Understanding Phytosanitary Irradiation Treatment of Pineapple Using Monte Carlo Simulation Jongsoon Kim*, Soon-Hong Kwon, Sung-Won Chung, Soon-Goo Kwon, Jong-Min Park, Won-Sik Choi Department of Bio-industrial Machinery Engineering Pusan National University, Busan, Korea Received: April 15 th , 2013; Revised: May 17 th , 2013; Accepted: May 21 th , 2013 Purpose: Pineapple is now the third most important tropical fruit in world production after banana and citrus. Phytosanitary irradiation is recognized as a promising alternative treatment to chemical fumigation. However, most of the phytosanitary irradiation studies have dealt with physiochemical properties and its efficacy. Accurate dose calculation is crucial for ensuring proper process control in phytosanitary irradiation. The objective of this study was to optimize phytosanitary irradiation treatment of pineapple in various radiation sources using Monte Carlo simulation. Methods: 3-D geometry and component densities of the pineapple, extracted from CT scan data, were entered into a radiation transport Monte Carlo code (MCNP5) to obtain simulated dose distribution. Radiation energy used for simulation were 2 MeV (low-energy) and 10 MeV (high-energy) for electron beams, 1.25 MeV for gamma-rays, and 5 MeV for X-rays. Results: For low-energy electron beam simulation, electrons penetrated up to 0.75 cm from the pineapple skin, which is good for controlling insect eggs laid just below the fruit surface. For high-energy electron beam simulation, electrons penetrated up to 4.5 cm and the irradiation area occupied 60.2% of the whole area at single-side irradiation and 90.6% at double-side irradiation. For a single-side only gamma- and X-ray source simulation, the entire pineapple was irradiated and dose uniformity ratios (Dmax/Dmin) were 2.23 and 2.19, respectively. Even though both sources had all greater penetrating capability, the X-ray treatment is safer and the gamma-ray treatment is more widely used due to their availability. Conclusions: These results are invaluable for optimizing phytosanitary irradiation treatment planning of pineapple. Keywords: Phytosanitary irradiation, Monte Carlo, MCNP, Pineapple Original Article Journal of Biosystems Engineering J. of Biosystems Eng. 38(2):87-94. (2013. 6) http://dx.doi.org/10.5307/JBE.2013.38.2.087 eISSN : 2234-1862 pISSN : 1738-1266 *Corresponding author: Jongsoon Kim Tel: +82-55-350-5426; Fax: +82-55-350-5429 E-mail: jongsoon-kim@pusan.ac.kr Copyright ⓒ 2013 by The Korean Society for Agricultural Machinery This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Introduction Agricultural produce is a basic need of humanity and its production has become increasingly internationalized over the past century. Thus, the countries have been aware that destructive pests in agricultural commodities gained entry to a country from which it was previously absent, because it can cause significant economic and ecological damage. It is estimated that the loss caused by these pests globally is about $1.4 trillion or 5% of the world gross national product (Pimentel et al. 2007). Phytosanitary treatments eliminate, sterilize, or kill pests in exported commodities to prevent their intro- duction and establishment into the new areas. Most phytosanitary treatments currently in use involve sub- jecting traded commodities to heat (~46℃), cold (~1℃) or chemical fumigants to acutely kill regulated pests. However, commodity tolerance is often the main limiting factors on the use of heat or cold treatments of fresh produce. Moreover, fumigants which have been toxic broadly on the environment and traded fresh produce will be phased out in the near future (UNEP, 2012). Irradiation is very effective against pests (insects and mites), cost competitive and fast, compared with other methods. Irradiation generally does not significantly reduce commodity quality, and even it can be applied to the commodity after packaging.