What's that in my bottle?
Sediment, crystals, sludge or wine diamonds? Potassium bitartrate in white wine. KHT, tartrates or KC4H5O6
Occasionally you may find crystals in the bottom of the glass or bottle. Most likely these are "wine diamonds" - crystals formed when the wine is chilled and the naturally occurring potassium and tartaric acid combine to form a precipitate. Potassium bitartrate is exactly the same cream of tartar that is used in kitchens around the world, so yes, it is completely safe!
In a red wine this precipitate can look like sludge as it will have anthocyanins (colour) and usually tannins and some other “long-chain” molecules – you may know these as proteins and starches.
Winemaking Balance: Flavour, Texture and Colour in Every Glass
We work hard to have our wines clean and shiny when they arrive on your doorstep or in your glass, however, wine is a complex creation and there is always a balance between maximising flavour, texture and colour and creating a stable/inert product. Many small wineries don’t filter for this reason as they chase flavour and complexity; most larger wineries do as they sell to a more diverse market. We have always kept this in mind and now that we are totally organic and also working on increasing our sustainability it has added an extra degree of complexity.
Organic and Sustainable Winemaking: A Complex Endeavor
Chilling a tank of wine is incredibly energy intensive - think about how long it takes to freeze a large bottle of water. A tank of wine could be 4000 litres up to 40,000 litres or more - 4 to 40 tonnes! The wine then needs to be heated to about 20° C prior to bottling - another massive energy input. Most of our tanks are in the 4,500 to 20,000 range so as we try to be more energy efficient, we are really trying to reduce this heating and chilling. On top of the global warming considerations there are also some really good quality reasons to not mess around with temperature - chilling to near freezing may lead to a loss of flavour and heating can also reduce aroma.
Wines that are aged for longer before bottling tend to leave most of the crystals in the barrel or tank so are generally more stable in the bottle.
Hopefully this helps reassure you that Australian wine is safe to drink – in moderation – even if you find some "goodies" in the bottom of your glass or bottle!
References: https://en.wikipedia.org/wiki/Potassium_bitartrate
Further reading - other winemakers thoughts:
https://www.jordanwinery.com/blog/tartrates-in-wine/
https://www.decanter.com/learn/advice/tartrate-crystals-in-wine-346248/
https://www.stonestreetwines.com/tartrates-crystals
Technical:
https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/potassium-bitartrate
