Antioxidant Protein Hydrolysates and Peptides from Catfish: Enzymatic Production, In Vitro Bioactivity, and...

Over the past decade, an increasing demand for natural antioxidants has driven research into antioxidant peptides and protein hydrolysates from fish and their processing by-products. Catfishes, especially species like Pangasius and Clarias, generate large amounts of protein-rich by-products, which represent a valuable bioresource for valorization. This review discusses advances from the past decade in the production, characterization, and antioxidant capacity of protein hydrolysates and peptides that have been discovered from catfish muscle and by-products. This review emphasizes enzymatic hydrolysis strategies, using Alcalase and other commercial and by-product-derived proteases. Potent antioxidant fractions, particularly those with low molecular weight (<3 kDa) and rich in hydrophobic/aromatic amino acids, have been obtained from the hydrolysates. Mechanisms of antioxidant action, which include hydrogen atom transfer and electron transfer, are discussed in this review, along with the efficacy of catfish-derived antioxidant peptides and protein hydrolysates as demonstrated in chemical and in vivo models. Applications in food systems, such as emulsion-type sausages, have shown potential for shelf-life extension. Nevertheless, knowledge gaps remain, which include an over-dependence on in vitro assays, limited identification of antioxidant peptide sequences, and insufficient data on sensory properties, intestinal permeability, bioavailability, and stability under food processing conditions. Future work should prioritize proteomic characterization, cellular validation, flavor-masking strategies, and scalable production protocols to accelerate the application of catfish protein hydrolysates as viable natural antioxidants for the functional food industry.