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| Preparation and Application of Indicator Labels for Identification of Pork Freshness |
| DU Yuehong, WANG Lin, GAO Xiaoguang, SUN Zhiwei, BAI Yingying, ZHAO Xi |
| 1.College of Bioscience and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China; 2.College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, China |
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Abstract Methylcellulose and polyethylene glycol-6000 were used as film-forming substrates, and synthetic dyes were added to prepare six easy-to-use indicator labels (FIL) for pork freshness assessment based on the fact that the color of indicator labels will change when absorbing the volatile ammonia released from pork during spoilage. When used for the detection of NH3, all color labels exhibited significant color changes showing obvious differences with the increase of gas concentration. To explore their feasibility for evaluating the freshness of pork stored at 4 ℃, the color changes of these labels were recorded and various spoilage indicators were measured at different storage times. The results also showed that the FIL made with bromocresol purple (at an initial pH of 4.24) was able to discriminate freshness, medium freshness, and spoilage. The statistical models obtained by partial least squares based on the color changes of labels 3 and 4 successfully predicted total volatile basic nitrogen (TVB-N) contents and aerobic plate counts (APC) of pork with regression coefficients (R2) greater than 0.92. Accordingly, pork freshness could be judged by the color changes of the labels.
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2020, Vol. 34 
