Water-injected Meat Identification Method Research Based On Bio-impedance Spectroscopy Measurement

Water-injected meat(WIM),the fresh meat which is injected with water to exaggerate weight for increasing profit,has become a serious damage to the public food safely.Traditional qualitative WIM recognition metheds like sensory evaluation and test paper method has low coarse accuracy,while the quantitative analysis methods like drying method and near-infrared spectroscopy method can't be used on the spot of the slaughter,shipping and exchanging fields.Fast WIM recognition has been a difficult problem to be solved.Starting from the conductivity difference between WIM and normal fresh meat,this thesis proposes a new fast WIM identification method based on bioimpedance Spectroscopy(BIS)measurement.The main researches include:1.Through the simulation and experiment,it is found that AD8130 current source is one of the most suitable circuit for BIS measurement by analyzing the output current and output impedance characteristics of different current source circuits.Its operating frequency is from 100Hz to 10MHz,and output impedance is 665k at 1MHz.This current source meet the requirements of general BIS measurement,and part of the high frequency measurement.2.A set of BIS measuring instrument is designed based on FPGA with dual channel synchronous sampling,including NIOS ? core design,U disk data storage,OLED display,key and software process design.Self-made BIS measurement instrument is calibrated by using the standard impedance instrument.3.Design a seven-needle electrode for WIM identification.Incentive electrode is on the center position,and response electrodes are on the circumference.Electrode length is 1cm.It is proved that the electrode repeated measurement is stable through the experiements.4.The BIS of three kinds of meat are measured before and after water injected by using self-made BIS measurement instrument.30 samples are set as the training sample,and other 30 samples of fresh meat mixed with WIM as the test sample.Finally we obtained Mahalanobis distance of the two training samples respectively.Recognition rate of Pork,beef and mutton are 90%,93%,100%.In this thesis,the BIS technology was applied in WIM recognition,a measuring instrument and its specialized electrode were developed,and fast WIM recognition was achieved by using the method of Mahalanobis distance.The results proved the feasibility of WIM recognition based on the BIS technology,and laied the theoratical and practical foundation for the development of specialized detecting instrument.