You cannot expect to produce clear wine from filtration alone. Passing a cloudy wine through a filter may not produce a good result as it is likely to clog the filter. Filter papers and pads perform much better when used for polishing a well prepared and reasonably clear wine. You can obtain this by means of simple enzyme and fining treatment beforehand.
Frequently, after fermentation and racking, the wine still remains cloudy with no sign of clearing. This can be due to hazes caused mainly by the presence of PECTIN and any wine filter kit has difficulty in producing brilliant wines where pectin is present. There is a need therefore, for treatment beforehand. Pectin is naturally present in wine making ingredients and is the substance which causes Jam to set. It can sometimes be recognised in the ferment as a kind of thick gel.
Prioritised list of ingredients which frequently cause PECTIN problems with Sloes being the worst:
|2||Currants -Black/Red||12||Sultanas or Raisins|
|3||Apples & Pears||13||Dates & Figs|
|9||Blackberries||19||Red or White Grapes|
You should always assume that pectin is present to some extent. To remove pectin, treat with Pectolase, an enzyme which breaks down pectin. This should be done preferably at the time of adding the yeast, or during fermentation. If added later you must then keep the wine in a warm place for 3-4 days. You can test for pectin prior to pitching the yeast by adding 3-4 fluid ounces (75-100ml) of methylated spirit to 1 fluid ounce (28ml) of wine. if jelly-like clots or strings form, then the problem is most likely pectin and should be treated with pectolase.
Starch is a white carbohydrate primarily present in root vegetables, cereals, bananas and unripe apples. There is a greater chance of starch problems if you boil these ingredients for too long. It will help if you use only cold water for the juice extraction when making these wines.To remove starch add a level teaspoonful per 4.5l (1 gallon) of Amylase at the same time as adding Pectolase.
After fermentation has completed, add finings to all wines that remain cloudy. Fining can remove up to 95% of the haze before filtering because In the wine there are millions of microscopic particles of all shapes and sizes that are too light to settle in a reasonable time on their own. It is the vast numbers of particles present that cause the haze and these particles can usually pass through the finest filter pads.
Finings cause these tiny particles to become attracted to each other, causing larger and heavier particles to form. These then fall as sediment leaving the wine much clearer. In racking off your wine you leave this sediment behind.
After filtering all hazes should have been removed. However, a further haze can develop later due to renewed fermentation. This is often due to filtering wines before they have finished fermenting. The blending of wines or even by adding sulphite may in some cases cause it. Whilst the wine is maturing, changes continue to take place and some bottling haze and/or bottom dusting can occur. In such cases uncork the bottles and pour the wine into a pre-sterilised jar. Allow standing for a few days, siphoning the wine into a clean jar leaving the sediment behind and then filter again. To prevent any further fermentation, it would be advisable to add a dose of Potassium Sorbate before bottling again.
White 'skin' or flecks in the wine; can be caused by lack of hygiene, or too much airspace in jars or bottles. To remedy this, filter again and then add 1 level teaspoon of Campden powder to each 4.5l (1 gallon). Let the wine stand for at least 6 weeks before sampling.
Thoroughly sterilise all equipment afterwards and always leave a minimum airspace in bottles and jars.
These recommendations are intended to get the best out of wine filtering. The information was obtained from Harris filters and we thank them for permission to use it in preparing this document.