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Glucose‐ and xylose laurate esters are enzymatically synthesized using equimolar substrate concentrations in 2‐methyl‐2‐butanol, comparing free lauric acid with methyl‐ and vinyl‐laurate as acyl donors. All reactions result in ≥70% acyl donor conversions after 72 h but the activated donors are also partially hydrolyzed to lauric acid, highlighting the difficulty in controlling water presence in this particular reaction system. The esterification of xylose generates a complex product profile, with several regioisomers of monoesters and diesters. The esterification of glucose is quite selective, forming mainly the 6‐O monoester (≥96%) with a small presence of two diester isomers (4%). Increasing substrate concentration up to 800 millimoles kg−1 results in lower conversion values (down to 58%) but shows that the reaction proceeds successfully even in the presence of high amounts of insoluble glucose. However, the reaction is less selective and the proportion of diester increases, becoming up to 46% (molar fraction) of the final product. Solvent recovery after esterification can be achieved by organic solvent nanofiltration through a polymeric membrane able to retain ≥80% of all reaction substrates and products. Practical Applications: The use of high substrate concentrations during the enzymatic synthesis of sugar ester biosurfactants leads to product titers that are more industrially appealing, without the need to find a solvent that can solubilize all initial substrate. The sustainability of the enzymatic conversion at mild temperatures can be enhanced by recycling of the reaction solvent through organic solvent nanofiltration, an energy efficient alternative to other traditional methods like distillation.

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Polyglycerol fatty acid esters, which have been widely used as emulsifiers in food, medicine and cosmetics industries, were the subject of solvent-free enzymatic synthesis<br /> in this study. There have been previous reports on enzymatic synthesis of various polyglycerol esters; however, this investigation extends the synthesis to PG-10 esters. The<br /> effects of substrate molar ratio, addition of emulsifiers to enhance mixing, and addition of molecular sieves or N2 flushing for water removal, was investigated. The solvent-free synthesis using N2 flushing leads to complete conversion of fatty acid, yielding a completely acid free product. The synthesis is validated for polyglycerol laurate and polyglycerol caprylate, both useful products in the cosmetic industry.