What do Guacamole and Oysters Have in Common?

03/20/2015

Guacamole and oysters – not a very likely food combination. But even though they may not go well together, they do have something in common: high pressure pasteurization. We recently received a question about high pressure pasteurization and whether there are any health concerns associated with this technology. To find some answers, we reached out to Diane Barrett, PhD, Fruit & Vegetable Products Specialist in the Department of Food Science & Technology and Site Director for the Center for Advanced Processing & Packaging at the University of California-Davis.

What is high pressure pasteurization (HPP)? Is it the same as ultra pasteurization?

Dr. Barrett: Pasteurization is a general term for a process that reduces viable pathogenic organisms. Both high pressure and thermal processes (including ultra high thermal) can accomplish this. HPP does so using pressure, rather than heat, as the primary mode of microbial destruction.

Is HPP widely used in the food industry? If so, which foods are subjected to HPP?

Dr. Barrett: HPP is one of the fastest-growing ‘novel’ technologies for food preservation. The first HPP product commercialized in the U.S. was guacamole – and a company called Avomex was the manufacturer. They have since changed their name to Fresherized Foods. Currently, Hormel uses this process for sliced meats, as does Starbucks for its Evolution Fresh juices. A number of shellfish (especially oyster) processors use it both for pasteurization and for release of the muscle that holds the meat to the shell.

Do foods/beverages that undergo HPP have to be labeled as such? Are there any specific requirements for what the labeling can/cannot say?

Dr. Barrett: I don’t believe so, although some companies do say things like “Fresher Under Pressure” or other things on the label. Prior to being approved, the Food & Drug Administration needs to evaluate this and other processes for safety. In that way, there are not ‘specific’ requirements that would be different from other processed foods. HPP processes are required to follow the same regulations that apply to other preservation methods.

Are there any benefits to HPP? Does HPP impact nutritional quality of foods?

Dr. Barrett: HPP often accomplishes preservation with less heat treatment, therefore retention of nutrient content, as well as flavor, color and texture, may be improved as compared to thermal preservation methods.

Are there any disadvantages to using HPP?

Dr. Barrett: HPP systems require a large capital cost for equipment, and at the moment they are only ‘batch’ processes, not continuous. Therefore, the cost may be higher.

Some claim that HPP destroys enzymes, nutrients, probiotics and minerals in juices – is this true?

Dr. Barrett: HPP has a different effect on enzymes than thermal. In some cases, it activates or increases the activity of some plant enzymes (like polyphenol oxidase, which catalyzes browning, or pectin methylesterase, which has an effect on texture) while in other cases it inactivates them faster than heat (like polygalacturonase, which effects texture). My research hasn’t been focused on nutrients, probiotics or minerals; however, using a preservation method that requires less heat should result in better retention of nutrients, probiotics and minerals.

Are there any concerns about the use of HPP? Should consumers be worried about the process?

Dr. Barrett: I’m not aware of any concerns associated with the use of HPP. If conducted appropriately, it is a relatively safe process.

_{The image “Guacamole” by anokarina is licensed under CC BY-SA 2.0.}