Research And Production Of Indicator Labels For Shrimp Freshness Monitoring Based On Natural Pigments

In recent years,with the advancement of science and technology and the change of consumer concepts,food smart packaging has played an increasingly important role in food quality and safety.The food freshness indicator smart packaging interacts with the volatile gas generated by food spoilage through the p H indicator material,and a specific color change occurs,thereby feeding back food quality information to consumers.Consumers are increasingly demanding natural food colorings,such as carotenoids,betaines,anthocyanins and chlorophylls,to replace synthetic colorings.Therefore,smart packaging based on natural colorants and biopolymers has become the latest technology in the field of food packaging.In this paper,the freshness intelligent indicator label was prepared by using the three natural pigments of mulberry anthocyanin,alizarin and curcumin in combination with bacterial cellulose membrane.The difference in structure and physical and chemical properties of different indicator labels was compared and used for the freshness of shrimp.Degree detection.The main research conclusions are as follows:1.Comparative study on the color stability of different natural pigmentsIn this experiment,mulberry anthocyanins,alizarin,curcumin and beet red pigment were used as raw materials to investigate their color response under different p H values,and to explore the effects of temperature and light on the stability of pigment,so as to select better natural pigments as p H sensitive indicators for the preparation of freshness indicator labels.The results showed that mulberry anthocyanin,alizarin and curcumin could be completely distinguished under weak acidic,neutral and alkaline p H values,while beet red pigment had no obvious color change,so it was not suitable for p H sensitive infectious material as indicator label;the influence of different light on the stability of pigment was acceptable;when the temperature was above 60?,the stability of pigment decreased and it was easy to degrade,but it was not suitable for practical use The upper limit of temperature is low,and the actual temperature is lower than 60?.Therefore,mulberry anthocyanins,alizarin and curcumin have the potential to be used as p H sensitive infectious materials for intelligent freshness indicator labels.2.Preparation and performance of freshness indicator labelsThis chapter uses bacterial cellulose membrane as a solid carrier,and mulberry anthocyanin,curcumin,and alizarin as p H-sensitive dyes.The freshness intelligent indicator labels are prepared according to the low,medium,and high pigment concentrations respectively,and they are compared.Differences in physical and chemical indicators and structural forms.The results showed that the indicator labels prepared by the three pigments had visible color changes under different p H;the natural pigments were successfully compounded and formed new interactions with the membrane;as the concentration of the embedded pigments increased,the indicator The thermal stability of the label is improved,but the crystallinity is reduced;the addition of natural pigments has a certain impact on the mechanical properties of the bacterial cellulose membrane;the indicator label has good stability at 4?;the medium concentration of pigment is prepared The indicator labels all showed high ammonia sensitivity.3.Study on the Application of Indicating Labels in the Freshness Detection of ShrimpIn this part of the experiment,the total volatile base nitrogen value,p H value,total number of colonies,and thiobarbituric acid value changes during the spoilage of shrimp under refrigeration at 4°C were measured to comprehensively evaluate the freshness of shrimp,and prepare instructions The label is applied to the freshness detection of shrimp,and its application potential is investigated.The results showed that when the shrimp was stored at 4?to the 4th day,the TVB-N value,TVC value,TBA value and p H value of the shrimp reached 25.89 mg/100 g,6.58 lg CFU/g,1.06 mg/100 g,respectively.And 7.48,the spoilage threshold was reached.The color change of the MA-BC-2 label prepared by mulberry anthocyanin corresponds to the freshness status of the shrimp.It was red on the 0th day,and the sample was medium fresh on the 2nd day.Turns to light pink,the sample is corrupted on the 4th d,the label becomes purple,and the change in the color difference of the label is significantly positively correlated with the production of volatile compounds.R~2=0.9645.Therefore,the MA-BC-2 indicator label can be used The p H sensitive indicator in the smart package can detect the freshness of shrimp in real time.