Research On The Changes Of Flavor Compounds From Egg White Antioxidant Peptides By SPME-GC-MS During Storage

This study was granted by the Key Projects in the National Science & Technology Pillar Program during the Twelfth Five-Year Plan Period(No.2012BAD33B03).In the present thesis,the egg white peptide powders(EWPPs)with molecular weight range from 3 to 10 k Da(EWAPs-II)and less than 1 k Da(EWAPs-I)were taken as material.The headspace solid-phase micro-extraction(HS-SPME)conditions were optimized.At the same time,the effects of storage temperature and relative humity(RH)on the volilate components of two fractions were detected by using HS-SPME-GC-MS,and the key volatile components responsible for the aroma changes were futher identified.In the end,the changes of structure and functional properties were also studied.The main results are as follows:(1)In the determination of molecular weight,different molecular weights of egg white antioxidant peptides(EWAP)were determined.The results showed that 3-10 k Da EWAP was 53.81 ± 0.91 % in the EWAPs-II,and less than 1 k Da EWAP was 53.58 ± 3.57 % in the EWAPs-I.(2)In the GC-MS analysis,30 and 33 volatile compounds were identified from EWAPs-I and EWAPs-II,respectively,including 5 aldehydes,5 ketones,4 alcohols,4 phenols,7 esters,4 aromatic hydrocarbons,4 fatty hydrocarbons and 1 acylhydrazine.(3)In the qualitative analysis,benzothiazole was generated after the 4 °C,50% RH;4 °C,75% RH;25 °C,50% RH;25 °C,75% RH of EWAPs-I.Compared with EWAPs-II,the special volatile compounds of EWAPs-I were methoxyl-phenyloxime,2,5-2 tert-butyl phenol and 3,4-diethyl-1,1'-biphenyl.In addition,dimethyl trisulfide,1-octene-3-alcohol,6-methyl-5-hept-2-ketone,3-ethyl1-2,5-dimethylpyrazine,2,2',5,5'-tetramethyl1-1,1'-diphenyl and benzothiazole were generated after the4 °C,50% RH;4 °C,75% RH;25 °C,50% RH;25 °C,75% RH.Compared with EWAPs-I,the special volatile compounds of EWAPs-II were aminoformyl hydrazine,2-methyl-3-hydroxy-2,4,4-trimethyl-pentanoate,salicylic acid-2-ethylhexyl ester,palmitate and isopropyl palmitate.(4)In the quantitative analysis,five clusters were obtained after the 4 °C,50% RH;4 °C,75% RH;25 °C,50% RH;25 °C,75% RH of EWAPs-I.The PC1 was 48.1% and PC2 was 22.4%.Six clusters were obtained after the 4 °C,50% RH;4 °C,75% RH;25 °C,50% RH;25 °C,75% RH of EWAPs-II.The PC1 was 48.1% and PC2 was 28.4%.25 ° C,75% RH was the most obvious storage conditions of peptide powder deterioration.EWAPs showed the strongest barbecue and rubber.At the same time,the changes of EWAPs-II were stronger than EWAPs-I.(5)The results of X-ray diffraction,electron microscopy,fluorescence spectra and ultraviolet spectrophotometry showed that,the EWAPs had physical changes after storage of 4 °C,50% RH;4 °C,75% RH;25 °C,50% RH;25 °C,75% RH.The peak content of X diffraction was reduced;the size of peptide powder was small;both the fluorescence and UV peak content decreased,and the changes of EWAPs-I were more obvious.