| Abstrakt: |
In this study, the antioxidant capacity of peptide fractions isolated from the Tra Catfish (Pangasius hypophthalmus) by-product-derived proteolysate using ultrafiltration centrifugal devices with 5 distinct molecular-weight cutoffs (MWCOs) of 1 kDa, 3 kDa, 5 kDa, 10 kDa, and 30 kDa was investigated. Firstly, the chemical composition of the Tra Catfish by-products was analyzed. The result showed that the Tra Catfish by-products contained 58.5% moisture, 33.9% crude protein, 50.1% crude lipid and 15.8% ash (on dry weight basis). Secondly, the effects of hydrolysis time, enzyme content on the antioxidant potential of the proteolysate were studied using DPPH• (2,2-diphenyl-1-picrylhydrazyl) radical scavenging method (DPPH• SM) and FRAP (Ferric Reducing Antioxidant Potential) method. Alcalase® 2.4 L FG was used for hydrolysis. The result of antioxidant activity of the hydrolysate showed that the 50% DPPH• inhibition concentration (IC50) of the hydrolysate reached about 6775 µg/mL which was 1645-fold higher than that of vitamin C and 17-fold higher than that of BHT (ButylatedHydroxytoluene) with the degree of hydrolysis (DH) of the hydrolysate of 14.6% when hydrolysis time was 5 hours, enzyme/substrate (E/S) ratio was 30 U/g protein, hydrolysis temperature was 55°C, and pH was 7.5. The antioxidant potential of hydrolysate using FRAP method reached about 52.12 µM Trolox equivalent which was 53-fold and 18-fold lower than those of vitamin C and BHT, respectively, when the hydrolysis time was 5 h, enzyme/substrate ratio was 30 U/g protein, temperature was 50°C, and pH level was 8. Next, the proteolysate was further fractionated using MWCOs of 1 kDa, 3 kDa, 5 kDa, 10 kDa, and 30 kDa and the peptide fractions were investigated for their antioxidant activity. The result showed that the <1 kDa fraction showed strongest antioxidant activity with the IC50 of 1313.31 ± 50.65 µg/mL and FRAP value of 906.90 ± 44.32 µM Trolox equivalent. The second strongest fraction was 1-3 kDa with the IC50 and FRAP value of 2897.85 ± 128.38 µg/mL and 517.7 ± 21.08 µM Trolox equivalent, respectively. The fractions of 3-5 kDa, 5-10 kDa were the third and fourth strongest, respectively. The 10-30 kDa fraction showed weakest antioxidant capacity with the IC50 of 8012.88 ± 280.68 µg/mL and FRAP value of 92.92 ± 0.61 µM Trolox equivalent. The antioxidant peptides derived from Tra Catfish by-products proteolysate showed the potential to be used as natural antioxidant components in pharmaceutical and food industry. [ABSTRACT FROM AUTHOR] |
