Complexation of WPI and microwave-assisted extracted agars with different physicochemical properties

The complex formation between whey protein isolate (WPI) and agar has been investigated and their interactions were monitored as a function of the physicochemical properties of agar, the pH and the ionic strength of the medium. Agars from Gracilaria vermiculophylla were extracted under different MAE conditions and characterized according to their physicochemical properties. By using microwave irradiation a wide variety of agars was obtained, as different MAE conditions results in polyelectrolytes with distinct properties. UV-vis (in optical dispersion (O.D.) model) spectroscopy and isothermal titration calorimetry (ITC) have been used to study the formation of insoluble (coacervate) complexes. MAE agars revealed excellent properties for complex formation with WPI. The binding of WPI to MAE agar samples has been shown to be the result of different contributions. O.D. and ITC results showed that the molecular mass and the sulfate content of different agars had a determinant effect on coacervate formation.