Comparison of macauba and soybean oils as substrates for the enzymatic biodiesel production in ultrasound-assisted system

•Investigated batch enzymatic production of biodiesel in ultrasound solvent-free system.•Developed novel concept of enzymatic biodiesel production from macauba fruit oil.•High yields of enzymatic biodiesel production in a short period of time was obtained. The objective of this study is to evaluate the batch enzymatic production of biodiesel in solvent-free system under ultrasound using as substrates ethanol, soybean oil and macauba fruit oil. For this purpose, a Plackett & Burman experimental design was carried out for soybean oil while a 24−1 design was conducted for macauba oil in order to maximize the biodiesel conversion for each system. Good conversions to fatty acid ethyl esters (FAEE), 88% for soybean oil and 75.2% for macauba oil, was obtained thus demonstrating the potential use of ultrasound for this reaction system.