Nondestructive Assessment of Egg Freshness using a Synchronous Fluorescence Spectral Technique

Freshness is an important index of egg quality. In this study, a synchronous fluorescence spectral technique was employed to determine the freshness of an intact egg. Synchronous fluorescence spectra of intact eggs were acquired using a fluorescence spectrometer supported by a laboratory fluorescence acquisition device and egg freshness (Haugh Unit) was obtained using destructive methods. Eggs feature fluorescence signals were mainly concentrated in two regions: A (excitation wavelength of 290 nm over the emission wavelength range of 320-380 nm) and B (excitation wavelength range of 380-570 nm over the emission wavelength range of 610-735 nm). The two regions were selected as regions of interest, which include 2581 Excitation-Emission (Ex-Em) wavelengths; stepwise discrimination analysis was performed on the 2581 Ex-Em wavelengths to choose optimal Ex-Em wavelength combinations. A Multiple Linear Regression (MLR) prediction model was built using fluorescence signals based on the optimal Ex-Em wavelength combinations. The results revealed that the freshness of an egg could be accurately predicted with Rp2 of 0.8879 and a root mean square error estimated by validation (SEP) of 6.2896. This work demonstrates that the synchronous fluorescence spectral technique has high potential for nondestructive sensing of egg freshness.