Morning Fo2
Anticipating a certain reply from AnFI (really!), I have since added 5ml of fairy liquid (washing up detergent) to the mix. and again shook vigorously for 10 seconds. After 6 seconds any bubbles had dissappeared leaving an 'island of scum' on the top of the surface the size of a 50p piece.
I suspect that the scum is the residue left from the milk, however without scientific analysis I am unable to confirm.
What I can conclude from these tests;
1. 'Foaming' as described by AnFI (really!), does not occur.
2. I now have a very clean 2.27l ex-milk container.