Physicochemical and Functional Properties of Pumpkin Seed Flour of Cucurbita maxima and Cucurbita moschata Species

Pumpkin seeds are rich source of nutrients and beneficial bioactive compounds. In Sri Lanka, pumpkin seeds are discarded without being used. Physicochemical characteristics of seeds and functional properties of pumpkin seed flour (PSF) of two varieties of Cucurbita maxima (Suprema and Bingha F1) and one variety of Cucurbita moschata (Padma) were determined. Seeds collected from each variety were subjected to different treatments before preparation of PSF: roast at 80-90°C for 15 min, germinate and dry at 50-60°C for 4h, and dry at 50-60°C for 4h as the control, prior to prepare PSF. Antioxidant activity, total phenolic, total flavonoids and flour properties such as water holding capacity (WHC), swelling capacity (SC), oil holding capacity (OHC), emulsion stability (ES), organic molecule absorption capacity (OMAC)) of nine types of PSF were determined. A sensory evaluation (Hedonic scale) was conducted to determine the effect of 25, 50 and 75% substitution with PSF in biscuit production. The variety × treatment interaction effect was significant (p<0.05) for WRC, OHC, SC and OMAC but not for WHC and ES. Germinated and dried PSF of the Suprema variety possessed the highest WHC (6.31±0.16 g/g), OHC (3.23± 0.07 g/g) and SC (6.00±0.28 mL/g) while the highest antioxidant activity (90.06±0.24%) and flavonoid content (19.87±1.08 mg QE/g) were observed in germinated dried seeds of Bingha F1 variety PSF. In roasted PSF, the highest phenolic content (1.52±0.02 mg GAE/g) was in Bingha F1 variety. Substitution with 25% PSF was selected as the optimum level in formulation of biscuit with the acceptable sensory attributes. Hence, PSF possesses a high potential as a source of functional food ingredient in the food manufacturing industry.