Commercial refined palm oil was purchased from a local department store in Thailand. 99.5% purity methanol, used for transesterification, was purchased from Qrëc. The NaOH catalyst purchased from Loba Chemie was ground and dissolved in methanol before use. Methyl heptadecanoate and heptane (internal standard and solvent for GC analysis, respectively) were high purity chemicals from Sigma–Aldrich and were used as obtained.