Mold is a type of fungus and fungus require oxygen. There is very little oxygen available inside a stick of butter so the mold will mostly be on the surface. If you can cut if off cleanly without contaminating the rest of the butter and if that butter doesn't taste of mold, it is probably safe.
But don't start scraping, which can release mold spores into the air or allow them to spread to your countertops or other foods. The only safe way to remove that mold is to cut away an inch of cheese all the way around the spot, she says. “You'll probably cut away some safe parts, but that's a good rule of thumb.”
To unmold, quickly run the mold under hot water, then carefully separate the halves. The butter will stay in one half of the mold – simply pop it out as though it were a one-piece.
"Butter is safe to eat after being out at room temperature," says Bri Bell, a registered dietitian, and food safety expert. "One reason it doesn't go bad as quickly as other dairy products at room temperature is because it's low in carbohydrates and proteins, which are mold and bacteria's preferred food sources."
Butter is not always a TCS food
Dairy products should be stored at 41 degrees Fahrenheit (5°C) or lower to avoid bacterial growth. If a dairy product is in a temperature higher than 41 degrees for 4 hours or more, it must be thrown out.
Any sour or off-putting smell means it's a goner. Same goes for taste: If it tastes sour or off, toss it out. 5 And don't worry, a small taste of rancid butter won't hurt you. Of course any visible mold, discoloration, and changes in texture are visible cues that it's time to throw the butter in the trash.
It should be pointed out that rancid butter can't make you sick, but it won't taste or smell very good. Rancidity is caused by exposure to oxygen, light and heat. So, to prevent rancidity, keep your butter in an opaque butter dish with a lid.
Is it OK to use expired butter? Unless you can see any visible signs of expiration or notice a sour, unpleasant smell, it's generally safe to use expired butter.
The first thing to do is, not panic as old butter cannot kill you or give you food poisoning. The worst that can happen is a stomach ache. Also, rancid butter can lower your vitamin E and vitamin B stores.
The white flecks are the milk solids, or fat component of butter, while the liquid contains a lot of water. The longer you heat the melting butter, you'll observe it move through different stages.
"This is mitigated by refrigerating butter and making sure it is well wrapped." In general, butter kept in the fridge will last one to three months, while butter stored in the freezer will last up to a year.
'Heat in the kitchen from cooking appliances is kryptonite to butter. ' And before you worry that you may be harming your health if you don't store your butter in the fridge, fear not. The Food Standards Agency recommends refrigerating purely for the quality of the product, rather than safety reasons.
Discoloration is a sign of rancid butter. Good butter has an even yellow color from inside out. Slice a small portion of your butter, if the inside looks brighter or lighter, then it has gone bad. Black spots on butter are signs of mold formation.
The USDA recommends leaving butter out at room temperature for only a day or two. But if it's stored in all of the proper conditions listed above, it can stay fresh for up to two weeks.
Salmonella can grow in butter at 25°C and is not eliminated by refrigeration or freezing (Sims et al., 1970).
Butter is perfectly safe to eat even after the expiration date has passed, so long as it still looks and tastes normal. Butter can last a longer period of time than, say, yogurt, milk, or sour cream because butter is made up mostly of fat, which makes it hard for harmful bacteria to form on the surface.
Fresh butter is usually a light yellow color, but as it begins to spoil, it may turn a darker shade of yellow or even beige.
A sour-bitter taste is identifiable with rancidity (i.e. soapy, baby-vomit, blue cheese). Rancid butter becomes yellow to brown and the flavor becomes harsh.
Both this and the darker yellow layer are both signs that the butter has started to go rancid. It is often because the butter hasn't been stored correctly – warm temperatures, light and moisture can all cause butter to deteriorate quickly and become rancid.
Essentially, a natural grass-fed diet will result in a yellow coloured butter while cows that are fed mostly grains will produce a lighter coloured butter.
Since butter contains quite a lot of fat, it's prone to oxidation. I'm sure you've seen butter with its surface oxidized before. Any time you cut a slice of butter and the inside is brighter than the outside, it's the result of oxidation.
If your butter smells or tastes sour or rancid, it's time to toss it.
You can keep it in the fridge for 10 days or two weeks if the box of butter is open. Also, make sure you store it in an airtight container. If the box is unopened, you can store it for up to a month.