Investigating the application of gel emulsifiers to reduce fat acidity in layered cake

Cake is one of highly consumed products as a breakfast and snack. One of the common industrial concerns in the quality control of bakery products with high amounts of fat, such as layered cakes, is related to lipolytic effects of free fatty acids. Egg yolk due to its possible high free fatty acids, phospholipids and lecithin is regarded as a main reason for possible high fat acidity content in the layer cakes. In addition, because of high cholesterol in the egg yolk, it may increase the possibility of health risk by cardiovascular diseases. Thus, the main objective of this research was to replace egg yolk with different industrial gel emulsifiers so called "Emulgels" to control the fat acidity content in the layer cake.
Six different formulations were used to prepare cake batters as follows: 1) Control cake with whole egg, 2) Batter with only egg white, 3) Batter with egg white plus Softex emulgel, 4) Batter with egg white plus Golden emulgel, 5) Batter with egg white plus Gilk 60 emulgel and 6) Batter with only egg yolk. In the aforementioned formulations three different industrial emulgels were replaced with egg yolk. Cake batter was prepared with single-stage method according to Gomez et al (2007). Physical properties of batter such as density were measured. Cake physical, chemical, textural and staling properties were analyzed during storage. For this reason, cake volume and height as well as loaf symmetry were characterized. To evaluate cake staling by instrumental method, crumb firmness was measured by universal testing machine (Instron). Cake moisture and water activity, fat acidity and peroxide value were also measured.
Batter density is a measure of how much air bulbuls can be incorporated during mixing or creaming. Increasing air inclusion into the batter increases the batter volume, and thereby, leads to a decrease in batter density. Results indicated that formulation with all three industrial emulgels had the lowest batter density (1.0-1.25 g/cm3) compared to those (1.5–1.75 g/cm3) of control and treatments with only egg white and egg yolk. Cake formulations with all three industrial emulgels used in this study had the highest cake volume (502-525 cm3/200 g batter) and height (60-69 mm) and the most loaf symmetry (24-33) compared to those (449-491 cm3/200 g batter for volume, 48-57 mm for height, and 15-22 for symmetry) of control/only egg white/only yolk cakes. As mentioned before, application of emulgels increased air incorporation into batter during the mixing process leading to a decreased batter density and thereby, an increased cake volume. Cake with only egg white showed the firmest (1.0-3.5 N) structure compared to other formulations (0.1– 0.5 N). The absence of egg yolk as an emulsifier can results in formation of a firm structure. Meanwhile, cakes containing gel emulsifiers all had the softest crumb structure as measured by Instron. Cakes containing gel emulsifiers without egg yolk had softer texture than that of control. Between three different emulges used there was no significant difference in terms of their effect on cake firmness. Results also indicated that crumb firmness increased upon 60 days storage. Nevertheless, this increasing rate was not significant (p