Abstract
The inactivation of Listeria monocytogenes in a kiwifruit puree by
conventional and microwave heating was studied. Survival curves at three microwave
power levels (6001000 W) and three temperatures (5060 °C) were obtained. Data
were properly fitted by a first-order kinetic model. Processing times under both
technologies were corrected to isothermal treatment for the kinetic study. Microwave
heating was shown to effectively inactivate L. monocytogenes. In the range of
microwave and conventional processing conditions assayed, the 5-log10 reductions of L.
monocytogenes recommended by the FDA for pasteurized products were achieved. The
level of microwave power applied had a considerable influence on the Listeria
monocytogenes inactivation rate. The higher the power level, the faster the inactivation.
The inactivation of Listeria monocytogenes under microwave heating at 900 W
(D60°C=17.35 s) and 1000 W (D60°C=17.04 s) happened faster than in a conventional
thermal process (D60°C=37.45 s). Consequently, microwave heating showed greater
effectiveness for Listeria monocytogenes inactivation than conventional heating.
