猪肉剩余货架期快速预测电化学设备的设计与试验

Design and experiment of electrochemical device for quickly predicting remaining shelf life on fresh pork

针对生鲜猪肉等短货架期食品对微生物快速检测的巨大需求,该研究依据微生物呼吸作用的电子传递规律,采用原电池的工作原理,结合构建的微生物生长预测模型（4～30℃）决定系数R2为0.9954以上,试制了操作简单、方便快捷的生鲜猪肉剩余货架期的电化学预测设备,并采用Labview编程语言开发了信号采集和数据分析软件。结果表明该设备检测时间为20 min,可预测4～30℃范围内生鲜肉的剩余货架期,预测准确度为1.02～1.06,研究结果为采用电化学方法预测食品中微生物含量及其货架期提供理论参考。

Fresh pork is popular due to its nutrient and good taste, and also one of the most important meat consumed. As the remaining shelf life is short, it is important for producers and retailers to evaluate the freshness and remaining shelf life of fresh pork under the storage temperature. Rapid detection on bacteria of fresh pork is required urgently. The rapid and accurate electrochemical detection are getting more and more concern. The purpose of this paper was to design and develop the device for predicting the remaining shelf life of fresh pork, which was combined with the prediction model of microbial growth and based on the electron transfer of microbial respiration and the principles of primary battery. And the signal acquisition and data analysis software of the device was developed with LabV IEW programming language. The dynamic growth model of total aerobic count was established and verified. The results indicated that the modified Gompertz model could well describe the growth of total aerobic count in fresh pork, and the coefficient of determination was 0.9954.The regression of Belehradek model finely described the effect of temperature on the maximum specific growth rate and the lag phase. The validation of the built model was carried out by comparing the actual and predicted growth curves of total aerobic count in fresh pork at 10 and 22 ℃, respectively. By calculating bias factor and accuracy factor, we found that the established model had high reliability and could predict the growth of total aerobic count in fresh pork in the range of temperature from 4 to 30 ℃ effectively. The electrode was constructed from platinum anode and cathode, and a proton exchange membrane filter was used for retaining the microbes and balancing the charge. The procedure of electrochemical signal from total aerobic count in fresh pork included 3 parts. Electron generated from oxidation of substrate was transmitted to the extracellular space by cytochrome C on cell membrane, then the electrochemical signal was amplified by electron shuttles from the exogenous, and finally it was delivered to Pt electrode. Samples containing microbes were attached to the surface of a platinum anode. The electrode was immersed in phosphate buffer solution（50 mmol/L, pH value of 7.0） containing a redox dye（2,4-dichlorophenolindophenol）, and the voltage generated was measured. The software combined with the established growth model of total aerobic count was developed by LabV IEW for predicting the remaining shelf life of fresh pork. The response time of the electrochemical device was 20 min, and the voltage generated was proportional to total aerobic count above 10^4 CFU/g. The accuracy factor of predicting the remaining shelf life of fresh pork was between 1.02 and 1.06. The accuracy factor at 10 and 22 ℃ was 1.04 and 1.03, respectively. But the sensitivity and accuracy of the predicted remaining shelf life between 10^4 and 10^5 CFU/g needed further improvement. As this study only focuses on one part of pork, to achieve an accurate prediction of any part of fresh pork sample, the parameters of device and the prediction models should be adjusted with more varieties of fresh pork portion.