ABSTRACT
Fish protein hydrolysates (FPH) have many desirable properties, however heating and shifts in pH can cause oxidation during enzymatic hydrolysis. The objective was to investigate oxidative processes during enzymatic hydrolysis of fish protein and the impact of oxidation on the antioxidant and immunomodulating ability of FPH. Protease P "Amano" 6 was used to hydrolyze cod protein in the presence and absence of pro-oxidants at pH 8 and 36°C to achieve 20% degree of hydrolysis. Results from thiobarbituric acid reactive substances (TBARS) and sensory analysis indicate that oxidation can develop rapidly during hydrolysis. A cellular antioxidant assay using a HepG2 cell model indicated a negative impact of oxidation products on antioxidant properties of the FPH while results obtained in chemical assays showed a negligible impact. Results from a dendritic cell model indicating that oxidation products may affect anti-inflammatory activity in the body. This study provides important information regarding bioactive FPH.
Subject(s)
Antioxidants/chemistry , Fish Proteins/chemistry , Immunologic Factors/chemistry , Peptide Hydrolases/chemistry , Animals , Antioxidants/pharmacology , Dendritic Cells/drug effects , Dendritic Cells/immunology , Fish Proteins/pharmacology , Food Handling , Gadiformes , Hep G2 Cells , Hot Temperature , Humans , Hydrolysis , Immunologic Factors/pharmacology , Oxidation-Reduction , Protein Hydrolysates/chemistry , Protein Hydrolysates/pharmacology , TasteABSTRACT
Heating and changes in pH often practised during fish protein hydrolysis can cause lipid oxidation. The effect of natural antioxidants towards haemoglobin-mediated lipid oxidation during enzymatic hydrolysis of cod proteins was investigated. Different variants of a washed cod model system, containing different combinations of haemoglobin and natural antioxidants (l-ascorbic acid and Fuscus vesiculosus extract), were hydrolysed using Protease P "Amano" 6 at pH 8 and 36°C to achieve 20% degree of hydrolysis. Lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS) were analysed periodically during the hydrolysis process. The in vitro antioxidant activity of the final products was investigated. Results indicate that oxidation can develop rapidly during hydrolysis and antioxidant strategies are preferable to produce good quality products. Oxidation products did not have an impact on the in vitro antioxidant activity of the hydrolysates. The natural antioxidants inhibited oxidation during hydrolysis and contributed to the antioxidant activity of the final product.