Phenols in white musts and wines contribute to enzymic browning; reduction of the phenols concn. is an effective method for improvement of colour stability of white wines. The conventional method for reduction of phenols content is use of fining agents; however, the indiscriminate removal of phenols may impair wine quality. Trials were conducted to assess use of fungal laccase (EC 1.10.3.2) fromPolyporusversicolor (Novo Nordisk Ferment Ltd., Dittingen, Switzerland) immobilized on a copper-chelate regenerable carrier. Trials were conducted with Malvasia, Trebbiano and Moscato musts. Effects of immobilized laccase treatment on total phenols concn., phenolic fractions (total flavanols, gallic acid, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, (--)-epicatechin, p-coumaric acid, ferulic acid, o-coumaric acid) and colour were determined. Laccase treatment reduced total phenols concn., all phenolic fractions, and colour intensity. No significant effect on pH, titratable acidity or sugars concn. of the musts was observed. Reductions in total phenols concn. were: Malvasia 29.69%; Trebbiano, 39.06%; and Moscato 32.56%. Corresponding reductions in total flavanols concn. were, respectively: 33.33%; 41.8%; and 33.96%. Of individual phenolic fractions, decreases were greatest for (--)-epicatechin, ferulic acid and o-coumaric acid. Phenols removal performance of regenerated carriers was slightly lower than that of carriers used for the first time.
A novel method for removing phenols from grape must.
SERVILI, Maurizio;
2000
Abstract
Phenols in white musts and wines contribute to enzymic browning; reduction of the phenols concn. is an effective method for improvement of colour stability of white wines. The conventional method for reduction of phenols content is use of fining agents; however, the indiscriminate removal of phenols may impair wine quality. Trials were conducted to assess use of fungal laccase (EC 1.10.3.2) fromPolyporusversicolor (Novo Nordisk Ferment Ltd., Dittingen, Switzerland) immobilized on a copper-chelate regenerable carrier. Trials were conducted with Malvasia, Trebbiano and Moscato musts. Effects of immobilized laccase treatment on total phenols concn., phenolic fractions (total flavanols, gallic acid, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, (--)-epicatechin, p-coumaric acid, ferulic acid, o-coumaric acid) and colour were determined. Laccase treatment reduced total phenols concn., all phenolic fractions, and colour intensity. No significant effect on pH, titratable acidity or sugars concn. of the musts was observed. Reductions in total phenols concn. were: Malvasia 29.69%; Trebbiano, 39.06%; and Moscato 32.56%. Corresponding reductions in total flavanols concn. were, respectively: 33.33%; 41.8%; and 33.96%. Of individual phenolic fractions, decreases were greatest for (--)-epicatechin, ferulic acid and o-coumaric acid. Phenols removal performance of regenerated carriers was slightly lower than that of carriers used for the first time.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
