Certain functional properties of defatted pumpkin seed flour.

Defatted pumpkin (C. pepo and C. maxima) seed flour has potential food uses because of its high protein content, 61.4 +/- 2.56%. The functional and electrophoretic properties of the defatted flour were investigated. Polyacrylamide gel electrophoresis and electrofocusing indicated 14 bands of water-soluble protein subunits with isoelectric points between 3.81-8.08 and apparent molecular weights between 19,200 and 97,000 daltons. Minimum nitrogen solubility was observed at pH values between 3.0-7.0 and exceeded 90% at pH above 9.0. Solubility was a function of ionic strength. It appeared that, even at the pH of minimum solubility, the pumpkin seed proteins could be dissolved up to high concentrations by increasing NaCl molarity. The viscosity of flour-water dispersion was affected by flour and salt concentrations, and temperature. The least gelation concentration was 8% (w/v) and the water and oil absorption 24.8 +/- 2.03 and 84.4 +/- 4.05 g/100 g respectively. Sorption isotherms, BET monolayer moisture and binding energy of sorption were also calculated. Both foam capacity and stability were pH dependent.