Publication Detail

2011

Authors: Jeong S, Marks BP, Elliott TR, Harte JB

Journal: International Journal of Food Microbiology (153: 365-371)

Supported by the ILSI North America Committee on Food Microbiology

Abstract: The overall goal of this study was to develop a set of process design principles for low-energy X-ray irradiation of tree nuts. Almonds and walnuts were inoculated with Salmonella Enteritidis PT30 and Salmonella Tennessee, and conditioned to four differentwater activities (0.23, 0.45, 0.64, and 0.84 aw). Thereafter, the inoculated/conditioned samples were irradiated to achieve up to a 5-log reduction in Salmonella using a pilot scale low-energy X-ray food irradiator. Greater efficacy (D10-value: the dose required to eliminate 90% of the microbial population) for inactivating
SE PT30 and S. Tennessee was seen on the surface of almonds (0.226–0.431 kGy) than on walnuts (0.474–0.930 kGy) at all water activities. Also, the efficacy did not change monotonically with water activity. Overall, no significant difference (P>0.05) in sensory characteristicswas seen between non-irradiated almonds and those irradiated
to achieve a 5 log reduction in Salmonella. However, irradiating walnuts to the dose corresponding to a 5 log reduction caused a perceivable change in flavor. Post-irradiation storage tests revealed that surviving bacterial counts did not change over 120 days, regardless of nut type, Salmonella serovar, and aw. Therefore, low-energy Xray
irradiation technology appears to be a promising non-thermal pasteurization strategy for certain types of nuts.

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