Inactivation of Microorganisms with Microwaves at Reduced Temperaturas

Abstract

We developed a pilot-plant nonthermal flow process using microwave energy to inactivate microorganisms. The process consists of multiple passes through the microwave generator. Each passed material goes to a receiving tank for subsequent passes. The flow rate was 0.96 to 1.26 kg/min and the dwell time per pass was 1.1 to 1.5 min. Five passes were used. The microwave energy is instantaneously and simultaneously applied to the system, and thermal energy is removed by a cooling tube within the process line in the microwave generator. The cooling tube maintains the temperature below 40 degrees C. There was significant reduction in microorganisms in water, 10% glucose solution, and apple juice, and in yeast in beer. There was a slight decrease in microorganisms in tomato juice, pineapple juice, apple cider, and beer; and no effect in skim milk.

Inactivation of Salmonella enteritidis on raw poultry using microwave heating

“…(Schiffmann, 1987(Schiffmann, , 1990. There have been some attempts (Cunningham, 1980;Culkin and Fung, 1975) to ascertain if microwaves have a non-thermal inactivation on the microorganisms, and predominant theories have been used to explain this effect (Kozempel et al, 1998). Regardless of the mode of action, microwave radiation has been reported to be feasible for achieving longer shelf lives of several food products.…”

Microwaving human faecal sludge as a viable sanitation technology option for treatment and value recovery – A critical review

“…Thus incident microwaves selectively energize such polar substances, causing irreversible damage to the cell membranes through DNA disruption. This subsequently leads to rupturing of the cell walls and membranes, and release of intracellular materials -leading to eventual denaturation electroporation and cell membrane rupture theories both seem to argue that electrical potential or voltage applied across the cell membrane causes a rupture or generation of pores, which subsequently results in leakage and release of intracellular materials (Kozempel et al, 1998). All the mechanisms points to the fact that microwave heating can attack coliform bacterial/microbial cell membranes, rupturing them and leading to their death.…”

“…The extents to which both effects contribute to pathogen kill are still relatively unknown. Selective heating, electroporation, cell membrane rupture and magnetic field coupling have all been reported as mechanisms behind the capacity of microwave heating to kill pathogens and enzymes (Kozempel et al, 1998). The selective heating and magnetic field coupling mechanisms suggest that the cell membranes of microbes are composed permeable lipids, which have a strong affinity for microwave absorption.…”

Design and Implementation of a Continuous Microwave Heating System for Ballast Water Treatment

“…The extent of heating produced depends on the dielectric properties of the medium (15,16). Microwaves have been used extensively in the past to successively inactivate enzymes and bacterial cells present in foods (17)(18)(19)(20)(21)(22).…”