Formulation of a nutrient-enriched sponge cake using drum-dried pumpkin powder

Abstract

Pumpkin (Cucurbita maxima), belonging to the family Cucurbitaceae, is a widely grown seasonal vegetable in Sri Lanka which often suffers postharvest losses. This study aimed to increase its utilization by formulating a sponge cake using drum-dried pumpkin powder as a partial substitute for wheat flour at 20%, 40% and 50% replacement levels. A preliminary sensory evaluation was conducted with 30 untrained panelists using a five-point Hedonic scale. Total phenolic content (TPC), total flavonoid content (TFC), total antioxidant capacity (TAC) and proximate composition of both pumpkin powder and sponge cakes were analyzed using the Folin Ciocalteu method, Aluminum chloride (AlCl₃) method, ferric reducing antioxidant power (FRAP) assay, and Association of Official Analytical Chemists (AOAC) standard procedures, respectively. Physicochemical properties and microbial counts of the sponge cakes were also determined. Pumpkin powder showed TPC, TFC and TAC values of 713.73 ± 48.29mg GAE/100 g, 655.67 ± 75.22 mg RE/100 g, 652.26 ± 26.89 mg TE/100 g, respectively, with moisture content (8.59 ± 0.25 %), ash (13.08 ± 0.72 %), fat (2.89 ± 0.82 %) and protein (7.42 ± 0.1 %). Among the formulations, the 40% pumpkin powder sponge cake, which showed the highest acceptability, was selected for detailed comparison with 100% wheat flour control sponge cake control.The 40% pumpkin powder sponge cake recorded significantly higher TPC (82.98 ± 2.35 mg GAE/100 g), TAC (116.73 ± 1.38 mg TE/100 g), and ash content (2.30 ± 0.14%), while showing the lowest fat content (17.75 ± 0.49%). TFC, protein content and textural hardness did not vary significantly among sponge cake samples. Microbial counts remained within acceptable limits during storage, two months for pumpkin powder and three weeks for sponge cakes. The 40% pumpkin powder-incorporated sponge cake shows potential as a nutritious bakery product, and the development of an instant mix may further enhance its commercial value.