Effects of operating parameters and nature of fouling behavior in ultrafiltration of sesame protein hydrolysate

Abstract

Sesame seeds contain important proteins like globulin, albumin, prolamine and glutelin. Sesame protein hydrolysate is also thought to be an important source of nutritional supplement. The work in this study was carried out to assess the feasibility of concentrating sesame protein hydrolysate by ultrafiltration (UF) and to obtain the effects of different operating parameters like transmembrane pressure (TMP), feed concentration and solution pH on UF flux and rejection. No studies regarding the application of UF in treating sesame protein hydrolysate have been reported in the literature elsewhere. A polyether sulfone (PES) membrane of 5 kDa molecular weight cut-off was used for this study. Results of investigation show the membrane fouling to be quite dominant, though in most of the cases, water flux could be recovered by following the suggested cleaning methodology. Capillary electrophoresis was carried out for feed characterization with an objective to obtain molecular weight distribution. Solute rejection with a 5 kDa PES membrane was found to lie within the range of 50–70% depending upon the operating condition—an observation which is commensurate with the molecular weight distribution results obtained through capillary electrophoresis. Minimum flux and maximum permeate concentration (i.e. minimum rejection) were obtained at the isoelectric point of the sesame protein hydrolysate. Adequate explanations for all the observations reported in this study were cited in appropriate places. The investigation clearly proved that UF could be used as an effective tool for concentration of sesame protein hydrolysate after proper choice of operating conditions.