Sandridge Food Corp. is no stranger to innovation. With consumers’ ever-changing taste and growing demand for freshness, forward thinking and technology are essential in the refrigerated foods industry. That’s why in 2010, the Medina, Ohio-based producer of refrigerated soups, salads, sides, sauces and specialty dishes invested in a food safety system called high-pressure processing (HPP).

Today, Sandridge is able to preserve foods naturally with HPP using cold water and pressure rather than heat or chemicals. This results in fresh chilled foods with superior appearance, taste and nutritional value.

There are several applications for HPP in the refrigerated foods industry, each with its own factors to consider. HPP can be utilized as a critical control point (CCP) in a HACCP program—an additional food safety hurdle—a method to increase product shelf life and an opportunity to develop new products that previously could not endure traditional distribution channels.

Why HPP?
As a valuable CCP, HPP kills most harmful bacteria while maintaining the structure of many types of foods. An applied 87,000 pounds of pressure per square inch for 180 seconds has been reported to reduce “cocktails” of Listeria species by 104 logs when applied to ready-to-eat sliced ham and turkey products. These parameters can be a good baseline for destroying vegetative pathogens.

If HPP is to be used as a CCP, pressure and time parameters must be validated with challenge studies, and the inoculum must be based on the pathogen of concern. Most refrigerated food applications would consider Listeria monocytogenes, Salmonella species and E. coli O157H7 as targets.

The inoculation level of the organism must also be considered when performing a challenge study. Using too low of a level may result in a false sense of security unless micro testing is completed throughout shelf life. This will allow for verification that the process destroyed the pathogen, not just damaged it. Additionally, the growth of non-pathogenic microorganism must be monitored throughout the duration of the challenge study. This will help to confirm that pathogen lethality or stasis was caused by HPP and not by bio-competition from other microorganisms. It is imperative to understand how lethality is affected by physical and chemical characteristics. Water activity, pH and fat content of a product can affect the lethality of the high-pressure treatment, so it is necessary to evaluate this information when validating HPP as a CCP.

The data generated from the analysis can be used by manufactures of USDA- and FSIS-inspected, ready-to-eat products. The results can support classifying those receiving HPP treatment as Listeria control Alternative 2 and possible Alternative 1 (depending on the use of antimicrobials) under the FSIS Listeria Control Compliance Guide.

Overcoming the food safety hurdle
HPP delivers the ready-to-eat refrigerated foods industry another weapon to manufacture safe food, even if it’s not used as a validated CCP in a HACCP program. This additional food safety defense—along with food safety prerequisite programs, a well designed and executed sanitation program and the use of preservatives and antimicrobials—can greatly minimize the risk associated with fresh chilled foods.

Extending shelf life
Besides creating a safer product from conception, using HPP can double or even triple the shelf life of a fresh refrigerated product. This is, of course, dependent on the product characteristics and the lethality of spoilage microorganisms. Each product type must be evaluated to determine the exact shelf life.

HPP can also allow the manufacturer to eliminate preservatives from an existing product and maintain or improve current shelf life. This results in better-tasting, cleaner products with no added chemicals—all without sacrificing the shelf life needed to move products through the distribution channel.

New product opportunities
With this advanced technology, it is possible to produce a wider variety of fresh prepared foods utilizing ingredients that could not be incorporated previously due to a short shelf life. For example, cherry tomatoes do extremely well and perform better than their non-HPP counterparts.

With that in mind, it is important to note the result of high pressure on product quality is directly related to the physical composition of the ingredients. Foods that contain air pockets, like marshmallows or strawberries, will become deformed when pressurized. While products with high moisture content, like lettuce, may lose cellular integrity, resulting in a loss of the desired moisture, texture and appearance. In addition, products with differences in water activity, pH and fat content may enhance or inhibit the ability of high pressure to destroy microorganisms.

The industry and HPP
The benefits of using HPP must be evaluated on a product-by-product basis, depending on the intended goals. In other words, there is no cookie-cutter approach to HPP—each product must be tested, evaluated and trialed for dependable results.

HPP can be utilized in the industry as a CCP and an additional food safety hurdle. It can also extend shelf life and open doors for new product development. Regardless of the intended use of HPP, the first step is to determine if the product will meet quality expectations after it has been high-pressure processed. HPP can have a detrimental or positive affect on the quality of products, depending on many influences such as product composition.

All factors considered, HPP creates great opportunities for the fresh refrigerated foods industry.

Joel Riegelmayer is the senior director of food safety and quality for Sandridge Food Corp., Medina, Ohio. Sandridge maintains more than 25 years in the ready-to-eat foods industry.