Quality Improvement of Kesambi-Seed Oil using Free Fatty Acids and Hydrogen Cyanide Adsorption

Abstract

Kesambi-seed (Schleichera oleosa) is an Indonesian potential feedstock to produce vegetable oil for energy resources and oleochemicals. Crude Kesambi-seed oil (KSO) contains 8.43% free fatty acids (FFA) and 128 ppm hydrogen cyanide (HCN), which exceeds the Indonesian National Standard (SNI) for refined oil. Purification process is needed for crude KSO to be high quality vegetable oil. This study aimed to improve the quality of KSO by reducing the FFA and HCN contents using adsorption. The adsorption equilibrium is also determined to obtain the equilibrium constants. The purification process was developed in 2 steps, i.e., degumming and adsorption. Degumming was developed using 2.5% v/v H3PO4 to separate phospholipids/phosphatides in the crude oil, while adsorption using activated carbon was introduced to reduce the FFA and HCN contents. Kesambi-seed oil purification using activated carbon adsorption could be used as one-step refining for bleaching and reducing FFA and HCN. More adsorbent is needed to reach the FFA standard for the shorter adsorption time. Adsorption using 10% activated carbon for 24 hours reduced hydrogen cyanide up to 36 mg/kg oil, lightened the oil color, and achieved the highest yield (74.62%). Meanwhile, the activated carbon concentration of 40% w/w for 96 hours obtained 0.16% FFA. All three parameters have fulfilled the Indonesian National Standard for refined vegetable oil. Furthermore, the Freundlich model best fits equilibrium adsorption of FFA in the KSO.