Why Concentrate?


The Memstar concentration process treats grape juice or wine to increase flavour intensity, colour and body. It does this by using reverse osmosis to remove a portion of the grape juice or wine as permeate.

Grape juice (or must) concentration by reverse osmosis has been used for many years for the removal of water to increase sugar and flavour concentration. It is ideal for treating juices and musts that have become heavily diluted as a result of rain just before harvest. It is a superior technique for alcohol augmentation compared to the addition of sugar (chaptalisation) but has limited benefits where the grapes are green and under-ripe.

Wine concentration after fermentation is the preferred option when sugar levels are already high but the concentration of flavour, colour and other quality components is low. Concentrating the juice in this situation, results in increased sugar levels. These in turn lead to excessive alcohol levels in the fermented wine. Concentrating the wine instead does not increase the alcoholic strength significantly because alcohol passes through the membrane into the permeate and is not concentrated

How Does it Work?

The grape juice or wine to be treated is recirculated at high pressure through a reverse osmosis system which separates the juice or wine into two flows – permeate and concentrate.

  • Permeate the low molecular weight stream passing through a semi permeable membrane
  • Concentrate the bulk juice or wine stream which is retained by the membrane and contains almost all of the vinous components

The permeate stream generated comprises essentially water, in the case of juice, and water plus alcohol in the case of wine. Because almost all of the vinous components remain in the concentrate, the juice or wine becomes more concentrated if the permeate being processed is not recombined but simply put aside or discarded.

Typically, winemakers notice a significant improvement in wine quality with the removal of 10% to 20% of the original volume as permeate. This is a simple, quick and reversible technique.

Winemakers’ Questions concerning Memstar processes