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acids, starting with initial values of 1-7 mg/kg dm, presented trends similar to that of uracil; however, acetic acidnever decreased during the storage of raw egg products. With few exceptions, all the three metabolites wereproduced by Enterobacter cloacae, Escherichia coli, Morganella morganii, Serratia liquefaciens, Aeromonashydrophyla, Pseudomonas fluorescens, Enterococcus avium, Enterococcus faecalis, separately inoculated inwhole egg samples. Uracil seems to be the most sensible marker, with a tolerance limit corresponding to thedetectable level.2. Hidalgo, A., Pompei, C., Galli, A. 2007. Uracil evolution in tomato pulp inoculated with differentmicrobial strains during long incubation time. Food Chem. 104: 1327-1332.Uracil has been previously proposed as a successful index of lactic acid bacteria (LAB) contamination in tomatoproducts. The uracil produced in tomato pulp, as a consequence of the hydrolytic activity of different LABstrains (Lactobacillus brevis, Lactobacillus fermentum, Lactobacillus plantarum, Leuconostoc mesenteroides,and Pediococcus spp.), remained constant over all the incubation time (180 days), confirming uracil as a goodindex of LAB contamination. An anaerobic spore-forming microorganism (Clostridium pasteurianum) was alsoable to produce uracil. In order to deepen the understanding of uracil formation mechanisms, uracil and uridinewere determined in De Man Rogosa uridine-enriched broth inoculated with some LAB strains: the maximumlevel of uracil formation corresponded to the total disappearance of the initial uridine, followed by a total orpartial uracil decrease. Only under stressful conditions, such as reduced glucose concentrations (0.2-0.02%) inculture media, LAB strains did not degrade or use the uracil produced, as observed in tomato pulp.3. Hidalgo, A., Pompei, C., Rossi, M., Franzetti, L. 2007. An innovative marker for hygienecontrol of raw material in pasteurised egg products. Proceedings of the XVIII European Symposiumon the Quality of Eggs and Egg Products, Prague, September 2-5, 040, 90-91.The recent modifications to the European legislation regarding egg products hygiene, in place since January 1st2006, abolished the total microbial count index, baffling industrial users and eliminating an important legalparameter. Only the limits for microbial indices such as salmonella and enterobacteria, and a chemical index ofincubator rejected eggs (3-hydroxybutiric acid) remain well defined for pasteurised egg products. On the otherhand, the only index considered for hygienic quality evaluation of raw material is lactic acid, but the officialreference value is for the untreated product (neither pasteurized nor fermented). Thus, at the moment theEuropean legislation does not give an index for the control of the raw material hygienic quality, as measured inthe pasteurised egg product. Consequently, the availability of chemical indices that, differently from microbialanalysis, permit the evaluation of raw material quality in the end product, is paramount. Of course, these indicesshould be thermostable, since they don’t have to be influenced by the heat treatments applied during egg productand food manufacturing, and must be quantifiable without analytical interferences of the food matrix.From this point of view, a very promising index is uracil, a thermostable base produced by microbialmetabolism. In this paper, uracil, uridine, lactic and acetic acids were determined by HPLC in several industrialand laboratory scale whole egg samples, before and after pasteurisation, and during storage at 4 and 25 °C. Totalbacterial count and identification of the main microbial strains involved in the spontaneous spoilage were alsocarried out. The results confirmed the reliability of uracil, absent in fresh eggs and in properly-treated industrialraw materials, as a marker of microbial spoilage, even after the contaminant microrganisms were destroyed bythermal treatments.3. Hidalgo, A., Rossi, M., Pompei, C. 2006. Estimation of equivalent egg age through furosineanalysis. Food Chem., 94: 608-612.The aim of this research was to study furosine as a reference index for expressing the age of commercial shelleggs in terms of equivalent egg age. Seventy five commercial samples of grade A eggs purchased on the Italianmarket 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 printedon the packages. At equal egg age, a wide data variation for all indices was observed, thus indicating the greatinfluence of commercialization condition on the assessed indices. An average kinetics of furosine developmentin albumen at 20 °C was also computed from nine storage experiments of shell eggs laid by hens of differentages and breeds. The equivalent egg age of the commercial samples, expressed as days at 20 °C, was computedby substituting the furosine value of each sample in the average kinetics equation.SISTAL - SOCIETA’ ITALIANA DI SCIENZE E TECNOLOGIE ALIMENTARIDipartimento di Scienze e Tecnologie Agroalimentari, Università degli Studi della TusciaVia San Camillo de Lellis, 01100 ViterboTel.: 0761- 35 74 94/7 , Fax: 0761- 35 74 98, e-mail: mmoresi@unitus.it192