Effect of heating time and drying method on the functional properties of soy protein isolate–maltodextrin conjugates for plant-based meringue cookies

Abstract

The Maillard reaction facilitates the conjugation of soy protein isolate (SPI) with carbohydrates such as maltodextrin (MD), thereby enhancing sensory properties. Additionally, the drying method plays a crucial role in determining the characteristics of the resulting conjugates. This study evaluates the structural and functional properties of SPI–MD conjugates formed via the wet Maillard reaction and their potential application as egg white substitutes in plant-based meringue cookies. SPI–MD conjugates were prepared by varying heating times, primarily utilizing spray-drying, with freeze-drying serving as a comparative control for the 1 h treatment. Results demonstrated that heating for a minimum heating time of 1 h is essential to improve the functional properties, including foaming stability, solubility, and surface hydrophobicity, with further enhancements observed beyond this duration. Meringue cookies incorporating SPI–MD conjugates heated for 1 h or more exhibited fine internal structures and textures comparable to egg white-based meringues, indicating their effectiveness as substitutes. However, the freeze-dried sample exhibited greater hardness due to its denser internal pore structure, underscoring the significant influence of drying methods on texture. Optimizing heating time and drying processes is, therefore, essential to maximize the performance of SPI–MD conjugates, facilitating their use as sustainable plant-based alternatives in food formulations.