| Aquatic products will be decomposed by microorganisms in the storage process and produce biogenic amines,which will affect the taste and quality and further change from freshness to spoilage.Rotten meat will cause health hazards,so it is particularly important to test the freshness of aquatic products.However,traditional methods for testing the freshness of aquatic products are time-consuming and cannot be tested in real time,which affects people’s judgment.Colorimetry intelligent indicator label detection is a simple,quick and reliable method to solve the above problems.People can judge the freshness of aquatic products by naked eyes according to the color change of the label.This is mainly because the indicator in the label reacts with the alkaline gas produced in the storage process of aquatic products to show different color changes.In this study,indicator labels with strong storage stability and high detection sensitivity were developed by electrospinning and co-pigmentation method,in which polyacrylonitrile(PAN)was the polymer,blueberry anthocyanin(BA)and phenolic acid were the indicators.At the same time,because of the different detection effects of different phenolic acids and anthocyanins on different volatile base nitrogen,two different fiber membranes were developed to detect the freshness of fish and shrimp.(1)To study the response effect of phenolic acid and anthocyanin to alkaline substances.By studying the co-pigmentation effect of gallic acid(GA),vanillic acid(VA),p-hydroxybenzoic acid(PHBA),ferulic acid(FA)and caffeic acid(CA)on BA in solution,and the response of phenolic acids and BA nanofiber membranes to basic gases(ammonia,dimethylamine,trimethylamine and triethylamine).CA-BA was sensitive to ammonia,GA-BA was sensitive to dimethylamine and trimethylamine based on the color difference before and after the reaction.(2)Optimize the conditions according to the parameters of electrospinning and the concentration of spinning solution.The conditions of electrospinning were explored from voltage,flow rate and distance,and the best conditions were optimized as voltage16 k V,flow rate 1.0 m L/h and receiving distance 23 cm,taking the state of the membrane as the index.Then,the influence of the mass ratio of PAN and BA on the performance of the nanofiber membrane was explored.With the diameter,the detection indexes were response to ammonia and color stability,the optimal response of PANBA nanofilms was optimized to be 10 %(w/w).(3)PAN-BA-CA electrospinning nanofiber membranes were prepared and ammonia gas was used as index to further detect the freshness of fish.With PAN as the carrier,BA as the indicator and CA as the co-pigment,the volatile ammonia sensitive food freshness indicator film was prepared.The influence of different ratios of BA and CA on the color of the indicator film was studied.With the response of nanomaterials to volatile amine as the indicator,intelligent packaging labels suitable for real-time detection of freshness of fish products during storage were developed.It was found that the color of the membrane could well reflect the freshness of the carp,and could clearly distinguish the fresh(pink),sub-fresh(gray pink)and spoilage(purple)stage of the fish.(4)PAN-BA-GA electrospinning nanofiber membranes were prepared.Dimethylamine and trimethylamine were used as indexes to monitor shrimp freshness in real time.With PAN as the carrier,BA as the indicator and GA as the co-pigment,a fresh indicator film sensitive to dimethylamine and trimethylamine was prepared.The influence of the ratio of BA and GA on the color of two alkaline gas indicator films was studied.The response of nanofilms to dimethylamine and trimethylamine ammonia as the index was used to develop intelligent packaging labels suitable for real-time detection of shrimp freshness during storage.During the fresh,sub-fresh,and spoilage stages of the shrimp,the color of the indicator membrane varies from pink to purple to yellow. |
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