Effect of chemical pretreatment and microfiltration on the composition, microstructure, and functional properties of whey protein concentrate.

摘要

Whey protein concentrate (WPC) that contain 35 to 80% protein, and are Generally Recognized as Safe (GRAS), are important functional and nutritional food ingredients. Functions such as heat-induced gelation and foaming capacity are essential for making certain food products, as for example, bakery and restructured meat and fish products. Though, residual lipids (RL) in whey were shown to affect WPC processing by altering membrane flux and to alter WPC functionality.This study was conducted to investigate the gelation and foaming properties of WPC made from control, pretreated and microfiltered commercial Swiss cheese whey.The two pretreatment (PT) procedures based on thermocalcic aggregation and isoelectric point (pI) precipitation that were developed, improved UF flux and reduced RL by 27 to 61%. The use of microfiltration (MF) allowed virtually total removal of RL (PT involving low pH UF/DF and pI precipitation resulted in WPC containing significantly lower calcium that exhibited highest gel strength (90 kPa), measured as shear stress (ST). Results indicated that the lipid content of WPC had little effect on water holding capacity (WHC) of their heat-induced gels. There was no apparent relationship between gel strength and WHC. Heat-induced gels made from microfiltered WPC exhibited significantly better sensory properties than control WPC. MF did not significantly affect gel strength but, improved greatly WPC foaming properties. Foam overrun and foam stability values observed on microfiltered WPC were excellent in that they were comparable or superior to egg white protein. Neither PT nor MF reduced whey proteins solubility significantly.Scanning electron microscopy examinations showed that WPC gels with compact structures exhibited higher ST values while WPC displaying loose structural networks were associated with lower ST values.