Sirene is a white brine cheese from Bulgaria that resembles feta cheese. It is sometimes called Bulgarian feta cheese, but does not have the correct ingredients to be a true feta. This cheese is soft, wet, and crumbly and is generally purchased in stores in vacuum-sealed packages. It is served as a part of many dishes, including soups and salads, as well as many breakfast dishes and some desserts. In many countries, a hungry traveler at a hotel breakfast will often find plain or pickled chunks of this cheese served buffet style with a spread of other cheeses, olives, and various snacks.
Commonly surreptitiously substituted for feta, another popular Mediterranean cheese, sirene is extremely similar to feta in the way it is prepared. It even typically comes from Bulgaria, an accepted area for technically correct feta cheese production. The main difference between sirene and feta cheeses is the type of milk used to make the cheese. While sirene is made from a varying mixture of sheep's, goat's and cow's milk, feta is only supposed to contain milk from goats and cows. In reality, the inclusion of cow's milk is only regulated heavily in the European Union and loosely in the United States, so some white brined cheeses listed as feta may actually be sirene.
These cheese varieties are made with yogurt. The milk destined to become sirene cheese is first turned into yogurt with enzymes added before the usual cheesemaking process is carried out. Yogurt enzymes used to make sirene can vary slightly, but they are sometimes similar to the ones found in buttermilk. The addition of the extra enzyme step converts the milk to yogurt that is then turned into a soft white cheese.
A brined cheese is a cheese that has been soaked in salt water. Brine can be light, medium, or heavy, based on the concentration of salts within the solution. Soaking cheese in brine gives the cheese a salty flavor and preserves it, preventing bacterial growth that can change the taste of the cheese. Besides sirene, other brined cheeses include feta and halloumi. Sometimes, brined white cheeses are pickled before they are served, which is common with feta cheese.