Detection Of Salmon Freshness Based On Biomarkers

Salmon is popular among consumers because of its delicacy and high-nutrition.Salmon is rich in protein and fatty acid,which make it easy to deteriorate during transportation and storage,reducing its nutritional value,and even producing harmful substances,threaten human health.Therefore,it is of great significance to study the freshness of salmon.The main results are as follows:(1)A method for the determination of 9 biogenic amines(?-phenylethylamine,tryptamine,putrescine,cadaverine,histamine,tyramine,spermidine,spermine and noradrenaline)in salmon by liquid chromatography tandem mass spectrometry was established.The change trends of nine biogenic amines produced by salmon at different storage temperatures were investigated.The recoveries ranged from 80.19% to 99.23%,and the detection limit was 0.0244?g/g ? 0.151 ?g/g.Under the two storage temperatures(4? and 25?),the change trend of the total content of nine biogenic amines was the same,The content of cadaverine,histamine,putrescine,tryptamine,tyramine and ?-phenethylamine increased,while the content of spermidine and spermine decreased.When stored at 4 ?,salmon rotted seriously after 4 days,the total biogenic amines of salmon were 57.07 mg / kg;When stored at 25?,salmon rotted seriously after 1 days,the total biogenic amines of salmon were 50.74 mg / kg.(2)The ATR-MIR spectra of salmon during storage were analyzed: the wave number of amide A band of salmon protein moved to high wave number in the early stage of storage,and to low wave number in the late stage of storage.It was found that the content of protein secondary structure changed during storage,The content of ?-folding decreased,The content of Irregular curl? ?-Helix and ?-corner increased.The changes of the wave number of amide A band and amide I band can be used as a reference for determining the freshness of salmon.(3)Identification and analysis of different proteome of salmon during storage: 22 differentially expressed proteins related to the freshness of salmon during storage were screened.These differentially expressed proteins were mainly enriched in glycolysis/gluconeogenesis pathway,amino acid biosynthesis pathway,carbon metabolism pathway,starch and sucrose metabolism pathway.Among the 22 differentially expressed proteins,there were 10 proteins related to glycometabolism,all of which were catalytic enzymes;8 proteins were related to muscle contraction;one protein was related to energy metabolism;one protein was related to fat metabolism;2 proteins were skeleton proteins.These proteins could be used as potential differential proteins to study the freshness changes of salmon,providing reference for studying the mechanism of freshness changes of salmon in different storage time.(4)A method was established for the quantification of apolipoprotein A1 characteristic peptide of salmon.Two characteristic peptides(VAVNVEETK,VAPLSEDFK)of apolipoprotein A1 were screened out.At different storage temperatures,the contents of characteristic peptides VAVNVEETK and VAPLSEDFK from apolipoprotein A1 decreased with the storage time,which could be used as biomarkers to indicate the freshness of salmon.