Uso de uma protease bacteriana na obtenção de hidrolisados antioxidantes a partir de subprodutos de origem animal

Abstract

Enzymatic hydrolysis of proteins receives continuous attention due to the possibility of releasing bioactive peptides with potential relevance to human health and food technology. Antioxidant capacity is among the bioactivities described for protein hydrolysates. Growing interest resides both in the use of agro-industrial by-products and wastes as substrates for obtaining antioxidant hydrolysates, and in the application of non-commercial microbial proteases in hydrolytic processes. This work aimed to evaluate the capacity of a crude protease from Bacillus sp. CL18 as a biocatalyst for the production of antioxidant protein hydrolysates from by-products of the food sector, more specifically meat processing. The bacterial protease was capable of hydrolyzing the 12 investigated by-products (from porcine, bovine, chicken and fish sources), as detected by the increase in soluble protein content after 4 h of crude protease activity. Hydrolysates (4 h) exhibited higher antioxidant capacity than non-hydrolyzed by-products, as demonstrated by free radical scavenging, Fe2+ chelation, and Fe3+ reduction abilities. Among the substrates analyzed, bovine lung was selected to evaluate the effect of hydrolysis time (0-8 h) and enzyme/substrate ratio (E/S; 384, 860 and 1,400 U/g) on the antioxidant potential of the hydrolysates. The higher E/S ratio accelerated the increase of antioxidant activities, although it did not result in bioactive potentials higher than those detected using the intermediate E/S ratio. It is indicated to obtain optimal antioxidant activities, the hydrolysis could be carried out for 6 h, applying an E/S ratio of 860 U/g. Hydrolysates showed soluble protein content (3.13 mg/mL), the ability to eliminate 2,2-diphenyl-1-picrylhydrazyl (DPPH) (10.2%) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (68.1%), Fe2+ chelation (70.8%) and reducing power [0.119 absorbance units at 700 nm (Abs700)], which were 3.6, 2.2, 4.3, 1.5 and 6.6 fold higher, respectively, than unhydrolyzed substrate. In summary, it is indicated that the evaluated by-products are potential sources of bioactive peptides, that can be released through enzymatic processes, as well as the ability of the Bacillus sp. CL18 protease for this purpose. This strategy is promising for the valorization of animal by-products generated in large amounts by agro-industrial activities.