Dough-Handling and Cookie-Making Properties of Wheat Flour–Watermelon Protein Isolate Blends

There is a growing interest in fortifying cereal-based products with proteins. In this study, protein isolates prepared from defatted seed meals of two watermelon cultivars, Mateera and Sugar baby, were blended with medium strength wheat flour at levels of 2.5% to 10%. Dough handling properties such as farinographic parameters, dough extensibility, pasting properties, textural and sensory properties of cookies revealed significant (p ≤ 0.05) changes in dough and cookies. Irrespective of watermelon cultivars, protein isolates at 5% and 10% levels, significantly (p ≤ 0.05) increased dough stability and mixing tolerance index while pasting properties decreased considerably with incorporation of 5% protein isolate in wheat flour. Similar changes were observed in textural, colour and sensory properties of cookies fortified with protein isolates. The protein content of cookies supplemented with protein isolates increased significantly (p ≤ 0.05) while a significant (p ≤ 0.05) decrease occurred in total carbohydrate content. Cookie fracture force (kg) significantly (p ≤ 0.05) increased above 5% fortification levels for both protein isolates. Cookie spread factor (W/T) increased with 2.5% to 7.5% fortification levels, but further increase in protein levels decreased spread factor. Sensory scores of cookies showed that protein isolates incorporation up to 7.5% were acceptable. This study revealed that watermelon protein isolates can be successfully incorporated in a range of cereal products to improve their protein quality and functionality.