Because in the process of heating, the temperature inside the pot continues to rise, and the pressure of the gas inside the pot also continues to increase. When the temperature rises to a certain level, the rice grains will gradually become softer, and most of the water inside the grains becomes water vapor. Because of the higher temperature, the pressure of water vapor is very large, so that the softened rice grain expansion. But at this time the pressure inside and outside the rice is balanced, so the rice will not burst in the pot.

When the pressure inside the pot rises to 4-5 atmospheric pressure, suddenly open the top cover of the popcorn pot, the rapid expansion of the gas inside the pot, the pressure will soon be reduced, making the rice grains inside and outside of the pressure difference becomes large, resulting in high pressure within the rice grains of water vapor is also rapidly expanding, instantaneous bursting of the grains of rice, that is, into the popcorn.

Expanded

Popcorn hazards:

Popcorn eat more fire. Popcorn is divided into fried and non-fried, common corn and rice to do, but no matter which kind of eaten are easy to fire, occasionally craving can be, but do not eat, this kind of food oil content is large, oily skin people eat less, easy to long acne beans.

Street popcorn popping machine avalanche of popcorn containing very high levels of lead. As the popcorn machine tin cans coated with a layer of lead alloy, when the popcorn machine when heated, part of the lead will become lead vapor into the popcorn, lead will enter the human body with the popcorn, and then damage to the human nervous system and digestive system.

Particularly children's lead detoxification function is weak, often eat popcorn is very susceptible to chronic lead poisoning, resulting in loss of appetite, diarrhea, irritability, purple gums, and slow growth and development. Therefore, parents do not let children often eat popcorn.

Baidu Encyclopedia - Popcorn