Following the structural changes of triolein films during lipolysis

A major challenge hampering the industrial and biological exploitation of lipases is the self-limiting effect of the lipolytic reaction. Defying sustained attention throughout history, the influence of lipase catalysed lipolysis on the internal structure of thin triglyceride films has proved elusive. An in-depth understanding of the lipolysis process at the triglycerides/aqueous interface will assist in creating innovative methods to enhance yields. This study furthers our understanding of the influence of solution pD (pH equivalent for aqueous solutions prepared with D₂O) on the effect of lipolysis on the structure of thin triolein films. All experiments were performed at pD 7.0 or pD 8.5, either side of the apparent pK_a of the primary product of the hydrolysis (oleic acid/oleate). Spectroscopic ellipsometry measurements were employed to kinetically track the changes in thickness of the triolein film after the introduction of 2 ppm Thermomyces lanuginosus lipase (TLL). Neutron reflectometry experiments revealed the internal structure of the thin films before and after TLL digestion, while fast kinetic measurements capturing changes to the reflectivity profile throughout lipolysis. Both techniques revealed significant variations in the physical properties and enzymatic conversion of the triolein films between pD 7.0 and pD 8.5.