Soak, roast, whack and roll: Swetha Sivakumar on how rice becomes poha

How do you turn a grain into a flat fluffy flake? Take a look at the science behind poha, and see which is better - thick flakes or thin. In this week’s Sound Bites.

Indians were consuming poha – flattened rice flakes – centuries before Dr John Kellogg patented his corn flakes in 1896. Both are popular breakfast foods, rich in carbohydrates and containing pre-cooked starches, which means they require little to no prep. Still, we don’t pour poha into a bowl of milk. And even before cooking, there are decisions to be made: to buy thin or thick, how long to soak, how to get that perfect fluffy texture. Thankfully, science can help.

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How is poha made, anyway? It starts with a long bath. Raw paddy is soaked in water for about eight hours so the grains hold more moisture (up to 30%). This increases the size of starch granules in the grain so they hold their shape for the roasting process ahead. When heated at about 170 degrees Celsius for 30 seconds, that starch gets cooked, its moisture content dropping down to 17%. Crucially, starch and water cook together, through a process called gelatinisation.

Then, some violence. The roasted paddy is literally whacked, disintegrating the starch and spreading it flat. The bran is removed, the grain gets polished, and with a final moisture content of about 14%, thick poha is ready for the shelf. There is a thin variety too. Thick poha is simply sent through another set of rollers, to flatten the grains further.

In the kitchen, poha recipes start with another bath. The starches in the poha are pre-cooked, but dried out (retrograded). We soak poha to increase moisture back in the grain. But soaking thick and thin poha in water has different effects on them. Thick poha will absorb water well, becoming the spongy grain we see at breakfast. Thin poha, on the other hand, has been so battered in the manufacturing process that it releases its starches into the water instead. Worse, when heated, the leached starch turns the water into gel – you end up with gooey upma, not fluffy grains of poha.

No one wants that. This is why cooks avoid thin poha, unless they’re making a fried snack or preparing dahi poha, in which the grains completely break down in the liquid.

Even thick poha can be fussy. Soak it too long, and the grain disintegrates when heated. Don’t soak it enough and those cooked starches on the inside stay dry and hard, similar to the texture of hard day-old-rice. Is there a hydration hack? Indore folks simply steam their thick poha. It’s the perfect way to keep the poha hot and moist without disturbing the structure of the grain. No constant stirring on a tava, risking grain breakage or a gummy mess. Hats off to them!

The retrograded starches in the poha play one more role. They do not absorb flavours as well as the raw starches do, which is why most poha dishes play on texture rather than flavour – crunchy fried toppings, chopped onions, pomegranate pearls, rather than heavy masalas or ground pastes. This is why it works so well for a simpler meal like breakfast.

So, there you have it, the science behind poha. Eat it hot, don’t let that starch retrograde on you. Oh, and don’t forget the crunchy toppings.

(To reach Swetha Sivakumar with questions or feedback, email upgrademyfood@gmail.com)