Antioxidant Activity of Porcine Skin Gelatin Hydrolyzed by Pepsin and Pancreatin

Gelatin is a collagen-containing thermohydrolytic substance commonly incorporated in cosmetic and pharmaceutical products. This study investigated the antioxidant activity of gelatin by using different reagents, such as 2,2-azinobis-(3-ethylbenzothiazoline- 6-sulfonic acid) (ABTS), 2,2-di (4-tert-octylphenyl)-1-picrylhydrazyl (DPPH), and oxygen radical absorbance capacity-fluorescein (ORAC-FL) in a porcine gelatin hydrolysate obtained using gastrointestinal enzymes. Electrophoretic analysis of the gelatin hydrolysis products showed extensive degradation by pepsin and pancreatin, resulting in an increase in the peptide concentration (12.1 mg/mL). Antioxidant activity, as measured by ABTS, exhibited the highest values after 48-h incubation with pancreatin treatment after pepsin digestion. Similar effects were observed at 48 h incubation, that is, 61.5% for the DPPH assay and 69.3% for the ABTS assay. However, the gallic acid equivalent (GE) at 48 h was $87.8{\mu}M$, whereas $14.5{\mu}M$ GE was obtained using the ABTS and DPPH assays, indicating about sixfold increase. In the ORACFL assay, antioxidant activity corresponding to $45.7{\mu}M$ of trolox equivalent was found in the gelatin hydrolysate after 24 h hydrolysis with pancreatin treatment after pepsin digestion, whereas this activity decreased at 48 h. These antioxidant assay results showed that digestion of gelatin by gastrointestinal enzymes prevents oxidative damage.