Instrumental method for characterizing protein foams

A whipping machine for cream analysis (Cream Tester CTII) was used to foam egg white, milk proteins and soy protein isolate. Foam formation and final rigidity were characterized by the current input to the beating motor. In addition, specific volume, rigidity (compressive strength by Instron) and stability (drainage) of the foams were determined by methods that minimized foam damage during handling. Current input during whipping distinguished fresh vs pasteurized egg white and positively correlated with compressive strength of final egg white foams. Such correlation was not found for milk protein and soy protein isolate foams of lower strength and stability.