Effects of Transport Vibrations on Quality Indices of Shell Eggs

Mechanical vibrations were measured on the floor of three means of transport (a truck semi-trailer and two trucks) during transportation of shell eggs from the packing house to market. The obtained values of the power spectral density (PSD) were reproduced on the vibrating table of an electro-dynamic shaker to stress a column of cardboard boxes that represents typical packaging for the distribution of eggs and the accelerations on the eggs at different levels of the column were measured. Samples of 30 eggs each were then stressed with PSD profiles obtained from the measures on the eggs in the column, by using an alveolate surface made of concrete mounted on the vibrating table of the shaker to fix the eggs. Haugh unit, vitelline membrane strength and air cell height were determined after 8 days of storage at 18°C. Results show a significant decrease in Haugh unit (28%) in the sample stressed with a PSD profile obtained at the highest level of the column, in comparison with a non-vibrated sample. Variations in the resistance of vitelline membrane (18%) were also observed among the samples which were vibrated with different PSD profiles.