Comparing Thermal Process Validation Methods for Salmonella Inactivation on Almond Kernels.

Area of Science:

• Food Science
• Microbiology
• Process Engineering

Background:

• Increasing regulatory demands necessitate reliable pathogen reduction validation for low-moisture foods.
• Current validation methods for thermal pasteurization of low-moisture products lack comprehensive reliability evaluation.

Purpose of the Study:

• To quantify the accuracy and repeatability of four distinct validation methods for thermal pasteurization of almonds.
• To compare biologically-based methods with time-temperature models under varying conditions.

Main Methods:

• Inoculated almonds with Salmonella Enteritidis or Enterococcus faecium at varying water activity (a_w).
• Utilized a pilot-scale moist-air impingement oven with controlled temperature and humidity.
• Calculated pathogen inactivation using traditional and modified time-temperature models, and a biological surrogate (E. faecium).

Main Results:

• Time-temperature models demonstrated superior repeatability compared to the biological surrogate.
• A modified time-temperature model, incorporating process humidity, showed the lowest prediction error for Salmonella inactivation.
• Both the modified model and the surrogate provided statistically equivalent lethality predictions to actual Salmonella inactivation.

Conclusions:

• Methodology, water activity, and process humidity are critical factors in validating thermal pasteurization for low-moisture foods.
• The modified time-temperature model offers a reliable and accurate approach for process validation.
• Findings aid food processors in selecting and interpreting validation methods to ensure product safety.