Cooking For Engineers

[Pie_Designs]

Hi there all,

I need help - yet again.

Imagine you are making pepper steak pies. You make you delicious steak mixture, but do not incorporate a pepper sauce or anything like that when cooking. You simply generously / liberally sprinkle coarse pepper on the pie mixture after cooking the mixture. You proceed to lid the pies, venting them as required.....and then on baking - they explode. Okay, maybe explode is a bit dramatic, but i think you know what i mean.

Why would this happen? What can we do about it?

Your learned and valued responses would be greatly appreciated.