Novel drying techniques for controlling microbial contamination in fresh food: A review

Fresh foods such as fruits, vegetables, grains, nuts, and meats are generally rich in water and are susceptible to microbial contamination. Drying and dehydration processes can reduce water content, but low water activity foods may not be microbiologically safe. Several novel drying techniques have demonstrated varying degrees of effectiveness in microbial inactivation, including supercritical CO2 drying, low-pressure superheated steam drying, microwave drying, radio frequency drying, infrared drying, vacuum drying, freeze drying, etc. Some typical microorganisms used as indicators of microbial inactivation including natural present microorganisms (e.g., mesophilic bacteria and their spores, yeast and mold) and various pathogens (e.g., Escherichia coli O157:H7, Listeria monocytogenes and Salmonella spp.). This paper reviewed novel drying techniques for controlling microbial contamination of fresh foods and analyzed their advantages/disadvantages and microbial inactivation capabilities. These novel drying techniques have the potential to ensure microbiological safety during drying and have the prospect of shortening the food processing chain by integrating drying and sterilization/decontamination into the same process.