Quality Evaluation of Shell Eggs During Storage Using a Dielectric Technique

This article reports on investigating the possibility of non-destructively predicting basic quality parameters of shell eggs using an open-ended coaxial probe dielectric measurement technique. The studied parameters include yolk index, thick albumen height, and Haugh unit as well as air cell size as a function of storage duration at room temperature. The probe was connected to an impedance analyzer from which the dielectric spectra (dielectric constant and loss factor) were collected using a data logger and analyzed by means of partial least squares (PLS) analysis. The tests were carried out in the 10 to 1800 MHz frequency band on shell eggs stored for 1, 2, 4, 8 and 15 days at 22°C, positioning the probe in three different points on the shell eggs. For storage duration, the results showed R2 values up to 0.985 and 0.980 in cross-validation and test-set validation, respectively, while the R2 for the air cell height was up to 0.927 and 0.921, respectively. Yolk index, thick albumen height, and Haugh unit were also predicted with R2 values ranging from 0.526 to 0.728 (test-set validation). No substantial differences in prediction power emerged by using the dielectric constant, loss factor spectra, or position of the probe on the shell egg. The best frequency band for prediction was from 10 to 700 MHz.