Effect of mild steaming treatment on the inactivation of Salmonella, Listeria monocytogenes, Escherichia coli O157:H7 and their surrogates on black peppercorns

Publication date: Available online 25 June 2019Source: Food ControlAuthor(s): Zijin Zhou, Sophie Zuber, Matteo Campagnoli, Thierry Putallaz, Frank Devlieghere, Mieke UyttendaeleAbstractThe microbial safety of black peppercorns (Piper nigrum L.) has raised concerns due to increasing numbers of reported foodborne outbreaks and food safety alerts. To avoid quality degradation caused by excessive thermal processing, mild steaming treatments (<80 °C) were tested in the present study as a promising solution to inactivate bacterial pathogens while maintaining the product quality of black peppercorns. Whole black peppercorns at three different water activities (aw) were inoculated with 1% v/w of single bacterial inoculum (including 4 Salmonella, 3 Listeria monocytogenes, 3 Escherichia coli O157:H7 and 4 non-pathogenic surrogates Enterococcus faecium, Escherichia coli P1, Escherichia.coli K12 and Listeria innocua), stored at 22 °C for 4 days to reach equilibrium and subjected to steam treatments at 70 and 75 °C for 5 min. Results indicated that steaming at 70 °C was sufficient to eliminate tested E. coli O157:H7 strains on black peppercorns at aw 0.57 and 0.69. Increased thermal resistance was observed on all pathogenic strains at the lowest aw 0.35 during treatments at 70 °C. Increasing the treatment temperature to 75 °C resulted in ≥ 5-log reductions of Salmonella and L. monocytogenes strains at all tested aw. Among the four surrogate strains, Enterococcus ...
Source: Food Control - Category: Food Science Source Type: research