Research On Biophysical Methods For Monitoring Duck Egg Inner Quality During Salting Process

Dielectric property of biomaterial is the corresponding reaction of the charge of biologymolecular to the external electric field. Studying the dielectric properties of agriculture andfood products are in favor of quantitative analyses, evaluates and monitors their quality. Theadvantage of this method is that it doesn’t necessarily damage the material during test, andwith it an automation test process could be achieved easily. Salted duck egg with a specialtaste is a very popular food all over the world. Disadvantages of its quality detect method, aslow detection efficiency and accuracy, couldn’t meet the scale production requirements.Currently, no studies have been reported based on dielectric properties ofNon-destructive testing (NDT) for the quality of salted egg and its salting process at homeand abroad. In view of this, primary study based on dielectric properties of NDT for thequality of salted egg and its salting process was carried on in this research. We established theexperimental system which can determine the dielectric property of commercially-salted eggsand fresh duck eggs through HIOKI-3532-50-LCR instrument. There was very significantdifference between the relative dielectric constant of fresh duck eggs and that of salted duckeggs. Further more, dielectric properties that of the whole egg during salting process werealso determined and discussed. Relative dielectric constant was considered preliminarily to bea dielectric index for duck eggs in salting process.The main results of this research were as follows:1. Within the entire test frequency range (500Hz~5000000Hz), the dielectric parameters(include relative dielectric constant ε′r, loss coefficient D, complex impedance Z) and testingfrequency were significantly (P<0.05) or highly significantly (P<0.01) correlated both infresh duck eggs and commercially-salted eggs. With analysis of fresh duck eggs and thesalted eggs, relative dielectric constant ε′rand loss coefficient D fluctuate with frequencyincrease.2. There was highly significant difference between the relative dielectric constant ε′roffresh duck eggs and that of salted duck eggs, and the fresh duck egg and salted egg could bedistinguished by ε′r; whereas the loss coefficient D of the two kinds showed no significantdifference, and because of the relative error of complex impedance Z is too large it couldn’tbe used to distinguish form the two test materials.3. During salting process of the duck eggs, the yolk index and ε′rof the eggs weresignificantly correlated (P<0.01) in the early days (0~15d); and there was no significantlydifference of yolk index after15d. Since then, the changes of ε′rbecame very complex. The reason for this phenomenon might be the oil-off from the yolk led the decline of ε′r.4. The relative dielectric constant ε′rfluctuate over time during the salting process. Withthe test frequency (200kHz~2MHz), we could confirm the time27d, which was the secondturn of the relative dielectric constant ε′rthat changed over time in this experiment, to be theend point of the salting process in this experimental environment condition.