Aproveitamento de subprodutos do abate de ovinos: extração e caracterização de colágenos e hidrolisados proteicos

Abstract

The objective of this study was to use sheep slaughter by-products to obtain and characterize collagens and protein hydrolysates, in addition to improving the pre-treatment process of the raw material. Sheep slaughter by-products proved to be a viable source for obtaining collagens and hydrolysates. Collagen and hydrolysates were obtained and characterized using a conventional pretreatment method (0.1M NaOH/48 hours, 1:20 (w/v); 0.5 M EDTA-2Na (pH 7.5)/5 days, 1:10 (w/v); and 10% butyl alcohol/48 hours, 1:10 (w/v)). The collagens showed a yield of 18.0% (lamb) and 12.5% (sheep) on a dry basis, similar FTIR spectra (collagen and hydrolysates) and digestibility, higher solubility at acidic pH, and good foaming capacity. Sheep collagen showed higher viscosity and emulsifying activity index. SDS-PAGE showed bands with molecular weights ranging from >250 to 5 kDa for collagens and peptides of molecular weight equal to/less than 15 kDa for hydrolysates. The collagen denaturation temperature was 39.32 °C (lamb) and 36.38 °C (sheep), while the hydrolysates did not undergo a thermal transition. Collagen and hydrolysates showed antioxidant and antimicrobial activity. Different concentrations and reaction times of NaOH and EDTA-2N were also tested; and different solvents (butyl alcohol, ethyl alcohol and petroleum ether) and enzymes (Thermomyces lanuginosus and Lipomax 80) to remove the non-collagenous fraction from samples of sheep slaughter by-products. For the removal of non-collagenous proteins, assay 3 (0.1M NaOH and 48 h time) was the best. For demineralization, assay 1 (0.1M EDTA-2N and 12 h time) and for degreasing, the petroleum ether solution was at a concentration of 16%/30 hours. The application of the best tests found makes it possible to obtain collagen and its derivatives in less time, less cost, and less harmful to the environment. Based on the study of optimization of the pre-treatment of the by-products, new extraction and characterization of collagens were carried out using the best tests obtained. The collagen yield was 16.1% (sheep) and 14.4% (lamb) on a dry basis, with FTIR (amide A, B, I, II and III) and SDS-PAGE (α1, α2 and β) similar. The denaturation temperature was 39.8 °C (sheep) and 38.6 °C (lamb). The solubility was higher at acidic pH, the highest foaming capacity was found for the concentration of 0.5%, the emulsifying activity index was 51.2 m² /g (sheep) and 37.8 m² /g (lamb), digestibility was higher for sheep collagen, where as lamb collagen had higher viscosity. Collagen and by-product hydrolysates from sheep slaughter showed potential for application in food and pharmaceutical products. They can be used in developing new ingredients, products, or foods, improving the diet, contributing to human health, and valuing and enabling a good destination for this by-product.