Paper Title
Lipase-Catalyzed Synthesis and Characterization of Red Pitaya (Hylocereus Polyrhizus) Seed Oil Esters

Abstract
Red pitaya seed oil esters (RPSOE) were synthesized through enzymatic transesterification of red pitaya seed oil (RPSO) with oleyl alcohol using commercial immobilized lipase (LipozymeRM IM) as the catalyst.The development of product from the reaction was monitored by thin-layer chromatography (TLC) plate and gas chromatography (GC). High percentage yield of esters (~82.48%) was obtained after reaction time of 4 h. Four main corresponding esters synthesized were oleylpalmitate, oleyl stearate, oleyloleate and oleyllinoleate. The synthesized esters were further analyzed by Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and tested for their antimicrobial activity to characterize the esters quality. Thermogravimetric analysis (TGA) analysis showed high thermal stability profile of RPSOE and antimicrobial activity test showed that the RPSOE exhibited slightly inhibitory effect against gram-positive bacteria named Staphylococcus aureus. Index terms - Red pitaya, Hylocereuspolyrhizus, lipase-catalyzed esters, characterization