Questions and Answers: High Pressure Processing with Universal Pure's Mark Fleck

Food Manufacturing had the opportunity to correspond with Mark Fleck of Universal Pure to discuss the topic of High Pressure Processing in the food and beverage manufacturing industry.

Q. What is High Pressure Processing (HPP)?

A. 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.

Q. What are the benefits of HPP in food manufacturing?

A. The primary advantage of using HPP is to enhance a food safety program and extend product shelf life without resorting to chemical preservatives or thermal processes. Older food preservation methods like thermal pasteurization can often negatively impact the organoleptic quality of foods and beverages. For instance, in the beverage space today, HPP is playing a role in the preservation of premium juices, plant-based protein drinks, cocktail mixers, nutrient dense shots, coffee & tea selections and bone broths. In the food manufacturing space, HPP is routinely used for ready-to-eat (RTE) meats, ground poultry, dips, guacamole, salsa, hummus and seafood. Adoption of HPP in other food and beverage market segments will occur as new product opportunities are researched and developed.

Many companies also implement HPP for brand protection. The HPP process can be performed in-house, or by using a growing network of HPP outsourcers. The cost of HPP varies depending on the size of production runs, fill efficiency of the product within the vessel and the HPP process parameters.

Q. How does HPP kill pathogens?

A. HPP inactivates vegetative bacteria (E. coli 0157:H7, Listeria monocytogenes and salmonella) and spoilage organisms (yeast and molds) by compromising the cell wall of the microorganisms which interrupts cell function. HPP is only minimally effective on enzymes, and not effective on bacteria spores. HPP food and beverages typically require refrigeration during storage and distribution.

Q. How does packaging impact HPP and shelf life?

A. Product shelf life varies depending on product ingredients, pH, water activity and the HPP parameters selected. It is generally understood that higher acid products require lower HPP pressure and hold times to achieve that longer shelf life.

Any packaging to be considered for HPP must be hermetically sealed. To achieve the maximum shelf life available when using HPP, packaging with barrier properties is often selected. By specifying low oxygen transmission rate (OTR) and moisture vapor transmission rate (MVTR) films, you will also help maintain optimal product quality over the entire shelf life of the product.

Q. What types of packages can be used with HPP?

A. 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.

Q. Do processing variables like pressure and time vary by product? How are settings determined?

A. The key processing parameters (namely pressure and hold time) can vary based on the product ingredients, pH, water activity and degrees Brix. Understanding the customer’s product, food safety requirements and shelf life goals help guide testing for optimal HPP parameters.

Q. How does HPP provide a clean-label approach to formulating food and beverages?

A. 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.

Q. What is the impact on formulating issues including sweeteners, color stability, stabilizers, added protein, etc.? Can probiotics survive HPP?

A. When considering HPP, formulation changes should be minimal, if at all. HPP preserves the nutritional value while maintaining the fresh-like taste and color of the product. Because HPP is a non-thermal preservation technology, chefs and food technologists are not burdened with working through the compromises/adjustments often required when heat preservation methods are utilized. 

HPP only minimally impacts the probiotics in foods provided the proper HPP recipe is selected. HPP is considered a “log reduction” technology which means the higher the pressure and longer the hold time, the greater the reduction of pathogens. By understanding the bacteria load, HPP processers can dial in the best HPP parameters to achieve their food safety goals without significantly impacting the high numbers of probiotics in a given product.

Q. Does HPP need to be declared on food labels? What type of label declarations/claims are permitted for shelf life, food safety and nutrient retention?

A. 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.

Q. What’s the future for HPP in food and beverages?

A. We anticipate double-digit growth will continue as consumers demand more high-quality products with cleaner labels and fresh-like attributes.