Studies On Preparation And Activities Of Walnut And Rice Bran Peptides

Peptide has been the research focus of a lot of scholars due to its prior properties including small molecular weight,easily absorption and a variety of biological activities.Walnut meal and rice bran are the by-product in food processing,which contain high quality protein and bioactive peptide.In order to improve the utilization,provide theory basis for food processing and clinical application of walnut and rice bran,a series of investigations were conducted on the preparation,activities and structure-activity relationship of bioactive peptides from walnut and rice bran.Firstly,walnut protein(WP)was enzymatic hydrolyzed by alcalase and trypsin under optimal conditions.The physicochemical properties,antioxidant activities and ACE inhibitory activities of WP and walnut protein hydrolysates(WPH)were comparatively studied.Stabilities properties of WPH and the antihypertensive activities in spontaneously hypertensive rats(SHRs)were also investigated.The results showed that WPH exhibited higher physicochemical properties,antioxidant activities and ACE inhibitory activity than WP and it had high stability against thermal treatment and gastrointestinal digestion.The results of antihypertensive effects in SHRs showed that the most potent decrease of WPH in the systolic blood pressure(SBP)occurred at 6 h(-30 mmHg)after administration.On the extraction of walnut three effective components,the water enzymatic technology were adopted to prepare walnut fatty acid,bioactive peptide and polysaccharide at the same time and the yields were 61.6%,24.2% and 11.3%,respectively.This study would provide a more convenient and quick method to extract effective components from walnut.In addition,rice bran protein(RBP)was extracted by alkali distillation and RBP was hydrolyzed by using trypsin.Then,the rice bran protein hydrolysate(RBPH)was purified sequentially by ultrafiltration,gel filtration chromatography and RP-HPLC.An antioxidant and ACE inhibitory peptide named as F2-a,Tyr-Ser-Lys(Mw: 395.0 Da),was identified by Quardrupole Time-of-flight Mass Spectrometer(Q-TOF-MS)with an electro-spray ionization(ESI)source.The molecular docking studies revealed that the ACE inhibition of Tyr-Ser-Lys was mainly attributed to the formation of strong hydrogen bonds with the active pockets of human tACE.These results indicated that rice bran might be a potential source of bioactive peptide possessing antioxidant and ACE inhibitory activities.Finally,the compound carrier of immobilized double enzyme magnetic nanoparticles(CT-DE-FMNPs)were prepared and characterized by physico-chemical technologies including FTIR,TEM,XRD and magnetic analysis.The results indicated that CT-DE-FMNPs was face-centered cubic crystal with diameter of less than 20 nm structure and exhibited superparamagetic.Then CT-DE-FMNPs was applied to obtain five kinds of bioactive peptides from rice bran,walnut,red bean and other protein.The activity recovery of CT-DE-FMNPs was still more than 60% after reused 10 times and the results indicated that CT-DE-FMNPs had good application properties.The study suggested the good application of magnetic nanopartioicles in the preparation of bioactive peptides and it might provide a new method for the preparation of bioactive peptides from other resources.