Grapevine & Wine 06/06/2011

Gum arabic to soften wines

Contraindications to the excessive use of this enologic additive. A correct procedure avoids filtration problems

CEE 822/87 regulation and following modifications has permitted the use of gum arabic for a long time already. The use in cellars is more and more common because, high doses of gum arabic soften wines. A few studies indicate that gum arabic alter the volatility of some aromatic compounds, through two types of actions:

- chemical bonds with different organic molecules

- influence on the mass transfer velocity of the liquid mass to the olfactory apparatus

It is necessary to recall that normally suggested doses for tartaric stabilization, which should be the primary function of gum arabic, that is 10-15 g/hl, are not sufficient to make this function possible, thus inducing to use much higher does, like 400-500 g/hl

Such doses, though, can cause issues on the enologic procedures, in particular on filtration, often associated to the wine from the beginning, e.g. microbiologic alterations, not correctly executed "clear", and initial rheological properties.

As a consequence, it is necessary to use stabilized gum arabic, practically pure, with a strong reduction of the clogging power. Gum arabic is a natural gum of the “Acacia Senegal” tree and other African acacias, composed basically of a polysaccharide of araban, galactans, and uronic acids. Gum arabic is extracted in form of blond or reddish buds or tears, with a delicate flavor and basically no smell. Normal industrial purification consists in removal of tannins and impurities. It can be traded in diluted form (20-30%) and after adding stabilizing compounds (citric acid and sulphur dioxide), and this is the reason of the most interesting features of this product, since doses of 500 g/hl can be reached without contraindications and with a backfilling index which appears unaffected by the contact with the gum arabic in 12/24 hours.

di Graziano Alderighi