Study On The Eggs' Dielectric Properties

Eggs'quality relates closely with its commodity levels, market competitiveness and economic benefits. Although some research has been conducted on this topic, the outcome is still far away from commercial application. If egg's classfication by freshness&size and pricing by quality being realised, it not only protects the interests of consumers, but also asist the producers and operators in scientific management. Therefore, the research on the quality of eggs has its real value and practical significance.In this paper the study was conducted on two aspects: First, frequency-dependence of non-destructive eggs'dielectric parameters; correlativity between the fresh eggs'dielectric parameters and internal quality during storage. Second, frequency-dependence of the fresh yolks and albumen; correlation between quality indicators and dielectric constant during storage as well as loss factor; and penetration depth of the yolk and albumen at the frequencies commonly used in food industry. Gains the following conclusions:1)Frequency have little influence on the relative dielectric constantεr' of the intact fresh eggs from 300kHz to 1MHz. Equivalent impedance Z decreases with increasing frequency from 100k to 1MHz and drops faster at low-frequency.2)A significant correlation exists between the relative dielectric constantεr' of the intact fresh eggs and Hough units and the yolk index(p<0.05), and there are no significant correlation between the relative dielectric constantεr' and the storage time(p>0.05).3)At room temperature of 25℃and the frequency of 10MHz~4.5GHz, the dielectric constant of fresh albumen and yolk decreased monotonously along with the increasing frequency.4)Log-log plot between the loss factor of the albumen and the frequency showed a significant linear relationship between 10MHz and 1000MHz,and the linear regressionequation of them was obtained. 5)Under the frequencies commonly used in the food industry, the dielectric constant and loss factor of the albumen varied remarkably with days of storage, while the yolk shows no significant differences.6)There is a significant correlation between the dielectric constant and loss factor of the fresh albumen and Hough unit at industrial frequencies 915MHz and 2450MHz, and it is reliable to evaluate the eggs'freshness by using Hough unit.7)The penetration depth of the yolk is higher than the albumen at each frequency, and the penetration depth decreased with the frequency's increasing.