Desenvolvimento de isolado proteico a partir da carne mecanicamente separada de carcaça e apara de tilápia

Abstract

The present research aimed to develop powdered protein isolates from tilapia residues using isoelectric precipitation by pH variation associated with spray drying. Four experimental treatments were established, combining two sources of mechanically separated meat (MSM), carcass (MSM-C) and carcass with “V” trimming (MSM-CV), and two extraction media (aqueous and saline). In the first article, protein solubility curves were constructed to determine the pH values of maximum solubilization and the isoelectric points, aiming to optimize protein recovery. The inclusion of trimmings reduced lipid content (MSM-C = 8.0%; MSM-CV = 5.15%) and increased protein content (from 13.0% to 16.15%), improving the nutritional value of the raw material. The aqueous solution showed higher recovery efficiency, with better performance of MSM-C under acidic conditions (pH 2.0) for solubilization and pH 6.5 for precipitation, while MSM-CV showed better results under alkaline conditions (pH 11.5) and pI at pH 5.5. The saline solution resulted in lower yields (MSM-C = 50.28%; MSM-CV = 71.31%), possibly due to the lower solubility of sarcoplasmic proteins in this medium. In the second article, the protein isolates were obtained under the previously defined optimal conditions, followed by spray drying and characterization regarding proximate composition, mineral profile, and amino acid profile, in addition to thermal (DSC) and morphological (SEM) analyses. The isolates showed high protein content (80.8% to 87.05%), lipid content between 7.03% and 12.93%, and high sodium content, especially in those obtained using saline solution, highlighting the influence of the extraction medium. The amino acid profile demonstrated the presence of all essential amino acids and nutritional adequacy for adults. The micrographs revealed predominantly spherical particles with irregular surfaces and indications of structural collapse, typical of the spray drying process. DSC analysis indicated endothermic events of protein denaturation, with variations in thermal stability depending on the extraction medium and the presence of trimmings. The results demonstrate that tilapia MSM is a promising raw material for obtaining protein isolates with high nutritional value, representing a sustainable alternative for the use of residues from the fish processing industry and with potential technological application in fortified products.