Grape expectations: Swetha Sivakumar on the science of wine

The recipe for wine is simple enough. But what unfolds in the barrel is a process so intricate that it was only decoded, by Louis Pasteur, in the 1800s.

As Valentine’s Day nears, with its promises of sugar and spice, let’s drift past the hearts and balloons and peer into a glass of wine.

The process depends, eventually, on the consumption and excretion patterns of a living thing – yeast – over an extended period. As a result, dramatic variations can occur, in ways that remain unexplained, even today. (Shutterstock)

From a scientific perspective, this is a fascinating liquid. The recipe seems simple enough. What unfolds in the barrels is a process so intricate, however, that it was only decoded, by Louis Pasteur, in the 1800s.

Most wine is made by pouring the juice of grapes into large vessels, and adding yeast (which is technically