Solvent-Free Production of High-Value Amphipathic Esters Derived from Byproduct Streams of Biomass Processing

The use of biomass-derived precursors to produce high-value products economically and sustainably is a current global goal. This study aimed to use two byproduct streams of biomass processing─free fatty acids from vegetable oils and fusel oil (FO) from bioethanol production─to produce isoamyl esters. Operational conditions of esterification reactions were systematically studied, and homogeneous acid catalysts were tested in contrast to an immobilized lipase from Candida antarctica. The lipase yielded esters free of byproducts at final conversions above 76% after 100 min, and its activity was fully maintained after 5 reuse cycles. A stable emulsion of a typical cosmetic preparation was obtained with the unpurified reaction product generated by a blend of free fatty acids with 64.98% stearic acid and 28.77% palm acid and untreated FO with a water content of 26%. Therefore, FO emerged as a green and inexpensive raw material to produce emulsifiers.