Enzymatic Hydroesterification of Soybean Oil Deodorizer Distillate: Sustainable Synthesis of Ethyl and Xylose Fatty Acid Esters

The enzymatic production of fatty acid ethyl esters (FAEEs) and xylose fatty acid esters (XFAEs) from soybean oil deodorizer distillate (SODD) was investigated using a hydroesterification strategy. SODD was enzymatically hydrolyzed, and the glycerol-free fraction was esterified with either xylose or ethanol. Free lipase from Pseudomonas fluorescens (PFL) yielded 84 wt% of free fatty acids (FFAs) production (with approximately 15% FFAs remaining as glycerides) after 48 h, using a SODD-to-water mass ratio of 1:4 and an enzyme loading of 5 wt% (based on oil mass). In the synthesis of FAEEs, free Eversa Transform converted approximately 82% of the FFAs into FAEEs after 48 h, using an ethanol-to-FFA molar ratio of 3.64:1 and an enzyme loading of 8.36% (w/v). For the synthesis of XFAEs, commercially immobilized lipases from Thermomyces lanuginosus (TLL-T2-150) and Pseudomonas fluorescens (IMMAPF-T2-150) were employed. These commercial lipase preparations are available in their immobilized form on Immobead T2-150. TLL-T2-150 resulted in a lower degree of xylose ester formation (80.20%) compared to IMMAPF-T2-150 (89.20%) after 24 h, using an FFA-to-xylose molar ratio of 5 in ethyl-methyl-ketone (xylose concentration of 7 mmol L−1) and an enzyme loading of 0.5% (w/v). However, TLL-T2-150 consumed more FFAs, suggesting a higher degree of xylose esterification. The final reaction mixture containing XFAEs obtained with this biocatalyst exhibited suitable emulsifying properties. A Life Cycle Assessment (LCA) revealed that the enzymatic hydroesterification process offers a sustainable route for FAEEs and XFAEs production, with configurations using free PFL in hydrolysis and IMMAPF-T2-150 in esterification showing the lowest environmental impacts due to higher catalytic efficiency. The findings point to a clear environmental edge in using SODD for ester production, offering a cleaner alternative to standard methods and making better use of a renewable resource.