Chemically vs Enzymatically Synthesized Polyglycerol-Based Esters: A Comparison between Their Surfactancy

Polyglycerol fatty acid esters (PGFAEs) are gaining interestinseveral industrial sectors due to their excellent surfactant propertiesand their wide range of hydrophilic-lipophilic balance (HLB)values. Moreover, they can be prepared from renewable resources, i.e.,fatty acids and glycerol. In this study, polyglycerol-2 stearic acidesters (PG2SAEs) were synthesized by the enzymatic esterificationof polyglycerol-2 (PG2) and stearic acid (SA) using the immobilizedlipase Novozym 435 as a biocatalyst in a solvent-free system. Reactionconditions, i.e., temperature (80 & DEG;C), reactantratio (1:1.8), and enzyme loading (2.7% w/w), were finely optimized;furthermore, biocatalyst recycling was studied by assessing the residualactivity of the lipase after each reaction cycle, up to 20 times.The composition of the enzymatically synthesized products (E) was roughly evaluated by chromatographic methods and mass spectrometryand compared with that of the esters obtained by acid-catalyzed esterification(C). Then, the surfactant properties of the preparedpolyglycerol-based surfactants were investigated by interfacial tensionstudies. Specifically, the emulsifying capacity and stability andthe rheological behavior of O/W emulsions prepared in the presenceof E were deeply investigated in comparison with thoseof the chemically synthesized and commercially available product C.

Automated summary

Polyglycerol fatty acid esters (PGFAEs) were synthesized using enzymatic esterification and their emulsifying properties were compared with chemically synthesized and commercially available esters.