Author:

Keywords:

sponge cake making, flour lipids, foam formation and stabilization, clean label, interfacial stability

Abstract:

Sponge cake, a foam-type cake used in Swiss rolls and layer cakes, is prepared from flour, sugar and eggs. High quality sponge cakes – i.e. cakes with high volumes, fine crumb structures and airy textures – are obtained by incorporating high levels of small gas cells during mixing. These also need to be stabilized after mixing. Industrially, increased incorporation and stabilization of gas cells in sponge cake batter is achieved by adding lipid-like surfactants. In Europe, such surfactants have E-numbers which are negatively perceived by consumers as part of the trend whereby consumers prefer clean label products. Our goal was to study the role of endogenous flour lipids during surfactant-free sponge cake making to obtain insights potentially leading to clean label alternatives. In our work, flour was defatted with hexane or hexane:isopropanol (3:2 v/v) to remove mainly non-polar (e.g. triacylglycerols) or non-polar and polar (e.g. digalactosyldiacylglycerols) lipids, respectively. Additionally, flour was treated with the same solvents. Here, lipids were only relocated and not removed. All flour samples were used for sponge cake making. With hexane:isopropanol (3:2 v/v) treated flour, slightly less air was incorporated during mixing and a coarser crumb structure was noted than with control flour. Removing flour lipids, regardless of the used solvent, resulted in increased air incorporation during mixing, increased cake volumes and fine crumb structures. Furthermore, light microscopy images of batter prepared with hexane:isopropanol (3:2 v/v) defatted flour showed an increased level of gas cells with a more homogeneous size distribution. It is therefore hypothesized that ‘free’ flour lipids – endogenously free or set free because of a solvent treatment – negatively impact sponge cake quality by disturbing air-liquid interface stabilization during mixing and the early phases of baking. Apparently, even though flour lipids are only a minor constituent, their removal or relocation significantly impacted batter and cake properties.