free download PNG images :Popcorn

Popcorn or popcorn is a variety of corn kernels that swell and swell when heated.

The hard shell of popcorn grain contains the hard, starchy endosperm of the seed. The moisture content is 14-20%. When the seed is heated, it will become steam. The pressure in the steam continues to increase until the hull breaks, allowing the core to expand from 20 times its original size to 50 times its strength - eventually cooling.

Some corn strains (classified as corn) are specially planted as popcorn. The most common of these corn varieties is the Zea mays variety everta, a special of stone corn.

The six main types of corn are dental corn, FL stone corn, pod corn, popcorn, flour corn and sweet corn.

Each kernel of popcorn contains a certain amount of water and oil. Unlike most other grains, popcorn kernels have a strong, water-resistant outer skin and almost completely rigid starch inside.

When the oil and water in the kernel are heated, they convert the water in the kernel into pressurized steam. Under these conditions, the starch in the kernel will gelatinize, soften and become soft. The internal pressure of the entrained steam continues to increase until it reaches the breaking point of the hull: approximately 135 psi (930 kPa) at 180 ° C (356 ° f). As a result, the hull quickly ruptured and exploded in real time, resulting in a sudden drop in the pressure inside the core and correspondingly causing the steam to expand rapidly, so that the starch and protein in the endosperm expanded to foam. With the rapid cooling of the foam, starch and protein polymers are condensed into familiar crisp puff. Planting special varieties can increase burst yield. Although some wild types of seeds will pop up, the cultivated strain is Zea mays everta, which is a special of stone maize.