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Evaluation and Application of Practices for Controlling Salmonella in Nuts and Nut Products

Investigators
Harris, Linda
Institutions
University of California - Davis
Start date
2009
End date
2012
Objective
This proposal integrates research and extension activities with a long-term goal to reduce foodborne illness associated with consumption of raw and processed nuts and nut-containing products. Our overall objective is to perform harvest and post-harvest microbiological risk assessments using three nut system models: peanuts, pecans, and pistachios.

The specific objectives are:

  1. To identify points during harvest and post-harvest handling where Salmonella may be introduced or amplified.
  2. To evaluate the efficacy of sanitation procedures appropriate to the harvest and postharvest nut-handling environment and to develop scientifically-based recommendations based on these data.
  3. To evaluate the factors affecting the storage survival and thermal resistance of Salmonella in nuts.
  4. To disseminate, through workshops and on-line publications, practical nut-general and nut-specific best pre-and post-harvest handling practices that will minimize the risk of foodborne illness from consumption of nuts and nut products.
The aim of this project is to evaluate a wide range of handling and treatment practices for their effects on infiltration, survival, growth, and inactivation of Salmonella on peanuts, pecans, and pistachios, and products produced from these nuts. Extrinsic and intrinsic factors affecting infiltration, survival during long-term storage, and inactivation during cleaning, conditioning, shelling, drying, and roasting processes commonly used in nut industries will be studied. Information gained from this research will reveal the adequacy and appropriateness of practices currently used in terms of controlling and eliminating Salmonella in in-shell nuts, nutmeats, and nut products. Modifications in some of these practices may be needed to assure that safety risks are minimal. Information gained from this research will reveal the adequacy and appropriateness of practices currently used in the nut industry in terms of controlling and eliminating Salmonella and will form the scientific basis for improving those practices, thereby reducing foodborne illness. The results of these studies will also provide tools for processors in particular to develop and validate their food safety programs.
More information
NON-TECHNICAL SUMMARY: This proposal is a collaboration among scientists from the University of California - Davis, University of Florida - Lake Alfred, and University of Georgia - Griffin and includes applied research and outreach aimed at reducing foodborne illness from consumption nuts and nut products. Once considered uncommon, outbreaks of salmonellosis from nuts and nut products have been recently recognized and may be underreported. Little is known about the ecology of Salmonella in nuts and their products. Our overall goal is to evaluate relative microbiological risk using three nut system models: peanuts, pecans, and pistachios selected for their distinct handling, lack of available data, broad applicability, and relevance to food safety. We propose to evaluate a range of commercial handling and treatment practices for their effects on infiltration, survival, growth, and inactivation of Salmonella in the model nuts. Factors affecting infiltration, survival during long-term storage, and inactivation during cleaning, conditioning, shelling, drying, and roasting will be studied. Results of these studies will be used for risk model development and for development of outreach training and publications. Information gained from this research will reveal the adequacy and appropriateness of practices currently used in the nut industry in terms of controlling and eliminating Salmonella in inshell nuts, nutmeats, and roasted nut products. This knowledge will form the scientific basis for the adequacy of or need to improve these practices. We will partner with the nut industry to disseminate this new information and to evaluate its application and implementation; ultimately improving the safety of these products.

APPROACH: Methods: Lack of adequate survival and inactivation data in nuts under different processing conditions hinders the ability to evaluate the relative risks of industry processes. Materials collected from pecan, pistachio and peanut growers, hullers/shellers or processors will be used in laboratory-based studies designed to mimic processing parameters. Special attention will be given to the influence of environmental humidity and moisture in test materials. A range of handling and treatment practices will be evaluated for their effects on amplification, infiltration, survival, and inactivation of Salmonella during hulling and/or shelling, drying and thermal processing particularly under conditions where cross-contamination may occur. These data will be used to identify risk reduction strategies that can be practically applied. Longer-term studies will be established first. Studies that require materials available only during harvest (e.g., pistachio or pecan hulls) will be limited to the fall but others such as thermal processing may be carried out at other times of the year. Laboratory-based studies are planned for year 1 and 2 with concurrent development of risk models. Extension activities will be carried out throughout the 3-year project but activities in years 2 and 3 will incorporate data generated from the research. Data will be analyzed using the appropriate statistical measures (ANOVA, T-test, etc) using statistical software to determine if statistically significant differences exist between different treatments. We will collaborate with nut industry organizations to both disseminate information (through joint workshops or webinars, preparation of extension materials) obtained from the proposed research and to evaluate the use of the information by industry members. The long-term impact of strategies developed for the nut industry would be a reduction in risks associated with Salmonella in raw and roasted (processed) peanuts, pecans, and pistachios and food products containing these nuts. This would include reductions in outbreaks, sporadic illnesses, and recalls. This impact can be realized through modifications of current harvesting, storage, and processing practices with the objectives of preventing contamination of nuts with Salmonella, applying treatments that will kill Salmonella, and protecting raw and post-processed nuts and nut products against contamination i.e., adhering to Good Agricultural Pratices and Good Manufacturing Practices. Simultaneously, interventions to achieve this goal would likely reduce risks associated with other foodborne pathogens, e.g., E. coli O157:H7. We have proposed to evaluate behavior change of the nut industry in collaboration with industry organizations. Selected individuals will be contacted several months post exposure to the workshops and to educational materials to determine behavior and organizational changes that have been made as a result of exposure, including whether any of the materials they received were used. Indicators will include knowledge gained, behavior change, and implementation of new safety controls.

Funding Source
Nat'l. Inst. of Food and Agriculture
Project source
View this project
Project number
CA-D-FST-2035-OG
Accession number
219349
Categories
Food Safety Modernization Act
Bacterial Pathogens
Natural Toxins
Commodities
Nuts, Seeds