Article by Charl Theron – Vino Fino Oenological Advice – www.wineland.co.za
The purpose of wine filtration is to clarify the wine. The degree of clarity depends on the stage of the vinification process. For example, just after fermentation a wine will be much less clear than just before bottling. This will determine the kind of filtration to be used. Four different kinds of filtration can be used:
1. Filtration with a filter aid.
2. Sheet or pad filtration.
3. Membrane filtration.
4. Cross flow filtration.
Filtration with a filter aid was discussed in a previous article. The filter aid is continuously dosed into the wine to ensure that the filter does not block too quickly. This kind of filtration is normally used to filter wine from the lees. Although it is able to filter large volumes of wine, one of the biggest disadvantages is that large volumes of used filter aid are being created as waste at the cellar.
Sheet filtration is the method that has been in use the longest in the wine industry. Filter sheets consist of cellulose and other material which is placed between the frames of the sheet filter, whereafter wine is pumped through it. The filter sheets have to be selected according to specific grades such as EK, K7 and K5, depending on the objective of the filtration. Handling, packing and preparation of the filter sheets must be done carefully for the filtration to be applied correctly. The cloudy particles in the wine are left behind on the filter sheet, either because of the thickness of the filter sheet or because of adhesion, and the clarified wine flows out at the other side of the sheet. Sheet filtration is done mostly just before bottling for the final clarification of wine …