Antioxidant and functional properties of bioactive peptide fractions derived from shrimp (Pleoticus muelleri) waste hydrolysates

Protein hydrolysates were prepared from shrimp (Pleoticus muelleri) waste through autolysis (Aut) and using 1 % and 2 % (v/v) Alcalase (Alc 1 and Alc 2, respectively). The degree of hydrolysis (DH) and antioxidant activities were assessed via 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^•+) scavenging assays at various hydrolysis times. After 90 min, Aut and Alc 1 were selected for fractionation by ultrafiltration, yielding peptide fractions: F1 (>10 kDa), F2 (3–10 kDa), and F3 (<3 kDa). Functional properties, antioxidant capacities, and lipid peroxidation inhibition in raw fish emulsions were assessed for both whole hydrolysates (WH) and their peptide fractions. Alc 1 achieved a significantly higher DH (42.02 ± 5.50 %) than Aut (28.75 ± 2.34 %). Both hydrolysates and their fractions displayed high solubility (>65.49 ± 2.07 %) across a wide pH range. The F1 fraction exhibited the strongest DPPH scavenging activity for both hydrolysates, with Aut's F1 reaching 445.90 ± 19.52 mg AEAC/100 g dry weight and Alc 1's F1 achieving 461.10 ± 15.81 mg AEAC/100 g dry weight. Aut's F3 fraction had the highest ABTS^•+ scavenging capacity (723.66 ± 36.58 mg AEAC/100 g dry weight), while Alc 1's WH exhibited superior activity (776.20 ± 52.55 mg AEAC/100 g dry weight). Overall, Aut's F1 fraction demonstrated the most favorable antioxidant and functional properties, while Alc 1's F3 fraction showed superior solubility and lipid peroxidation inhibition. These findings underscore the potential of shrimp (P. muelleri) waste for producing functional hydrolysates and bioactive peptides with diverse applications.