Functional properties of protein isolates from bell pepper (Capsicum annuum L. var. annuum) seeds

Abstract

Bell pepper seeds comprise the bulk of solid waste from bell pepper processing. Aiming to utilize rather than waste these seeds, we investigated the functional properties of bell pepper seed protein isolates extracted using two methods. Ultrasound-assisted extraction of bell pepper protein isolates (BPPIU) achieved a higher yield (6.05 g/100 g), protein content (83.93 g/100 g), and oil absorption (5.63 g/g), while the solubility and water absorption were lower, and emulsifying and foaming properties diminished, compared with those of bell pepper protein isolates from alkaline dissolving and acid precipitating (BPPI). We also evaluated effects of pH and NaCl concentration on BPPI and BPPIU because they were significantly correlated with the functional properties. The antioxidant properties of bell pepper protein hydrolysates were studied in vitro by measuring the radical scavenging capacity (DPPH, O2·ˉ, ABTS·) and Fe2+ chelating capacity. Flavourzyme protease hydrolysates (FH) showed better DPPH and ABTS radical scavenging, while alkaline protease hydrolysates (AH) exhibited higher O2·ˉ scavenging and Fe2+ chelating activities.