Wine fining is little understood outside the winemaking community. When someone reads the back label, they often get a confused look with “Do you really put milk in wine?” We do in fact put a few things in wine that sound quiet strange but once the process is understood is really quite simple.
Wine fining is a “pass through” operation meaning you add a little milk, stir it up, it combines with a few molecules and settles out. After a few days you pump the wine off the settled lees and voilà, it tastes better. Although there is unlikely to be any detectable milk left in the wine it is required that any allergens be listed on the label.
Milk isn’t the only thing that can be added to wine… There are a few other things we can fine the wine with like egg whites, gelatin and yeast hulls. The object of fining is to improve the taste, smell, colour, clarity and stability of the wine. Through experience winemakers usually have a reasonable idea of which fining agent is going to be most effective. However, things change from wine to wine and year to year so it is always best to set up a group of fining trials to see what has the most desired effect.
When setting up a fining trial I line up heaps of 100ml sample bottles using a series of five rates for each fining agent to be evaluated. The fining reaction happens quite quickly so the bottles are stirred, settled overnight and compared the next day. It requires a lot of concentration with particular focus on the colour, clarity, aroma and the exact spot in the palate that you want to improve. The object is to use as little fining agent as possible to remove the offending molecule from the wine because fining agents will usually remove some desirable molecules from the wine as well as the bad guys.
Fining agents have varying modes of action but many work because molecules have electrical charges, so when adding a fining agent with an opposite charge (+ or -) they bond together and become large enough to settle to the bottom of the tank. Each fining agent reacts with molecules of different size or electrical charge so the successful fining agent will be the one that forms a bond with the offending molecule in the wine and drags it to the bottom of the tank.
Not all wine needs fining, however since grapes are a natural product exposed to all kinds of elements fining agents can correct for damage caused by rain, hail, sunburn, insect damage etc., every year is different.
Hope to see you soon and I promise not to hit you with a big wack of “winemaking 101” when you visit Cellar Door.