P-101. The Effect of Electron Beam Radiation on Raw Almonds Contaminated with Different Salmonella Strains

C. Duong, D. Foley;
Chapman University, Orange, CA.

Approximately 1 billion pounds of California almonds were produced in 2003 of which 5% were sold for raw consumption (Almond Board of California, 2002). As of May 21, 2004, a producer recalled approximately 13 million pounds of raw almonds due to the identification Salmonella enterica serotype Enteritidis (SE) in almonds. In 2001, researchers had also identified an outbreak of SE infections linked to raw almond consumption over a 6 mo period, mostly in Canada. (Chan, 2002). Since irradiation is a process that does not involve heat, the product can be sanitized without cooking, an essential characteristic for raw nut meats. In this study, we utilized different electron beam radiation doses to identify the decimal reduction value (D-value) of different Salmonella strains on contaminated almonds. We hypothesized that the D-value for Salmonella on almonds would be similar to that found for alfalfa seeds (Thayer and others, 2003). Nonpareil variety raw almonds were inoculated with approximately 8 logs of Salmonella Anatum, S. Enteriditis PT30, S. Hartford, or a cocktail of 4 strains (S. Anatum, S. Infantis, S. Stanley, and S. Newport) and irradiated at doses of 0 (for control), 1, 1.5, 2, 2.5 and 3 kGy. The samples were then diluted and plated to selective media. Plate counts from 4 replicate experiments were used to calculate the dose required to eliminate 1 log (90%) of the contaminating organism (a D-value). The D-values for the inactivation of Salmonella on almonds ranged from 1.05-1.36 kGy, higher than the average of 0.97 kGy found for many of the same strains of Salmonella on alfalfa seeds (Thayer and others, 2003). Thus, approximately, 6 kGy would be required to inactivate 5-logs of the pathogen as required by the U.S. Food and Drug Administration. Ongoing work will determine if organoleptic changes occur in irradiated almonds at the dose required to eliminate this pathogen.