Reduction of Salmonella enteritidis population sizes on almond kernels with infrared heat.
Catalytic infrared (IR) heating was investigated to determine its effect on Salmonella enterica serovar Enteritidis population sizes on raw almond kernels. Using a double-sided catalytic IR heating system, a radiation intensity of 5,458 W/m2 caused a fast temperature increase at the kernel surface and minimal temperature differences between the top and bottom kernel surfaces. Exposure of dry kernels to IR heat for 30, 35 and 45 s resulted in maximum kernel surface temperatures of 90, 102, and 113 degrees C, and when followed by immediate cooling at room temperature, yielded a 0.63-, 1.03-, and 1.51-log reduction in S. enterica population sizes, respectively. The most efficacious decontamination treatment consisted of IR exposure, followed by holding of the kernels at warm temperature for 60 min, which effected a greater than 7.5-log reduction in S. enterica on the kernels. During that treatment, the kernel surface temperature rose to 109 degrees C and gradually decreased to 80 degrees C. Similar IR and holding treatments with lower maximum kernel surface temperatures of 104 and 100 degrees C yielded reductions of 5.3 and 4.2 log CFU/g kernel, respectively. During these treatments, moisture loss from the kernels was minimal and did not exceed 1.06%. Macroscopic observations suggested that kernel quality was not compromised by the IR-holding combination treatment, as skin morphology, meat texture, and kernel color were indistinguishable from those of untreated kernels. Our studies indicate that IR heating technology is an effective dry pasteurization for raw almonds.
Produce Safety and Microbiology Research Unit, Agricultural Research Services, U.S. Department of Agriculture, Albany, California 94710, USA. mbrandl@pw.usda.gov
Maria T
MT
Brandl
Zhongli
Z
Pan
Steven
S
Huynh
Yi
Y
Zhu
Tara H
TH
McHugh
D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control*; D005511:Food Handling / Q000379:methods*; D005519:Food Preservation / Q000379:methods*; D006358:Hot Temperature; D006801:Humans; D007259:Infrared Rays; D027861:Prunus / Q000382:microbiology*; D012477:Salmonella enteritidis / Q000254:growth & development / Q000528:radiation effects*; D013997:Time Factors