Traditional food preservation technologies, like heat pasteurization, have significantly increased the safety of the food supply over the years. Unfortunately, many of these commonly used preservation techniques negatively impact the flavor, texture, nutrients, and color of food products. Additionally, consumers have become familiar with the not-so-fresh flavors of products with chemical preservatives. These concerns combined with the food production industry’s latest focus on keeping labels as clean as possible have made High Pressure Processing (HPP) a popular technology in the food production industry.
Having evolved from a novel food preservation concept to a go-to method called for by food manufacturers and their retail partners, many companies are finding themselves under pressure to learn more about how to best use the pressure of water. The following is a primer on what HPP is and can do, and the best practices companies can adhere to when making the transition to the HPP.
The 411 on HPP
Unlike heat pasteurization, which often negatively impacts food vitamins and nutrients when addressing bacteria, HPP’s cold pasteurization offers the opportunity to enhance food safety, while at the same time maintaining the fresh taste, bite, and color of the product in its natural state. HPP interrupts the cellular function of microorganisms by applying enormous pressure to foods for a period of just a few minutes. In most cases, this isostatic (equal from all sides) pressure is applied after the food is packaged, virtually eliminating any chance of recontamination.
Most HPP-processed foods are technically non-sterile, i.e. not shelf-stable, but research studies completed on a wide range of food products and categories confirm that HPP technology effectively inactivates vegetative bacteria like Listeria monocytogenes, Salmonella, E. coli 0157:H7, and Campylobacter as well as yeasts, molds, and other fungi. It is a log-reduction food preservation technology which, in simplest terms, means that the higher the process pressure and longer the hold time, the greater the reduction of microorganisms—to a point. However, HPP is not effective on some enzymes and bacterial spores, including Clostridium botulinum. Producers need to tap into other techniques, such as blanching (for vegetables), and possibly adding a very small amount of natural antimicrobials or anti-clostridia ingredients to address those components not affected by HPP.
HPP provides additional value beyond its food safety benefits in the form of significantly increased shelf life. Because HPP inactivates most spoilage organisms, food processors frequently report dramatically increased product shelf life, often by more than twice the results without HPP.
Delivering a high-quality, cleaner-label product with prolonged shelf life can unlock all kinds of value. Some processors use HPP as an opportunity to increase their batch size and reduce the frequency of production runs. Because of the much longer product shelf life, a manufacturer on the East Coast can now tap markets in the Midwest and the West Coast. Others have seen HPP as an opportunity to provide new kinds of offerings or foods in different parts of the store. For example, avocados have traditionally been sold as a perishable item in the produce section and must be sold, donated, or thrown out within a matter of days. Avomex/Fresherized Foods was able to slice, pit, hermetically seal, and process avocado halves using HPP for a new product in the retail refrigerated sections. With HPP, the avocados last 30 days without turning brown or losing their optimal taste and quality—all done without the use of chemical preservatives.
Four Keys to Implementing HPP
While the benefits of switching from thermal pasteurization to high pressure processing are often well worth the cost, changing processing methods is a major step that ought to be carefully considered before any definitive action is taken. The following four things are what food brands keep in mind as they consider making the switch.
1. Determine Your Goals. There are many reasons to switch to HPP. Understanding and acknowledging your goals and setting benchmarks for what success looks like are key to settling on the most beneficial transition possible. Some providers utilize HPP to enhance their food safety program, while others are hoping to create a cleaner-label product and reduce sodium levels. Still others use HPP to reduce food waste/shrink or streamline their operations. Depending on the product, HPP may be able to make some or all of those dreams a reality.
Whether it’s expanding market reach through extended product shelf life, increasing your margins, or simply addressing changing consumer demands by converting a product currently distributed frozen to fresh, it’s critical to set an emphasis on what you plan to accomplish from the transition. Doing so helps evaluate success and guides future processing decisions.
2. Know Your Product. It is always important to thoroughly understand your product. HPP is effective on a wide variety of products, but differences among those products or even differences between varying types of the same product can have an effect on process hold time and level of pressure needed with HPP. The following are examples of information you should have about your current product.
- The product pH and water activity—very important with beverages.
- Your target product shelf life compared with your current shelf life.
- Your current packaging—does it provide an air tight/hermetic seal, and is there at least one surface or a combination of surfaces that can accommodate a 15 percent temporary volume change?
- Package barrier properties—does your current package/film have barrier qualities (OTR and MVTR) to maximize the increased shelf life benefit of using HPP?
- Labeling—if there is one, is it waterproof or could it be applied post-HPP?
3. Conduct Research and Obtain Consultation. Once you understand your goals and have defined the characteristics of your existing or new product, you can begin evaluating whether HPP is the right technology for your application. The next step is conducting research—microbiology challenge studies, product shelf life studies under various conditions, and organoleptic/sensory analysis i.e. taste and flavor, texture, mouth feel, visual appearance, smell, and more.
If you already have an in-house product development team and micro lab, they can research available HPP technical literature on pathogen validation and shelf life studies. If not, there are knowledgeable resources available to you from universities and third-party companies who provide these services. You may simply need to try processing a few samples to know where to start. There are HPP test vessels available at multiple universities and third-party research organizations.
In addition, the two principal HPP equipment manufacturers (Avure Technologies and Hiperbaric) have many of these capabilities in-house or close working relationships with local labs to perform these analyses for your company. The growing network of HPP outsourcers like Universal Pasteurization have facilities located across the U.S. and may be able to assist with getting your evaluation process started.
4. Choose Whether to Insource or Outsource Your Processing. Numerous companies have invested in in-house HPP systems as a long-term, go-to-market business strategy. One of the questions you and your team will want to answer is whether you have the space and product volume to justify an HPP equipment purchase. The seven-figure capital expenditure, space and facility requirements, the implementation time, and ongoing staffing to operate and maintaining the HPP process are key considerations to keep in mind. The weight of the larger HPP systems typically require special foundations to support the equipment load.
Understand that HPP is a batch-process and doesn’t lend itself well to traditional food processing lines. Manufacturers often create a staging area pre-HPP to provide product queues. Post-HPP, the product package will typically pass through an air knife to remove the moisture remaining from the HPP process. One may need to consider the additional floor space for any pack-off requirements, e.g. ink jetting, kitting, sleeving, overwrapping, boxing, and palletizing.
Many companies wishing to take advantage of the benefits of HPP don’t have the volume or resources to justify the investment and upkeep for purchasing and maintaining their HPP operation in-house. Even some of the larger companies who have sizable product volumes don’t want to invest their time and capital in bringing HPP in-house. They may have only a few products at each of their production facilities that would benefit from HPP. If so, the setup and upkeep costs of purchasing and operating an HPP machine may overwhelm the financial benefits from implementing the process in-house.
Fortunately, today there is a network of HPP outsourcers who fulfill this step in the production process for companies both large and small. Outsourcers own and operate HPP machines on behalf of clients. Leveraging these service providers can be a much more economical way for smaller producers to use HPP for their products. Additionally, many of these HPP outsourcers offer pack-off, cold storage, and logistic services. Outsourcers also support companies who have their own HPP vessels. They will assist in processing overflow during peak times of production or as a backstop if the manufacturer’s HPP system is temporarily out-of-service for maintenance.
Is HPP right for you? Certainly, the answer and the nuances are highly variable, but HPP is a fast-growing food preservation technology offering many benefits across a broad product spectrum.
Fleck is a consultant and HPP specialist with Universal Pasteurization, an HPP outsourcing service provider for food and beverage producers. Reach him at email@example.com.