Feta cheese is a brined white cheese traditionally made from sheep’s milk or a blend with goat’s milk. Its characteristic tangy, salty flavor and crumbly texture make it a unique ingredient, but like all dairy products, it is perishable. Recognizing the signs of spoilage is important for food safety and ensuring the best culinary experience.
Shelf Life and Storage
The shelf life of feta depends heavily on its packaging and storage method, particularly the presence of brine. Unopened feta fully submerged in its original brine can last for up to three to six months in the refrigerator. The high salt content acts as a preservative, inhibiting the growth of spoilage microorganisms.
Once opened, the cheese’s shelf life shortens significantly, typically lasting only one to two weeks, even when refrigerated. This reduction occurs because the seal is broken, exposing the cheese to air and contaminants. To maximize storage time, opened feta must remain completely submerged in brine or a homemade saltwater solution (about one teaspoon of salt per cup of water).
Proper storage requires keeping the feta in an airtight container in the refrigerator. If the cheese is not kept moist, it will quickly dry out and develop an unappetizing texture. Refrigeration and submersion in brine prevent the rapid growth of bacteria and fungi that lead to spoilage.
Sensory Indicators of Spoilage
The most reliable way to determine if feta has spoiled is by examining its sensory characteristics: smell, sight, and texture. Fresh feta possesses a clean, tangy, and slightly acidic aroma. When the cheese begins to spoil, the smell changes dramatically, often becoming strong, sour, or rancid.
A strong indicator of spoilage is an ammonia-like odor. This smell is caused by the breakdown of proteins in the cheese, which releases nitrogen compounds, including ammonia, as a byproduct. While a slight ammonia scent can sometimes be present in tightly wrapped cheese and may dissipate after airing, an overpowering or acrid smell indicates that the cheese has degraded and should be discarded.
Fresh feta is a bright, pure white color, but spoilage can cause the cheese to develop a yellow, pinkish, or dark tint. The presence of visible mold, appearing as blue, green, or black spots, is a clear sign that the cheese is no longer safe to consume. Also, check the brine; if the liquid becomes excessively cloudy, thick, or slimy, it suggests that bacteria are proliferating rapidly.
The texture of the cheese also changes as it spoils. Fresh feta is firm and easily crumbles when handled. Spoiled feta loses this firmness and may become mushy, excessively soft, or sticky to the touch. A slimy surface texture indicates bacterial growth and means the cheese should not be eaten.
Food Safety and When to Discard
If sensory indicators suggest the feta is compromised, discard it immediately. Consuming spoiled dairy products carries the risk of food poisoning and digestive upset. If there is any uncertainty about the cheese’s condition, follow the principle of “when in doubt, throw it out.”
Feta is a soft, high-moisture cheese and cannot be salvaged by simply cutting off a moldy section. Unlike hard cheeses, where mold growth is confined to the surface, feta’s high moisture content allows the mold’s root structure, known as mycelium, to penetrate deep into the cheese. Even if visible mold is removed, toxins and unseen mold threads may remain throughout the block. Therefore, any sign of unwanted mold requires the entire portion to be thrown away.