π day

Love it, hate it, or don't care at all—today is still π ("pi") day. 😊 (Coincidentally, it also happens to be Albert Einstein's birthday today as well.) Could you identify which one is the stargazy pie on my drawing above? 😉 (Hint: The eccentric–looking one!)
(media: pencil and coloured pencils on plain A4 paper)

“...We must have a pie. Stress cannot exist in the presence of a pie.”

—said by Anna to Claire in Boston Marriage (a 1999 play by David Mamet; p. 23)

For many of our friends who are mathematicians or maths enthusiasts out there, they're probably celebrating this unusual day: π day. π is the Greek letter "pi" and is also the symbol for that mathematical constant which represents the ratio of the circumference of a circle to its diameter. (😵 Sorry, what was that again? hehe...) I'm probably not the best person to discuss about maths as I'm quite poor at it, haha... So I'll just refer you to this interesting article about π and π day by the late Professor Jonathan Borwein from the University of Newcastle 🇦🇺.

While π is a very special number in the domain of maths—yet still with practical applications—we shall now concern ourselves in the realm of food where pie is something from an oven that is usually delicious, am I right? 😋 A pie is a baked dish of fruit, meat, poultry, fish, and/or vegetables, typically with a top and base of pastry. It can either be savoury or sweet: from meat pies, buko ("young coconut") pies, apples pies, mince pies, and so forth—the variations are virtually endless! More often than not, we use pâte brisée (or shortcrust pastry) to wrap all of that yummy filling inside.

Shortcrust is a crumbly pastry made with flour, fat, and a little water, typically used for pies, flans, and tarts. We want this kind of texture as we don't want our pastry to be tough and hard when eaten—which would be a result of too much gluten formation. Gluten is a mixture of proteins present in cereal grains, especially wheat (and thereby wheat flour), which is responsible for the elastic texture of dough. What makes shortcrust crumbly in nature is due to the action of fat (e.g. butter). We use fat in a shortcrust pastry recipe as a shortening agent that inhibits continuous gluten development.

In order to make shortcrust pastry, we need to interrupt the gluten structure formed when flour and water are mixed together. This is achieved by using the fat as the shortening agent and involves mixing the pastry in two stages: In stage 1, the flour and fat are mixed together so that the flour particles become coated with fat. In stage 2, the water is added and the pastry is mixed until it just holds together. Overmixing at this stage will increase gluten development which reduces the shortening effect and results in tough eating baked products. The figure below shows how this process works to prevent continuous gluten development (Patient 1994).


Structure of shortcrust pastry Fat coats fragments of gluten to prevent them from forming a continuous sheet (Patient 1994)


Anyway. That's all for now my friends. Happy π Day to everyone! 😊 🎉


P. S.  Have you found the stargazy pie on my drawing above yet? 😉 It's a kind of fish pie traditionally made in Cornwall (in the UK), with the heads of the fish appearing through the crust. 🐟 I hope I can make this Cornish pie too someday should I be able to buy pilchards/sardines over here in Perth. 😋