Have you ever thought that it is weird that winemakers add milk, fish and egg products to wine? Here is why.
As the grapes are processed into wine, we add products and do things to the wine to stabilise it. We ‘stabilise’ it so that it will remain clear, fresh and fruity after you have bought it
Making crystal-clear wine is an important objective in white winemaking. Grape juice and wine contain many naturally occurring particles and compounds. Here is a summary of the products we add and why:
- Skim milk removes any brown colour and phenolics (the gritty sensation when wine is drunk). Skim milk is not a harsh fining agent
- Fish products help the juice to clear up by acting as bridges between the tiny particles that otherwise make the juice cloudy. These tiny particles join together via these bridges and then sink to the bottom of the tank so the clear juice can then be pumped away
- Gelatine can be added to remove phenolics. However it also removes flavour and aroma precursors so if the juice has a lot of phenolics a small amount of gelatine and a larger amount of skim milk are used
- Bentonite is a special clay helps remove protein from the juice and/or wine. If it is not removed a haze can form if the wine gets too warm (for example left in a warm car)
- Egg whites can be added to red wine to help remove some tannins
With the exception of egg whites it is best to use fining agents at the juice stage so that you aren’t affecting the flavours and aromas that the yeast have produced during fermentation.
We also stabilise white wines by chilling them to -4 degrees C and hold them at that temperature for one week. This makes crystals form and the wine is then filtered. If this is not done the crystals will form when you refrigerate your bottle of wine. Sometimes these crystals are mistaken for glass!
Red wines are usually fined less because they are aged before bottling. Generally throughout the aging process, tiny amounts of oxygen enter the wine and soften the wine by acting as a bridge between tannins and colours. These tannins and colours drop out hence making the wine softer.