| Food packaging plays an important role in the field of food safety.However,due to the single function of ordinary food packaging,it has been unable to meet the needs of consumers for food safety.Therefore,the development of intelligent and active food packaging has become a research hotspot.On the one hand,the active ingredients in intelligent active packaging can change the internal environment of food packaging;On the other hand,it can monitor and reflect the changes of the internal environment of food packaging,so as to feed back the food quality information to consumers.In addition,more and more new food packaging materials have entered people's vision.Chitosan and cellulose sodium sulfate as a natural polymer materials in food,medicine,chemical industry and other fields is widely studied,their sources,biodegradability,and can be used as a substitute for traditional plastic material such as polyethylene,in line with the green environmental protection concept of society,and have unique biological properties such as biocompatibility and antibacterial.In this study,chitosan and sodium cellulosic sulfate were used as film-forming materials,and curcumin,naringin and grape seed proanthocyanidin were used as functional active additives to prepare food packaging composite film with freshness preservation and freshness indicator functions.The application of composite film in freshness preservation and freshness indicator of pork was investigated.The main research contents are as follows:1.Preparation and characterization of chitosan/sodium cellulose sulfate composite film with different charge ratios.Five groups of chitosan and cellulose sodium sulfate with different charge ratios were used as film substrates to prepare chitosan/cellulose sodium sulfate composite films.FTIR showed that chitosan and cellulose sodium sulfate were compatible,and the polyelectrolyte complex was formed by electrostatic bonding between them.The formation of polyelectrolyte complex had a positive effect on the tensile strength of the composite films.When the charge ratio of cellulose sodium sulfate and chitosan was the same,the electrostatic force was the largest.The tensile strength of CH/Na CS2:2 was the highest(8.17MPa),which was significantly higher than that of single component films(P<0.05).Its water content is the lowest,which is 16.68%.2.Preparation and characterization of p H-responsive composite films with different additives.Three natural extracts,curcumin,grape seed proanthocyanidin and naringin,were used as functional active additives,and chitosan and cellulose sodium sulfate were used as film substrates to prepare p H-responsive composite films.The antibacterial properties of the three additive materials were determined,and it was found that they all had a certain antibacterial effect.FTIR showed that the three additive materials were compatible with the film forming substrate.The p H responsiveness of three kinds of composite film with p H response was measured by using phosphoric acid buffer solution with different p H values.The results showed that the composite film loaded with curcumin had the best p H responsiveness.The addition of curcumin had the best effect on improving the barrier ability of the composite film,and the WVP was 8.61×10-11gm-1s-1Pa-1,which was significantly lower than that of other composite films(P<0.05).The tensile strength was 10.99MPa,which was significantly higher than the blank film(P<0.05).Its water content and water solubility were the lowest,14.23%and26.01%,respectively.3.Intelligent and active food packaging composite film is used to keep fresh pork and monitor its freshness.Chitosan/cellulose sodium sulfate composite film loaded with curcumin was used as intelligent active food packaging film for fresh pork preservation at 4?.The results of TVB-N analysis showed that the pork in the composite film group deteriorated on the 6th day,while the pork in the blank group deteriorated on the 2nd day,which indicated that the composite film delayed the spoilage of pork by 4 days.The results showed that the composite film had a good antibacterial effect,and the total number of bacteria was significantly lower than that of other groups(P<0.05).The results of lipid peroxidation value showed that the composite film had the ability to inhibit the oxidative rancidity of pork lipids.From fresh pork to spoiled pork,the?E of the composite film changed significantly(P<0.05),the color changed from orange to khaki,and the visibility changed.The results showed that the chitosan/cellulose sodium sulfate composite film loaded with curcumin could be used for the preservation of pork and the monitoring of pork freshness.The results of this study could provide a basis for the further research of intelligent and active food packaging. |
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