Effect Of Ultrasonic Assistance On Extraction Of Chicken Lung Collagen And Antioxidant Activity Of Enzymatic Hydrolysis Products

At present,poultry meat has become the world's largest meat.Broiler production and consumption are increasing year by year.In 2018 alone,global production reached 92.5 million tons.As the scale of the broiler industry continues to expand,chicken lungs have also increased as a by-product of broiler chickens,but currently there is little research and use of chicken lungs at home and abroad.Through pre-experiment,it is known that chicken lungs are rich in collagen,which can be further processed and used to improve resource utilization and reduce environmental pollution.In this experiment,chicken lung was used as raw materials to analyze the three factors of ultrasonic power,material-liquid ratio,and extraction time.The collagen extraction process was optimized by response surface method.The physical and chemical properties of collagen extracted by ultrasonic-assisted acid extraction and conventional acid method were analyzed and their functional characteristics were studied by UV,SDS-PAGE,FTIR,X-ray diffraction,particle size,DSC,SEM and other indicators.Collagen peptides were extracted by ultrasonic-assisted enzymatic method,then studied their antioxidant properties and moisturizing properties,and provide new ideas and theoretical guidance for the extraction of collagen in chicken lung and the high-value development and utilization of chicken lung.This experiment is divided into three parts: 1.Response Surface Methodology for Optimization of Ultrasonic-assisted Acid Extraction of CollagenIn this study,an optimized ultrasonic-assisted acid extraction model was obtained by performing a response surface experiment.The optimal conditions for ultrasonic power,material-liquid ratio,and extraction time were 365 W,1:90,and 320 min,respectively.The optimized ultrasonic-assisted acid extraction parameters obtained in this study can provide certain data support for the development and utilization of collagen in chicken lung.2.Effect of ultrasonic-assisted acid extraction on the physicochemical properties of collagenIn order to understand the physical and chemical properties of the collagen assisted by the ultrasonic acid extraction,the collagen extracted under the optimal process conditions was compared with the collagen extracted by the conventional acid method.The collagen extracted by acid method was compared and analyzed by UV spectrum,SDS-PAGE,FTIR,X-ray diffraction,particle size,DSC,SEM and other indicators.The results of amino acid analysis showed that the content of glycine in collagen extracted by conventional extraction and ultrasonic-assisted acid extraction was the highest,reaching 24.12% and 23.93%,followed by the content of imino acids,reaching 19.74% and 22.28%.DSC results showed that ultrasonic-assisted acid extraction collagen had better thermal stability,which was consistent with the results of sub-amino acid content.The results of SDS-PAGE and UV showed that the structure of the extracted collagen remained good and its purity was high.The X-ray diffraction pattern and Fourier transform infrared spectroscopy results show that the chicken lung collagen extracted by the two methods maintains the intact triple helix structure and the molecules are closely arranged.It indicates that after the ultrasonic assisted extraction of collagen,the triple helix structure is not destroyed.Particle size distribution,SEM analysis,and collagen solubility indicated that the cavitation effect and mechanical effect ultrasound in the auxiliary acid extraction process can change the hydrogen bond composition and particle size of the protein,make the structure more loose,and the internal hydrophobic groups are exposed.Thereby significantly improving the hydrophobicity,oil-holding,emulsifying and hygroscopic properties of collagen(P <0.05).3.Study on Anti-oxidation of Collagen Ultrasound-Assisted Enzymatic Hydrolysis ProductsCollagen peptide was extracted by alkaline protease and papain combined with sonication(365W,10min).Then obtain the collagen peptides through the ultrafiltration device(molecular weights <1000 Da,1000-3000 Da and 3000-5000 Da).The antioxidation ability was analyzed by using the ·OH scavenging rate,DPPH· scavenging rate,ABTS + · scavenging rate,chelating ability of Fe2 + and reducing ability.After property analysis of peptides with different molecular weights prepared at 75 ?,the results showed that the peptides were denatured,the secondary structure was destroyed,and the triple helix structure could not be recovered after ultrasonic and enzymatic hydrolysis.Due to the mechanical effect and cavitation effect of ultrasound,the protein peptide chain becomes loose,hydrophobic groups are exposed,and enzymatic hydrolysis also exposes more hydrophobic groups embedded in the interior,both of which jointly promote the enhancement of hydrophobicity of collagen peptide.The results of different antioxidant indexes showed that the peptide chain with smaller molecular weight had stronger antioxidant activity,which was consistent with the hydrophobicity.Under the same conditions,the antioxidant and hydrophobicity of collagen peptides treated with alkaline protease were better than those extracted by papain.