"limey" > wrote in message
...
>
> "Boudica" wrote in message >
>
> > I grew up with this family recipe of a Hot Water Pie Crust & have
> > always wondered why & how this works. Especially since every
> > cooking/baking show I ever watch & book read says it has to be cold
> > throughout.
> >
> > Can anybody who knows about cooking science explain this?
> >
> > Denise, Brian & Wyatt (May 31, 02)
>
> That cold shortening, icewater, keep everything cold puzzles me, too. I
> took Domestic Science in school (same as Home Economics in the US). We
had
> no refrigeration so used room-temperature lard, rubbed it into the flour
> with the tips of our fingers, and then used tap water to bind. It always
> came out great. I wonder what method the UK uses now? I also wonder
what
> method was used in the US before refrigeration was common?

Flakiness in pastry comes from having particles of fat interspersed in the
dough. You need to keep the dough cold to prevent the fat from melting and
combining with the dough before it goes into the oven. Some fat, like
butter, has a very sharp melting point that is close to body temperature.
Pie pastry made with butter can be a challenge to roll out and if it is too
warm. The butter will simply melt and make the dough a greasy mess. Once
in the oven, the heat melts the fat and turns the water to steam. You need
to bake pie pastry in a very hot oven so the proteins and starches set
quickly before the fat melts. The dough sets with spaces left where the fat
was and the steam gives it some lift or puff. If the fat melts into the
dough before it is baked you get a very tender but uniform pastry that isn't
flaky. Pie pastry is just a very crude, unorganized puff pastry. Just
think what puff pastry would be like if you simply mixed warm fat and flour
together and rolled it out. It wouldn't have all the organized layers of
dough separated by voids left from where the butter used to be.

I haven't tried the pie pastry recipes that are made with vegetable oil or
melted shortening. I can see how they would be very tender, but I don't
understand how they could be flaky. If the fat in the hot water pie crust
is completely melted by the hot water, then there would be no particles of
fat interspersed in the dough.