Research And Development Of Indicator Card For Characterization Of Fresh Meat Freshness Based On Trimethylamine

China is a big country in meat production and consumption.Data from the National Bureau of Statistics show that the total output of meat in China in 2020 is up to 76.39 million tons.Meat has become the main product for daily consumption due to its large amount of protein required by human body.In the process of processing,storage and circulation,it is easy to be affected by microbial pollution and other environmental factors and deteriorate,resulting in food safety and waste of food resources and other problems.Studies have shown that,under the action of bacteria and enzymes,protein in meat is gradually decomposed into peptides and amino acids,and finally degraded into ammonia,amine and other small molecular compounds.These nitrogen-containing small molecular compounds are highly volatile,and are the main source of meat corruption odor.Therefore,relevant products with food freshness indicator function emerge at the right moment.Most of these products are intelligent indicator labels,boards and films.Mainly through the volatile gas as the main research object,but the freshness indicator function of the preparation of volatile gas as the research object of the related products.Therefore,it is clear that both trimethylamine and dimethylamine can characterize the freshness of mutton,but trimethylamine has a higher ability to characterize the freshness of mutton than dimethylamine.The optimal freshness indicator card was determined by comparing the different concentrations of neutral red,bromophenol blue and methyl red prepared by chitosan/cassava starch,polyvinyl alcohol sugar/cassava starch as the base.The method was applied to the detection of mutton freshness to provide a theoretical basis for the rapid detection technology development of mutton freshness.(1)Taking the longissimus dorsi muscle of chilled mutton as the research object,the relationship between the contents of trimethylamine and dimethylamine in the package and meat of chilled mutton and the freshness indexes such as color,total colony,volatile base nitrogen,thiobarbituric acid and so on was explored at 0±0.5℃ for 0,1,3,5-21 days.The results show that the cold fresh mutton color during storage,the total number of colonies,volatile base nitrogen freshness index change with storage time is relatively consistent,such as meat and trimethylamine content in the packaging and the total number of colonies,volatile base nitrogen,sulfur,generation of barbituric acid significantly positive correlation(p<0.05),and trimethylamine and dimethylamine has characterized the determination of the freshness of cold fresh mutton potential,Compared with dimethylamine content in packaging,the correlation coefficient between trimethylamine content in packaging and total number of bacteria,volatile base nitrogen and thiobarbituric acid is relatively high.Therefore,trimethylamine can be used as a marker gas substance of chilled mutton under such conditions,and has the ability to characterize the freshness of chilled mutton.(2)using 0.1%,0.2%,0.3%neutral red ethanol solution,bromophenol blue ethanol solution and methyl red ethanol solution as the core materials,using chitosan cassava starch and polyvinyl alcohol cassava starch as substrates,determination of freshness indicator card Scanning electron microscope,thickness and mechanical properties,specificity,stability,etc..The results showed that the freshness index cards prepared on the polyvinyl alcohol substrate had better mechanical properties than those prepared on the chitosan substrate,when the concentration of the freshness indicator card was 0.2%,the color of the polyvinyl alcohol indicator card was most obvious in trimethylamine solution.The color of the freshness indicator card changed from black-red to red and finally to orange.(3)The changes of meat samples and freshness indicator cards with storage time were observed at 4℃.Sheep and pork longissimus dorsi muscle were stored for 0,1,3,5,7,9 and 11 days.Storage of chicken breast for 0,1,2,3,5,7 days.processing on the same day,every day out random 4 samples to test and use camera photograph specimens and freshness indicator CARDS every day,and specimens are measured pH value,the total number of colonies content,volatile base nitrogen content freshness indicator card ΔE value,trimethylamine content in the box,and observe freshness indicator card color changes,and establish the model.The results showed that the Δ E value of freshness indicator card had a higher determining coefficient with the storage period.