ABSTRACT
The microstructure of α-gel and β-crystalline emulsifiers and their effects on cake batter foam have been studied with polarized light microscopy, confocal laser scanning microscopy (CLSM) and image analysis, freeze-etching, and transmission electron microscopy (TEM). The emulsifiers Colco and Aroplus, which are commercial α-gels, and the monoglyceride Dimodan P in its α-gel and β-crystalline forms were added to the batter in concentrations of 0.8, 2.0, 3.1, and 4.2%. Dimodan P α-gel was also prepared with three NaCl concentrations (0.05, 0.67, and 1.35‰). The distribution of air in the foam was evaluated with density measurements and with image analysis of bubbles in optically sectioned batter. In the cake batter, all the α-gel emulsifiers decreased the density, thereby increasing the incorporation of air, more than the β-crystalline emulsifier, which did not have any effect on the density. There were noticeable differences in microstructure between the different α-crystalline emulsifiers. Large, regular α-structures seemed to increase the batter volume and interfacial area more than smaller aggregates. Adding salt in the emulsifier gel changed the structure, probably into α-lamellar liposomes, which impaired the aerating effect at lower concentrations.
