Effects of lecithin on thermally induced whey protein isolate gels

The effect of lecithin on fundamental fracture properties (true shear stress and true shear strain at fracture) and water holding capacity of heat-induced whey protein isolate (WPI) gels were investigated. Adding egg yolk lecithin to WPI gels substantially increased the fracture stress of gels containing less than or equal to 50 mmol/dm(3) NaCl but slightly decreased the fracture modulus at concentrations > 100 mmol/dm(3). The fracture strain and water holding capacity were decreased by lecithin addition across the NaCl concentration range examined (30-500 mmol/dm(3)). These results suggest that the gel network type and/or the dispersed state of lecithin changing with NaCl concentration in the system is responsible for the mechanism of lecithin-whey protein interactions. Lecithin can play a beneficial role in promoting gel strength but there is an optimal level which is strongly related to the amount of NaCl in the system. (C) 1999 Elsevier Science Ltd. All rights reserved.