Improving Radio Frequency Heating Uniformity Using A Novel Rotator For Microorganism Control And Its Effect On Physiochemical Properties Of Raisins

In the present study, a novel material rotator was designed to evaluate the possibilities to improve radio frequency (RF) heating uniformity in raisins. The rotator provided a means to rotate materials when subjected to RF heating. The results showed that RF heating uniformity was significantly (p 0.05) improved with the rotation of raisins. The relative heating uniformity parameter (?) reduced to less than 15% at rotational speed of 40 and 60 rpm. No significant (p 0.05) influence on heating rate was observed. Pasteurization experiments showed the total bacterial (4.88 log) count was reduced by 2.55 log CFU/g and the molds (4.83 log) were completely inactivated when raisins were heated to 80 ?C and maintained for 10 min, which indicated a great disinfection efficiency of RF heating. Quality evaluation showed the physiochemical property changes of raisins were satisfied with acceptable color and nutrients loss. Therefore, the method used in this experiment could be expanded to develop an effective treatment protocol for controlling microorganisms in raisins.