Yogurt along with many other dairy products is prone to growing mold at a rapid rate under the correct circumstances.
So, it can be very frustrating to take out a pot of yogurt for a snack or to use as an ingredient, only to find green and blue patches of fluffy mold growing on it.
In this circumstance, what do you do? Can the yogurt be saved in any way, why has it grown mold so quickly and is there anything you can do to stop this from happening again?
In this article, we answer these questions and more, so for everything you need to know about mold growth in yogurt, keep reading!
If mold is found growing on yogurt, the item should be discarded. Ingesting the mold could cause symptoms in those susceptible to them, such as people with suppressed immune systems. The taste and texture of the yogurt will also be very unpleasant due to enzymes released by mold leading to spoilage.
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Can you eat moldy yogurt?
Yogurt found with mold growing on it should be discarded. Some strains of mold have the ability to produce a toxic substance called mycotoxins that can cause allergic reactions in some, and other unpleasant health conditions if the mold or its spores or inhaled or ingested.
It is not safe to scrape the visible mold off the top of the yogurt and consume the rest, as mold has roots that can go deep within the remaining yogurt that are not visible to the naked eye.
There would also be little point in removing the top layer, as once mold has begun to grow, it secretes enzymes that break down the food item is it growing on, increasing the rate of spoilage and tarnishing both the taste and texture of the yogurt.
Why do yogurts become moldy?
Improper storage is the number one reason for yogurt becoming moldy. Storing yogurt at a temperature higher than 40 degrees Fahrenheit can allow mold and bacteria to begin growing very quickly.
Molds and bacteria can still grow at temperatures lower than 40 degrees Fahrenheit of course, but this is less common, and if stored at temperatures between 60-80 Fahrenheit for even a short period of time, mold can begin to grow at its most rapid rate.
Opened containers of yogurt will also spoil much faster than sealed, as cutting off the air supply removes the chances of any spores or bacteria being able to find their way into the food via cross-contamination or otherwise.
It is possible that you could open up a pot of store-bought yogurt to find it already moldy, even if you have stored it correctly. In this instance, it is highly likely that mold spores and bacteria had found their way into the milk they were used before the fermentation process had begun.
If making your own yogurt at home, ensure the finished product is stored in an air-tight container and consumed within 7 days. Commercially produced yogurts increase the shelf-life of the product by introducing food cultures and additives to inhibit the growth of bacteria and molds, without these components available at home, your yogurt is prone to growing mold more quickly once stored.
How to tell if yogurt has mold
One of the most simple methods to determine whether yogurt has become moldy is to inspect it visually.
Mold on yogurt appears as blue-green patches of circular growth, often with a powdery texture that sits on the surface.
This will only be what is visible to the naked eye, however, as mold can have deep roots that run through the rest of the yogurt. This is the reason surface mold should not be scraped off and the remaining yogurt consumed, as you could be ingesting large amounts of mold by doing so.
If no visible mold is present, a simple sniff test can also be useful. Mold has a distinct musty scent to it, and upon opening a yogurt, if this musty scent is smelt, it’s highly likely that mold has begun to form. As a general rule, if any unusual smells are noticed upon opening a pot of yogurt, it should always be discarded.
What kind of mold grows on yogurts?
The most common strain of mold to grow on yogurt and other dairy products, is penicillium, a type of fungi that is commonly found growing on many food items.
Whereas some strains of penicillium are used to enhance flavors and produce certain types of food, such as Penicillium roqueforti (used in the production of Roquefort cheese), the strains found growing in your yogurt do not make for good eating, they can spoil the taste and texture of the yogurt, as well as cause unpleasant symptoms after being consumed.
Another mold that can be found growing in yogurts and some other dairy products is Mucor circinelloides. This strain is most often found growing within soil, dung, and on root vegetables, but can make its way into the milk used for yogurt production.
Mucor fungi can be identified by its slightly off-yellow coloration and fluffy texture. It often starts white and turns more yellow as it matures.
Are the molds dangerous?
Both Penicillium and Mucor circinelloides have the ability to cause symptoms if ingested, or the spores inhaled, however, this is rare and mostly affects people with suppressed immune systems or people who are allergic to mold strains.
