Sterilization of oil palm fruit utilizing continuous microwave sterilizer

Abstract

This study evaluates the performance of a continuous microwave device in the sterilization of oil palm fruits spikelet. The device comprises four microwave generators (magnetron), a tunnel cavity driven by a belt conveyor, and a tray as a container for palm fruit. This study aims to evaluate the distribution and penetration of microwave energy into palm fruit and to examine the quality of palm oil concerning power density and residence time adjusted in this study. Continuous microwave sterilizer was operated at various masses of oil palm fruit (0.5, 1, 1.5 kg), residence time (6, 8, 10, 12, 14 min), and microwave power (180, 300, 450, 600, 800 W). The resulting temperature in this study ranged from 39 to 97 °C. Observation of the temperature gradient inside-out of a single fruit indicates the interior temperature at the kernel nut is always higher as compared to exterior temperature (abscission layer), with temperature differences ranging from 3 to 23 °C. A minimum power density of 300 W/kg, a residence time of 6 min, and a temperature of 50 °C were required to produce palm oil with FFA less than 5%. Performance indicators of the prototype used in this study are a number of moisture loss dan oil quality. The moisture loss during the sterilization process was around 0.5 to 10.6% which indicates some water content in the fruit, while the content of water, FFA, β-carotene and vitamin E ranging between 1.9 and 17.6%, 0.32-1.74%, 186.14-608.59 ppm and 165.47-610.17 ppm, respectively. © 2001 Elsevier Science. All rights reserved.

Keywords

• β-carotene
• FFA
• Microwave
• Sterilization
• Vitamin E
• Water content