Recovery of Whey Proteins and Enzymatic Hydrolysis of Lactose Derived from Casein Whey Using a Tangential Flow Ultrafiltration Module

Abstract

In this study, ultrafiltration (UF) of pretreated casein whey was carried out in a cross-flow module fitted with 5 kDa molecular weight cut-off polyethersulfone membrane to recover whey proteins in the retentate and lactose in the permeate. Effects of processing conditions, like transmembrane pressure and pH on permeate flux and rejection were investigated and reported. The polarised layer resistance was found to increase with time during UF even in this high shear device. The lactose concentration in the permeate was measured using dinitro salicylic acid method. Enzymatic kinetic study for lactose hydrolysis was carried out at three different temperatures ranging from 30 to 50 °C using β-galactosidase enzyme. The glucose formed during lactose hydrolysis was analyzed using glucose oxidase–peroxidase method. Kinetics of enzymatic hydrolysis of lactose solution was found to follow Michaelis–Menten model and the model parameters were estimated by Lineweaver–Burk plot. The hydrolysis rate was found to be maximum (with Vmax = 5.5091 mmol/L/min) at 30 °C.