The functional role of eggs and plant-based alternatives in cake systems: design considerations based on colloidal and structural dynamics.

Eggs play a critical role in bakery products, providing essential functionalities such as foaming, emulsification, and gelation, leading to structure formation. Traditional egg replacement approaches rely on trial-and-error methods focused on matching texture and sensory properties. However, such strategies fall short due to the multiple techno-functional properties of egg components and a lack of understanding of their interactions with other ingredients. Most studies on egg functionality have been conducted on simplified model systems, which do not consider the impact of processing conditions, such as mixing, baking, and cooling, on final product quality. Substituting eggs with plant-based alternatives is challenging due to limited mechanistic knowledge of egg properties and unknown interactions between plant proteins and batter components, such as lipids, emulsifiers, wheat proteins, and starch. Furthermore, knowledge of key colloidal structures forming during physicochemical transformations throughout processing steps is lacking. This review highlights the need for a new approach bridging ingredient-level functionality and cake quality by mapping colloidal and structural dynamics occurring during cake-making. We examine egg functionality in foam-based (sponge cake) and emulsion-based (pound cake) systems and evaluate plant-based replacement strategies. This work proposes a bottom-up approach connecting molecular and colloidal interactions to macroscopic functionality, providing a mechanistic foundation for designing egg replacers.