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Biodegradation of phenols by laccase immobilised in a membrane reactor

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 oxidatio

Antimicrobial activity of nisin immobilized onto membrane

The efficiency of the antimicrobial peptide nisin was examined against Lactobacillus brevis in a free and immobilized form after its adsorption to polyethersulfonic membrane in spiral UF-module. Results indicated that immobilized nisin can be used to control malolactic fermentation and may have potential for use as a food grade antimicrobial agent on food contact surface

Red and white wine lees as a novel source of emulsifiers and foaming agents

Wine lees are an under-exploited sludge-like material mainly consisting of yeast cells that, upon fermentation, settle at the bottom of wine tanks. Lees from commercial red and white winemaking were processed to yield mannoprotein-rich extracts. An established autoclave-based extraction protocol, as well as a simplified version of it, were applied. The composition of the obtained wine lees extracts was determined. Extracts were tested as emulsifying and foaming agents in model food systems and benchmarked against analogues extracts derived from laboratory-grown yeast cultures of the same two strains used for red and white wines production. All extracts showed good functionalities as emulsifying and foaming agents. However, some differences were noted in both composition and functionality, and these were related to the purification process used, yeast strain, and to the extract's origin (red lees, white lees, lab-grown yeasts). Extracts from real wine lees, which contained also grape-derived polyphenols, performed equally or better than the corresponding extracts derived from laboratory-grown yeast cultures of the same strains. Both red and white wine lees can be a novel and effective source of emulsifiers and foaming agents representing a valid alternative to the yeast biomass produced in bioreactors to be potentially used in the food industry

Solubilization and Activity Detection in Polyacrylamide Gels of a Membrane-Bound Esterase from an Oenological Strain of Saccharomyces Cerevisiae

none6noDue to the importance of esters in determining wine aroma, the presence of different esterases in soluble and insoluble cell fractions of an oenological strain of Saccharomyces cerevisiae was studied. Cells of an oenological yeast strain were separated into three fractions corresponding to the cytoplasm, periplasm and plasma membrane, all showing esterase activity. The conditions for optimal solubilization of the membrane-bound esterase were found, as well as those allowing its electrophoretic analysis, using the detergent disodium-n-lauryl-β-iminodipropionate (Deriphat) in the cathodic buffer. Comparison of the activity bands detected on gels revealed the presence of different esterase isoforms in the three sub-cellular fractions. The method can also be used as the first electrophoretic step in two-dimensional PAGE. Therefore, the procedures described are also a promising tool for the study of the yeast enzymes in relation to their effects during winemaking.noneRizzi C.; Lomolino G.; Lante A.; Crapisi A.; Spettoli P.; Curioni A.Rizzi, C.; Lomolino, G.; Lante, A.; Crapisi, A.; Spettoli, P.; Curioni, A

Characteristics of laccase immobilized on different supports for wine-making technology

Commercial laccase was immobilized in different supports. The enzyme immobilized by covalent binding on polysaccharide carriers displayed the best activity yields ranging from 51 to 63%. The immobilization caused a decrease in Vmax and an increase in Km