Free Fatty Acid Formation Points in Palm Oil Processing and the Impact on Oil Quality

Abstract

Background: The level of free fatty acids (FFAs) is an important oil quality index that is consistently measured at mills and refineries to ensure that palm oil is within specification limits. FFAs can accumulate at any point throughout the process, for example, during fresh fruit bunch (FFB) harvesting or during the mill process before sterilisation. Another key contributor to FFA build-up is loose fruit (LF), which is collected following FFB harvesting and is commonly processed together with FFB into crude palm oil (CPO) at the mill. The aim of this study was to identify pivotal points of FFA formation during the process of crude palm oil production. Results: The present study shows that the highest FFA accumulation occurred during the conveying process at the mill before sterilisation due to significant fruit damage. The rapid formation of FFA occurred during the first 15 min of oil palm fruit bruising. A minimum temperature of 60 °C for one hour was needed to deactivate the lipase activity, which is responsible for FFA formation. Blending high-FFA CPO with standard CPO affected indices of palm oil quality, such as the deteriorated peroxide value (PV) and anisidine value (AV), and particularly worsened the bleachability index (DOBI). Conclusions: This study suggests that the conveyor system in the mill could be the prime area to focus on in terms of FFA reduction, along with minimising bruising events. In addition, loose fruits (LF) with high FFA content should be processed separately from FFB, and high-FFA CPO derived from LF should not be mixed with standard CPO.

Keywords

• crude palm oil
• free fatty acids
• loose fruits
• lipase activity
• deterioration of bleachability index
• peroxide value