Valorisation of blood protein from livestock to produce haem iron-fortified hydrolysates with antioxidant activity

Abstract

Blood is the main by-product from slaughterhouses bearing high levels of suspended solids (18% w/w) and BOD5 (250 000–375 000 mg O2/L), which makes difficult its handling and disposal. This study proposes the valorisation of blood protein to produce enzymatic hydrolysates rich in haemic iron and antioxidant peptides. Haemic iron presents higher bioavailability compared to its inorganic form, but its incorporation into foodstuffs is restrained by its high tendency to oxidation. Six commercial proteases of animal, plant and bacterial origin were employed to produce the enzymatic hydrolysates. Subtilisin and trypsin treatments were able to recover 70% of haem iron as soluble peptides, in contrast with plant enzymes where the proteolysis was reduced. Moreover, some enzymatic treatments led to hydrolysates with high levels of some in vitro antioxidant activities such as radical scavenging (Protamex, IC50 3.52 mg/mL) or metal chelating activity (trypsin, IC50 0.27 mg/mL). We conclude the enzymatic valorisation of blood protein increases haemic iron bioavailability and produces antioxidant peptides. Both properties are of interest for their use as iron fortification supplements.