I imagine it’s got more to do with ingredients than processing. Local restaurants might make fresh bread with a bleached flour product that has various dough conditioning agents added to it, while puffed rice absolutely requires an industrial process to create and has one ingredient.
> puffed rice absolutely requires an industrial process
“Traditional methods to puff or pop rice include frying in oil or salt. Commercial puffed rice is usually made by heating rice kernels under high pressure in the presence of steam, though the method of manufacture varies widely” [1].
If I had to guess, the commercial stuff is more thoroughly and homogeneously gelatinized. That, in turn, probably raises its glycemic index.
The texture is completely different. The industrial method involves heating it under very high pressure with steam and releasing the pressure extremely quickly. The closest non-industrial analog is a Chinese popcorn cannon… but it’s much more controlled. It incorporates much more air into the final product without imparting any flavor from the heat source.
