| Meat contains a high proportion of easily digestible proteins,high-calorie fats,vitamins and other micronutrients.These ingredients are essential for the normal functioning of the human metabolism,which makes meat products indispensable in people’s daily lives.However,during the storage of meat products,amino acids are easily decomposed into volatile amines(ammonia,trimethylamine,cadaverine,putrescine,spermine,etc.)under the action of microorganisms.It has been proven to be an index of freshness of the meat products.This paper selects volatile amines as the testing object,and prepares a kind of solid dye.The dye is composed of anthocyanin from blueberry and degradable polylactic acid.It is easy to process into many forms.The one form(nanofiber membranes)is used to test the freshness mutton to verify its feasibility.The main conclusions are as follows:1.Application analysis of solid dyes.Anthocyanins are successfully extracted from blueberries.Anthocyanin extracts are sensitive to changes in pH.When exposed to different pH values(pH=2-14),the color of anthocyanins changes from red to golden yellow.Select it as the core instruction material.Polylactic acid is used as the substrate,chloroform and DMF are used as the solution to prepare the solid dye.The dye is successfully used as an ink,and a transparent film is prepared under solution casting.For the high sensitivity of the nanofiber membranes,it is chosen to indicate the freshness of the mutton.2.Characterization and performance of nanofiber membranes.Anthocyanin nanofibers with different concentrations are studied.Structural characterization and performance studies are performed using SEM,contact angle,Fourier infrared spectroscopy,color stability,oxidation resistance,amine reaction and reusability.Element is successfully introduced into the nanofiber membrane.Under the microstructure,the membrane is composed of uniform fiber filaments of about 250nm,and the whole of the cut film still exhibits the hydrophobicity of polylactic acid.The change of △E of the fibrous membrane after the membrane is stored for 15 days in different environments does not exceed 5%.The scavenging rate of free radical of the fiber membrane can reach more than 85%.The nanofiber membrane is sensitive to ammonia with a detection limit of 37 ppm and can be reused.3.Testing on Freshness of Mutton with Nanofiber Membrane.Storing mutton in an temperature of 10±2℃ to measure the data of volatile basic nitrogen(TVB-N),total number of colonies,pH value,acidity/oxidation coefficient,hydrogen sulfide(H2S),catalase,etc.Based on the result of physical and chemical indicators of freshness,it shows that when the lamb is stored for 72 hours,severe corruption had occurred.At the same time,the color and △E of the nanofiber tag were observed and measured during the process.It was found that the color of the fiber membrane gradually changed from pink(freshness)to colorless(corruption)as the mutton spoiled.At 72h,△E increased to 13.6(TVB-N=32.9mg/100g),which is consistent with the change law of the standard TVB-N.4.Application and verification of Nanofiber Membrane in mutton market.According to the correlation analysis,the △E of the fiber membrane was negatively correlated with Sensory Evaluation(P<0.0001)and negatively correlated with the Acidity/Oxidation Coefficient(P<0.0034).The Volatile Basic Nitrogen(TVB-N)and the total number of colonies and pH are positively correlated(P<0.0001).In the principal component analysis,they are all regarded as the first principal component that affects meat quality,and the load factor occupied by △E in the first principal component is 0.92.The above results indicate that AE can be used as an evaluation index of freshness of lamb.Prediction model equations of △E and TVB-N of nanofiber membranes are established through JMP,with an accuracy rate of 88.7%,indicating that TVB-N can be accurately predicted by △E,and then the freshness of mutton can be divided.The tab was successfully applied in the sales market.The initial estimate of the tab is 0.0027 yuan. |
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