Improving the Emulsion Stability of Sponge Cake by the Addition of ?-Polyglutamic Acid

The batter properties of sponge cake with the addition of γ-polyglutamic acid (PGA) at different levels (0.05, 0.1, 0.5 gkg-1, w/w) was evaluated. The viscosity, emulsion stability and foam stability increased at the addition of 0.5 gkg-1 PGA level. PGA caused significant declines in the differential scanning calorimetry (DSC) enthalpy, onset and peak temperatures of ice-melting transition of sponge cake. Sponge cakes manufactured with 0.5 gkg-1 PGA addition were in general lighter on crumb color and white index than the control. Scanning electron microscopy showed that sponge cake with the addition of 0.1 and 0.5 gkg-1 PGA exhibited microstructures having thinner walls of pores on cake crumb. The internal structure of sponge cake with the addition of PGA (0.1 and 0.5 gkg-1) was finer and smoother than without. The addition of γ-PGA was shown to delay staling of cake crumb as well as improve texture of sponge cake.