Hot water treatment as a kill-step to inactivate Escherichia coli 0157:H7, Salmonella enterica, Listeria monocytogenes and Enterococcus faecium on inshell pecans

摘要

In-shell pecans are susceptible to microbial contamination. This study was performed to investigate feasibility of using hot water treatment as a Idll-step for food-borne pathogens during pecan shelling. In-shell pecans were subjected to hot water at70, 80 or 90 °C for 1, 2, 3, 4 or 5 min. The time-temperature treatments to achieve a 5-log reduction of Sabnonella enterica, Escherichia coli 0157;H7, Listeria monocytogenes, and non-pathogenic Enterococcus faecium were determined. Thermal death valueswere determined for each tested condition. L. monocytogenes was most susceptible to heat treatment and were reduced by 4.6 ± 0.35 log CFU/g at 70 °C for 5 min, while 3-5 min at 80 and 90 °C treatments was required to achieve a similar reduction levelfor S. enterica, E. coli 0157:H7, and E. faecium. S. enterica were most resistant and required 4 min treatment time to achieve a 5-log reduction at 80 and 90 ”C. The D-values ranged from 1.15 to 1.72, 0,83 to 1.19, and 0.41-0.92 min at 70, 80 and 90 "C, respectively. E. faecium had the highest D-value (1.72 min at 70 °C), indicating a potential surrogate for process validation for pecan industries. Utilizing proper hot water treatment during pecan shelling could reduce food safety risk.