The Importance of Sugar Chemistry in Taste Perception of Wine
The structure of sugar molecules is very important to its function in biochemical reactions. The empirical formula (or ratio of elements) for sugars is Cn(H2O)n. So for every carbon ©, there is one water (H2O). However, the structure is not similar to water, it just has the same ratio of molecules.
This molecular ratio is the basis for the name of sugars, carbo-hydrates. The name carbohydrate also indicates its relationship with water. Sugars are water soluble, which means they dissolve in water. This has important consequences in the grape growing and winemaking process.
Sugar molecules also play an integral role as molecular precursors. This means that other important chemicals are built from the atoms of sugar molecules. For example; citric, malic and succinic acid are made from glucose in the aerobic glycolyse pathway.
However, the most important function of sugar is its role in alcoholic fermentation. Fermentation was one of the first biochemical energy producing reactions to develop in nature. This is why it is seen in yeasts ; one of oldest organisms on earth.
Alcoholic fermentation begins with glycolysis (glucose splitting). Glycolysis is one of the fundamental processes that life was built on. Almost every organism on Earth uses glycolysis for energy. The reaction looks like this:
> Glucose = > 2 Pyruvate + Energy + CO2
This may look very foreign, but it is of critical importance. This reaction is probably happening in the majority of your cells as you read. But how does this relate to wine?
The next step for animals is aerobic respiration. This is where we use oxygen to make energy, and lots of it. But for yeast and bacteria, the next step is alcoholic fermentation. They use the pyrvuate molecules to make energy, with alcohol as a byproduct. What a wonderful process. Fermentation looks like this:
> Pyruvate + NADH = > Ethanol + NAD + H+
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