This post might get a little geeky, so readers beware…
If you remember from the last post, I talked about the second fermentation that occurs in the bottle for the Methode Champenois. It is in this fermentation where the magic happens and where carbonation is produced.
I hope we all know the equation for alcoholic fermentation by now: sugar+yeast—–>alcohol + CARBON DIOXIDE (CO2). CO2 is linear molecule looking something like this : O=C=O. 2 carbon dioxide molecules are produced for every molecule of sugar during fermentation. The CO2 molecules float to the top(because gas is less dense than liquid) and get trapped between the liquid and the enclosure. Eventually enough CO2 will cause the pressure to increase in this space. As the pressure increases, so does the solubility of the CO2. The concentration of molecules increases and more wind up back into solution(more and more are coming into contact with the surface of the liquid). The molecules are essentially forced back into the liquid because this will best relieve the pressure that has been applied to the system. Henry’s Law states that: The solubility of a gas in a liquid is directly proportional to the pressure of that gas above the surface of the solution; the higher the pressure higher the solubility.
When CO2 is forced back into solution some of it does not remain as CO2, it is changed to carbonic acid by attaching itself to a water molecule. The molecular formula is H2O + CO2 <—> H2CO3. Carbonic acid is important because it gives champagne a noteworthy “zing”.
The pressure inside a champagne bottle is very large, and is roughly equal to pressure in a tire of an 18 wheeler. For this reason the bottles are made of thick glass and have a large bell or punt at the base(that indentation on the underside of the bottle). CO2 does not like to be trapped inside a bottle its like a prison for those little guys. When the pressure is released by popping the cork, the CO2 rushes to the top. This is known as effervescence and the smell of the erupting CO2 can be quite beautiful.
When you pour champagne in a glass you will notice some strings of bubbles streaming from one or several parts of the glass. This stream of bubbles is called the perlage. Some people think that the more or less you have of these streams of bubbles the better your champagne is. Well that is totally false. The streams of bubbles occur because of small defects on the surface of the glass. These defects trap the tiny carbon dioxide molecules and the gas bubble begins to grow until it expels gas. This process repeats itself until you have a stream of bubbles. So essentially, the more streams you see, the cheaper your glass is. The most important thing to look for in bubbles is the size. In this case, the smaller the better. Smaller bubbles make the wine feel creamier and more elegant on your palate. Take for example club soda, these bubbles are large and aggressive compared to those of fine champagne. I don’t know about you but after all this champagne talk, I am gettin pretty thirsty.
If you’ve ever had a sweet liquor like anisette or blackberry schnaps you will know that mouth coating smoothness , roundness and richness that I am talking about. A bottle of dry wine can contain anywhere between 10-15% of alcohol, of course there are certain exceptions in either direction. Sugars can range from any where between .1-1%. Most dry red and white wines fall between .02-.05% to give you a rough estimate.
Depending on the type of wine being produced, wines can be fermented to dryness or fermentation can be stopped leaving residual sugar creating a “sweet” wine. The alcohol produced is ethanol. Another type of alcohol that is produced in the fermentation process is called glycerol. This type of alcohol contributes slightly to the presence of sweetness and smoothness. Glycerol is also found in soaps, used as sweeteners in food products, bio diesel, and is a precursor to the explosive nitroglycerine. Another interesting fact about glycerol is that even though it tastes sweet, it does not raise your blood sugar levels because it is not metabolized by the same biochemical pathways as are “conventional” carbohydrates (starches, sucrose, fructose, glucose etc.).
Well there are 2 hydrogen molecules bound to one oxygen. Think of oxygen like a negatively charged magnet and hydrogen as a positively charged magnet. These atoms are naturally drawn to each other, making an H2O molecule. To give you an idea of just how small atoms are imagine taking a glass of water and say you were able to label all the atoms in that glass. Then you took that glass and dumped it into the ocean and mixed all the oceans with a huge spoon. For all intents and purposes we’ll say that the glass of labeled water is now evenly distributed in all of the oceans. Now if you were scoop up a glass of water from any ocean you would be able to find 7 of those labeled atoms. Pretty small right?
