Bacterial decline at each sampling point during storage was calculated by subtracting the levels determined at the sampling point from the levels measured at the beginning of storage.
The declines among the three genera were similar at all sampling points except for three; greater declines were observed in
L. monocytogenes populations than in Salmonella and E. coli O157:H7 populations at 27, 83, and 97 days of storage.
Over 97 days of ambient storage, declines of Salmonella and
E. coliO157:H7 were estimated to be less than 1 log CFU/nut and the decline of L. monocytogenes was 2 log CFU/nut. These declines were less than the 2.8- to 3.8-log decline observed for Salmonella Enteritidis PT 30 on walnuts inoculated at 10 or 7.5 log CFU/nut,
respectively, and stored for a similar length of time (83 to 139 days)