Characteristics of coconut protein separation process by means of membrane ultrafiltration

Abstract

AbstractCross‐flow ultrafiltration has been reported as a promising technique to concentrate the coconut protein in the liquid by‐product called coconut skimmed effluent, which is produced from coconut oil wet process. However, the cake developed on the membrane surface always causes a measurable resistance, which extremely impedes the filtration efficiency. This study investigated the cross‐flow filtration performance under different operational conditions, which included membrane molecular weight cut‐off (10 and 30 kDa), transmembrane pressure (0.1, 0.2, and 0.3 MPa) and cross‐flow velocity (0.5, 1.0, and 1.5 l/min), and molecular electrostatic interaction by adjusting the feed suspension pH (2.0, 4.0, 6.3, 9.0). The results showed that there was no substantial difference in the filtration performance between 10 kDa and 30 kDa membrane because the number of molecules, in which the particle size was larger than 30 kDa, was high. Furthermore, the results confirmed that the permeate flux increased with the cross‐flow velocity but decreased with the transmembrane pressure due to the cake layer compressibility. For the suspension chemistry effects, although a thick cake layer was developed on the membrane when the feed suspension pH was very close to pI (pH 4.0), the permeate flux was surprisingly greater than the other pH conditions.Practical ApplicationThis research was carried out by focusing on the evaluation of the alternative method other than the traditional one, such as precipitation or centrifugation, for coconut protein concentration. The membrane ultrafiltration, which is widely used to improve the quality of many dairy products, has been applied to the coconut suspension and filtration performances including fouling behavior under various conditions have been investigated. The results obtained could provide extensive information for the operational optimization of the coconut liquor cross‐flow filtration process considering the hydrodynamic factors. Furthermore, since the experiment was conducted with a real polydispersed biopolymer mixture, its unique characteristics that depend on the change of pH would be able to extend the knowledge including the influence of the electrostatic interaction on the cake formation of such plant‐based protein–polysaccharide mixture.