Preparation,Properties And Indication Of The Membrane Based On Natural Composite Dye Freshness Its Application Research In Cod

With the increasing awareness of food safety,consumers hope to understand the quality of the food they buy in a more efficient and intuitive way.Thus comes the food freshness indicator packaging that can provide people with food quality information during the process of food transportation and storage.Considering the safety of food,more and more researchers are starting to use natural pigments extracted from plants as indicators.From the micro and macro perspectives,we selected the better anthocyanins,and prepared a composite dye freshness indicator film based on curcumin and anthocyanins,biodegradable materials soybean separation protein and chitosan as the base film material.While ensuring food safety,it improves the relevant properties of the indicator film and realizes the reasonable application in cod.The main research contents are described as follows:(1)Determine the total anthocyanins content and composition of anthocyanins extracted from black rice,black bean,black barbary wolfberry,purple potato,purple cabbage and flower;analyze and compare the properties of anthocyanins.The order of total anthocyanins content from high to low is: roselle > black barbary wolfberry> black rice> black beans> purple purple potato> purple cabbage.Lorshen flower anthocyanins showed the highest DPPH radical clearance.The stability of purple potato and anthocyanins of purple cabbage and purple cabbage is also the best,with obvious color changes at different pH values.(2)Six single anthocyanin indicator membranes were prepared and the relevant properties were determined.The addition of the six anthocyanins did not cause an interaction between the substances with the base membrane material.All the four indicator membrane manifestations,except the purple potato and purple cabbage indicator membrane,showed folds and rough cross sections,and the mechanical properties of the indicator membrane were also low.However,the water resistance properties of the indicator membrane was improved with the addition of anthocyanins.The color response of roselle indicator membrane in different pH solutions and ammonia has the best sensitivity,and the color change is obvious.Roselle in is selected as the dye to prepare natural composite dye indicator membrane.(3)Prepare the freshness indicator film based on natural composite dye and determine its related properties.The ratio of curcumin and roselle anthocyanins of 1:3 and 1:5 is excellent.The addition of curcumin can improve the moisture resistance of the membrane,and the composite dye indicator membrane has good antioxidant capacity.With the increase of anthocyanin content,the initial color of the indicator membrane deepens red,the yellow becomes lighter,and the transparency decreases.The ammonia sensitivity of the indicator membrane was positively correlated with the amount of anthocyanin added,and the indicator membrane with a composite dye ratio of 1:5 had the best sensitivity,and the indicator effect was obvious.(4)According to the freshness,physical and chemical index of cod samples,it is determined that cod samples belong to fresh fish from 1 to 2 d,3 d is second fresh,and fish from 4 to 6 d is not easy to eat.Among them,the composite dye ratio of 1:5 indicator film color changes significantly,from the beginning of red to green,and the color difference value changes the most,the indicator effect is better.Correlation analysis shows that Δ E values are closely related to the four physicochemical indicators.It can be explained that...