Four years ago, I posted the basics on the phase equilibria of pie crust in this blog. A summation of that post, as well as an update, appears below:
With American Thanksgiving and Christmas rapidly approaching, the pie baking season is rapidly approaching. One of the most important, but least quantified, aspects of pie creation is the crustal composition. A simple ternary phase diagram for three-phase pie crust is presented below.
While the “traditional composition” point is plotted to scale, the positions and shapes of the curve are poorly constrained approximations. Lack of accurate thermodynamic data for the system precludes accurate prediction of these fields. It is the shapes and positions of the top two curves that is of paramount importance; anyone who reaches the butter-water two phase field should be banished from the kitchen.
As anyone with baking experience knows, the stability region for pie crust is a relatively small area on the wet side of the two phase flour + dough field. This field is generally approached by adding water to a flour/butter mixture, as is shown below.
Four years ago, I suggested the following approach:
However, if the approximated slopes shown above are correct, then a radical new approach to crustal formation might be advisable. By generating a flour-water mixture, and then adding butter, a wider range of valid crustal compositions should be achievable before exiting the edible portion of this phase diagram. This approach is shown below.
In hindsight, this was silly. There are two reasons. Firstly, accurately ganguing the initial water/flour mixture is difficult, as your starting composition is in the 2 phase flour water field. And secondly, this procedure generates a crust with the minimum possible butter, and butter is yummy. So this year, I will endeavor to explore the left hand side of the diagram. I suspect that the dough / slime boundary curves over a bi farther than is illustrated here.