Functionalization Of Nano-melanin From Cuttlefish Ink And Application In Food Quality Control

Food preservation plays an important role in food quality control.In the process of food preservation,it is not only necessary for proper food packaging to ensure the safety and quality of food,but also very important to determine the change of some ingredients in food to judge whether the quality of food has changed.In recent years,nanotechnology has developed rapidly in the field of food preservation.Natural Melanin is a polyphenol substance with distinct physical,chemical,and biological properties.It has the potential to be a natural nanomaterial.Cuttlefish ink,which has a long medicinal history,is an important source of natural nano-melanin derived from food.Natural nano-melanin extracted from cuttlefish ink has a high concentration of functional groups and metal chelating sites on its surface,making it useful in the biomedical field.However,there are few reports on the use of natural nano-melanin in the food industry.On this basis,we extracted natural nano-melanin from cuttlefish ink and functionalized them with metal ions.Firstly,the enzyme-like catalytic activity of different metal ions functionalized cuttlefish ink nano-melanin was studied.In addition,the possibility of application of functionalized cuttlefish ink nano-melanin in food packaging and food quality analysis was explored.The main results are as follows:（1）A photothermal antibacterial food packaging film based on cuttlefish ink nano-melanin:The nano-melanin（NMPs）was first obtained from cuttlefish ink using a simple differential centrifugation method.Then,different concentrations of NMPs were added into pectin（PC）matrix to prepare the NMPs photothermal film（PC/NMPs）,and the photothermal performance,physical properties and antibacterial properties of the composite film were evaluated.The results showed that with the increase of the content of NMPs,the photothermal conversion performance and thermal stability of NMPs-based composite film were increased,and the tensile strength and elongation at break increased first and then decreased.The addition of NMPs gave PC/NMPs composite film excellent UV-blocking property.Furthermore,the successful addition of NMPs conferred the PC/NMPs composite film with antibacterial activity.The pectin film containing NMPs had strong antibacterial property against Listeria monocytogenes.Finally,PC/NMPs composite film was applied to the preservation of beef.The results showed that the composite film could effectively reduce the growth of microorganisms in the beef during storage.（2）Antioxidant packaging film based on Cu²⁺functionalized nano-melanin SOD-like activity of cuttlefish ink:The NMPs was functionalized with Cu²⁺（Cu-NMPs）to have superoxide dismutase（SOD）-like activity,and the NMPs was mixed with carrageenan（Carr）to prepare a fresh-keeping composite packaging film（Carr/Cu-NMPs）.The SOD-like enzyme activity and CAT-like enzyme activity of Cu-NMPs were thoroughly evaluated,as were the physical properties of the composite film.The results showed that when Cu-NMP reached 10μg m L^-1,the removal rate of·O₂^-could reach more than 80%,and the rate of dissolved oxygen production was greatly increased.Furthermore,the addition of Cu-NMPs increased the hydrophobicity and ultraviolet shielding property of the composite film while decreasing the elongation at break.Finally,Carr/Cu-NMPs composite film was applied to preserve cherry tomatoes.The results showed that the composite film could effectively reduce the weight loss of cherry tomatoes and delay the changes in p H and hardness.（3）Detection of total antioxidation ability of foods based on Fe³⁺functionalized NMPs POD-like activity in cuttlefish ink:In order to monitor the quality changes of food during the preservation process,we further developed the total antioxidant capacity（TAC）detection technology using Fe-functionalized nano-melanin（Fe-NMPs）.The results were as follows:Fe-NMPs was synthesized using the simplest stirring method.Fe-NMPs exhibited peroxidase（POD）-like catalytic activity with a Km of 0.376 m M and a Vmax of 10.1×10^-8M s^-1 after Fe functionalization.Compared with the natural horseradish peroxidase（HRP）,the enzyme catalytic activity of Fe-NMPs is higher.The resulting Fe-NMPs exhibited excellent performance in the detection of TAC in foods.The linear concentration range was 5-250μM,with a detection limit（LOD）of 12.61μM.When Fe-NMPs was used to determine the TAC of fruits and beverages,the results were similar to the ingredient list.In this work,the cuttlefish ink NMPs was functionalized and successfully applied to food quality control,which laid a theoretical foundation and provided a scientific basis for the application of natural nanoparticles in the field of food.