Effect of ultrafiltration on the antioxidant activity of alcalase-hydrolyzed catfish (

Catfish (Clarias sp.) is one of Indonesia's leading aquaculture commodities with potential utilization as a source of functional protein. Protein hydrolysis using alcalase enzyme can generate bioactive peptides with antioxidant activity. These antioxidant properties are typically more prominent in low-molecular-weight peptides, thus requiring separation via ultrafiltration. This study aimed to evaluate the effect of ultrafiltration on the antioxidant activity of catfish protein hydrolysate. Hydrolysis was carried out using alcalase at concentrations of 1%, 2%, and 3%, followed by fractionation using a 3 kDa molecular weight cut-off (MWCO) ultrafiltration membrane. Antioxidant activity was assessed using the DPPH and ABTS assays. The highest degree of hydrolysis (62,42%) was obtained at 3% enzyme concentration. The <3 kDa fraction exhibited the highest antioxidant activity, with IC50 values of 41,20 ppm (DPPH) and 2,80 (ABTS), both categorized as very strong antioxidants. These findings indicate that ultrafiltration is an effective method for enriching short peptides with high antioxidant potential.