How does rubbing butter into flour make things rise?

Question

like in puff pastry?

how does fat make things light and fluffy n airy

im not making pastry im just doing an asignment on functional properties of foods.

oh and another question:

how does the creaming of fat (butter) and sugar aerate food?

Answer 1

I was hoping there would be an explanation on this, one of my favorite websites (http://www.exploratorium.edu/cooking/ind... but it looks like there's none.  I might hazard an explanation myself (being a chemist) ... but if you can find John Emsley's book "Chemistry Connections", that is supposed to have an explanation of it.

This is what I think happens: the thin dough layers of puff pastry contain moisture.  What the butter (or oil) does is coat it, sort of trapping it in.  Put that in a hot oven and the water vaporizes, expanding as steam and pushing the layers apart, making them fluffy.  Then the butter fries the layers crispy, so the result is crispy, flakey and not gummed together.

Answer 2

rubbing butter into flour doesnt make something rise.  it just makes things flakier...

creaming butter and sugar allows the crystals to "rip" little holes allowing for steam to develop as the dough (if mixed with flour later) cooks...this makes cakes more evenly airated so the small little holes are all even...unlike in a muffin where some holes are big and some are small...