Enzymatic strategies for solvent‐free production of short and medium chain phytosteryl esters

Abstract

AbstractTransesterification of phytosterols with short and medium chain fatty acids (MCFAs) ethyl esters and with tributyrin catalyzed by Candida rugosa and Pseudomonas stutzeri TL lipases in solvent‐free medium was studied including the effects of temperature, fatty acid specificity, enzyme quantity, the residual activity of each lipase and reduced pressure. More than the 90% of the original phytosterols were transformed into their corresponding phystosteryl esters after 3–4 h reaction at 50–60°C and at 100–350 mbar. The product mixtures containing 40–50% (w/w) phystosteryl esters were then vacuum distilled to remove molar excess of SCFA and MCFA ethyl esters utilized in the enzymatic reaction. By this methodology, purities >95% in short and medium chain phytosteryl esters were finally obtained.Practical applications: The methodology presented here describes a rapid and easy process to prepare phytosteryl esters with short and medium chain fatty acids. The phytosteryl esters produced in this study are expected to have improved their hydrodispersibility and bioavailability in comparison with their corresponding free phytosterols. A lower melting point than the original phytosterol and an improved oil and fat solubility are also expected. Moreover, the SCFA and MCFA could act as a lipid vehicle for fatty acids, improving their half‐life in the body and promoting their biological activities.