In the present study, the ability of two ultrafiltration (UF) polymeric membranes to clarify synthetic glycerin-rich solutions containing triglycerides (TGs) was evaluated. The membranes were made of poly(ether sulfone) (PES) and poly(vinylidene fluoride) (PVDF) and had molecular-weight cutoff (MWCO) values of 25000 and 30000 Da, respectively. A commercial TG (RBD Palm Olein) was employed, and the effects of membrane surface chemistry and solution pH on the permeation flux and TG retention rate were studied. In glycerol-water mixtures containing TG, the contribution of the solute to fouling was more severe than that of fatty acid (FA), with lower permeation rates being shown. Furthermore, the present study revealed that the nature of the membrane and the pH of the solution have significant effects on the fouling potential and can be used to quantitatively determine the TG rejection rate. Moreover, PVDF membranes were found to provide higher fluxes and lower TG rejection rates (81%) than PES membranes (91%).