Electric Parameters In Low Frequency And Other Physical Parameters Characterise The Quality Of Milk

The experiment was to study the dielectric characteristics, mechanicalcharacteristics and the biological rheological properties of local milk and paging milk. Theparameters of dielectric characteristics include impedance Z, loss factors D, conductance G,resistance R, and capacitance C. And the mechanics parameter was surface tension, rheologicalproperties parameter was viscosity coefficient. In order to searcher the best physicalparameters, for providing biophysics measurement theory of milk (dairy). The conclusions wereas follow:1. There is a close relationship between electrical parameters and frequencychosen in the experiment. In lower frequency range, the electrical parameters undulatedsevere, not stable, but the change in value is clearly; when the frequency increased, the resultsof experiment were more stable, while the rangeability of value also became smaller, andwhen the frequency increased to a certain value, the loss factor D can’t be detected.2. When all the electrical parameters changed versus the temperature, they wereinfluenced by the test frequency. In the test frequency, impedance Z, resistance R increasedwhen temperature rise, conductance G increases when temperature rise; when f <10KHz,theloss factor D decreased when temperature rise,1MHz≥f＞10KHz, it can’t be measured;when f <1KHz, the value of Capacitance C was not stable, when the temperature was30℃,the value was minimum,20℃was maximum, but when f>1KHz, it increased versustemperature rise.3. When milk was placed until it was decayed at (40±1)℃, the change ofelectric parameters, surface tension and viscosity coefficient were different. Testing frequencyrange was1KHz≤f≤10KHz. when f=1KHz,2.5KHz and5KHz, impedance Z, the lossfactor D and resistance R kept decreased trend with time, conductivity G kept increased trendwith time, while the change of capacitance C was not normal rules; and surface tension isfluctuated, and the difference of surface tension of milk before and after decayed was notsignificant; Viscosity coefficient was While the viscosity coefficient of pure milk keepsalmost constantly during0–11h, after11h it increased sharply. 4. Added different amount of distilled water to milk at room temperature, and thendetected the parameters. The testing frequency range was1KHz≤f＜7.5KHz, and allparameters had significantly changes. When f=1KHz，2.5KHz，5KHz, there were goodliner relationship between electrical parameters and added water respectively, except thecorrelation coefficient of capacitance C was0.862, the rest electrical parameters were morethan0.9. And the correlation coefficient of surface tension and viscosity coefficient and addedwater were0.944and0.955.5. when testing a variety of different brands packaging milk, The testingfrequency range was1KHz≤f＜10KHz, resistance R had best discrimination, in the testingfrequency range,the value of these milk’s resistance had significant difference. conductivityG and impedance Z were taken second place, and the discrimination of capacitance C andviscosity coefficient were the worst, and in the testing frequency range, there were linearrelationship between the loss factor D and the frequency, their correlation coefficient were allmore than0.9.