Anna Lante

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.

Evaluation of Red Chicory Extract as a Natural Antioxidant by Pure Lipid Oxidation and Yeast Oxidative Stress Response as Model Systems

The search for renewable and abundant sources of antioxidants has recently focused on agricultural byproducts, especially promising due to their natural origins and low costs. In particular, plant raw materials are sources of important compounds such as dietary fiber, carotenoids, tocopherols, and polyphenolics, which are mostly discarded during harvesting and processing. Among these vegetal crops, red chicory is attractive because of the large quantity of its byproducts (residues as leaves and stems); moreover, there is no information on its role as a food and feed ingredient. In this study, red chicory leaf residue was evaluated as a natural substitute for synthetic antioxidants for the food and feed industry. After lyophilization, a red chicory extract (RC) was characterized for its phenolic profile and its oxidative stability as compared to BHT. RC was shown to reduce lipid peroxidation of different oils in the Rancimat test. In addition, the antioxidant property of RC was studied in a model system by evaluating the Saccharomyces cerevisiae response to oxidative stress by means of gene expression. In this analysis, the RC extract, added to the yeast culture prior to oxidative stress induction, exhibited a pleiotropic protective effect on stress responsive genes.

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.

Antibrowning potential of Brassicacaea processing water

The effects of Brassicacaea processing water on polyphenol oxidases from different plant sources were investigated. Results showed that processing water (PW) prepared by cooking young Brassicacaea leaves with water has the capacity to inhibit both commercial tyrosinase and plant polyphenol oxidases. PW was freeze-dried (LPW) in an attempt to increase its utility and improve its efficiency at inhibition of polyphenol oxidases, however this resulted in a loss of activity, probably due to the stresses of the freezing and/or drying processes. The addition of PW to ascorbic acid resulted in complete inhibition of grape polyphenol oxidase, suggesting that the combination of the two antibrowning agents may be a promising tool to control this enzymatic activity.

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.

Essential amino acids: master regulators of nutrition and environmental footprint?

The environmental footprint of animal food production is considered several-fold greater than that of crops cultivation. Therefore, the choice between animal and vegetarian diets may have a relevant environmental impact. In such comparisons however, an often neglected issue is the nutritional value of foods. Previous estimates of nutrients’ environmental footprint had predominantly been based on either food raw weight or caloric content, not in respect to human requirements. Essential amino acids (EAAs) are key parameters in food quality assessment. We re-evaluated here the environmental footprint (expressed both as land use for production and as Green House Gas Emission (GHGE), of some animal and vegetal foods, titrated to provide EAAs amounts in respect to human requirements. Production of high-quality animal proteins, in amounts sufficient to match the Recommended Daily Allowances of all the EAAs, would require a land use and a GHGE approximately equal, greater o smaller (by only ±1-fold), than that necessary to produce vegetal proteins, except for soybeans, that exhibited the smallest footprint. This new analysis downsizes the common concept of a large advantage, in respect to environmental footprint, of crops vs. animal foods production, when human requirements of EAAs are used for reference.

Study on the antioxidant and antimicrobial activities of Allium ursinum L. pressurised-liquid extract

Allium ursinum L. is widely used as a spice as well as a traditional medicine. The aim of this work was to evaluate the antioxidant and antimicrobial activities (AMAs) of A. ursinum extract, obtained by pressurised-liquid extraction. Several reliable procedures such as 2,2-diphenyl-1-picrylhydrazyl, 2,2-azinobis-3ethyl benxothiazoline-6-sulphonic acid, ferric-reducing antioxidant power assay and oxygen radical absorbance capacity assays were carried out. Vegetable oil stability was evaluated by using Rancimat test. Moreover, AMA was performed on different microorganisms. On the basis of the results obtained, it is confirmed that the A. ursinum extract could be used as a natural ingredient in food and/or pharmaceutical industries.

Evaluation of antibrowning and antioxidant activities in unripe grapes recovered during bunch thinning

Background and Aims Research into new systems for controlling enzymatic browning in the agro-food industry has been focused on eco-friendly alternatives to conventional thermal treatments and traditional additives, which could impair the sensory, nutritional and health properties. The use of unripe grapes for reducing alcohol concentration and pH of wines has been previously reported; however, no studies have been made of the evaluation of unripe grapes as potential functional ingredients to control enzymatic browning and to enhance antioxidant properties of plant products. Methods and Results Unripe berries were collected in two seasons during bunch thinning of Barbera and Merlot vineyards. Merlot grapes, which had the highest antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl and ferric reducing ability of plasma assays, were also the most effective in preventing enzyme browning, as confirmed by spectrophotometric assays using commercial mushroom tyrosinase, by zymographic techniques on the isoforms isolated from some plant polyphenol oxidases and by in vivo trials on fresh-cut fruits and vegetables. Conclusions The juice of unripe grapes showed not only antibrowning but also antioxidant and whitening activities. Significance Unripe grapes discarded during bunch thinning of vineyards represent for the agro-food industry a significant source of bioactive compounds that are easy to produce and safe for human health, thus converting these agricultural wastes into value-added products.