Preparation Of Chicken Bone Protease Hydrolysate Maillard Product And Study On Its Antioxidant Activity

Chicken bone is an abundant by-product of chicken meat processing in China.It is rich in protein from the adhering meat,cartilage,and bone marrow.Most of the chicken bone left in the deboner is discarded,which is a waste of valuable nutrients.Any nitrogenous compound can be used as a substrate for the Maillard reaction.Thus,hydrolysis processing and Maillard reaction methods are required to convert chicken bone as a byproduct into more profitable and marketable products.The aim of this study was to prepare the MRPs from chicken bone protein hydrolysates,and evaluated the possible relationship between MRPs and antioxidant activity of the MRPs.The characteristic of the MRPs including UV absorbance,browning intensity,and fluorescence intensity were also determined.?1?Chicken bone was treated by high-pressure cooking.The optimum condition was solid-liquid ratio 1:1.5,cooking at 130°C for 20min.In this optimum conditions,water soluble protein content of chicken bone was 19.46±0.16 mg/mL,free amino acid content was 58.79±0.31 mg/100 g.?2?Through single factor experiments and Box-Benhnken,the optimum hydrolysis condition was obtained as:the ratio of paptain,neutral protease and trysin?1:1:2?,the ratio of enzyme and chicken bone 2200U/g,hydrolysis at 55°C for 3.5h.Under the optimal conditions,the recovery rate of protein was 95.38%,and the degree of hydrolysis?DH?was 34.28%.The hydrolysis kinetic model of hydrolysis degree was established as the equation:DH?28?.2985?ln?_?^?1?10?_??_?^?16566.?_SO^EO-.78856?_?^???.0335?t?_?^??3?Through single factor experiment,the optimum condition of Maillard reaction was obtained as:the galactose concentration 24 g/L,reaction at 100°C for 90 min.During the Maillard reaction,the changes of browning intensity degree,UV absorption of the intermediate products and pH value were in accordance with zero order kinetics,and the changes of free amino was with in first order kinetic model.The activation energy of the changes in pH,free amino,browning intensity degree(A_420nm)and generation of intermediate products(A_294nm)were 68.34 kJ/mol,19.04 kJ/mol,145.35 kJ/mol,80.99 kJ/mol,respectively.On the other hand,antioxidant activity of CBPH-MRPs in neutral and weak acidic environment was stabler than in alkaline environment.And some metal ions including Cu²⁺,Fe²⁺and Fe³⁺and oxidation H₂O₂resulted in a decreased antioxidant activity of CBPH-MRPs.?4?The antioxidant activity of CBPH and its peptide fractions?LCBPH,MW<3kDa;HCBPH,MW>3 kDa?before and after a Maillard reaction with galatose was also evaluated.CBPH and its peptide fractions showed moderate DPPH radical scavenging activity and reducing power,but poor hydroxyl radical scavenging activity.After the Maillard reaction,all the tested activities of CBPH and its peptide fractions were significantly improved.And Maillard reaction products?MRPs?derived from LCBPH had a higher antioxidant activity than that from HCBPH.But higher increase in the antioxidant activity was observed with the MRPs derived from HCBPH.?5?The ultrafiltrated fractions?CM-I,CM-II and CM-III?from CBPH-MRPs was prepared,and their spectral characteristics and the antioxidant activities was also studied.CM-II had the highest UV absorbance and fluorescence intensity at 425 nm,while the highest browning intensity was observed in CM-III.CM-III consistently exhibited the strongest antioxidant action than CM-I and CM-II fractions,evidenced by DPPH radical scavenging activity,reducing power and hydroxyl radical scavenging activity.