Response Surface Methodology for Optimization of Free Fatty Acid Glycerolysis in Crude Palm Oil Using Crude Glycerol

Abstract

The free fatty acid (FFA) content in crude palm oil (CPO) must stay within acceptable limits to meet product quality standards. As a result, managing and reducing FFA levels is crucial for preserving CPO quality. This study aimed to evaluate the impact of glycerolysis on reducing FFA levels in CPO under Response Surface Methodology (RSM). Four key operational parameters affecting FFA reduction were examined: reaction temperature (65–85°C), stirring speed (150–250 rpm), molar ratio of glycerol to FFA (3:1–5:1), and catalyst loading (0.5–1 wt.%). A statistical analysis employing analysis of variance (ANOVA) was conducted to evaluate the importance of each factor.  The optimal conditions for glycerolysis, which successfully reduced the FFA content in CPO from 6.15% to 0.24%, were identified as a reaction temperature of 75.17°C, stirring speed of 235.06 rpm, glycerol to FFA molar ratio of 3.57:1, and catalyst loading of 0.98 wt.%, with a reaction duration of 90 minutes. The statistical models demonstrated high significance, with a p-value <0.0001 and a coefficient of determination (R²) of 0.95. The reliability of these models was further validated through experimental trials under the optimal conditions, yielding an actual FFA content of 0.27%, confirming the model’s predictive accuracy. This study highlights the utilization of crude glycerol for the reduction of FFA levels through glycerolysis reactions. The results of this study are expected to serve as an alternative to the esterification processes that have been applied in the industry to lower FFA levels in palm oil.