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Therefore, it is possible to forecast that the treatment of grape just after harvesting could contribute to stronglyreduce or even avoid the occurrence of OTA on grape.3. Fidaleo M, Esti M, Moresi M (2006) Assessment of Urea Degradation Rate in Model WineSolutions by Acid Urease from Lactobacillus fermentum. J Agric Food Chem 54, 6226-6235.The specific activity (π A ) of a whole cell acid urease preparation was assessed in model wine solutions at differentlevels of malic (M) and lactic acids, metabisulfite, ethanol, and pH by performing a central composite design.M and then pH resulted to be the most controlling variables, their effects being practically coincident but of oppositesign. For urea concentrations up to about 1 mol m -3 the ammonium formation rate was assumed of thepseudo-first order with respect to urea, this being confirmed by two independent validation tests performed at20°C for as long as 24 h. In the case of real wines the effective pseudo-first order kinetic rate constants werefound to be smaller than those pertaining to the model solutions having the same wine composition and pH by afactor varying from 10 to 1000, this affecting significantly the specific urease treatment costs per litre of winetreated.4. Esti M, Fidaleo M, Moresi M, Tamborra P (2007) Modeling of Urea Degradation in Whiteand Rosé Wines by Acid Urease. J Agric Food Chem 55 (7), 2590-2596.The specific activity of a whole cell acid urease preparation was tested in 5 five wines manufactured in theApulia region of Italy in the 2003 vintage both at short and long treatment times, thus confirming the validity ofthe pseudo-first order kinetic model to describe urea removal. The experimental pseudo-1st order kinetic rateconstants (kIe) as referred to those (kIm) concerning model wine solutions having the same composition and pHof the real wines tested reduced from about 0.21 to 0.02 as the overall content of phenolic compounds (P) increasedfrom 109 to 853 g m-3 of gallic acid equivalent (GAE). The well known inhibition model was used toexplain the specific inhibitory effect of such compounds, thus finding that the equilibrium constant (KP) of theirreaction with the enzyme ranged from about 16 to 45 g GAE m-3 when the model wine solution was enrichedwith tannins extracted from grape seeds or skins, respectively, while it was equal to about 21 g GAE m-3 for thereal wines tested. A sequential experimental procedure consisting of accelerated acid urease tests at high dosesof enzyme followed by accelerated urethane tests on the resulting acid-urease treated wine was recommended toassess preliminarily the techno-economic feasibility of the acid-urease hydrolytic process.5. Benucci I., Liburdi K., Esti M. (2007) Immobilizzazione di una proteasi acida ed applicazionein vino modello. Atti del 8° Congresso Italiano di Scienza e Tecnologia degli Alimenti,Milano, 7-8 maggio 2007, 490-494.Le proteasi hanno la capacità di catalizzare sia reazioni di idrolisi che di sintesi delle proteine e rappresentanouna delle categorie di enzimi più importanti nell’industria alimentare. Questi enzimi in soluzione acquosa sidegradano rapidamente per ‘self-digestion’, tuttavia diversi autori sostengono che la loro immobilizzazione susupporti solidi potrebbe risolvere questo problema, aumentandone la stabilità. L’applicazione industriale dicatalizzatori immobilizzati consentirebbe di: separare l’enzima dalla matrice alimentare, garantire unamanipolazione più sicura da parte degli operatori e riutilizzarlo per più cicli produttivi. L’obiettivo di questolavoro è stato quello di immobilizzare una proteasi acida di origine vegetale, la bromelina, testandone l’attività invino modello per una sua eventuale applicazione nel settore enologico. La proteasi è stata legata covalentementesu sfere di vetro amminopropiliche usando la glutaraldeide come “cross-linker”. L’enzima immobilizzato è statotestato a 25°C in tampone tartarico (pH 3.2) contenente etanolo al 12%; l’attività proteolitica è stata determinataimpiegando come substrato la caseina. I risultati ottenuti sono stati confrontati con quelli della proteasi in formalibera. La bromelina immobilizzata, oltre ad avere una migliore stabilità rispetto alla forma libera, ha mostratoanche una maggiore attività nel vino modello in cui è stata applicata.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.it474