Optimization Of Antioxidant Hexapeptide In Pine Nut (Pinus Koraiensis) Protein Treated By Non-thermal Processing Technology PEF

The study was granted by National 863 Program under Grant research and development on the stability and processing applicability of active protein of pine nut(Pinus koraiensis)(2013AA102206-5).Pine nut peptides of 3-10 k Da with the best antioxidant activity obtained from previous studies,would be adopted in this project.The two peptides of KCHAGP and QCHAGP were identified by HPLC-MS.After peptide of DPPH,ABTS radical scavenging capacity and electric conductivity were determined,the orthogonal experiment of L4(23)was carried out,in order to obtain the optimal parameters of the anti-oxidative activity of hexapeptide.The changes of the secondary structure of the six peptide were observed through the CD and Zeta potential of the antioxidant peptides treated with optimal parameters.The results of this study were as follows:(1)The anti-oxidative activity of the synthetic peptide was determined by DPPH and ABTS radical inhibition.The synthesis peptides KCHAGP and QCHAGP had good antioxidant activity.The DPPH and ABTS radical inhibition of KCHAGP were higher than that of QCHAGP under the same conditions.The ABTS radical inhibition of the two peptides were better than that DPPH radical inhibition of peptides.The results of electric conductivity showed that the electric conductivity of the peptide has a great relationship with its concentration.,and the electric conductivity of antioxidant peptide KCHAGP was higher than that of QCHAGP at the same concentration.(2)L4(23)orthogonal tests of DPPH radical inhibition and ABTS radical inhibition were studied.The optimal treatment conditions which the solution concentration is 4 mg/m L,the electric field intensity is 10 k V/cm,and the electric field frequency is 1800 Hz were obtained.In L4(23)orthogonal test of electric conductivity,the optimal treatment conditions(8 mg/m L,15 k V/cm,1800 Hz)were obtained.(3)The following conclusions of CD and Zeta potential value were obtained by comparing the untreated peptides and PEF-treatment peptides.Different peptides have different conformation in aqueous solutions.KCHAGP was mainly distributed in the aqueous solution with random coil,and QCHAGP was mainly distributed in the aqueous solution with β-sheet.When the peptide solution was processed by PEF,the conformation in the solution would change.The Zeta potential of the untreated KCHAGP was much higher than that of QCHAGP under the same condition,however,the Zeta potential difference of the two peptides after the PEF treatment was very small.The Zeta potential of the anti-oxidant peptide KCHAGP and QCHAGP was reduced after the treatment of PEF.