B. C. Rankine1,2, W. W. Emerson1,3
1Australian Wine Research Institute Adelaide South Australia
2Australian Wine Research Institute, Adelaide.
3Division of Soils, C.S.I.R.O.. Adelaide
Tóm tắt
AbstractAddition of bentonite to young wines is a normal clarifying procedure widely used in Australian winemaking. Flocculation is usually rapid but poor flocculation has been observed, particularly in wines which have been passed through a sodium cation‐exchange resin to prevent deposition of potassium bitartrate.The behaviour of bentonite in wines treated by cation‐exchange resin was examined in detail. Dispersion was associated with a high proportion of sodium and a low proportion of calcium and magnesium, in conjunction with the presence of a dispersing compound of high molecular weight. Results were consistent with the dispersing agent being a negatively‐charged carbohydrate. Such a compound was shown to be present by electro‐phoresis. Flocculation in wines treated by a cation‐exchange resin will then depend on the relative amounts of this carbohydrate which disperses bentonite, and protein which flocculates it.Some commercial bentonites flocculate much more easily in low concentrations of divalent cation than the natural sodium bentonites, but these were found to remove protein far less effectively.In practice, bentonite fining should be carried out either before cation‐exchange treatment, or a protein such as gelatin may be added to the treated wine to ensure flocculation.
