A few days ago, I did a crème pâtissière (thick vanilla custard), using
- milk (300ml/1.25 cup)
- egg yolks (2)
- sugar (15g/1tbsp)
- potato starch (10g/1tbsp).
The end result had a relatively thick consistency, fit for my purpose. I had a bit left over, so I put it in the fridge after it cooled down. After a few days in the fridge, the custard got thinner, like a crème anglaise (thin vanilla custard, picture an eggnog-like consistency).
I wonder what happened. One of my guess is that the amount of starch was too small, but I can't explain the change of consistency.