Sugar

Sugar, n. shoo-gar, a sweet granular substance, obtained from sugar cane, and also from beet, maple and other plants; any kind of various sweetish soluble carbohydrates, as glucose, dextrose, saccharose, etc[chem.]; flattery[fig.]: a. made of sugar : v.t., to impregnate, season, cover, sprinkle, or mix with sugar, or as with sugar ; to sweeten. (Fr. sucre.)

Sugar means raw alcohol. When you feed sugar to yeast, it miraculously gets turned from a boring white powder into fizzy gas (carbon dioxide), and a simple molecule called ethanol.

Ethanol, or alcohol as it is usually called, is the stuff that breathes life into our wines.

The amount of sugar that is added, and the time it is added has been the source of more debate in the field of winemaking than any other subject. This is perhaps surprising when you realise how little it matters. It's primarily a matter of tase.

At one extreme the amount of sugar must be merely sufficent to produce the minimum percentage alcohol to preserve the wine. This coresponds to about 10% alcohol by volume. This means about 1 kilo of sugar added to a gallon of wine-to-be.

Another extreme states that the more sugar you add, the stronger the wine, which has got to be good. This is a valid point, but if you add so much sugar the yeast falls over drunk, you are left with undrinkable syrup.

The amount of sugar per unit liquid is measured with a hydrometer, which is a sort of glass floaty thing with lines drawn on the side. Technically, it measures the specific gravity, but that's only interesting if you want to take this game seriously.

Through experiment and argument, it has been decided that a wine should be started with a specific gravity of 1090 to 1100. To achieve this, either keep adding sugar and testing until the gravity is correct (fiddly), or just throw in a pack and a bit of sugar and hope it's about right (unpredictable).

If you work it out, a gravity of 1100 corresponds to around 42oz or 1.2kg of sugar per gallon. Don't worry too much about accuracy in measuring the sugar you add, the sugar contained in the ingrediants you use will make it impossible to gauge accurately without a hydrometer.

As with all things of this ilk, adding too much is worse than adding too little. You can always add more sugar later if you fancy a sweeter or stronger wine (often when you try to get one, you end up with the other. C'est la vie)

As a rule, if things go reasonably well, your wine will usually end up at about 15% alcohol by volume.