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Masala Lab: Why your granny was right about cooking rice

Decoding the science of rice to maximise nutrient intake and answer the eternal question—how much water is too much?

Illustration by Krish Ashok
Illustration by Krish Ashok

Rice is the seed of an erstwhile tall grass that, thanks to human ingenuity a few thousand years ago, was domesticated by the cunning use of a transplantation technique aimed at stunting the height of the original wild plant, which was too tall to be practical for harvesting. It now feeds more people on the planet than any other food crop.

The seed itself is designed to nourish the next generation of rice plants and is thus protected by a fibrous husk that is largely inedible unless one is a cow. Underneath the husk is the incredibly nutritious bran, which contains micronutrients, proteins and also fat—the latter, when extracted, becomes rice bran oil. This is why brown rice, which is rice with the bran left intact, has a very short shelf life; fats tend to go rancid over time with exposure to air. So, if you buy brown rice, store it in the freezer to extend its shelf life.

The most common kind of rice that we normally eat is therefore polished, meaning that the husk, bran and germ (the next-generation baby rice plant) have been removed, leaving behind just the starchy endosperm. Polished white rice has a fantastic shelf life and can last for years as long as you keep bugs away. Wheat, on the other hand has a very short shelf life in the form of flour, and storing the whole grain is largely useless unless you have a flour mill at home.

And since the endosperm is mostly just starch, a diet based entirely on polished raw rice will result in micronutrient deficiencies. So it is parboiled before being dehulled and polished, and that pushes a lot of the nutrients from the bran and germ into the starchy endosperm, significantly improving its nutritional qualities. Most rice-eating cultures tend to use both raw and parboiled rice. In south India, for instance, the rice used to make idli or dosa is parboiled rice, while the rice used in regular meals tends to be raw rice. But it is now common to see parboiled rice being used more frequently in the main course as well.

And this brings us to starch—long chains of sugar molecules that, in a balanced diet, provide close to 50% of our daily calories. In rice (and in every other starchy food), starch exists in the form of two kinds of molecules—amylose and amylopectin. The former produces a firm, waxy texture when cooked and the latter, a gelatinous, sticky goo. The ratio of amylose to amylopectin determines whether the rice will turn out grainy and separated (like basmati, which has a higher amylose content) or stick together (like ponni or gobindobhog).

So, let’s get cooking now. For the purposes of this column, we will focus on how to cook rice perfectly for both plain steamed rice or a pulao. For pulao, you need to pick a high-amylose variety of rice basmati or seeraga samba (which, in my personal opinion, blows away basmati when it comes to aroma). For plain steamed rice, pick a low-amylose variety like gobindobhog.

You now have two options—you can use a pressure cooker or cook in an open vessel. A pressure cooker rarely results in the kind of perfectly fluffy rice texture you can get from open pot cooking.

The very first thing you will need to do is wash the rice thoroughly till the water you are using to wash it runs completely clear. What is happening here is that you are removing all the loose amylopectin on the surface of the rice grain. Amylopectin, when cooked, will cause the grains to stick to each other, and we do not want that in a pulao. The next step is to soak the washed rice for at least 20 minutes. This will result in a more evenly cooked finished product.

Now comes the mother of all rice cooking challenges—estimating the right amount of water. But this is a challenge only because most food writers are giving wrong advice. Measuring water in terms of volume ratios (cups) is wrong and tends to throw off cooking newbies regularly. The scientific way to do this is to learn from your grandmother—she will add enough water to the vessel till it comes up to the first knuckle of her index finger placed above the level of the rice. To understand why this is the right way requires us to first appreciate how much water rice needs to absorb to get the perfect pulao texture. The answer to that is, rather surprisingly, a ratio of 1. A cup of rice absorbs a cup of water, and the only reason we add more water is to account for evaporation. The problem with using ratios is that it will work for small amounts of rice and fail spectacularly if you are cooking for a family gathering. Using four cups of water for two cups of rice will result in congee, not pulao. The index finger heuristic, on the other hand, estimates the amount of extra water above the surface of the rice that will be lost to evaporation, and that’s why it works reliably.

Now that you have added water, bring it a boil and let it simmer at high heat till the water reaches the level of the rice. At this point, the starch has gelatinized, and we want to let the rice slowly absorb the remaining water without turning into mush. So we lower the heat to a minimum, close the lid and wait 10-12 minutes for the remaining water to get absorbed. But we aren’t done yet. Now turn off the heat and let the rice sit for 15 more minutes. What happens now is a process called retrogradation, where the starch granules that were broken by the process of gelatinization at high heat recrystallise, resulting in perfectly separated and fluffy grains of rice.

Now that you know how to cook rice perfectly, all you have to do is start with hot ghee, add spices and other ingredients of your choice and then add the rice and water—follow the method above and you can make an infinite variety of rice dishes.

Illustration by Krish Ashok.
Illustration by Krish Ashok.

Masala Lab is a fortnightly column on practical food science in the Indian kitchen. Krish Ashok is the author of Masala Lab: The Science of Indian Cooking (to be published Dec 2020). @krishashok

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