Chromatographic techniques were used in order to determine the modifications induced in egg, by a spray-drying treatment, on the native constituents and on the formation of cholesterol oxidation products (COPs) and early Maillard reaction products. The same powdered egg was stored for 12 months at room temperature and at 4 degrees C, and sampled at 1, 3, 6 and 12 months, respectively. The spray-drying treatment did not affect tocopherol or retinol composition, but caused a severe Maillard reaction (furosine increased from 15 to 500 mg/100 g protein) and accelerated cholesterol oxidation (the sum of Cops increased from 24 to 55 mu g/ g fat). Only slight modifications were registered in powdered egg stored at 4 degrees C. During storage at room temperature, however, Cops increased significantly (up to 167 mu g/g fat), tocopherols and retinols decreased, whereas furosine was not significantly modified. Thus, furosine can be considered as a suitable technology marker, whereas CON are important markers of the storage conditions. (c) 2004 Elsevier Ltd. All rights reserved.