How much water do use while cooking rice?
The answer, of course, depends on the type of rice you are using and how you want it to turn out. Nevertheless, the quantity of water has to be optimal. Too little water, and the rice turns out uncooked and hard to bite into. Too much water, and it turns into a slurry mush.
Most people use one of two approaches to get the best results:
A. Measure ratios of rice to water (e.g. 2 cups of water for 1 cup of rice)
B. Ensure that the water level is 1 knuckle above the immersed rice in the vessel (The ‘Indian Grandmother’ technique)
Which of these methods is more scientific? Can you hazard a guess?
To answer that question, let us delve into the science of cooking rice. Rice grains are mostly starch, and for this starch to gelatinize (cook properly) the center of the grain needs to reach 65 degrees Celsius. For this to happen, the water around the rice needs to be at 100 degrees Celsius.
Since water boils at 100 degrees Celsius, rice and water in equal quantity might seem to make sense. However, the catch here is that the water around the rice evaporates as we cook. This water needs to be compensated by adding a little more when we start off, and the crucial factor here is the shape of the vessel we use. A wider vessel loses more water to evaporation than a narrower vessel. Therefore, cooking rice in a pan would require more water.
Once we have understood this, we realize that the water level above the rice turns out to be more crucial than strict ratios. By sticking to ratios, when the quantity of rice is large, one stands the risk of adding too much water, since all that water collects above the rice that settles below. Ergo, rather counter-intuitively, the grandmother’s method of one knuckle higher than the rice level is more scientific than fixed ratios.
The world is too complex for the simple, intuitive heuristics we use to understand it. In this case, a method that intuitively seems more scientific (ratios) turns out to actually be less scientific. The key is to not stop at intuition, but to dig deeper for an explanation.
Good scientific theories are foremost good explanations – not measurements or extrapolations.
Inspiration: Masala Lab