A new approach to the identification of incubator reject eggs in pasteurized whole egg products obtained from fresh eggs

The use of incubator reject eggs (IR) for the preparation of egg products is not allowed in the EU. The content of 3OH-butyric, lactic and succinic acids is limited by specific laws, which are intended to protect consumers from the illegal use of IRE and to guarantee the hygienic quality of products. The aim of this study is to outline an analytical procedure for the detection of IRE addition in pasteurized whole egg products. Six samples (of 120 eggs each) of eggs candled at the 18th day and four candled at the 8th day were shelled, homogenized and added at different levels to homogenized fresh eggs. All mixes were pasteurized in batch at 64 °C for 3.5 min. All raw fresh eggs, raw IRE samples and pasteurized mixes were analyzed for pH, 3OH-butyric, lactic, succinic, pyroglutamic, pyruvic, uric, and formic acids, uridine, uracil furosine, and reaction with tetramethylbenzidine. With the exception of pH and succinic acid, raw fresh eggs differed significantly from raw IRE by all the variables analyzed. Succinic acid contents in both IRE and fresh eggs were below the detection limit, thus confirming the excellent hygienic quality of the eggs analyzed. The average 3OH-butyric acid content in pasteurized fresh egg samples was 3.88 ± 1.26 mg/kg (d.m.), and the average lactic acid content was 265.05 ± 55.37 mg/kg (d.m.). this study outlines a step-by-step analytical procedure based on the content of 3OH-butyric, lactic, and succinic acids and uracil for the detection of IRE addition (at least 3%) to pasteurized whole egg products.