Thermal inactivation of Salmonella Mississippi on hazelnuts

Salmonellosis has been linked to consumption of tree nuts and nut products, including almonds, pecans and hazelnuts. In Tasmania, Australia, where hazelnut production is a growing industry, validated process controls are needed to reduce risk posed by endemic strains of Salmonella Mississippi. Thermal inactivation is commonly used to control Salmonella on nuts, as documented in published studies. However, no reports describe thermal inactivation of Salmonella on hazelnuts, a product increasingly popular worldwide. Inactivation kinetics of Salmonella Mississippi strains M1 and M14 were measured on hazelnuts from 50‚ÄövÑvÆ70 vÄv¿C, demonstrating an initial linear inactivation phase followed by a lower rate of tailing. Linear models were fitted separately to both inactivation phases, as well as to the full curve, demonstrating Z-values ranging from 16.2 to 27.8 ¬¨‚àûC. The time to achieve a 5-log reduction at 70 and 50 ¬¨‚àûC ranged from 49 - 125 min and 668 - 2020 min, respectively. A Weibull model was also evaluated, however a weak correlation was observed between temperature and parameters p and ˜í¬• over the temperature range.