The production of reduced-alcohol wines using Gluzyme Mono® 10.000 BG-treated grape juice

  • B.N.E. Biyela Department of Viticulture and Oenology, Stellenbosch University, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa
  • W.J. du Toit Department of Viticulture and Oenology, Stellenbosch University, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa
  • B. Divol Institute for Wine Biotechnology, Stellenbosch University, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa
  • D.F. Malherbe Institute for Wine Biotechnology, Stellenbosch University, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa
  • P. van Rensburg Department of Viticulture and Oenology, Stellenbosch University, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa. Institute for Wine Biotechnology, Stellenbosch University, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa. Distell, P.O. Box 184, Stellenbosch, 7599 South Africa.

Abstract

High alcohol wines have become a major challenge in the international wine trade. Several physical processes are
used to produce wines with reduced-alcohol content, all of which involve the selective extraction of ethanol based
on volatility or diffusion. In this study, the possibility of Gluzyme Mono® 10.000 BG (Gluzyme) (Novozymes, South
Africa) to reduce the glucose content of synthetic grape juice before fermentation was investigated in order to produce
wine with reduced-alcohol content. Gluzyme is a glucose oxidase preparation from Aspergillus oryzae, currently used
in the baking industry. Glucose oxidase catalyses the oxidation of glucose to gluconic acid and hydrogen peroxide
(H2O2) in the presence of molecular oxygen. Gluzyme was initially used in synthetic grape juice, where different
enzyme concentrations and factors influencing its efficiency were investigated under winemaking conditions. The
results showed up to 0.5% v/v less alcohol at an enzyme concentration of 20 kU compared to the control samples.
This reduction in alcohol was increased to 1 and 1.3% v/v alcohol at pH 3.5 and pH 5.5 respectively in aerated (8
mg/L O2) synthetic grape juice using 30 kU enzyme. Secondly, Gluzyme was used to treat Pinotage grape must
before fermentation. Gluzyme-treated wines at 30 kU enzyme concentration after fermentation contained 0.68%
v/v less alcohol than the control wines. A decrease in acetic acid concentration of the treated compared to control
wines was also observed.
Published
2016-12-12
Section
Articles