Sediments in Wine: ‘Out of School’ With Annabel Jackson

Wednesday. 31 October. 2012. 10:00 am

Annabel Jackson talks about the “bits and pieces” of wine.

In class, there’s an often extreme fascination with looking at the wine in the glass. I duly explain that the colour of the wine is the first clue as to the age and condition of the wine. Case in point, just the other day I opened a 2010 bottle of Italian Chardonnay and was immediately suspicious of the rich colour, and double-checked the vintage, expecting it to be a 2005 or thereabouts.

The nose was well developed and on the palate the acidity had all but disappeared. Once I also ordered a glass of Pinot Grigio and what emerged was similarly richly golden. I said to the waiter that it was obviously not Pinot Grigio, but he brought me the bottle to prove that it was. The producer? Yellowtail.

So examining the wine in the class is well worth it, though I get the impression that students are expecting a quiet revelation when they hold up the glass at often impossible angles. Perhaps a genie will appear – to help reveal the secrets of wine so that they can pass their exam with a high grade?

And then they start complaining about all the “bits and pieces” they find in a wine. One time it’s tartrates, another time some sediment, and perhaps some tiny little pieces of cork. Of course none of these are at all harmful and in the first two cases, tend to speak of a wine’s quality, and a winemaker’s non-interventionist policy.

The presence of tartrates – which is actually tartaric acid that combines with a wine’s naturally occurring potassium content and looks almost like shards of broken glass – can be avoided though the process known as cold stabilization, when the wine is brought almost to freezing point.

Sediment occurs during a number of stages. One is during the fermentation process when the so-called “lees” sediment, consisting of dead yeast cells, proteins, stems, tiny pieces of grape skin and so on, settle at the bottom of the fermentation tank.

Wine is left “on the lees” for a while to develop additional character and complexity, and the lees are later separated from the wine. More sediment can form while the wine is ageing in barrel, and the wine is usually removed from these lees through a process known as racking – the clear wine is separated from the solid matter and moved to another barrel.

The third time it occurs is when a red wine has been ageing in bottle for some years. This kind of sediment is formed from tannins and other solid matter that gradually gathers at the bottom of the bottle, or on the side of the bottle, if the wine has been stored lying down.

Finally, little pieces of cork floating in the wine are usually there because of careless opening of the bottle. And for that, the students have no one to blame but themselves.

Annabel Jackson has been involved in the wine industry for more than 20 years, variously as educator, writer, public relations consultant and event organiser.

Read past Out of School columns here.