A Novel Technique for Sterilization Using a Power Self-Regulated Single-Mode Microwave Cavity

Abstract

In this paper, a novel technique to achieve precise temperatures in food sterilization has been proposed. An accurate temperature profile is needed in order to reach a commitment between the total removal of pathogens inside the product and the preservation of nutritional and organoleptic characteristics. The minimal variation of the target temperature in the sample by means of a monitoring and control software platform, allowing temperature stabilization over 100 °C, is the main goal of this work. A cylindrical microwave oven, under pressure conditions and continuous control of the microwave supply power as function of the final temperature inside the sample, has been designed and developed with conditions of single-mode resonance. The uniform heating in the product is achieved by means of sample movement and the self-regulated power control using the measured temperature. Finally, for testing the sterilization of food with this technology, specific biological validation based on Bacillus cereus as a biosensor of heat inactivation has been incorporated as a distribution along the sample in the experimental process to measure the colony-forming units (CFUs) for different food samples (laboratory medium, soup, or fish-based animal by-products). The obtained results allow the validation of this new technology for food sterilization with precise control of the microwave system to ensure the uniform elimination of pathogens using high temperatures.

Effect of Microwave Heating on the Acrylamide Formation in Foods

“…Some researchers have claimed non-thermal or enhanced thermal effects, to be associated with microwave heating on the destruction of microorganisms and inactivation of enzyme. Many researchers, however, rejected and continue to reject any molecular effects of electric fields compared with thermal energy [ 63 , 71 , 72 , 73 , 74 , 75 ]. According to U.S. Food and Drug Administration [ 76 ], the additional inactivation or non-thermal inactivation effect of microwave process on the destruction of microorganisms and inactivation of enzymes is inadequate in degree.…”

“…Despite the passage of years and many studies the issue still remains controversial. The effects of microwave and dielectric heating are clearly fields where there are knowledge gaps, and further studies are needed [ 63 , 71 , 72 , 73 , 74 , 75 ].…”

“…The studies demonstrated better results for microwave sterilization of food in terms of nutrient quality retention and microbial elimination in comparison with earlier results. However, the uniform temperature profile in the whole food product is not clearly confirmed [ 63 , 74 ].…”

Biocontrol Processes in Fruits and Fresh Produce, the Use of Lactic Acid Bacteria as a Sustainable Option

“…In addition, food pH significantly influences the effectiveness of the process. Recently, the use of 915 MHz instead of 2.45 GHz has been studied to improve the uniformity of the electric field applied (Reverte-Ors et al, 2017).…”

Non-invasive Neurologic Assessment in Recovery and Treatment Phase Acrylamide Exposure in Ageing Wistar Rats

“…It has been found in certain starchy foods [2,3] like potatoes [4,5] that have been cooked and processed at high temperatures [5,6]. Based on animal studies, previous evaluations reveal that acrylamide in food potentially increases the risk of developing cancer for consumers in all age groups [7]. Since acrylamide is present in a wide range of everyday foods, this concern applies to all consumers but children are the most exposed age group on a body weight basis [8].…”