Non invasive methods for egg quality evaluation

During the last century, egg production, transport and handling became a specialized industry. Egg quality was for a long time based on visual inspection. Today, the total number of the handled eggs and the rate of grading (up to 180 000 eggs/hour) is such that this visual inspection becomes impossible. This leads to a search for new non invasive devices to measure egg quality parameters. In the last decade, at least three types of quality sensing devices became commercially available. A first type is based on mechanical techniques that measures eggshell properties as there are the presence of cracks and the eggshell strength. A second type of sensors is based on spectroscopic principles for interior egg quality. Originally, the spectroscopic information was based on one or a limited number of wavelengths using filter systems (e.g. to detect blood or other inclusions). Later, with sophisticated spectroscopic equipment, the hyper spectral information carried by transmitting light could be linked with albumen properties like pH, Haugh Units and viscosity. Finally a third type of sensor system uses computer vision techniques to get information about the outside of the egg. (e.g. eggshell colour and the detection of dirty shells). It also allows the rapid detection of open cracks that are a problem for hygienic conditions and cleanliness of egg grading equipment. Ongoing research also focuses on new sensors based on ultrasonic, magnetic resonance and electronic nose techniques. Moreover, by combining two different measurement techniques other characteristics become assessable (e.g. eggshell conductance). These sensor devices became available in egg quality research groups, relationships between a specific quality parameter and the general condition of the measured egg and the sampled layer flock have been established. Estimations about both the general egg quality and the health of the layer flock can be made and used for flock management in order to correct problems before they cause large economic losses or hygienic problems. This will increase the general egg quality and reduce the risks for the consumers when eating eggs and egg products.