Separation of whey protein based on continuous microfiltration
The objective of this paper is to investigate the effect of transmembrane pressure on the process parameters,separation effect and fractions of continuous microfiltration membrane separation technology.Whey protein and casein were separated from skim milk using 0.1 μm ceramic microfil-tration membranes in a three-stage continuous on-line diafiltration filtration process.Three gradients of 0.08,0.11 MPa and 0.14 MPa were used for continuous production at 50 ℃ and 3.5 times the concentration for 240 minutes.The transmembrane pressure is calculated and the content ofα-lactal-bumin,β-lactoglobulin and metal ions such as potassium,calcium,sodium and magnesium are measured in the retention and permeate solutions.The variation of membrane flux with time was investigated and the decrease of primary membrane flux was the main factor leading to the decrease of overall membrane flux,which was about 17.2％after 240 minutes of experiment.The fluxes at different transmembrane pressures were investigated,and the membrane fluxes were positively correlated with the transmembrane pressure,and the wash recovery rate was negatively correlated with the transmem-brane pressure.With the extension of the experimental time,an irreversible fouling layer formed on the membrane surface,the whey protein separation rate decreased,the whey protein content in the permeate decreased,and the whey protein content in the retention solution increased significantly,and the α-lactalbumin concentration decreased by 37％and the β-lactoglobulin concentration decreased by 36.5％after 150 minutes.The ratio of the two major proteins in whey protein varies with transmembrane pressure,and theβ-lactoglobulin content gradually increases with increasing transmembrane pressure.The maximum separation of whey protein is about 90％(90.4％for α-lactalbumin and 92.7％for β-lactoglobulin)after three stages of continu-ous membrane filtration.The morphology and function of lactoproteins are influenced by metal ions,with monovalent cations being more uniformly distributed on both sides of the membrane(Removal rate＞80％),while divalent cations are mainly concentrated on the retention fluid side(Calcium ion removal rate of38％).The proportion ofmetal ions per gram of protein in the permeate is much greater than its proportion in the retention solution.
万方数据
维普
