Puffed grain

The oldest puffed grain was found in west-central New Mexico in 1948 and 1950. Ears of popcorn were found that were up to 4,000 years old. These pieces of puffed grain were smaller than a penny to two inches in size and can be made in a similar way to popping popcorn.[2]

Rice has been puffed since ancient times using a technique called hot salt frying in which parboiled rice (e.g. steamed and then dried) is puffed by preheated salt.[3]

The modern process of making puffed grains was invented by Dr. Alexander P. Anderson in 1901 in Red Wing, Minnesota. He was doing an experiment dealing with the effect of heat and pressure on corn starch granules where he put them in six glass tubes, sealed them, and put them in an oven until they changed color. When Dr. Anderson took them out and cracked them open an explosion happened, he had made the corn starch turn into a puffed, white mass.[4] Dr. Alexander's invention of puffed grain was first introduced at the World's Fair in St. Louis in 1904. The puffed grain was shot from a battery of eight guns and on a poster, it was called “The Eighth Wonder of the World.”

Puffed rice can be produced using the simple but effective method of hot salt frying. Salt is heated in a pan until it is hot enough to pop rice added to it within seconds. Parboiled or dried pre-cooked rice is added to the heated contents of the pan and stirred. Puffing starts almost immediately and completes in less than a minute and the rice is scooped out by a sieve.

Puffed grain machine in Haikou, Hainan, China. Sometimes called a "popcorn hammer"

High pressure puffed grain is created by placing whole grains under high pressure with steam in a containment vessel. When the vessel's seal is suddenly broken, the entrained steam then flashes and bloats the endosperm of the kernel, increasing its volume to many times its original size.

Puffed rice or other grains are occasionally found as street food in China, Korea (called "ppeong twigi" 뻥튀기), and Japan (called "pon gashi" ポン菓子), where hawkers implement the puffing process using an integrated pushcart/puffer featuring a rotating steel pressure chamber heated over an open flame. The great booming sound produced by the release of pressure serves as advertising.

Manufacturing puffed grain by venting a pressure chamber is essentially a batch process. To achieve large-scale efficiencies, continuous-process equipment has been developed whereby the pre-cooked cereal is injected into a high pressure steam chamber. It then exits the steam chamber via a Venturi tube to an expansion chamber, where the puffed cereal is collected and conveyed to the next process step. These devices, generally called stream puffing machines, were perfected in the latter half of the 20th century in Switzerland and Italy, but are now available from manufacturers in China as well.

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  Puffed wheat
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  Popcorn (left) and popped sorghum (right)
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  Filipino cornick made from glutinous corn that is puffed by soaking in water for three days, unlike popcorn.
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  Awaokoshi, puffed millet sweets from Japan

Wikimedia Commons has media related to Puffed grains.

• Research notebooks and papers of the inventor of the process of puffing rice and starches, Alexander P. Anderson, are available for research at the Minnesota Historical Society