Evaluation Method Of Fresh Pork Freshness Based On Biogenic Amine And Research On Putrescine Sensor

In this paper,the common freshness index and the changes in biogenic amine contents of cold fresh pork under 4℃aerobic conditions were studied,the shelf life and characteristic corruption biogenic amine of cold fresh pork were determined,and the freshness evaluation method based on the characteristic corruption biogenic amine with the electrochemical detection method of putrescine were established.The main contents are as follows:（1）Through simulating cold chain logistics,transport and storage conditions of cold fresh meat,the changes in common freshness indicators of the four parts of cold fresh meat under 4℃,such as the pig small fillet,pig back longest muscle,pig shoulder and pig leg,were studied.The results showed that the sensory index,quality and structure index（hardness,elasticity）,TVBN and pH had good correlation.Sensory evaluation could rapidly show quality change of the cold fresh pork.However,TVBN and pH displayed a certain hysteresis in freshness evaluation of the cold fresh pork.According to comprehensive changes in freshness indicators,the shelf life of cold fresh pork during 4℃storage was determined to be 6 to 8 days.（2）Using high performance liquid chromatography method to determine the content change of cadaverine,putrescine,tyramine,spermine,spermine,histamine,tryptamine and phenethylamine in different parts of the cold fresh pork during 4℃,and the correlation between biogenic amine and freshness were studied and analyzed.The results show that the cadaverine,putrescine,tyramine,tryptamine has good correlation with cold fresh pork freshness index.Cadaverine,putrescine,tyramine is closely related to the decomposition of cold fresh pork,to propose the three amine as the biogenic amine freshness evaluation index in cold fresh pork,according to the shelf life of cold fresh pork in 4℃storage,the freshness evaluation limit range can be respectively decided as:tyramine 2.5⁴.5mg/kg;cadaverine 3⁴ mg/kg;putrescine 4⁶ mg/kg.And it’s also can use the sum of content（tyramine,cadaverine and putrescine）as the cold fresh pork freshness evaluation index,and the evaluation limit value was 11¹3 mg/kg.（3）Based on the production of hydrogen peroxide through the catalyzation of diamine oxidase to putrescine and the good catalytic ability of unfolded Hb to hydrogen peroxide,an electrochemical biosensor was established to determine putrescine.The concentration of diamine oxidase,the kinds of peroxidase（simulation enzyme）,the stability of the modified electrodes,and test conditions were optimized.Electrochemical impedance spectroscopy（EIS）and cyclic voltammetry（CV）were used to characterize.The results showed that DAO-GLU/uHb/Clay/GCE,which was prepared through adsorbing Hb denatured by acid and urea（uHb）to the surface of Clay/GCE,and 2.5%glutaraldehyde（GLU）as crosslinking agent to immobilize diamine oxidase（DAO）,had good detection effect to putrescine using square wave voltammetry.The difference of reductive peak currents had good linear relationships with putrescine concentration in the range of 1.0×10^-111.0×10^-10mol/L and 1.0×10^-101.0×10^-99 mol/L（r≥0.997）,respectively.The detection limit was 3.3×10^-1212 mol/L based on the signal to noise ratio of 3.The recovery rates of putrescine in pork were 92.2%¹12.6%.The modified electrode had good reproducibility and stability,and high sensitivity,and was suitable for the detection of putrescine in pork and other food samples.