Nuts and Grains: Microbiology and Preharvest Contamination Risks

Area of Science:

• Food Safety
• Microbiology
• Agricultural Science

Background:

• Low-water-activity foods, including nuts and grains, are implicated in a rising number of foodborne disease outbreaks and recalls.
• Factors contributing to this increase include higher consumption, improved detection, and insufficient implementation of food safety programs.
• Pathogenic microorganisms like *Salmonella*, *Escherichia coli* O157:H7, and *Listeria monocytogenes* can survive long-term on dry foods.

Purpose of the Study:

• To review foodborne microorganisms associated with nuts and grains.
• To identify preharvest contamination sources for these dry food commodities.
• To provide recommendations for good agricultural practices (GAP) to mitigate risks.

Main Methods:

• Literature review focusing on preharvest contamination pathways.
• Analysis of existing research on pathogen survival in low-water-activity environments.
• Synthesis of information on food safety systems and control measures.

Main Results:

• Preharvest contamination of nuts and grains can occur via soil, animal intrusion, equipment, handling, and storage.
• Low water activity inhibits pathogen growth but does not prevent long-term survival.
• Milling can reduce microbial load on grains, but prevention is key.

Conclusions:

• Implementing robust food safety systems, including GAP, is essential for preventing contamination.
• Proactive measures targeting preharvest stages are critical for mitigating foodborne risks in dry foods.
• Further research and application of best practices are needed to ensure the safety of nuts and grains.