Home made wine can be filtered to improve its clarity, but not to remove cloudiness or hazes. Filtration is fine for early-drinking wines, but best avoided for long-maturing wines like elderberry because it can interfere with how their body develops over time. Kit wines don’t usually need to be filtered.
Filtration is an issue that has divided home wine makers for years. On one side you have the purists, insisting that the single ingredient that clears wines best is patience. On the other side, you have the pragmatists – people who aren’t interested in complex or long-maturing wines, and simply want to produce an attractive, drinkable wine in as little time as possible.
While this argument has been going on, filter manufacturers have been quietly working away to improve their products. Modern filters are simple to use and there is very little risk of damaging the wine. But despite what the makers say, there’s probably no need to filter wine as a matter of routine. At the heart of the matter there is this simple truth: filtration is a tool for polishing a wine that is already clear – not for clearing a cloudy or hazy wine.
There’s absolutely no doubt that filtering wine improves its appearance. We’re talking here about the difference between wine being ‘clear’ (i.e. not visibly cloudy) and being ‘brilliant’. ‘Brilliant’ wines have no suspended particles, so they really catch the light and show off their colour. We’re well used to mass-produced wines being ‘brilliant’ because they are filtered to improve their storage qualities.
It’s worth mentioning again that you can’t filter cloudy wine, because cloudy wine still has lots of junk floating around in it. This will block the filter in no time, meaning you have to dismantle everything and risk ruining the wine. Don’t do it. Filtration is done after your wine has already cleared – or nearly so – and been treated with suitable finings.
Filtering wine makes it store better because it removes most live yeast cells and proteins. This means that the wine is less likely to undergo a secondary fermentation which can cause cloudiness and burst bottles. It also means that it should not throw hazes or sediments while you store it, which can spoil its appearance.
Filtering wine doesn’t improve its flavour, but provided you choose a filtration kit that excludes as much air as possible (such as the Vinbrite, pictured) it shouldn’t damage it either. There are, however, a couple of BUTs.
Secondary fermentation (see stability, above) isn’t always a bad thing. A wine that is given time to clear naturally can sometimes undergo a ‘malo-lactic fermentation’ (where ‘sharp’ malic acid breaks down to ‘buttery’ lactic acid). This can transform a wine into something you really want to let your friends try – although you might insist they only get a tiny glassful!
Removing dissolved protein isn’t always a good thing, either. In full-bodied wines that traditionally take a long time to mature, a lot of complex chemistry is still going on after fermentation is complete. In other words, the processes that eventually lead to sediment formation are part of what makes these wines ‘mature’. Filtering them out early can mean that the wine doesn’t mature properly, and instead stays flat and uninteresting.