A multiscale approach to linking batter properties to baked cake structure in sponge cakes

Sponge cakes are hierarchical, aerated structures. Despite their texture being key to their appeal, predicting their final structure as a function of composition remains a challenge. This study aimed at understanding how key physical properties of the batter relate to the final structural properties. The structure of three model sponge cakes, based on egg, whey protein concentrate (WPC), and a plant-based egg replacer (PB), were studied at various length scales throughout the baking process. By relating the aeration (density), rheological properties, and microstructure of the batter to the internal crumb structure (tomography) and mechanical integrity (texture analysis) of the baked cake, this study provided a detailed description of the properties underpinning the transition from batter-to-cake. Although PB and egg batters had similar densities, PB cakes exhibited lower volumes despite a soft crumb, indicating that batter density and viscoelastic properties of the batter before baking do not alone determine the final cake structure. WPC showed a clearer link between batter density and cake volume. The contrasting properties of PB and WPC illustrate how distinct molecular assemblies may govern early-stage structure formation, and suggest the importance of air retention, gas bubble stabilization, protein aggregation, and starch gelatinization during heating. These findings highlight the need to consider how supramolecular assemblies and their colloidal properties form during whipping and how they are modified during baking. By using such a multiscale approach, this work shows how the nature of the ingredients and their interactions may influence each stage of cake production, reducing reliance on trial-and-error approaches. • Microcomputed X-ray tomography gave quantitative insights into the structure of the cake crumb. • The rheological properties of the plant-based egg replacer was dominated by the hydrocolloids in the formulation. • The batter properties alone could not predict the resulting cake properties, indicating difference in the thermal transitions during baking.