examined the variables affecting the yields of fatty acid methyl ester (FAME) derived from vegetable oils such as soybean, sunflower, peanut, and cottonseed oil, with or without refining, and provided the most fundamental information. They reported that a molar ratio of alcohol to oil of 6:1 gave optimum conversion to the ester, 1% sodium hydroxide was an effective catalyst, and ester conversions of 96%–98% were obtained by transesterifying refined oils with methanol at 60 °C. Following that, more research that focused on parameter effects and transesterification reaction optimization has been conducted. It is generally believed that temperature and catalyst concentration are the most important factors impacting the reaction, while reaction time and molar ratio of methanol/feedstock oil are less important. Recently, statistical optimization methods such as factorial design and response surface methodology (RSM) have also been employed to optimize transesterification conditions and study the interaction effects among the reaction variables.