Puffed grain

In 1948 and 1950, ears of popcorn, up to 4,000 years old, were discovered by Harvard anthropology graduate student Herbert W. Dick[2] and Harvard botany graduate student Earle Smith, in a complex of rock shelters, dubbed the "Bat Cave", in Catron County,[3] west-central New Mexico, the oldest puffed grain known.

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.

[7] According to University of Hong Kong researcher Xiaomeng Liu and Chinese media,[9][7] The original invention was likely spread to other European countries around World War I to improve the longevity of the food under difficult conditions.

[9] In 1940s, Yoshimura Toshiko (吉村利子) heard German people were using old cannons to puff grain; thus, she designed a portable grain-puffing device called Pongashi ki (ポン菓子機) in 1944 to 1945.

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.

To achieve large-scale efficiencies, continuous-process equipment has been developed whereby the pre-cooked cereal is injected into a high pressure steam chamber.

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.