099: Application of Continuous Radio Frequency Heating Technology for Pest Control in Packaged Rice

Introduction

Pests in packaged organic rice pose a significant challenge to the food industry, affecting quality and safety. Moreover, chemical fumigation treatments may lead to potential health risks and environmental issues, making them unsuitable as a pest control method for organic rice. RF heating, which can rapidly and uniformly heat packaged rice, offers a promising alternative for pest control. Therefore, this study aims to investigate a continuous 10 kW, 40.68 MHz RF heating of 2 kg packaged rice to 60℃ for disinfestation.

Methods

The 2 kg of packed rice were placed between the parallel RF electrodes in the following ways: (A) a single package, (B) two packages placed side by side, (C) two packages stacked vertically, or (D) two sets of two packages stacked vertically, totaling four packages. Various gaps (8~12 cm) and loadings (2, 4, and 8 kg) were utilized for measuring output power. Then the 10 kW, 40.68 MHz RF with a 9 cm gap was employed to heat four types and surface temperature was measured to determine the heating rate. Finally, 20 adult rice pests were placed in each packet of rice and heated by RF every 30 s to determine the number of dead and surviving pests until 100% mortality was achieved.

Results

RF heating performed well in heating packaged rice and controlling rice pests. The temperature rise curves for various electrode plate gaps revealed changes in RF heating rate and heating time when the gap was between 8 cm and 10 cm. Under conditions A, B, C, and D with a gap of 9 cm, the heating times to 60℃ were approximately 120, 180, 90, and 140 s, respectively, resulting in a 100% mortality ratio of adult rice pests.

Significance

This study recommends a continuous 10 kW, 40.68 MHz RF operation (D) for disinfestation in the food industry. Two sets of vertically stacked rice packages, totaling four packages took only 140 s to attain 60℃.

Author: Su-Der Chen