The present research aimed to determine the freshness of brown eggs with non-destructive UV/VIS transmission spectroscopy in the wavelength range of 350-1020 nm and viscosity measurement during storage period of 7 days. The eggshell color varied from light yellow-brown to dark red-brown as per human visual perception which were distributed near the edge of the spectral locus of orange to red spectral wavelength region in the CIE 1931 chromaticity diagram. Quantitatively characterized luminance (CIE Y) values of the eggshell brightness were 7.77 (darkest) and 49.1 cd/cm2 (brightest). The L* value (brownness) of the eggshell increased while the a* value (redness) decreased. The correlation between luminance and transmittance values was evaluated using a linear regression model which showed a correlation coefficient of 0.92. The transmittance spectra were collected on each day which showed gradual increase from 36.0 % (day 1) to 38.8% (day 3). The slope of this increment became steeper after day 3 and reached 50.8% (day 7). The freshness of the eggs calculated based on the transmittance value of 100% on day 1 showed inverse relation with the storage time and was reduced by 59% on day 7. The viscosity of the egg white exhibited non-Newtonian shear thinning behaviour and showed 13.7% reduction on day 7 with respect to day 1. The spectral analysis and viscosity results clearly demonstrated that the freshness of the eggs declined with increase in storage time.
Keywords: Freshness of brown eggs, CIE 1931, light transmttance, viscosity of egg white