For people with such allergies, symptoms can present as:
- Breathing difficulties
- Watery eyes
- Itching (skin irritation)
In otherwise healthy individuals, it is possible that ingestion of either penicillium or Mucor circinelloides could cause stomach upset, gastrointestinal discomfort, and vomiting. It’s more likely, however, that the taste of the yogurt would be spoiled, rather than any serious health complaints occur.
How long does it take for a yogurt to go moldy?
Mold can begin to grow in an opened container of yogurt within only a few hours If left unrefrigerated and out in the open.
The higher the temperature the yogurt is left out in, the faster mold and strains of bacteria will begin to grow on its surface. The mold and bacteria will be invisible to the naked eye at this point, but within one to two days, visible patches of mold will begin to appear.
If stored in the refrigerator at 40 degrees Fahrenheit or lower, mold will grow much more slowly, and the yogurt should remain edible for several days or up to one week.
Once opened, most types of yogurt are safe to consume for up to one week, with the products remaining at their best when consumed no more than 3 days after opening, and still within their “use by” date listed on the container.
Should you use “use by” or “best before” dates on yogurts?
A commonly misunderstood aspect of food labeling is the difference between the suggested “best before date” and “use by” dates added to food packaging.
The “best before” date simply states that the product is at its finest in terms of taste and texture before the date issued, it does not mean the product will become inedible after this point.
The “use by” date, however, means that after the date specified, the product will begin to perish and go bad. There are some exceptions where you can still consume products several days after their “use by” dates without any impact on health, but these are guidelines set by governing bodies, so in most cases should be followed.
Some yogurts may be edible for a day or two past their listed expiration dates, however, good judgment should be used when inspecting the product. If it smells odd or has any noticeable change in taste or texture, it should not be consumed.
How to prevent mold on yogurt
To keep yogurt for longer and prevent mold growth, keep it in an airtight container and store in the refrigerator under 40 degrees Fahrenheit.
If possible, store the yogurt on the lower shelves of the fridge, as these tend to have a more consistent temperature. Yogurt is sensitive to temperature changes, and even small differences can lead to rapid spoiling.
It’s also a good idea to put it towards the back of the fridge, as this keeps it away from the door area where it is warmest, and more susceptible to temperature variations.
What is the white fuzz on yogurt?
There are two common strains of mold that have a white fuzzy appearance, pennicilium, and Mucor. Penicillium growth starts its life with a white color and powdery texture, gradually changing to a blue-green hue.
Mucor also begins white and fluffy in nature but turns more yellow over time, so it could be either of these strains. Without the use of a home mold testing kit, it would be very difficult to determine for certain which strain you dealing with.
What is the pink mold on Greek yogurt?
Despite often being called pink mold, Serratia marcescens, is actually a strain of bacteria that feeds off fat within yogurt and other dairy products. The bacteria usually finds its way into the milk the yogurt is made with via cross-contamination, or from within the air around the tanks that held the milk.
The bacteria can be hazardous to human and animal health, so if it is discovered growing on yogurt or any other dairy product, it should be discarded.
Why did your homemade yogurt become moldy?
Homemade yogurt will spoil faster and be more prone to mold growth than store-bought, as food manufacturers often add preservatives as well as additional, specific live cultures that help to slow mold growth.
Store-bought yogurt comes in packaging that have had gas added to them which further prohibits the growth of molds and bacteria, extending the product’s shelf life. Without these preservation methods available, homemade yogurt will spoil and become moldy much more quickly than store-bought.
What happens if you accidentally eat moldy yogurt?
In most cases, very little. Most people will have few (if any) symptoms after eating a small amount of mold from yogurt.
People with allergic asthma or suppressed immune systems would be more likely to suffer from symptoms after ingesting mold, but for the majority, very few symptoms would be noticed.
What does moldy yogurt taste like?
Mold in yogurt has often been described as having a gritty texture and a taste similar to dirt. Its smell is often compared to that of a basement or old attic, which would also come through in its taste.
Mold can grow quickly on yogurt if not stored correctly and at the right temperature. 40 degrees Fahrenheit or lower is best for preventing mold growth and prolonging its shelf life. If mold of any kind is found growing on yogurt, it cannot be saved and should be discarded.