Freshness parameters for shell eggs

Furosine, an index of the initial steps of Maillard reaction, has been used for the evaluation of shelf life in UHT milk and of heat damage in various food products. The aim of this paper was to study furosine as an index for egg freshness. Fresh eggs from different hen breeds were used to assess HPLC method repeatability, to investigate natural variability of furosine content in fresh shell eggs, and to study furosine formation during storage at 5, 20, 30, and 38°C. Furosine, present in fresh egg albumen at a level of about 10 mg/100 g of protein, increased during storage with dependence on temperature, reaching after 40 days at 20°C a level of about 100 mg/100 g of protein. The modification of furosine content in yolk during storage at 20°C was minimal. Furosine, when measured in albumen, resulted in a very reliable index for egg freshness. In albumen, maximum furosine contents of 60 and 90 mg/100 g of protein, respectively, for grades A-extra and A eggs commercialized in the European Community are suggested.