Traditionally feta was made with unpasteurized milk however industrial diaries now use pasteurized milk due to concerns over public health and export regulations. They also use commercial lactic acid cultures.
The milk is pasteurized at a minimum of 72 °C for 15 seconds or any equivalent time-temperature combination.
After pasteurization, lactic acid starter cultures and calcium chloride are added, as the milk is being held at 34-36 °C. After the milk has been refrigerated for 20 minutes enough rennet is added to coagulate the milk and coagulation takes place in about 40-45 min.
Coagulation process is essential for the development of a uniformed gel and finally Feta with firm texture. When coagulation is complete, the curd is cut into small cubes and, in order to increase cohesion, it is left to stand in the whey for about 5–10 min.
The small cubes are transferred into molds, in order to drain and shape the small pieces. The filled molds are stored at 16-18 C for 18 up to 24 hours and turned upside down every 2–3 h to ensure even drainage occurs and that all the curds are subject to equal amounts of pressure.
When the desired amount of whey has been removed, the fresh cheese is taken out of the mould and placed temporarily either in wooden barrels or metal containers, where salt is added in layers. The final concentration of salt in the mass of cheese is roughly 3%.
The next stage is to mature the salted cheese for 14 – 20 days in brine, at 16-18 °C in order to obtain humidity less than 56% and pH 4.4 – 4.6. At this temperature and RH a product of better texture and flavor is produced.
The second phase of maturation takes place when feta cheese is kept refrigerated in its brine, at 1-4 °C, for two months. Usually formed in square-shape blocks, Feta cheese has a somewhat grainy consistency (and is therefore crumbly), usually is white and has tangy and salty flavor.
Finally, when the cheese is ready to be distributed to consumers, it is cut up, shipped, and sold still in its brine, typically in a plastic container.
Processing of Feta cheese
