Heat Transfer Evaluation on Microwave Sterilization: Case Study of Oil Palm Fruit

Abstract

Microwave energy can be used for oil palm fruit bunch sterilization. It penetrates onto the core of oil palm fruit bunches and generates heat inside out. This sterilization aims to inactivate lipase that influences palm oil quality. This study evaluates effect of dielectric properties power developed per unit volume and interior temperature distribution on heating rate during heating process. The experiment carried out at various combinations of microwave power and the oil palm bunches portion in microwave oven. This study observed that distribution of interior temperature in a single oil palm fruit was influenced by power density and fruit’s diameter. Greater power density provides high microwave energy per kg sample to attain greater temperature of microwave heating and vice versa. Distribution of interior temperature in the fruit with the thickness (r) of 6 mm and above indicated non-uniformity heating. Furthermore, interior temperature of fruitlet with r = 4.5 mm indicated distribution of temperature from endocarp to exocarp, meanwhile simulation temperature on smaller fruit diameter (r = 3 mm) indicated thermal runway effect after 5 min heating duration.