or freeze drying.”
While HPP technology can help protect food from pathogens and can help extend product shelf life, HPP machines are a substantial capital investment.
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In the pet food industry, HPP can be applied to various products, including raw and fresh pet food, to help ensure food safety assurance through the 5-log reduction of pertinent pathogens, such as Salmonella, Listeria and E. coli, which can prevent recalls related to spoilage or pathogen issues.
Additionally, it helps to retain nutritional quality while preserving digestibility and nutrient bioavailability and lets companies develop clean-label products without compromising the quality or safety of the food.
Jeff Barnard, president at Universal Pure, noted the company works with a growing number of fresh and frozen pet food manufacturers to enhance their food safety.
“HPP is applied to the final packaged product, which enhances food safety from the outside of the package and all throughout the product,” he said. “HPP basically crushes pathogens due to the extreme amount of pressure applied — preserving the freshness and safety of the product. Not only does this make the product safer for pets, it also makes the product safer for pet owners and families to handle.”
Jason Meents, vice president of research and technology, Instinct Pet Food, St. Louis. Mo., noted the company currently runs all freeze-dried and frozen products through HPP via an external processor. Starting in March 2025, the company will move the process to internal operations.
“HPP allows minimal processing, which is a core tenet of our category and follows our brand promise to provide the highest quality, safest pet food,” he said. “This prevents the denaturing of proteins, starch gelatinization, or destruction of phytonutrients that you see in cooked products and allows us to still provide the benefits of a raw diet.”
Benefits of HPP
There are several key benefits of using HPP in pet food production compared to traditional preservation methods, such as thermal processing or chemical preservatives.
“Improved food safety for one,” Soto-Castro said. “HPP effectively inactivates harmful pathogen bacteria, ensuring a safer product for pets.”
Universal Pure is a high-pressure processing service provider for food manufacturers including those making pet food.
|JBT-Avure Technologies, Middletown, Ohio, manufactures HPP machines of varying capacities for processing products of all types, including pet food.
Austin Lowder, Ph.D., food science manager of Avure Technologies, explained that food technologists talk about “reducing the pathogen load” meaning that the high pressures denature the proteins in the bacteria, yeasts and mold that may be present, which makes it impossible for the pathogens to absorb nutrients and process them.
“This effectively renders them harmless,” he said. “The HPP process makes the product safer as it reduces but does not eliminate the pathogen load. So, while it may improve shelf life, we should be clear that it does not create a shelf-stable product.”
HPP provides food safety benefits by inactivating potentially harmful microorganisms within the product. HPP does this naturally, without the use of added chemicals or heat, which can negatively affect nutritional properties. This allows for a more natural product.
This also allows companies to comply easier with food safety regulations, which are increasingly more rigorous. HPP-treated pet food products can be labeled as “all-natural” or “preservative-free,” appealing to pet owners seeking healthier and more natural options.
“When HPP is applied to bulk product prior to freeze-drying, it acts as a kill-step and provides an additional layer of food safety for the final dried product,” Barnard said. “HPP does not degrade the product’s nutritional properties or affect the way it is digested by its four-legged consumers.”
Unlike thermal processing, HPP preserves the nutritional value of pet food ingredients, including vitamins, enzymes and antioxidants. This helps expand the market opportunities by protecting the health benefits of the added ingredients. As a result, HPP maintains the natural flavor, color and texture of the pet food, providing a fresher taste and appealing texture for pets while making it safe to handle and consume.
For example, Cottonwood Heights, Utah-based Steve’s Real Food’s “Study of High-Pressure Processing on Raw Meat Diets” reports the effects of HPP on 95 different vitamins, proteins, essential amino acids, fats and fiber in pet food. The results showed that HPP did not alter the concentration of the analyzed nutrients of interest.
“Only four out of the 95 tested components presented a notable concentration decrease following HPP, which can easily be solved by increasing the ingredients with high contents of these nutrients,” Soto-Castro said.
Lowder noted that in order to meet AAFCO (Association of American Feed Control Officials) standards, retort pet foods must mix in high doses of nutritional additives since many of them are destroyed during heating.
“HPP products do not have to use additives, retaining their original nutritional benefits,” said Austin Lowder of JBT-Avure Technologies.
