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studied. Vastedda, according to Codex Alimentarius, resulted a semi-hard, medium fat cheese, but the large variabilityof composition makes the definition of a narrow standard of the product difficult. Lactic acid bacteria were thedominant microflora in spite of the heat stress given by the stretching of the curd. Listeria monocytogenes and Salmonellaspp., were absent and coagulase positive staphylococci were always lower than 100 cfu/g. The variabilityamong producers is amplified by the variability of the cheese during shelf-life. Sugars and organic acids contentlargely changed during the 60-day storage, mainly for the brine unsalted variety. To continue to identify this cheeseas a fresh one, the storage of traditional Vastedda cheese should not be longer than 30 days.2. Mucchetti G, B. Bonvini, S. Francolino, E.Neviani, D. Carminati (2008) Effect of washingwith a high pressure water spray on removal of Listeria innocua from Gorgonzola cheese rindFood Control 19, 521–525Contamination of Gorgonzola cheese surface by Listeria is a difficult problem to solve by only applying goodmanufacturing practices.Treating of the cheese rind at the end of ripening may be a tool to improve cheese safety. The aim of this study wasto evaluate the effect of a high pressure water spray washing technology in reducing Listeria load from Gorgonzolacheese rind without using oxidizing agents.The surface of Gorgonzola cheese was contaminated (up to 10 7 cfu g _1 of scraped rind) with a mixture of fourstrains of Listeria innocua. The count of Listeria was made by scraping (2 mm depth) the rind of the cheese. Thecontaminated cheeses were then washed at different pressures, ranging from 1 to 5 MPa for 1 min. The lower thepressure, the lower was the removal of Listeria. A reduction of up to 99.89% was achieved washing the cheese at 5MPa, followed by rinsing at 1 MPa for 1 min. Changing the inoculum size (10 2 , 10 4 , and 10 7 cfu g _1 ), did not changethe efficacy of Listeria removal, when the same water pressure was applied.The washing of Gorgonzola cheese with pressurized jet water, without adding any preservative to the water, can beconsidered a further important physical hurdle, in controlling pathogenic bacteria and improving cheese safety.3. Locci F. R. Ghiglietti, S. Francolino, R. Iezzi, V.Oliviero, A. Garofalo, Mucchetti G. (2008) Detectionof cow milk in cooked buffalo Mozzarella used as Pizza topping Food Chemistry 107,1337–1341One of the most popular worldwide meals is Pizza. Among the main ingredients, buffalo or cow Mozzarella are thecheeses most widely used. Different prices between buffalo and cow Mozzarella can stimulate frauds but it is unknownwhether the European official method can differentiate Mozzarella from cow or buffalo milk after ovencooking when used as a Pizza topping. Preliminary experiments with Pizza dough and Mozzarella cheeses, followedby analysis of pure buffalo, pure cow and mixed Mozzarella separated from Pizza after cooking confirmed the reliabilityof the official method and the possibility to quantify low amounts of cow milk. The results of a survey onmore than 50 Pizzas declaring only buffalo Mozzarella as cheese ingredient, showed the fraudulent use of mixedMozzarella. This study showed that the official method is an effective tool to demonstrate this kind of fraud, protectingconsumers against improper practices and guaranteeing fair trade.4. Carminati D., B. Bonvini, E. Neviani, G. Mucchetti (2008) The fate of potentially pathogenicbacteria during the preliminary steps of Grana cheesemaking: a laboratory-scale study on thenatural creaming process of raw milk. Milchwissenschaft. 63 (4) 416-419The spontaneous creaming is a step in the production of many Italian raw milk hard cheeses. During creaming testscarried out at temperatures between 8° and 25°C for 16 h, the behavior of four pathogens (Listeria monocytogenes,Salmonella spp., Staphylococcus aureus and Escherichia coli O157:H7) has been investigated. At 8 and 15°C nogrowth of the pathogens was detected, and the increased counts in the cream were due to the dragging of the bacteriaduring cream separation. At 20 and 25°C the pathogens grew both in the partially skimmed raw milk and in thecream. Staphylococcal enterotoxin was found only in the cream separated at 25°C. The temperature control duringspontaneous creaming resulted fundamental to maintain hygienic quality and to improve cheese safety.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.it347