More than once, though, I’ve found a rogue block of feta that I’ve forgotten about at the back of the fridge, and I’ve wondered how long it takes the cheese to go bad—and what the indicators would be if it were past its prime.
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How Long Does Feta Last?
According to Sommer, feta packed in liquid salt brine can last for as long as 6 months if stored correctly: You can keep the cheese in its original container, but be sure that the block is completely submerged in brine and that care has been taken to avoid contamination.
And if longevity is what you’re after, you’re best off skipping dry packed versions of feta altogether. Once those packages are open, it’s best to use the product within a week or so.
How Can You Tell If Feta Has Gone Bad?
If your feta is nearing its best-by date and you’re not sure whether you should eat it, look for the following indicators.
Mold: If you see any spots of greenish mold on the cheese, throw the whole block out.
A yeasty aroma: “Yeasts tend to be acid and salt tolerant, which makes feta cheese a near perfect growth medium,” Sommer explained to me in an e-mail. “So if the product starts to smell yeasty, like proofed bread dough, the product has gone bad.”
Harsh, unbalanced flavors: Feta should taste like fresh, mildly tangy dairy. If your feta tastes overly piquant, bitter, rancid, or otherwise unbalanced, it’s past its prime.
Can You Freeze Feta?
When we asked Sommer if we could extend our feta’s life even further by stashing it in the freezer, his answer was emphatic:
“To get right to the point: Never freeze feta!” he wrote.
Sommer has found that freezing completely destroys the texture of feta cheese, even when it is thawed gently in the refrigerator. In his experience, Sommer describes, defrosted frozen feta is “over the top crumbly.”
The crumbles might be acceptable as a topping, he said, but for ideal texture, you’re much better off keeping your feta out of your freezer.
How to Extend the Life of Your Feta
There are a couple of ways you can keep your feta fresh longer.
First, when you’re removing a portion of the cheese from the brine, be sure to use tongs, a fork, or some other clean implement.
Touching the brine or cheese with your fingers or any utensil that isn’t clean and dry introduces microbes into the feta’s environment, which could encourage spoilage.
Second, if you find that you don’t have enough brine to submerge your feta, try making your own to keep the cheese fresher longer.
How to Make Additional Brine to Preserve Feta
Instead of making a simple salt-and-water brine (which can dry out the cheese and make it taste oversalted with time), we recommend creating a brine featuring milk and vinegar to replicate the calcium and acetic acid in commercial brines.
1. Mix ½ cup whole milk, ½ cup water, 1½ teaspoons table salt, and ½ teaspoon distilled white vinegar.
2. Place the feta in the brine in an airtight container and refrigerate for one week or use it to top off your container of feta in brine if the liquid level has dropped below the top of the cheese.