Recovery of proteins present in by-products of white shrimp Litopenaeus vannamei using pH variation process
Fish processing, in general, involves 50 to 60% of by-products such as shrimp exoskeleton and cephalothorax, which contain proteins, lipids, carbohydrates and carotenoids that are not used by the food industries. The protein recovered from the by-products has been investigated in recent years, for offering more nutritious foods with improved functional properties. The aim of the present study was to use the pH variation process to recover proteins from solubilization and precipitation at the isoelectric point of the same and which are present in the by-products (head and shell) of white shrimp (Litopenaeus vannamei) from cultivation using Biofloc technology (BFT) and its subsequent inclusion in a sausage-type food product. The proximal composition of the by-products showed 58,45% protein (b.s.). The precipitation point of the protein that resulted in pH 4 with 24% protein solubilization was investigated. The protein concentrate showed 73.60% protein (bs). The mass yield of the protein concentrate was 47.8% (b.u.). On the other hand, when analyzing the functionality, the greatest solubility found of the protein concentrate was at pH 2 resulting in 34.6% and in pH 8 with 51.3%. The oil and water retention capacity resulted in values of 8.5 and 2.5 mL/g of protein, respectively; the greatest emulsifying capacity was found at pH 8. The amino acid profile of the by-products and the concentrate confirmed the presence of sixteen amino acids, six of which are considered essential amino acids. The proximal composition in the different sausage formulations was: control (6% fat); F1:4% fat (pork fat) 2% shrimp protein concentrate (CPC); F2: 5% fat 1% CPC. The amount of protein in the F1 sample was higher than in the commercial sausage in (b.u.). There was a statistical difference in lipids (p≤ 0.05) between the control and F1 samples. The ash values showed differences for samples F1 and F2. For firmness the F1 and F2 sausages were similar to the commercial sausage. The value of L* was higher in the control sausage, the values of *a were higher in the commercial sausage and *b obtained higher value in the F1 sausage. In general, the protein concentrate of the shrimp showed potential to be included as an ingredient in food formulations.