Characterization of main protein fraction from red pepper seeds: antioxidant capacity, physicochemical and functional properties, and enzymatic hydrolysis for peptides generation

This study aimed to investigate the major protein fractions (<i>E</i>-RPSP and <i>Z</i>-RPSP, near 48 kDa) of seeds of Erjingtiao and Zidantou red peppers. The results showed that Z-RPSP had great antioxidant capacity. It exhibited 59.7 %, 47.6 % and 38.9 % of 1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and hydroxyl radical scavenging rates at 0.8 mg/mL. Besides, Fe²⁺ chelating rate of <i>Z</i>-RPSP (0.8 mg/mL) was 70.9 %. Z-RPSP is an α + β protein and displayed good functional properties, such as emulsifying (emulsifying activity and stability indexes at pH 8: 37.9 m²/g and 60.8 %) and gel-forming properties (least gelation concentration: 140 mg/mL). <i>Z</i>-RPSP components were identified by liquid chromatography tandem mass spectrometry. Enzymatic hydrolysis techniques of Z-RPSP were preliminarily explored by combining computer simulation. Significant improvements of antioxidant activities and flavor (bitter to saline taste) were observed after trypsin hydrolysis. Various bioactive peptides were found in the protein hydrolysate.