Effects of Radio Frequency Heating on Sitotroga cerealella (Olivier) and Milling Quality of Rice cv. Khao Dawk Mali 105

Abstract

The objectives of this experiment were to study effects of radio frequency heating at  27.12  MHz to control Angoumois grain moth, Sitotroga cerealella (Olivier) and to examine radio frequency (RF) effects on milling quality of Rice cv. Khao Dawk Mali 105. By heating the RF power of 700 watts to egg, larval and pupal stages of Angoumois grain moth a tolerant  stage was evaluated. The rough rice containing egg, larva and pupa of  Angoumois grain moth mixed with 800 g of rough rice at 14% moisture content  were packed  separately in 20 x 25 cm jute bag and then treated with 700 watts RF at 120 seconds.  The result found that the mortality was ignificantly different (P< 0.05) among egg (80.04%), larval (88.82%) and pupal  (68.75%) stages respectively. Pupal stage as an RF tolerant stage of Angoumois grain moth was treated for 140, 160, 180, 200 and 220 seconds. The result showed that RF heating for 700 watts for 220 seconds caused 100% pupal mortality.  The milling quality by heating with 700 watts RF for 220 seconds was assayed. There was significantly higher percentage of head rice compared with control. The color of milled rice was significantly changed to more yellow (higher b*) and the percentage of moisture was also significantly decreased. The percentage of brown rice, white rice, color brightness (L*), and amylose content showed no significantly changed.