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A study on the use of natural antimicrobial compounds to improve the microbiological stability of refrigeratedamaranth-based homemade fresh pasta is presented in this work. In particular, the antimicrobial activity of thymol,lemon extract, chitosan and grapefruit seed extract (GFSE) has been tested against mesophilic and psychrotrophicbacteria, total coliforms, Staphyloccocus spp., yeasts and moulds. A sensory analysis on both fresh andcooked pasta was also run. Results suggest that chitosan and GFSE strongly increase the microbial acceptabilitylimit of the investigated spoilage microorganisms, being the former the most effective. Thymol efficiently reducesthe growth of mesophilic bacteria, psychrotrophic bacteria and Staphyloccocus spp., whereas it does not affect,substantially, the growth cycle of total coliforms. Lemon extract is the less effective in preventing microbialgrowth. In fact, it is able to delay only total mesophilic and psychrotrophic bacterial evolution. From a sensorialpoint of view no significant differences were recorded between the control samples and all the types of loadedamaranth-based pasta.3. Corbo M.R., Speranza B., Filippone A., Granatiero S., Conte A., Sinigaglia M, Del NobileM.A. 2008. Study on the Synergic Effect of Natural Compounds on the Microbial QualityDecay of Packed Fish Hamburger. International Journal of Food Microbiology, 127, 261-267.The effectiveness of natural compounds in slowing down the microbial quality decay of refrigerated fish hamburgeris addressed in this study. In particular, the control of the microbiological spoilage by combined use ofthree antimicrobials, and the determination of their optimal composition to extend the fish hamburger MicrobiologicalStability Limit (MAL) are the main objectives of this work. Thymol, grapefruit seed extract (GFSE) andlemon extract were tested for monitoring the cell growth of the main fish spoilage microorganisms (Pseudomonasfluorescens, Photobacterium phosphoreum and Shewanella putrefaciens), inoculated in fish hamburgers, andthe growth of mesophilic and psychrotrophic bacteria. A Central Composite Design (CCD) was developed tohighlight a possible synergic effect of the above natural compounds. Results showed an increase in the MAL valuefor hamburgers mixed with the antimicrobial compounds, compared to the control sample. The optimal antimicrobialcompound composition, which corresponds to the maximal MAL value determined in this study, is:110 mgL -1 of thymol, 100 mgL -1 of GFSE and 120 mgL -1 of lemon extract. The presence of the natural compoundsdelay the sensorial quality decay without compromising the flavor of the fish hamburgers.4. Sinigaglia M., Bevilacqua A., Corbo M.R., Pati S., Del Nobile M.A. 2008. Use of ActiveCompounds for Prolonging the Shelf Life of Mozzarella Cheese. International Diary Journal.18, 624-630.The effectiveness of lysozyme and ethylenediaminetetraacetic disodium salt (Na2-EDTA) against the spoilagemicroorganisms of mozzarella cheese was studied. Mozzarella cheeses were packaged in a conditioning solution(diluted brine), which contained lysozyme (0.25 mg mL1) and different amounts of Na2-EDTA (10, 20 and 50mmol L1), and stored at 4 1C for 8 days. The population of spoilage microorganisms (total coliforms and Pseudomonadaceae),along with the functional microbiota of mozzarella cheese (lactic acid bacteria) was enumerated.Lysozyme and Na2-EDTA significantly inhibited the growth of coliforms and Pseudomonadaceae during thefirst 7 days of storage, whereas the functional microbiota (or lactic acid bacteria) were not affected. The results ofthis study showed that it is possible to extend the shelf life of mozzarella cheese through the use of lysozyme andNa2-EDTA in the conditioning brine.5. Conte A., Scrocco C., Sinigaglia M., Del Nobile M. A. 2007. Innovative Active PackagingSystems to Prolong the Shelf Life of Mozzarella Cheese. Journal of Dairy Science. 90, 2126-2131.In this work the effectiveness of different antimicrobial packaging systems on the microbial quality decay kineticduring storage of mozzarella cheese was evaluated. Lemon extract, at three different concentrations, was used asactive agent, in combination with brine and with a gel solution, made of sodium alginate. Shelf life tests were runat 15 °C to simulate thermal abuse. The cell load of both spoilage and dairy functional microorganisms weremonitored at regular time intervals during storage. By fitting the experimental data through a modified version ofGompertz equation, the shelf life of dairy product packaged in the different systems was calculated. Results showan increase in the shelf life of all active packaged mozzarella cheeses, confirming that the investigated substancemay exert inhibitory effect on the microorganisms responsible for spoilage phenomena, without affecting thefunctional microbiota of the product.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.it124