I frequently make yogurt at home, and I decided to try to make Shankgleesh, a spicy Middle Eastern cheese that is difficult for me to find at local markets. Several recipes said to heat the yogurt until the proteins coagulate and separate from the liquid. They should look like clumps or curds. Then the liquid is drained off and the curds strained for several days. When I heated the yogurt, it just got soupy. It never formed curds or separated. I simmered it for more than a half hour. There didn't seem to be anything difficult about the recipes. I wondered why I could not get it to work. The only thing that is unusual about my yogurt is that it is fermented for 24 hours so that the bacteria consume all of the lactose. Could this have affected the coagulation of the proteins? Thanks for any help.
Yogurt is very sensitive and there are many possibilities here regarding why this recipe hasn't worked out, however the very main point that stands out for me is that you heated the yogurt to coagulate the protein.
This is not how it is done in traditional shanklish making. The yogurt is poured into an elongated container and gets covered and put on the floor. Then you need to sit on the floor and shake the container from front to back. Every ten minutes or so stop, uncovers the container and skims the butter which has formed on top. Continue doing so, until half of the butter is removed and the yogurt has become low in fat (partially skimmed). At this point you should be able to use the skimmed yogurt (known as shenineh) to heat it up and separate the curds from its water and make the cheese.