Optimization of gluten-free cake formulation by replacement of rice flour and baking powder with different levels of eggshell powder using response surface methodology

The shell and membrane of the egg constitute approximately 11% of the whole egg and is an important food industry waste. Eggshells can be used as an additional source of calcium to the diet because of their low cost and high bioavailability. This study aimed to design and produce the optimum formulation for the gluten-free cake using eggshell powder as rice flour and baking powder replacer by Face-Centered Composite Design. According to the results, it was determined that the optimized formulation should contain 9.85% eggshell powder as a rice flour replacer and 32.78% eggshell powder as a baking powder replacer to obtain a gluten-free cake with a desirable profile in terms of hardness, specific volume, color ( \({\text{L}}_{{{\text{crust}}}}^{*}\) ${\text{L}}_{\text{crust}}^{\ast }$ and \({\text{L}}_{{{\text{crumb}}}}^{*}\) ${\text{L}}_{\text{crumb}}^{\ast }$ values), ash content, calcium content, and overall acceptability. The gluten-free cake with eggshell powder obtained was characterized as a product rich in calcium, high in ash content, high in specific volume, with a brighter colour and good sensory acceptability. Also, the proximate properties of the gluten-free cake produced with the optimum formulation were also reported. These findings show for the first time that eggshell powder can be used as a rice flour and a baking powder replacer for the formulation of gluten-free cake.