Antonella Crapisi

Biodegradation of phenols by laccase immobilised in a membrane reactor

Abstract The results of a study of immobilisation of a commercial laccase onto a spiral-wound asymmetric polyethersulphone membrane are described. The immobilised enzyme system displayed a promising half-life of more than 150 h for oxidation of syringaldazine. The laccase membrane reactor was applied to the biodegradation of a model phenol solution containing 18 phenolic substrates, including chlorophenols, cresols and methoxyphenols. It has been confirmed that the type and/or the position of substituent group affect the level of substrate oxidation.

Enhanced microbial cell lysis by the use of lysozyme immobilized on different carriers

Abstract Lysozyme was immobilized on chitosan and silica gel by adsorption, on cross-linked polystyrene divinylbenzene matrix (Deacidite KMP) by ionic binding and on non-porous glass beads by covalent attachment to improve the lytic activity towards complex substrates such as Micrococcus luteus . The lysozyme immobilization yields decreased on decreasing the amount of enzyme loaded, whereas the activation yields (defined as percentage ratio of immobilized active enzyme to immobilized enzyme) increased. Chitosan, silica gel, Deacidite KMP and non-porous glass bead preparations showed activation yields of 10%, 13·20%, 26·67% and 12·77%, respectively.

Immobilized Laccase for Must and Wine Processinga

Whereas the use of enzyme preparations in the food industry is a wellestablished, rapidly expanding technology, their utilization in enology is less frequent. The “classic” wine industry is in fact still largely based on traditional methods. Moreover, musts and wines represent a hostile environment for purified enzymes, i.e., low pH, high ethanol concentration, presence of sulfur dioxide and tannins. White and ‘‘rosk” wines are known to be more sensitive than red wines to browning and to the development of madeirized flavor, which are mainly due to the presence of polyphenols. Aiming at the replacement of traditional stabilization treatments (i-e., sulfur dioxide, fining agents) with mild technologies to prevent madeirization, unconventional systems like the use of oxidative enzymes (chiefly laccase) have been proposed.’,* However, the residual enzyme activity in wine during storage or, in the case of musts, its inactivation by heat treatment could lead to negative effects, i.e., color browning. Therefore, the use of immobilized oxidative enzymes that can be easily recovered from the reaction mixture and reused could be exploited. Studies have been reportedly carried out on fungal laccase immobilized by covalent attachment to CNBr-activated Sepharose 4B and by adsorption to Concanavalin A-Sepharose? covalently bound to a diatomaceous silica product (R-650 Celite): immobilized on porous glass beads5s6 to detoxify the environment polluted with aromatic and phenolic compounds of agricultural or industrial origin. Taking into account our previous trials on the approach to the use of immobilized oxidative enzymes in white wine stabilization,7vu in the present work we report the results on a commercial laccase (p-diphenol: oxygen oxidoreductase; EC 1.10.3.2) immobilized by adsorption on silica gel carrier followed by treatment with glutaraldehyde and by covalent binding on polymer carrier VA-Hydroxy Biosinth, and CNBractivated Sepharose 4B, respectively. In addition, the possibility of an enzymatic removal of phenolics was tested in model solution, in must, and in wine.

Detection of Saccharomyces cerevisiae carboxylesterase activity after native and sodium dodecyl sulfate electrophoresis by using fluorescein diacetate as substrate.

A simple method for the visualisation of wine yeast esterase (carboxylesterase EC 3.1.1.1) activity on electrophoretic gels was developed, using the fluorescent substrate fluorescein diacetate. The zymogram system allows a sensitive detection of esterase bands in only 5 min of incubation of both native and sodium dodecyl sulfate gels.

Chemical parameters, biologically active polyphenols and sensory characteristics of some Italian organic wines

Abstract This paper describes 23 commercial Italian wines, made from organic grapes, by their chemical parameters, biologically active polyphenol concentrations and sensory analysis. Our data show inconsistent differences in the trans-resveratrol and p-coumaric acid contents in comparison with non-organic wine, with the exception of quercetin concentrations in Chianti samples. Furthermore, the chemical analyses and sensory data of organic wines did not significantly differ from those previously cited. In general the organic wines display satisfactory sensory properties such as flavour intensity, body and a general acceptance.