Brix is a measure of sugar content in the grapes. Now I'm neither a winemaker nor a scientist but I do know that degrees of brix is the percentage of sugar that exists in the must (fermenting grape juice). Every degree of brix is roughly 1% of sugar or, for every 100 grams of grape juice there is 1 gram of sugar for every degree of brix. Got it? If the grape juice has a brix degree of 22 then approximately 22% must be sugar. When yeast works on the sugar .... (a favourite saying relating to lazy people is "he/she wouldn't work in a barrel full of yeast) ... the sugar is converted to ethyl alcohol and Carbon dioxide. About 55% is ethyl alcohol. A rough calculation to work out how alcoholic the wine is going to be is:
Brix x 55% = alcohol.
There are other variables like type of yeast, how much sugar there was to start with (too much limits the yeast activity at the high end etc) but this is a good simple guide.
What this means is that in cool growing areas or in a cool growing year like 2012, on average the grapes grown are very likely to have lower brix levels than in warmer areas or in a warm growing season.
What do the winemakers do if they don't want to have wines with lower alcohol?
Firstly, why do they want higher alcohol?
Body is the simplest answer. By this I don't mean that they want to get lots of this ...............
although alcohol is a great inhibition loosener and might mean some winemakers will get lucky .......no, body is the 'weight' or 'mouth-feel' of a wine that gives it balance. If a wine is light on alcohol and not counterbalanced by sweetness then it can taste thin. The ideal alcohol level for most dry wines is between 12 and 14%. Higher and they can become unbalanced and taste 'hot' unless there is a great amount of fruit and tannin and good use of wood
|High in alcohol and unbalanced|
lower and they can taste thin and weedy unless they are medium sweet or sweet.
What a winemaker does, if the brix levels are low and the resultant wine is likely to be 'thin' is to add sugar to the must to bring up the potential alcohol. This is called 'chaptalisation' and is allowed by winemaking law in most civilised countries. Some exceptions are Australia, Argentina, Italy, South Africa, USA (except Oregon) which is surprising given the power of the sugar lobby in a couple of these countries and given that 'pure-white' sugar is the best additive.
There is a downside. If there wasn't why grow grapes if you could just ferment some sugar. Chaptalised wines (and most countries limit the amount that can be added) tend to 'flatten' out the flavours. This is not surprising as there will be a lack of that natural grape -juice 'zing'. Imagine having a teaspoon of sugar and water vs a teaspoon of grape juice. The grape juice, even if the same sweetness as the sugar/water mixture will have other interesting flavours and acids. The
So, to recap - if the harvest is a bit poor and the resultant wine is likely to be thin and medicinal - do a Mary Poppins and add a spoonful of sugar.
Who is likely to do best in the 2012 vintage?