Impacts of inoculation strategy on survival of Salmonella enterica and Enterococcus faecium at low water activity on dry peppercorn and cumin seeds

Salmonella contamination of spices and other low water activity foods is a growing concern for the food industry due to increased frequency of salmonellosis outbreaks and detection-based product recalls. The impact of inoculation preparation on the survival of a Salmonella enterica and its proposed surrogate, Enterococcus faecium NRRL B-2385, on the whole black peppercorns and cumin seeds was examined. Three liquid inoculation methods (biofilm-inclusion, agar-grown, broth-grown) for Salmonella enterica and surrogate Enterococcus faecium and one dry transfer method for Salmonella enterica were developed then applied to whole peppercorn and cumin seeds. Spices were returned to original water activity (aw 0.3) and stored for 28 days with periodic sampling (0, 1, 7, 14, 21, 28 days) and surviving bacteria enumerated. Average log reductions (LR) over time were statistically analyzed to determine differences in stability during storage. Inoculation preparation was associated with significant differences in recovered Salmonella and Enterococcus from both peppercorn and cumin over the storage period. At 28 days, the most stable inoculations of Salmonella resulted from the biofilm-inclusion (-0.04 CFU/g LR) and agar grown (-0.75 CFU/g LR) methods on peppercorn and the biofilm inclusion method (-0.28 CFU/g LR) on cumin. Log reductions of Enterococcus faecium (-0.02 CFU/g LR biofilm-inclusion-peppercorn, -0.19 CFU/g LR agar-grown-peppercorn, -0.61 CFU/g LR biofilm-inclusion-cumin) were comparable to Salmonella after 28d desiccated storage. These results will guide the inoculation strategies for validating inactivation processes for reducing Salmonella on whole spices, and for comparisons of inactivation of Salmonella and its proposed surrogate Enterococcus faecium.

Name thesis:degree_name

Master of Science in Life Sciences

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Food Science and Technology

Department dc:contributor.department

Food Science and Technology

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2015

Author dc:creator

• Bowman, Lauren Stewart

Chair dc:contributor.committeechair

• Ponder, Monica A.

Committee members dc:contributor.committeemember

• Mallikarjunan, Parameswaran Kumar
• Williams, Robert C.

• Salmonella
• Enterococcus
• low water activity
• surrogate
• spice
• biofilm

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

vt_gsexam:6325

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/63926