Effects of ohmic pretreatment on crude palm oil yield and key qualities

Pretreatment is an important step that can increase the oil yield and improve the extraction efficiency of palm oil production. However, the conventional pretreatment method widely employed in the palm oil industry requires a relatively long time and high energy. In this research, ohmic heating was employed to pretreat oil palm fruit and the effects were studied of heating conditions on the hardness of the oil palm fruit, yield and qualities of the extracted crude palm oil. Oil palm fruits were ohmic heated using various heating conditions (temperature: 60-100 degrees C; voltage: 0-150 V; heating time: 2-10 min). Crude palm oil was then extracted from the heated samples using a screw extruder and determined for its qualities (free fatty acid, moisture content and deterioration of bleachability index). The results revealed that the voltage, temperature and heating time significantly affected the hardness of the pretreated oil palm fruit. Increasing the voltage, temperature and heating time resulted in an increase in the yield (maximum at 46%w/w) and improved the oil qualities. It was also found that ohmic pretreatment can reduce the heating time to 8 min and decrease the energy consumption of the process to 0.12 kW-h/kg. The results suggested that ohmic heating can be used as an alternative method for oil palm fruit pretreatment. (C) 2016 Elsevier Ltd. All rights reserved.