Purpose: The purpose of this study was to evaluate the thermal inactivation kinetics of Salmonella spp. and Listeria monocytogenes during sunflower seeds processing.
Methods: Sunflower seeds samples were individually inoculated with cocktails of Salmonella spp. and L. monocytogenes to achieve a target level of 108 CFU/g. Following inoculation, samples were brined and roasted at oven settings of 225°F or 275°F. Roasting times were between 5 to 45 minutes. The study constituted 3 replicates. Samples inoculated with Salmonella spp. were enumerated using Tryptic Soy Agar (TSA) pour plates overlaid with Xylose-lysine-desoxycholate agar. Samples inoculated with Listeria monocytogenes were enumerated using TSA pour plates overlaid with Modified Oxford Agar. Water activity analysis was performed using AquaLab Dew Point Water Activity Meter 4TE. Log-transformed data were fitted to a multiple regression model using least squares regression. 95% prediction intervals were generated to predict the minimum thermal processing parameters required to achieve a 4-log reduction in Salmonella spp. and L. monocytogenes.
Results: Modeling of sunflower seed data indicated that to meet a minimum 4-log reduction in Salmonella spp. and L. monocytogenes, thermal processing parameters of 275°F (hot air temperature) for 20 minutes were needed. A water activity of 0.620 and product temperature of 180°F were found to be the corresponding food safety verification parameters. The adjusted R-square values ranged from 0.91-0.99.
Significance: The study findings indicate that the hot air roasting process achieves acceptable lethality of vegetative pathogens. The data generated in this study provides scientific basis for the facility’s food safety plan.