Microbial response to some nonthermal physical technologies

Background: In response to the worldwide interest in safe, nutritious and minimally processed food products, innovative nonthermal processing for microbial inactivation has been developed as one of the major growth sectors in the food industry. In contrast to traditional thermal processing, nonthermal physical technologies have the ability to inactivate microorganisms at lower temperatures and maintain the organoleptic and nutritional qualities of food products. However, microbial cells can also develop a range of strategies to adapt rapidly to environmental stimuli and to survive under harsh conditions, posing a potential hazard to the food processing industry. Scope and approach: This review concluded the microbial response to nonthermal technologies from the perspective of three states of microbes, sublethal cells, viable but non-culturable cells, and apoptosis. This work describes the responses of microorganisms to nonthermal physical technologies, mainly focusing on their physiological modifications and genetic regulatory mechanisms. Key findings and conclusion: Most nonthermal physical treatments are unable to sterilize thoroughly, thereby resulting in suppressed or sublethally injured microbial cells instead of killing them completely. This poses food safety hazards since microorganisms may re-grow at post-processing stage as favorable conditions are available again. Studying the mechanism of these responses on microorganisms may help us to do better in anticipating possible risks during food processing and preventing potential food safety incidents.