Estimation of equivalent egg age through furosine analysis

The aim of this research was to study furosine as a reference index for expressing the age of commercial shell eggs in terms of equivalent egg age. Seventy five commercial samples of grade A eggs purchased on the Italian market were analysed for air cell height, Haugh Units, 3,3′,5,5′ tetramethylbenzidine test, and furosine level. The values obtained were reported as a function of egg age calculated from the minimum durability dates printed on the packages. At equal egg age, a wide data variation for all indices was observed, thus indicating the great influence of commercialization condition on the assessed indices. An average kinetics of furosine development in albumen at 20 °C was also computed from nine storage experiments of shell eggs laid by hens of different ages and breeds. The equivalent egg age of the commercial samples, expressed as days at 20 °C, was computed by substituting the furosine value of each sample in the average kinetics equation.