Study type: Medical/biological study (experimental study)

Lethal effect of microwaves on spores of Bacillus spp. med./bio.

Published in: J Food Prot 2003; 66 (4): 604-609

Aim of study (acc. to author)

Strains representing four common species of bacilli (bacteria) were used to monitor the survival of bacteria after microwave treatment at different power levels. Various conditions were designed to mimic different viscosities and water activity values (associated with food). The effects of materials used in the containers and of different incubation times were also investigated.



Exposure Parameters
Exposure 1: 2.45 GHz

General information

Samples exposed in salt solutions, starch solutions and containers in a microwave oven at 60%, 80% and 100 % of power levels.

Exposure 1

Main characteristics
Frequency 2.45 GHz
Modulation type unspecified
Exposure setup
Exposure source
Measurand Value Type Method Mass Remarks
power 700 W - cf. remarks - max power rating of the microwave oven.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The findings showed that B. licheniformis spores had the highest microwave tolerance at a power level of 100% for different incubation times. B. coagulans spores showed the lowest microwave tolerance in salt solutions, and B. licheniformis spores were the most resistant in the tested salt solutions at different incubation times. An analysis of the effect of the viscosity revealed that the bacteria had the lowest microwave resistance in a medium containing <0.8% starch in solution. The microwave resistance levels of the bacteria were lower in glass containers than in polypropylene containers and aluminum foil-enclosed pouches. Of the four species, B. licheniformis had the highest microwave tolerance under all conditions.

Study character:

Study funded by