Haloumi melted in whey

[Ba3281]

I've made Haloumi before but decided to follow a new recipe. Unfortunately it was an epic fail. The pressed curds melted when I added it to the hot whey. I was left with melting cheese which I had to pour out instead of scooping. First sign of something being wrong was that the curds were floating when I added to the whey (which was at 174 F). After 5-7 mins they had melted and there was nothing I could do.
Can anyone tell me what went wrong. This is the recipe I used
https://www.sbs.com.au/food/recipes/homemade-haloumi

[mikekchar]

The acidity of the cheese was too high.  Given that the recipe has no starter culture, this means that you were either using raw milk, or milk that had gone off.  In both cases, you need to use very fresh milk for halloumi because it needs to have a fairly high pH.  In the case of raw milk, you might consider thermising it, just to stop the naturally present bacteria from acidifying the milk (just raise it up to 63 C/145 F for about a minute and cool it back down again).  However, even using raw milk, it should not have acidified to the extent that you saw it unless the milk was on the brink of going off.

[Ba3281]

I guess that was it, I live in Asia and got the raw milk from the milkman. Stored it in the fridge overnight and made it the next day. I guess the milk was at room temperature for too long before I bought it. Will stick to bottled milk for cheese making.
I also added 2 spoons of yogurt at the start of the process as suggested in the recipe. Could that have affected the milk?

[mikekchar]

Yes, adding 2 spoons of yogurt and waiting an hour before adding the rennet will definitely make the milk more acidic -- especially with raw milk.  You certainly shouldn't do that for a halloumi recipe (for exactly the reason you found).  Probably you would have been fine if you hadn't have done that.