Wine is, in essence, a colloidal suspension – that is, a mixture in which small particles are dispersed throughout a liquid. Over time, two things happen. The first is that gravity will naturally draw these particles to the bottom of the liquid, in this case, a bottle of wine. Secondly, the particles will polymerise. That is, they will join together to become bigger molecules. This makes them heavier, and they come out of suspension sooner.
It’s important to understand that the sediment in wine is purely natural. In fact, it is a sign of a wine that has not been overly treated by excessive fining or filtration. In red wine, the sediment will comprise two principal types of molecules: anthocyanins and tannins. Anthocyanins are natural substances from the grape itself, part of a molecular family known as the flavonoids, which give the wine its colour. As these polymerise and settle, the wine will become lighter in colour, and shift on the spectrum from more blue towards more red. Tannins are sourced from both the grape itself and from oak ageing. As these polymerise, the wine will become softer and less astringent in the mouth.
Detritus Matter Does Not Shine Like Glitter
The level and amount of sediment in a bottle of wine will depend on and its grape variety and its age. White wines may throw tartrate crystals, but will rarely have sediment per se – although very old whites may have some. Deeper and more tannic grape varieties such as Cabernet Sauvignon will tend to have more sediment than lighter grapes such as Pinot Noir. Older wines will tend to have more sediment than younger ones. A fine red wine of 10 or more years of age will almost invariably have some sediment in the bottle.
If a bottle has been lying on its side in one position for many years, some sediment will probably be stuck to the inside of the bottle where it has been lying. However, if it has been recently moved, especially if it has been jolted around somewhat, there may well be sediment that has gone back – briefly – into suspension. In this case, the wine should appear somewhat cloudy for a day or two.
Sediment is, in effect, dead organic matter, and so should appear dull in colour. It should also appear flaky rather than granular in shape.
A Sparkly 1894 Lafite
What To Look For
The first thing to check is whether or not there is sediment. If you are looking at a white wine, there may be a little, but with few tannins and no anthocyanins, sediment should not be excessive. Tartrate crystals may be present. If, however, it is a red wine, there should be sediment commensurate with its age and grape variety (see above). The absence of sediment should be a major warning sign.
Check to see how the sediment is lying – has it stuck to the glass at all? A very old bottle should show some signs of fairly fixed sediment if the wine has been lying on its side for a considerable period of time. If there is no adhesion to the bottle, this could be a sign of frequent movement, or that the wine is not what it purports to be.
Finally, have a look at the sediment itself. To do this, shine a light through the bottle up through the sediment. It should appear a dull red or purple colour, never shiny. It may be black, but should not be grey. In a red wine it should also appear as flakes, not as globules or granules. In a white wine, there may be tartrate crystal deposits, which should look like lumps of white sugar or glass in the wine. It should never, ever, be sparkly.
There are relatively few anti-counterfeit measures that producers can take specifically with respect to sediment, although there are some that will reduce the risk. Principal safeguards include bespoke printing on the cork and capsule, and bubble tag or strip technology on the cork and capsule to guard against refilling.
Although producers are limited in their actions, it’s important to note that consumers and restaurants are not. The risk of bottles being taken from trash or recycling is much higher at commercial premises. As a result, many top-level restaurants – at least, those with an understanding of the problem of fake wine and a commitment to helping reduce it – will break their bottles before putting them out for recycling or rubbish collection. Less scrupulous restaurateurs will not do this, and some will even help facilitate a fraud. Famous wine fraudster Rudy Kurniawan persuaded Robert Bohr of Cru Restaurant in LA to ship him the (unwashed) empty bottles from the restaurant, so he could reuse the sediment as well as the bottles.
It can be hard for consumers to break all their bottles – not least because domestic recycling collectors will often refuse broken glass. Even where they do accept it, it can be dangerous to break bottles around a home. The solution here is to rinse out the bottle, so that there is no sediment left. To be extra-safe, a truly vigilant consumer could mark the bottle with “invisible” ink, noting the date consumed.