The Effect of Microwaves on Microorganisms

Considering the popular use of microwave ovens to prepare foods, inhibitory effect of microwave cooking on foodborne pathogens was studied. Whiting and salmon blocks were inoculated either with E. coli O157:H7, Staphylococcus aureus or Listeria monocytogenes, then cooked in microwave oven to the internal temperatures of 50 and 70°C. Cooking of fish fillets to both internal temperatures resulted in approximately 4 log cfu/cm2 reductions in E. coli O157:H7 population. After cooking to the internal temperatures of 50°C S. aureus counts reduced by 2.78 and 1.06 log cfu/cm2 on whiting and salmon fillets, respectively. L. monocytogenes counts reduced by 1.70 and 0.14 log cfu/cm2 on whiting and salmon fillets, respectively, cooked to 50°C. S. aureus and L. monocytogenes counts reduced below detectable level (2 log cfu/cm2) when cooked to 70°C. The results suggest that internal temperature should be higher than 70°C during microwave cooking to destroy completely these pathogens. Practical applications This research shows that pathogens of Listeria monocytogenes, Staphylococcus aureus and E. coli O157: H7 cannot be completely inhibited by microwaving at 50 and 70°C (internal temperatures) in both fish species. The findings revealed that using a microwave oven to cook fish could be a problem regarding pathogen inactivation in terms of food safety and human health. The study may also help microwave oven producers and caterers to prepare the manufacturer's recommendations, and to determine CCPs in HACCP plans.

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Microwave Heating for Food Preservation

Laguerre¹,

Hamoud-Agha²

2020

Food Preservation and Waste Exploitation

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Since food is generally of low thermal conductivity, heating by conventional methods remains relatively slow. Thanks to its volumetric and rapid heating, microwave (MW) technology is successfully used in many applications of food processing. In this chapter, fundamental principles of MW heating are briefly presented. MW drying and MW microbial decontamination are extensively reviewed as innovative methods for food preservation. However, the complex interactions between microwaves and materials to be heated are not yet sufficiently controlled. Moreover, MW heating heterogeneity and thermal runaway are the main drawbacks of this technology. Several methods have been proposed and investigated in the literature to overcome these problems in order to assure the microbiological safety and quality of food products.

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The Effect of Microwaves on Microorganisms

Cited by 3 publications

References 26 publications

An innovative hybrid steam-microwave sterilization of palm oil fruits at atmospheric pressure

An innovative hybrid steam-microwave sterilization of palm oil fruits at atmospheric pressure

Effect of microwave cooking on foodborne pathogens in fish

Microwave Heating for Food Preservation

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