Alkaline hydrolysis of porcine blood haemoglobin: applications for peptide and amino acid production

Abstract

Alkaline hydrolysis of proteins recovered from slaughterhouse blood is a method to obtain profitable peptides and free amino acids for animal feed, besides decreasing the waste produced by this industry. The current trend to use enzymatic hydrolysis may need reconsidering due to its high cost in materials and the need for control processes that are both complex and expensive. The use of caustic soda (NaOH), which is a low-cost product, to obtain useful peptides from porcine haemoglobin is studied in this paper. Concentrations of 6 M NaOH at 50°C for 24 h afforded an 80% peptide recovery yield with an average peptide size of 13 kDa. Product obtained at 24 h was composed of soluble haemoglobin (7%), peptides larger than 10 kDa (63%), peptides between 6 and 10 kDa (16%), peptides between 1 and 6 kDa (1%), free amino acids (4%) and non-soluble compounds (8%). A kinetic model was subsequently developed. It is proposed that neutralising the alkaline product using acid products allows the processing of a higher amount of protein while employing the same amounts of reagents, although this topic requires further research.