I recently bought a fairly old bottle of wine (bottled in 2008) and I noticed that there was a bunch of schmutz clinging to the top third of the inside of the bottle after I poured a glass.
What is this and what does it mean about my wine? Is it a bad thing?
Sediment is normal in "older" wines, it can simply be small particles of yeast that was not caught by the filtration.
As time goes by, the particles will stick together and fall to the bottom of the bottles.
Most of the time it will not affect the (taste and flavor) quality of the wine, but will show up more when not being cautious when pouring the wine.
Just be more careful when pouring wine; you can also use a decanter.
Slowly pour the wine into the decanter from the bottle to let the sediment get caught in the shoulder of the bottle.
If there are sediments, you will loose maybe 1 teaspoon of wine; but you will be assured that the wine in the decanter will be free of sediment and when pouring for friends at the table there will not be any sediment in the glasses.
The particles and cloudiness might be one of two things:
If the particles don't settle to the bottom (form a sediment), it could be bacterial fermentation which is undesirable and it "spoils" the wine, producing off-flavors. If you sipped it thought it was "off", then best to avoid it.
If the particles settle, these are probably just excess acid molecules and that's okay.
Source: On food and cooking by Harold McGee
Sediment in wine, is not only a good thing, but can be seen as a sign of quality...or at least that the wine was made without filtration (which is often seen as a short cut). As you can see here sediment is made up of colloids and tartrates. If you remove the entire foil cap before uncorking and older wine, you can often see the sediment clinging to the neck of the bottle, if it has been stored on its side. It's a good idea to stand older bottles upright for a while before opening so that any additional/loose sediment will sink to the bottom. Then, once opened, you can decant or simply pour slowly from the bottle so as to avoid stirring up the sediment and pouring it into the glass (or decanter). The sediment is perfectly safe. It is an unpleasant experience, but not harmful if you happen to ingest some.
it is normal that older red wines hold some sediment. Usually, the sediment remains in the bottom of the bottle and becomes an issue when pouring the last couple glasses. In your case, I'd think that the bottle has been moved (a lot?) before you opened it?
With old red wines, it is best to store them "standing". At least for the 24h before intending on drinking it. Because then the sediment has time to falls to the bottom and accumulate there. And then it is best to decant the red wine. Use a decanter or any vessel fitting. It is best if the vessel has a flat base. Because then you can use for two things: 1. separating the wine from the sediment and 2. to continue with the actual decanting process.
"Sediment and crumbled cork that can often be found in, for example, older red wines and Vintage Ports. So pouring into a decanter can help by filtering and removing any sediment. As well as bitter tastes and flavours that are associated with aged wines." -quoted from a page I'll refer to later.
There are different ways of decanting. One of them is the candle method. Here is explained how to do it: How to use a wine decanter and The Candle Method The same page I quoted from. Well, that's how I do it. You can also read there about the decanting process if you're interested.
