Development And Application Of Meat Freshness Indicative Packaging Film

Meat is rich in protein.However,it is very susceptible to spoilage due to the influence of endogenous enzymes and external microorganisms during storage and transportation.Therefore,real-time monitoring of the freshness of meat is a great way to improve food safety and reduce food waste.This thesis uses Meldrum’s activated furan（MAF）and grape skin anthocyanidins（GSAs）as meat freshness indicators,and polyvinyl chloride（PVC）,polyvinyl alcohol（PVA）and/or starch as membrane support materials,to develop freshness-indicative intelligent packaging film for monitoring the freshness of fish and pork.The main contents of this thesis include:（1）Using MAF as volatile amine-sensitive material and PVC as the supporting film,MAF/PVC films were prepared by spin coating method,and the sensing properties of the films were investigated with NH₃ as the model target.Results showed that the film prepared with 15%mass content of MAF and 2000 r/min of coating speed reveals the best sensing property towards NH₃.Using MAF/PVC film as the freshness indicator for fish,the lightness（L）,redness（a）and yellowness（b）values of films were recorded.Calculations results of the color difference value（ΔE）was according to the L,a,b of the MAF/PVC films.At the same time,the TVB-N contents of fish samples were determined.Results showed that the change trend of theΔE value of the MAF/PVC film have a good correlation with the TVB-N content of the sample.Therefore,the freshness indicator based on MAF/PVC film could accurately and rapidly indicate the freshness of fish,thus showing a broad application prospect in the detection of freshness of aquatic products.（2）Colorimetric sensing films were developed by using PVA and starch as the degradable film substrate to immobilize GSAs and MIL-101 crystals for visual monitoring of pork spoilage.The color changes and UV-vis spectrum of GSAs in the p H range of 2-12 were studied.The Scanning electron microscopy（SEM）images and Fourier transform infrared（FTIR）spectra indicated the successful fabrication of colorimetric sensing films.Nitrogen adsorption experiments showed that the introduction of MIL-101 significantly increases the BET surface area of the films.The colorimetric sensing films are exposed to ammonia and the results shows that the addition of MIL-101 significantly improves the sensitivity of the detection.The film showed visible changes from purple-rad to gray-green when employed to monitor the freshness of pork stored at 25?°C and 4?°C.The good agreement of our results with the TVB-N content of the sample indicated that the colorimetric film can be used as non-destructive and real-time detection of pork freshness.