The Bacteriological Quality of Retail-Level Peanut, Almond, Cashew, Hazelnut, Brazil, and Mixed Nut Kernels Produced in Two Australian Nut-Processing Facilities over a Period of 3 Years

An investigation of the bacteriological quality of ready-to-eat peanuts, almonds, cashews, hazelnuts, and brazil nuts processed in two Australian nut-processing facilities was performed over a period of 3 years. A total of 564 ready-to-eat retail packs were analyzed for aerobic plate count (APC), Salmonella, coagulase-positive staphylococci, Listeria monocytogenes, and Escherichia coli. Of these samples, 343 were peanuts, 45 cashews, 42 almonds, 40 brazil nuts, 51 hazelnuts, and 43 were mixed packs containing all five types. There was no Salmonella, E. coli, or coagulase-positive staphylococci detected in any sample. L. monocytogenes was detected in two of the mixed packs after enrichment, but was not detected from samples by an alternate enumeration method (detection limit = 10/g). The APC percentages of positive samples with counts above the detection level of the plating method used (100 CFU/g) for peanuts, almonds, cashews, hazelnuts, brazil nuts, and mixed nuts were 48%, 36%, 62%, 36%, 56%, and 44%, respectively. Of the samples containing more than this detection limit, the means were 2.7, 2.4, 2.4, 2.6, 2.8, and 2.7 log CFU/g, respectively. The maximum APC was 3.9 log CFU/g. The bacteriological quality of roasted peanut, almond, cashew, hazelnut, brazil, and mixed nut kernels processed in Australian facilities does not appear to suggest a public health concern.