“HPP products do not have to use additives, retaining their original nutritional benefits,” he said. “There are some who believe that naturally occurring nutrients are better for our pets.”
Extending shelf life
HPP extends shelf life by slowing down the growth of spoilage microorganisms like yeasts and molds. This helps achieve between 14 and 35 days of shelf life in refrigerated storage, compared with 7 to 10 days of unprocessed products.
“Bacteria and other microorganisms adapt to unfavorable environments and might survive freezing, freeze-drying or fermentation,” Soto-Castro said. “Applying HPP acts as a ‘kill or lethal step’ for foodborne pathogens, and the combination with other hurdles like cold storage (refrigeration, freezing) or freeze-drying further minimizes the risk and can help extend the shelf life.”
For example, the combination of HPP and freezing yields up to two years of shelf life. Freeze-drying lasts up to two years but makes the HPP pet food stable for ambient temperature storage.
Before products at Petsource by Scoular are formed and sent on to freeze-drying, raw proteins and dry ingredients are mixed, extruded into chub casings and shipped offsite for high pressure processing at Universal Pure, just 30 minutes away from the plant.
|Because HPP preserves freshness and extends shelf life up to two times, processors can choose to distribute their products to a broader geographic range.
“Longer shelf life also means less product waste and increased profit margins,” Barnard said. “Additionally, staying fresher longer gives the end user more time to use the product at home before having to freeze it or discard.”
While the shelf-life benefits are impressive, according to Kevin Kennedy, regional sales manager at JBT-Avure, that is not the reason most manufacturers utilize HPP in the production of their products.
“HPP is almost exclusively utilized to reduce pathogen loads,” he said. “Freeze-dried products are not concerned with shelf-life extension. Similarly, IQF frozen bulk ingredients are not focused on shelf life. That leaves the fresh pet food category where shelf life is typically three to six months.”
Money matters
Pet food manufacturers looking to incorporate HPP into their production process might want to consider the benefits of working with an HPP service provider.
“By working with an experienced provider, manufacturers can focus on their brand and leave the technical expertise to the HPP provider,” said Jeff Barnard of Universal Pure.
“By working with an experienced provider, manufacturers can focus on their brand and leave the technical expertise to the HPP provider,” Barnard said. “The HPP provider can help guide the process, including lab verification and additional resources to support the manufacturer.”
After all, purchasing HPP equipment can be a significant capital investment, not to mention the process of learning the technology and gaining expertise, hiring HPP laborers, and planning for fluctuations in demand and potential downtime for maintenance.
“A solution to overcome the initial capital investment challenge is to work with a third-party service provider, known as HPP tollers,” Soto-Castro said. “HPP tolling refers to the business model in which HPP equipment owners offer processing services on a pay-per-use basis. HPP tollers have installed large-scale, industrial HPP systems and charge fees to outside food companies to run their packaged products through their HPP equipment. It enables food companies to utilize HPP’s many benefits without purchasing their own HPP machines.”
Since HPP requires a high capital investment even if working with a toll processor, the cost of HPP can cut into product margins. To overcome these challenges, Meents said processors need to believe in and be truly committed to HPP.
“Otherwise, you wouldn’t be able to put together a ROI to support the investment,” he said. “So, it is really a commitment to added processing cost, along with time and resources to understand your product and develop the process that fits your needs.”
Gaining prominence
While HPP is a rapidly growing technology for pet food products, it is still relatively new to the industry.
“There has been some uncertainty around the benefits of HPP for pet food, but as more research is conducted, the benefits are really beginning to be realized by brands, which trickles down to their customers,” Barnard said. “As HPP continues to gain traction in the industry, pet owners will be more aware of HPP and the benefits for them and their pet friends.”
Raw pet food diets have been perceived as healthier than kibble or canned food, with potential digestibility benefits. However, Soto-Castro noted that raw pet food poses a health risk for both pets and humans, since it can more easily contaminated with pathogenic bacteria.
“HPP is an excellent method to control foodborne pathogens with minimal impact on the nutritional composition of the food while preserving its freshness,” said Daniela Soto-Castro of Hiperbaric.
“HPP is an excellent method to control foodborne pathogens with minimal impact on the nutritional composition of the food while preserving its freshness,” she said. “HPP pet foods have earned the trust and acceptance of pet owners and pets, making pet food companies more confident in switching to HPP.”
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