The Preparation Of Natural Composite Films And Indicator Label Of Freshness And Their Application In Chicken Meat

Nowadays,food packaging was mainly synthetic plastic based on petroleum,but it was difficult to degrade in nature.Therefore,the green,sustainable and edible packaging materials received widespread attentions.The raw materials of edible packaging were protein,polysaccharides,lipids and their composite.Among them,polysaccharides could be used to carry active ingredients due to their wide sources and low price.However,owing to its strong hydrophilicity,its utilization rate and range in meat showed a downtrend.Therefore,how to improve the hydrophilicity of polysaccharide films or coatings was a key issue to be solved urgently in meat industry.In addition,the traditional methods for detecting the freshness of meat had the disadvantages of time-consuming,high cost and destructive.The active smart indicator film containing anthocyanins and curcumin could indicate the freshness of meat by detecting changes in the environment inside the packaging.Therefore,this study used konjac glucomannan(KGM)and carrageenan(Kappa-carrageenan,KC)as the raw materials of packaging film to explore the effect of camellia oil on the properties of konjac glucomannan-carrageenan film firstly,and secondly,the film-forming emulsion was used for extending the shelf-life and maintaining the quality of chicken meat.On this basis,a smart packaging material based on anthocyanins and curcumin was developed and used to indicate the freshness of chicken meat.The main research contents were as follows:(1)Emulsified blend film based on konjac glucomannan/carrageenan/ camellia oil:Physical,structural,and water barrier propertiesThe objective of this study was to develop a new hydrophobic film based on konjac glucomannan and kappa-carrageenan(KGM/KC)incorporating camellia oil(CO)(2,4,and6 %).CO was directly emulsified as a dispersed phase into KGM/KC matrix.The physical,structural,and water barrier properties of the film were studied.The results of Fourier Transform Infrared and Scanning Electron Microscopy suggested that CO was successfully distributed in KGM/KC matrix by emulsification.Contact angle of the film indicated that addition of CO increased the hydrophobicity and water-resistance properties of film,which corresponding to the moisture content,total soluble mass,water vapor permeability,water vapor adsorption kinetics and water vapor adsorption isotherms.Addition of CO by emulsification improved thermal stability of film,optical properties,and mechanical properties.In conclusion,the incorporation of CO by emulsification is an effective and promising pathway to improve the properties of polysaccharide-based film.(2)Effect of konjac glucomannan/carrageenan-based edible emulsion coatings withcamellia oil on quality and shelf-life of chicken meatThe quality and safety of chicken meat tend to deteriorate due to bacteria reproduction and oxidation reaction.In the present study,the antimicrobial and antioxidant effects of KGM/KC coatings incorporated CO were confirmed in extending the shelf-life of chicken meat.The quality,chemical and microbiological properties of coated and control samples were determined.The result showed that the KGM/KC-CO coating significantly(P < 0.05)decreased weight loss,pH,thiobarbituric acid reactive substance(TBARS),total volatile nitrogen(TVN)and microbial counts when compared to uncoated samples.The obtained results revealed that KGM/KC-based coating incorporated with CO significantly extended the shelf-life of chicken meat by restraining the oxidation of lipid and protein,and retarding the microbial growth.The shelf-life of chicken meat was extended up to 10 days using KGM/KC-based coating containing 3.5% CO at refrigeration(4 ?)compared to control samples.These results indicated CO could be used as an active agent to be dispersed in KGM/KC matrix by emulsification method,and the prepared emulsion coating had positive effects on extending the shelf-life of chicken meat.(3)pH-responsive double-layer indicator films based on konjac glucomannan/camelliaoil and carrageenan/anthocyanin/curcumin for monitoring meat freshnessDouble-layer indicator film(DIF,the indicator layer made of carrageenan(CAR),curcumin(CUR)and/or anthocyanin(ATH),and the emulsified layer(named KC layer)made of konjac glucomannan(KGM)and camellia oil.)was manufactured to monitor the chicken meat freshness in this study.The three kinds of DIFs(CAR-ATH-KC,CAR-ATHCUR-KC and CAR-CUR-KC)were tested.The results of FTIR demonstrated that different components were bound together by hydrogen bond.The double-layer structure films were clearly observed by SEM images.The presence of KC layer significantly improved the thermal stability,water-and UV-resistance performance,and mechanical properties of the indicator layer.Furthermore,Visual observation indicated that the CAR-ATH-KC and CARATH-CUR-KC labels used to monitor the chicken meat freshness at 25 °C presented the more obvious color change than the CAR-CUR-KC label.