Preparation and Functional Properties of Protein Isolates from Pumpkin Seeds

Protein isolates from pumpkin seeds were obtained by alkaline extraction and acid precipitation. The extraction process was optimized by orthogonal array design method, and some functional properties of the protein isolates were determined. The results showed that the optimum process conditions for the extraction of protein isolates from pumpkin seeds were as follows: pH 11.0; extraction temperature 50 ℃; solid-to-liquid ratio 1:30; and extraction duration 1.5 h. Under these conditions, the extraction yield and the protein purity were up to 85.52% and 91.07%, respectively. The isoelectric point of the protein isolates was around 5.5, and both the water-binding and oil-binding capacities approximately ranged from 1.2 to 1.6 g/g, and the emulsifying capacity was over 80% under a suitable pH, but the foaming capacity was relatively weak.