Lipase-catalyzed esterification of glycerol-derived acids: Toward sustainable production of value-added esters

Short-chain acids are known for their excellent exfoliating and moisturizing properties. However, their high acidity often leads to skin irritation, limiting their use in cosmetic and pharmaceutical formulations. Esterification presents a promising strategy to reduce their acidity. The present study reports the esterification of glycolic acid with butanol and octanol using a free lipase using conventional (solvent) and green (solvent-free) media. An HPLC method was employed to find the optimal reaction conditions and the Michaelis–Menten kinetic parameters. The data revealed that the optimal conditions for achieving the highest glycolate ester yield (approximately 93 %) were 0.4 M glycolic acid, 1.6 M alcohol, 2.5% Novozym® NS88007 at 40 °C in n-hexane with 5% molecular sieves, showing the highest affinity for octanol. For safety and environmental reasons, solvent-free ester synthesis was recommended, achieving ester yields of about 90%. Data showed that the free lipase efficiently esterified the short-chain acid mixture enzymatic affinity following the order: glycolic acid > formic acid > lactic acid. Furthermore, lipase retained approximately 90 % of its initial activity after two reactions without any regeneration treatment. This enzymatic approach represents a promising strategy for the recovery and valorization of short-chain acids derived from the chemical oxidation of glycerol, with potential applications in pharmaceutical and cosmetic formulations. • Esterification of acids with C4 and C8 alcohols was done using free lipase • Esterification was performed in conventional (solvent) and green (solvent-free) media • Optimal conditions were 0.4 M acid, 1.6 M alcohol, 2.5% lipase at 40 °C • Ester yield of hydroxy acid was almost 93% with highest affinity for octanol • lipase retained almost 90 % of initial activity after two reactions without treatment