Methods To Obtain Thermal Inactivation Data For Pathogen Control In Low-Moisture Foods

Background: Outbreaks of foodborne pathogens (including Salmonella spp., Escherichia coli, and Listeria monocytogenes, etc.) in low-moisture foods (LMFs), such as butter, cereal, cheese, dried vegetable, nut, and spice, are emerging concerns of food safety in recent decades. The food industry is in urgent need for reliable thermal inactivation data on these pathogens in a wide range of LMFs in order to develop effective pasteurization processes. Over the past ten years, research laboratories in academia have developed several effective test methods to obtain thermal inactivation data for LMFs. The data are generally fitted to thermal death models to obtain thermal processing parameters, which are then used in the design and validation of new thermal processes. An example of novel thermal processing technologies is the rapid and volumetric radio frequency (RF) heating, which has shown unique advantages over conventional heating in pasteurization of LMFs. Scope and approach: Temperature and water activity are the key factors in determining thermal resistance of pathogens in LMFs. This review summarizes the recently published work on testing methods for thermal inactivation of bacteria, and discusses their unique features in controlling the key parameters, including temperature, and water activity (or moisture content) of the samples. This paper provides a systematic summary of the thermal inactivation models for pathogens in LMFs. It also illustrates the use of the thermal inactivation data and the predictive models to develop and validate pathogen control in LMFs using RF energy. Key findings and conclusions: The closed and controlled system test methods are proven to be appropriate and effective approaches for obtaining thermal inactivation data of pathogens in LMFs. Key factors can be either constant or adjustable by using of the above experimental methods. Those data are used in developing and validating RF treatments for control of Salmonella in several LMFs.