Preparation of Intelligent Indicator Label and Its Application in Beef Freshness Monitoring
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Graphical Abstract
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Abstract
Xinjiang beef has high quality and is one of the famous livestock products resources in Xinjiang. In order to achieve the real-time monitoring of beef freshness, hydrogels were prepared by physical freeze-thaw method using carboxymethyl cellulose and polyvinyl alcohol as raw materials. The physical characteristics of hydrogels were also characterized. Furthermore, an intelligent indicator label was made using Perilla leaf pigment extract as the optimum color pigment, and its intelligent indication effect on the freshness of Xinjiang beef during cold storage was studied. The result showed that the optimum ratio of polyvinyl alcohol to carboxymethyl cellulose was 4:3, and the hydrogel prepared by three freeze-thaw cycles had good water absorption ability(2937.39%), pigment inclusion rate(24.62%), porosity(97.71%), hardness, elasticity, glue viscosity and loose porous network microstructure. The color difference value(ΔE) of indicator label on the second day was 10.2, and which was 26.5 on 18th day. This color change was larger than the threshold of color difference discerned by human eyes(ΔE=3.5). Correlation analysis showed that the ΔE values of indicating label were significantly correlated with pH and volatile base nitrogen contents of beef(P<0.01), which indicated that the intelligent indicating label could accurately and sensitively indicate the changes of freshness of Xinjiang beef during cold storage.
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