Bioactive peptide isolation from animal sources and their effects on quality characteristics of fermented sausages

Investigation of bioactive and functional properties of bovine liver hydrolysates (BLHs) and their low molecular weight of fractions was aimed. Mixed peptides were prepared from Alcalase:Protamex (1:1)-hydrolyzed (24 h) bovine liver, and two fractions (3 and 10 kDa) were obtained by ultrafiltration. Optimal conditions were identified as hydrolysis at 45°C for 24 h, resulting in the generation of BLHs and peptides with the highest antioxidant activity. BLHs at different concentrations (0.1%, 0.3%, and 0.5%) were added to emulsions after emulsification and to liposomes. The peptide fractions were applied in fermented sausage (with inoculated fermentation) at two different concentrations (0.5% and 1%). Stability of the systems was tested for 14 days of storage at 25oC. Quality characteristics of fermented sausages containing bioactive peptides (BPs) were examined during manufacturing, and 90 days of storage (at 4oC). Total peptides (added and fermentation-induced) were extracted from the sausages, and the stability of the added peptides was determined. Lipid oxidation occurred more rapidly in emulsions without BLH during the storage. Phase separation was observed only in lecithin emulsion without BLH after 14 days. 3 kDa peptides possessed inhibitory effect against molds and yeasts. 10P2 had the lowest protein and lipid oxidation rates. Peptides extracted from 10P2 had 2-fold higher radical scavenging activity than control, indicating the stability of the added peptides during the storage. In general, sensory score of 10P2 was the highest. The results suggested that the use of antioxidative peptides in fermented sausages is an applicable method to improve antioxidant capacity and product's quality in long term storage.