连续式微滤膜分离乳清蛋白的研究

Separation of whey protein based on continuous microfiltration

文章研究了跨膜压力对连续式微滤膜分离技术工艺参数、分离效果及组分组成的影响。以脱脂乳为原料,使用0.1μm陶瓷微滤膜三级连续在线洗滤工艺分离乳清蛋白和酪蛋白。实验使用0.08、0.11、0.14 MPa 3个梯度,在50℃,3.5倍浓缩的条件下连续生产240 min。计算跨膜压力并且检测截留液和透过液中的α-乳白蛋白(α-La),β-乳球蛋白(β-LG)含量及钾、钙、钠、镁等金属离子的含量。结果表明一级膜通量下降是导致整体膜通量下降的主要因素,经过240 min实验通量下降约17.2%。研究了不同跨膜压力下的膜通量变化情况,膜通量与跨膜压力呈正相关关系,水洗恢复率与跨膜压力呈负相关关系。随着实验时间的延长,膜表面形成不可逆的污堵层,乳清蛋白分离率下降,透过液中乳清蛋白含量下降,150 min后α-乳白蛋白浓度下降37%,β-乳球蛋白浓度下降36.5%。乳清蛋白中2种主要蛋白质比例会随着跨膜压力变化而变化,随着跨膜压力的升高β-乳球蛋白含量会逐渐升高。三级连续膜过滤后,乳清蛋白最高分离率90%左右(α-乳白蛋白为90.4%,β-乳球蛋白为92.7%)。乳中蛋白质的形态和功能受金属离子影响,分离过程中一价阳离子在膜两侧分布较均匀(脱除率大于80%),而二价阳离子则主要集中在截留液一侧(钙离子脱除率为38%)。透过液中的每克蛋白质所对应的金属离子比例远远大于其在截留液中的比例。

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 0.1μm ceramic microfiltration 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°C and 3.5 times the concentration for 240 minutes.The transmembrane pressure is calculated and the content ofα-lactalbumin,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 transmembrane 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 theα-lactalbumin concentration decreased by 37%and theβ-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%forα-lactalbumin and 92.7%forβ-lactoglobulin)after three stages of continuous 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 of 38%).The proportion of metal ions per gram of protein in the permeate is much greater than its proportion in the retention solution.