Cold Pressed Juice is a Hot Trend

“In recent years, the functional beverage category has shown an average annual growth rate of 20 percent in the U.S. and Europe,” Dr. Lee points out. “One of the top five trends for the functional juice sector is cold pressed juice.”

Cold pressed juice is typically made using a hydraulic press, compared with juices extracted using centrifugal presses.

High pressure processing (HPP), which employs pressure without heat, is a technique often used for juice, Dr. Lee says, noting that the primary advantages of HPP over thermal processing are the minimal chemical and physical effects exerted on most foods while imparting a microbial kill step.

“With fruit juices, HPP significantly reduces the number of spoilage microorganisms such as yeasts and molds, and pathogens like Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes,” Dr. Lee relates.

“The finished juices give consumers the sensory perception of ‘fresh’ and ‘natural’ products, while they meet consumer demands for fresh, healthy, and great-tasting safe foods,” he notes. “The refrigerated shelf life of such products can be up to 30 days or longer, and they have superior sensory quality compared with those prepared in a conventional manner.”

HPP treated juices typically produce darker greens for vegetables and redder reds for fruits that the consumer perceives to be healthier, Dr. Lee adds.

“HPP juices, often processed without addition of additives, preservatives or sugar, usually command premium prices compared to traditional heat processed juices,” Dr. Lee continues. “The U.S. is the largest market for HPP juices, followed by the U.K., Germany, France, and Switzerland.”

HPP-Treated Juices Research Project

Dr. Lee is the director of a landmark research project that is addressing the impact of juice characteristics on pathogen inactivation by HPP. Titled “Enhancing the Safety of High Pressure Processed Juices,” the work is well underway, courtesy of a $258,253 grant from USDA’s National Institute of Food and Agriculture that runs from June 2017 to May 2020.

The IFSH’s Kathiravan Krishnamurthy, PhD, is co-director of the project. Collaborators include Nathan Anderson, PhD, and Glenn Black, PhD, representing FDA’s Division of Food Processing Science and Technology, Yinqing Ma, PhD, from FDA’s Division of Plant Products and Beverages, and IIT IFSH PhD candidate Catherine Rolfe.

In explaining the project, Dr. Lee says HPP-treated juices are required by the FDA Juice HACCP regulations to demonstrate a 5-log reduction of colony forming units per milliliter of the pertinent organism in the juice. “Even though HPP-treated juices are now available at retail, there is currently no consensus amongst industry, academia, and government on a ‘standardized’ validation protocol for juices to be treated by HPP,” he relates.

According to Dr. Lee, it appears there is no common approach to preparing bacterial strains for validation and challenge studies, no consensus on the HPP parameters required for treatment of the juices and no common approach on how shelf life studies are conducted.

“Our project seeks to develop coordinated industry and regulatory science-based consensus from the generated data and develop guidance on how validation should be conducted for HPP-treated juices,” he says.

Safe Harbor in Development

Dr. Lee elaborates that the project aims to develop a safe harbor, which scientists define as a recognized procedure that can be employed without further validation studies and approved as delivering a safe product; and when implemented in industry, can be assured that the foodborne hazards are controlled during production and delivery of a safe product to consumers.

“The development of the safe harbor concept will allow stakeholders, including regulators, to better understand HPP technology and thus develop regulations based on sound science and provide quicker turn-arounds for validation approvals,” Dr. Lee points out. “Our project will also provide guidance for industry laboratories or academia evaluating the microbiological safety of HPP-treated juices to follow a reliable protocol to quickly detect pathogens and easily assess microbiological safety with confidence.”