Information about Vinification

Malolactic fermentation

membrane filtration

Méthode ancestrale

Filtration media: surface filtration
Surface filtration (absolute filtration) causes the liquid to pass through a membrane with a specified size of holes: material smaller than the holes cannot pass through. The name reflects the fact that the filtration occurs at the surface of the filter instead of within it. This is also called membrane filtration or cartridge filtration. The disadvantage is that the holes can become blocked. The advantage is that the rigor of filtration can be set by choosing the mesh size. It can be used only at a late stage of production, after the wine has previously been cleaned by depth filtration or other methods. This is often the last stage before bottling, to ensure the absence of microorganisms. Filters come in sizes from 1.2 µm (removes most yeast), 0.8 µm (removes all yeast), 0.45 µm (removes bacteria), 0.2 µm (small enough to remove flavor components). Membrane filters are clogged by particles that can penetrate the filter. Clogging depends on the mix of particle sizes rather than on turbidity; this is measured in terms of the fouling index. Polysaccharide colloids are the biggest cause of clogging. Pectolytic enzymes reduce the effect. Glucan produced by botrytis is particularly powerful in clogging filters; addition of glucanase before filtration reduces the problem. Membrane filters may be used at bottling, typically where sterile filtration is required.