A New Approach to Estimate Salmonella Inactivation Parameters During Dynamic Elevated Heat Treatment: A Case Study...

Area of Science:

• Food Microbiology
• Food Process Engineering
• Thermal Processing

Background:

• Limited data exists on Salmonella inactivation in low-moisture foods (LMFs) at temperatures above 90°C without direct heating medium contact.
• Commercial processing of LMFs like baking and roasting often involves non-isothermal conditions exceeding 90°C.

Purpose of the Study:

• To investigate Salmonella inactivation kinetics in flaxseeds under dynamic, elevated temperature conditions (>90°C) without direct contact with the heating medium.
• To compare primary and secondary models for predicting thermal inactivation of Salmonella in flaxseeds.
• To estimate Salmonella inactivation parameters (D-value, z-value) under simulated commercial processing conditions.

Main Methods:

• Flaxseeds were inoculated with Salmonella Enteritidis PT 30 and equilibrated to a water activity of 0.55 ± 0.03.
• Heat treatment was conducted using a silicon oil circulator at 95, 105, and 120°C for short, evenly spaced time intervals.
• Salmonella inactivation was modeled using log-linear, Weibull, and Geeraerd primary models and log-linear/Bigelow and Weibull/Bigelow secondary models, with parameters estimated via ordinary least squares (OLS).

Main Results:

• The log-linear/Bigelow model demonstrated the best fit for describing thermal inactivation kinetics at elevated temperatures, indicated by the lowest Akaike Information Criterion (AICc) values.
• A tenfold reduction in Salmonella (D-value) at 105°C required a 35.9°C increase in temperature.
• Higher oil bath temperatures improved the estimation accuracy of D-value, z-value, and n due to larger scaled sensitivity coefficients.

Conclusions:

• A novel method was developed to estimate Salmonella inactivation parameters in flaxseeds under dynamic, high-temperature conditions.
• The findings provide valuable data for food processors to develop and refine predictive models for Salmonella control in low-moisture foods during commercial processing.
• This research contributes to enhancing the safety of low-moisture food products against Salmonella contamination.