Low Water Activity Environment

A number of recent global outbreaks and recalls related to microbial pathogens in low water activity foods (e.g., beef jerky, grain flours, ground spices, peanut butter) have resulted in increased concerns within the food industry and research community about low water activity food safety. Bacterial pathogens such as  Salmonella spp. can survive in low water activity foods for extended periods of time. To reduce these pathogens in low water activity foods, different processing technologies such as steam and radio-frequency heating are used in the food industry. Atmospheric non-thermal plasma is a recent advanced potential technology, currently being evaluated at research laboratories to understand its antimicrobial efficacy. Several product- and process-factors influence the efficacy of these technologies in pathogen reduction. Among these factors, the presence of water is one of the most influential.

The overall aim of this research program is to enhance our knowledge of how product- and process-related water properties impact microbial inactivation at low water activity environment. These include water activity (aw), glass transition temperature (Tg) and protein mobility in Salmonella cells and relative humidity of the surrounding environment during processing. The long-term objective of this research program is to develop atmospheric non-thermal plasma and pulsed LED treatments to enhance food safety at low water activity environment.

Research Directions:

  • Potential of Atmospheric Non-thermal Plasma and High-Intensity Pulsed LED [275 nm, 365 nm, 395 nm, and 455 nm wavelength] treatments
  • Understanding the influence of water properties on microbial resistance and quality of foods during thermal, non-thermal plasma and pulsed LED treatments in low water activity environments
  • Water activity, water mobility and glass transitions

Current Projects:

  • Understanding the influence of water properties on microbial inactivation during processing of low water activity foods
  • Thermal and antimicorbial treatments to improve low water activity food safety
  • Influence of water activity on thermal resistance of pathogens in low water activity foods
  • High intensity pulsed LED treatment to improve low water activity food safety
  • Cold plasma treatment to reduce mycotoxins in animal and poultry feed products


Amritha Jaya Prasad, Harleen Kaur Dhaliwal, Ehsan Feizollahi and Dr. Basheer Iqdiam


Dr. Michael Gänzle (Department of AFNS)
Dr. Lynn McMullen (Department of AFNS)
Dr. Xiaonan Lu (University of British Columbia)
Dr. Ruurd Zijlstra (Department of AFNS)
Dr. Stephen Strelkov (Department of AFNS)
Project Sponsors:
NSERC Discovery, Alberta Livestock and Meat Agency (ALMA), Alberta Agriculture and Forestry, Alberta Canola Producers Commission (ACPC)