Study On Evaluation Method Of Mackerel Freshness Based On Biogenic Amine

Commonly used indicators for the freshness of aquatic products are volatile base nitrogen(TVB-N),total number of colonies(APC),pH,color difference,texture index and sensory score.Based on the fact that biogenic amines are important chemical markers for the freshness of reaction aquatic products,the above-mentioned indexes and bioamine content of horse mackerel under 4 ℃ storage conditions were studied to determine the freshness level and spoilage characteristics of mackerel.Biogenic amines have established a comprehensive assessment method for freshness based on the characteristic biotin of spoilage.The main contents are as follows:(1)The changes of fish freshness index of mackerel under 4 ℃ storage conditions and 8 kinds of biogenic amines(putrescine,cadaverine,tyramine,histamine,spermine,spermidine,tryptamine,phenethylamine)were studied.Generate rules and conduct correlation analysis.The results showed that there was a good correlation between the freshness indexes of mackerel fish meat during storage at 4 ℃,and the freshness index was significantly correlated with storage time.Based on the changes in various indicators,it is recommended to classify the freshness level of mackerel at 4 ℃ storage: fresh(≤1 d);second fresh(1~4 d);and spoilage(≥4 d).The contents of cadaverine,putrescine,tyramine and histamine in mackerel showed a significant increase with the increase of storage time,and there was a good correlation between the four bioamines and the freshness index of mackerel.The sum of these four kinds of spoiled characteristic biogenic amines was used as an indicator for evaluating the bioavailability of mackerel.In combination with the classification of the freshness level of mackerel stored at 4 ℃,the caloric freshness evaluation limit of biogenic amine(the sum of cadaverine,putrescine,tyramine and histamine content)can be determined as: Fresh(≤7.1 mg/100g);second fresh(7.1~40.7 mg/100g);spoilage(≥40.7 mg/100g).The freshness of the mackerel can also be evaluated by using the sum of the four kinds of spoiled characteristic biogenic amines such as histamine or the content of each other as an index.(2)In view of the frequent occurrence of high histamine fish and histamine poisoning in horse mackerel,a simple and sensitive group was established by using colloidal gold modified glassy carbon electrode(AuCS/GCE)and current-time curve method.Amine detection method and tracking detection of horse mackerel stored at 4 ℃.The pH value of the bottom liquid and the electrochemical test methods and conditions of histamine were optimized,and the electrochemical performance of the modified electrode was investigated.The results showed that the response current difference(-ΔI,nA)of histamine on AuCS/GCE showed a good linear relationship with the concentration(c,μmol/L)in the range of 0.1~64 μmol/L.The detection limit was 0.033 μmol./L,the spiked recovery rate of histamine in mackerel was 98.8%~103.6%.The method is simple in operation,fast in detection and low in cost,and is suitable for the determination of histamine in food samples such as mackerel.It can also be used to monitor the freshness change of mackerel and determine the freshness of mackerel with histamine as an indicator.The evaluation limits are: fresh(≤3.90 mg/100g),sub-fresh(3.90~21.43 mg/100g),and spoilage(≥21.43 mg/100g).(3)The results of TVB-N,APC,sensory score and histamine content of horse mackerel under 4 ℃ storage conditions were analyzed respectively.The results of the freshness evaluation of these four indicators were further used to support the support vector machine.The SVM method is used to classify and predict the freshness of mackerel,and discusses the effects of normalization and kernel function selection on the correct classification rate.The results show that the selection and normalization of the kernel function have a certain impact on the SVM method to achieve the classification accuracy of the mackerel freshness.The SVM method can comprehensively process the above four indicators to make the malt’s freshness classification correct.The rate reaches 100%.