Partition of Free Fatty Acids in Deacidification of Macauba Pulp Oil by Liquid-Liquid Extraction using Ethanol/Water as Solvent

摘要

Free fatty acids (FFA) is one of the most frequently determined quality indices in fats and oils industry because it has the economic impacts on production [1]. The FFA in macauba pulp oil is usually very high (10 to 40%) due to enzymatic activity in the raw material [2]. In this case, alkali neutralization is not economically recommended due to neutral oil loss by occlusion in soapstock. The differential solubility of fatty acids and triacylglycerides (TAG) in various organic solvents has formed the basis of several processes for deacidification of crude oils by liquid-liquid extraction [3]. The aim of the present work was to evaluate the influence of raw oil acidity, ethanol/water ratio, water content in ethanol and temperature extraction on partition coefficients of FFA during macauba oil deacidification. The macauba crude oil presented high acid index, about 86 + 1.2 mg KOH/g. The extraction data for the system macauba oil + free fatty acids + ethanol + water was determined for oil:solvent mass ratios 1:1. Alcoholic solutions containing 2 to 10 % (w/w) of water were used to FFA extraction and the partition coefficients were determined after 24 hours at room temperature (293 K). The phase's separation was observed for water content in the mixture above 4%. After solvent evaporation, the FFA in oil phase was evaluated by AOCS standard method. Regarding the high acid oil, the single stage liquid-liquid extraction reduced the FFA in macauba pulp oil in about 23 % while the three batch stages reduced up to 60%. At the selected parameters (ethanol 94°GL, solvent/substrate ratio = 2), the partition coefficients in the firs stage to FFA (K~FFA) were 30.45, 12.00 and 1.95, respectively to high acid, acid and low acid macauba oils and the partition coefficients to TAG (K~TAG) were 7.07, 0.04 and 0.02, respectively to high acid, acid and low acid macauba oils. These results show the potential of ethanol to vegetable oil deacidification. Besides reduced generation of environmental pollutants, this new approach could also lead to reduction in oil losses, especially for low acid oil.