Preparation And Functional Activity Of Pearl Oil Apricot Almond Protein And Antioxidant Peptides

Almond is a traditional medicinal and edible homologous resource in China.It is rich in protein and is a good raw material for preparing bioactive peptides.Excessive accumulation of free radicals and reactive oxygen species in cells can produce oxidative stress,and then results in organism damage.Endogenous antioxidant defense system plays a major role in maintaining redox homeostasis of human cells,while exogenous antioxidants,especially foodborne natural antioxidants,are also very important.In this study,the almond protein in pearl oil apricot was prepared by ultrasonic-assisted alkali solubilization method,and its structural and functional properties were detected.The antioxidant peptides were prepared from almond protein by enzymatic hydrolysis.Then the antioxidant peptides were isolated,purified and identified.The component with the highest antioxidant activity in vitro was selected and its antioxidant activity in cells was studied.On the basis of the above research.The main research results were as follows:(1)Almond protein was extracted by ultrasonic-assisted alkali solubilization method.The optimum extraction process was as follows: liquid to material ratio 30:1,temperature 45.1?,time 30 min,and ultrasonic power 250 W.Under the optimal condition,the protein yield was61.57%.(2)Almond protein is a ?+? type structure with abundant low molecular weight subunits.The particle size is uniform,and the surface bulge is relatively gentle.The almond protein has good functional properties,and its solubility,water holding capacity,emulsification and foaming properties are better than soybean protein.(3)The almond antioxidant peptide was prepared by enzymatic hydrolysis method,and the optimum enzymatic conditions were obtained by using the DPPH free radical removal rate as the index: substrate mass fraction 1.5%,enzyme addition 4.9%,enzymatic temperature55?,p H 8,and enzymatic time 2.5 h.The actual scavenging rate of DPPH free radicals under these conditions was 50.67%.(4)The APHs were separated by ultrafiltration and gel column chromatography,and APHs-1 and APHs-1-c with the best antioxidant capacity,were obtained.(5)APHs-1-c has a significant protective effect on oxidative damage of HepG2 cells induced by TBHP,and has a very strong scavenging effect on intracellular ROS.APHs-1-ccould also protect HepG2 cells from TBHP-induced oxidative stress damage by activating the Keap1-Nrf2/ARE signaling pathway.(6)40 peptides sequences were identified from APHs-1-c by LC-MS/MS.Thr-Glu-Asp-Asp-Trp-Arg-Trp-His,Trp-Tyr-Asp-Asn-Glu-Trp-Gly-Tyr-Arg and Ala-Glu-Asp-His-G lu-Trp-Trp-Trp-Arg with the most potential antioxidant activity were screened by molecular docking test.