Summary of Awards to Date

Improving pasteurization validation methods for pistachio processing

Date

Jan. 1, 2015 - Dec. 31, 2016

Funding Agency

Center for Produce Safety

Amount Awarded

$279,859.00

Investigator

Bradley Marks, Ph.D.
Michigan State University

Co-Investigator(s)

Linda J. Harris, Ph.D., University of California, Davis

Summary

Microbial safety of low-moisture foods is a particularly difficult challenge, as reflected in recent outbreaks and/or recalls associated with Salmonella-contaminated nuts and other low-moisture products. Therefore, processing interventions are an emerging imperative to reduce the risk of Salmonella in low-moisture products, including pistachios. The Food Safety Modernization Act (FSMA) proposed Preventive Controls rule will mandate that the low-moisture food industry implement and validate interventions against identified hazards, such as Salmonella. Although a number of pathogen-reduction technologies are available to the pistachio industry (e.g., dry heat, steam, radio-frequency), there are several significant problems: (1) No single technology will be universally applicable, so that product-specific/scalable solutions are needed; (2) The cost of stand-alone pasteurization technologies is an impediment to small processors; and (3) Robust validation protocols have not been widely tested or disseminated.  Therefore, the overall goal is to improve the methods for validating pathogen-reduction processes for pistachios, with particular attention to improving existing processes and enabling any processor to reliably validate those processes. The work plan includes laboratory- and pilot-scale experiments with Salmonella-inoculated pistachios, and a process validation demonstration at the commercial-scale. A key project outcome will be a guidelines document for methods to validate preventive control measures for pistachios.

Technical Abstract

Microbial safety of low-moisture foods is a particularly difficult challenge, as reflected in recent outbreaks and/or recalls associated with Salmonella-contaminated nuts and other low-moisture products, including 2009 and 2013 recalls of pistachios. Therefore, processing interventions are an emerging imperative to reduce the risk of Salmonella in low-moisture products, including pistachios. The Food Safety Modernization Act (FSMA) proposed Preventive Controls rule will mandate that the food industry implement and validate interventions to prevent or control identified hazards, such as Salmonella in low-moisture products; large, small, and very-small facilities will need to comply by 2016, 2017, and 2018, respectively.  Therefore, the overall goal of this project is to improve the methods for validating pathogen reduction processes for pistachios, with particular attention to enhancing existing operations and enabling processors of any scale to reliably validate those processes. The specific objectives are: (1) To develop and test process modifications suitable for existing processing equipment (e.g., roasters) that could improve achievement of preventive controls (i.e., log reductions of Salmonella), and (2) To develop, test, and disseminate a “Guidelines for Validation of Pistachio Pathogen Reduction Processes” document that will assist processors to effectively validate various thermal treatments. Laboratory-scale experiments will quantify the effects of key product and process factors (i.e., salt, water activity, process humidity) on Salmonella inactivation. Pilot-scale roasting/pasteurization experiments (with Salmonella-inoculated pistachios) will validate the laboratory-scale data. Results from these tests, and from significant prior and current work by the PI/co-PIs, will be used to develop, test, and distribute a process validation guidelines document. Industry partners will play a key role in that effort by assisting with commercial-scale tests to quantify process variability and by evaluating the practical relevance and completeness of the protocols outlined in the guidelines document. Therefore, this proposed project will provide timely information to help the pistachio industry comply with the requirements of the forthcoming rule. This project will help ensure the microbial safety of processed pistachios, prevent unnecessary capital expenses, and ensure continued operation of existing processes.