Decontamination of food-packing material using moist heat

Depending on the microbiological quality, it may be necessary to reduce the number of microorganisms on the packing material before use with food products. Treatment with hydrogen peroxide at elevated temperatures is most commonly used. Residues of hydrogen peroxide, however, are undesirable. Systems not using chemicals obviously would be preferable. For products which do not allow the growth of bacteria, such as many acid products and products with a low water activity, often it is sufficient to inactivate moulds and yeasts. Moulds and yeasts can be inactivated by temperatures below 100°C provided the water activity is high enough. At low humidities at the same temperatures hardly any reduction in viable count is obtained. A prototype machine was built to investigate the inactivation of microorganisms on the surface of packing material, using moist heat for a short time, similar to the time needed for decontamination by peroxide. The number of viable dry spores of Penicillium roqueforti can be reduced by a factor of >1000 within 3 s at 90°C and 100% humidity. Moist heat decontamination is a promising method which could help manufacturers pack food in a microbiologically safe manner, without the use of chemicals. Further work is needed, however, to determine the inactivation of other relevant microorganisms.