Potencial funcional e antioxidante do colágeno hidrolisado da pele de tilápia-do-nilo (o. niloticus)

Abstract

Nile tilapia (Oreochromis niloticus) is among the most widely farmed fish species worldwide due to its high adaptability and productivity. The state of Paraná stands out as one of Brazil's main production hubs, reaching approximately 273 thousand tons in 2025. This high production volume results in the generation of significant amounts of by-products, such as skin, which represents both an environmental challenge and an opportunity for valorization. In this context, tilapia skin has great potential as a source of collagen, a protein that can be extracted and hydrolyzed to obtain peptides with functional and bioactive properties. The present study aimed to extract collagen from tilapia skin, promote its enzymatic hydrolysis, characterize its technological and antioxidant properties, and evaluate its potential application in meat products. Collagen was hydrolyzed and analyzed at two reaction times (2 and 4 h). The sample that exhibited the best technological performance was selected for antioxidant activity determination. Subsequently, it was incorporated into fresh pork sausage formulations, in which physicochemical and textural characteristics were evaluated. A Bacillus sp. protease was used to perform hydrolysis for 2 and 4 h, increasing the degree of hydrolysis from 7.25 ± 0.25% to 9.29 ± 0.29%, respectively. The results demonstrated significant differences between treatments regarding the evaluated functional properties. The 4 h reaction time resulted in a higher degree of hydrolysis, greater emulsifying capacity, enhanced emulsion stability, and reduced oil retention capacity. Solubility varied according to pH, being highest at pH 5 and lower at pH 7 and 9. Due to this superior performance, the sample obtained after 4 h was selected for the subsequent stages of the study.The collagen hydrolysates produced after 4 h of hydrolysis exhibited expressive antioxidant activity, with values of 12.46 ± 2.54 μmol TE/g in the FRAP assay, 256.52 ± 2.39 μmol TE/g in the ABTS assay, and 233.36 ± 0.98 μmol TE/g in the DPPH assay, demonstrating their ability to neutralize free radicals. FTIR analysis revealed that the collagen structure was partially preserved despite changes in the characteristic amide bands. Thermal analyses (TG/DTG and DSC) indicated a reduction in thermal stability due to the fragmentation of protein chains caused by hydrolysis. Regarding the application of collagen hydrolysates in fresh pork sausages, the physicochemical parameters of color and pH showed no significant differences among formulations, indicating that their incorporation did not compromise product appearance or stability. Concerning technological properties, differences were observed in water-holding capacity (WHC), cooking loss (CL), and lipid oxidation. The formulation containing collagen peptides exhibited the lowest lipid oxidation after seven days of storage (0.56 ± 0.01 mg MDA/kg). Texture analyses revealed variations in hardness, springiness, chewiness, and cohesiveness during storage, suggesting that the addition of these peptides influenced the protein matrix structure and the technological properties of the product. The results highlight the potential of tilapia skin as a source of bioactive peptides with functional and antioxidant properties, as well as its promising application as a technological ingredient in meat products.