Effect of baking on dietary fibre and phenolics of muffins incorporated with apple skin powder

Apple fruit skin, a rich source of dietary fibre and phenolics, is a by-product of apple processing. The effect of baking on the dietary fibre, phenolics, and total antioxidant capacity was investigated using a model system of muffins incorporated with dried apple skin powder (ASP) as a value-added food ingredient. The blanched, dehydrated, and ground ASP contained approximately 41% total dietary fibre and oxygen radical absorption capacity (ORAC) of 52 mg Trolox equivalents g⁻¹ dry weight. The total dietary fibre content, total phenolic content, and total antioxidant capacity of muffins were positively correlated to the amount of ASP incorporated into muffins. The mean percent recovery of quercetin glycosides, catechins, chlorogenic acid, phloridzin, and cyanidin galactoside after baking were 61%, 57%, 53%, 44%, and 20%.