Why do our milk demulsify ?

Question

My mom boils UHT milk with papaya fruit (sliced, not mashed) for hours. Sometimes it comes out right and delicious, sometimes it comes out demulsified (the milk solid is separated from the water). Why?

I've googled a little and protein seems to be the emulsifier. (Protein is the part of milk that coagulates to create curds like cheese)

If that is true, what could have happened to the emulsion and the emulsifier (protein)?

Thanks

Answer 1

Best Answer - Chosen by Voters

Boiling will coagulate milk. It coagulate more quickly if it has been opened longer, so the age of the milk could be a factor. Also acid is a factor. If the fruit is more acid it will cause the coagulation of the proteins.