Development of Ultrasonic Processes to Improve Pathogen Inactivation
Environmental Microbial and Food Safety Laboratory
2012 Annual Report
1a.Objectives (from AD-416):
ARS is interested in developing effective intervention technologies during post-harvest handling and fresh-cut processing to inactivate pathogens, and/or reduce their survival and growth while maintaining produce quality and shelf-life. A team has been assembled, consisting of researchers from University of Illinois, North Carolina State University, University of Arizona, and University of California, each contributing their unique expertise to achieve the goals of the research. The proposed research is a part of an awarded NIFA grant entitled “Innovative Technologies and Process Optimization for Food Safety Risk Reduction Associated with Fresh and Fresh-cut Leafy Green Vegetables”.
1b.Approach (from AD-416):
The Cooperator has expertise in developing ultrasonic processes to improve pathogen inactivation while maintaining produce quality. Specifically, in year one: ultrasound treatment will be optimized at the bench scale, and reductions in microbial populations in wash water and on produce and impact on produce quality will be documented. In year two: ultrasound treatment with sanitizers and surfactants will be optimized at bench scale, and reductions in microbial populations in wash water and on produce and impact on produce quality will be documented. In year three: a pilot-scale unit for testing of optimized ultrasonic treatment will be completed and the efficacy of on the unit in disinfecting whole-head lettuce will be documented.
Ultrasound has been used as a cleaning tool in a number of industrial sectors for surface decontamination applications. It has also been studied due its ability to enhance the efficacy of selected sanitizers in reducing pathogen population on fresh produce. Iceberg lettuce sanitation with Tsunami® in combination with ultrasound significantly improved the efficacy of Tsunami® against E. coli bacteria. The combination of Tsunami®, ultrasound and surfactant had a detrimental effect on the overall quality of romaine lettuce after 14 days of storage. Sanitation of iceberg and romaine lettuce with chlorine for different lengths of time (seconds) showed significant differences, indicating that consistency in treatment time is important for achieving the highest cell-count reduction. Ultrasound power level has also been determined to be a key factor in affecting chlorine efficacy.