Why does rice expand by more than the liquid volume it's cooked in?
Does air get trapped or sucked into the rice during cooking?
Best Answer
Starch is composed of two polymers (linked chains) of glucose (sugar): Amylopectin and Amylose. Amylopectin is a branched and much larger molecule than Amylose.
Starch molecules in a grain of rice are actually arranged in a semi-crystalline state. The granules are about 2?m in size in rice (different plants have different granule sizes).
Starch becomes soluble in water when heated. The granules swell and burst, the semi-crystalline state is lost, and the smaller amylose molecules leach out and form a network that holds water. Although the network of molecules holds water, it will of course have a larger volume than the volume of neatly-aligned molecules plus water. This process is called gelatinization.
So you can imagine that in a dry rice grain, the strands of starch are like the fairly neatly stacked threads in my T-shirt, some shorter, some longer branched nets. As you heat it, the threads get moving and tangled up, absorbing the water, but also expanding even more in size like that big mess of lint in my clothes drier.
A similar process happens with popping corn, except the water is contained in the kernel of corn and not added. It's quite apparent to see how much larger the volume of a bowl of popped corn is compared to the small package of unpopped corn with water inside.
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Quick Answer about "Why does rice expand by more than the liquid volume it's cooked in?"
The granules swell and burst, the semi-crystalline state is lost, and the smaller amylose molecules leach out and form a network that holds water. Although the network of molecules holds water, it will of course have a larger volume than the volume of neatly-aligned molecules plus water.Does rice increase in volume when cooked?
Most varieties of rice absorb roughly twice their volume of water, so at the end of your cooking time they'll have tripled in volume. That means for every cup of uncooked rice you started with, you'll have approximately three cups of cooked rice.Why does rice increase in size?
They multiply in size due to water being absorbed during cooking. Each grain increase is size making the total volume increase.What happens to the liquid you cook rice in?
The liquid will cook down some and become concentrated in the grain, so too much flavor or salt can become overwhelming. It's also important to match the flavors of your alternative liquid with the dish you are making.Why does ice float in water? - George Zaidan and Charles Morton
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