Using a continuous microwave system for postharvest almond disinfestation

This paper reports on the development of a physical technology for the sanitization of shelled almonds from E. kuehniella as an alternative to chemical treatments. A continuous microwave (MW) system was developed and a program of experimental trials of treating almonds by administering different increasing levels of specific energy from 7.3 to 18.1 kJ kg(-1) was performed. Insect mortality in three different life stages: 24-hour old eggs, 24-hour old larvae and mature larvae was evaluated. Lipoxygenase (LOX) activity and sensory analysis was carried out to evaluate the quality of the almonds treated. One hundred percent mortality of mature larvae was achieved in all test conditions explored, while mortality of 24-hour old eggs and 24-hour old larvae was achieved by administering specific energy of at least 12.1 kJ kg(-1) with the almonds surface temperature of 55.7 degrees C. No significant differences in the LOX activity were found and, regarding the sensory analysis, the authors assessed that both MW treated almonds and the control sample retain all the main organoleptic properties. Furthermore, no off-flavors were detected either from the olfactory or taste points of view. This study demonstrated that continuous microwave treatment can be used as an effective pest control treatment of almonds, with potential for use also for other foodstuffs, thus proving to be a valid alternative to chemical treatments.