What are you to do when you go to pick out a kiwi fruit as a snack, only to find it has mold growing on it? Should you throw it away? or can it still be safe to eat?
In this article, we answer these questions in detail, so, for all you need to know about mold growth on kiwis, keep reading.
Mold on kiwi fruit presents as small patches of powdery growth that is either blue, green, white, grey, or even black. Areas of the fruit that are damaged (such as split areas of its skin) are more prone to growth, with Botrytis cinerea, Penicillium, and Rhizopus stolonifer being common strains.
What does mold on a kiwi look like?
In the very early days of their growth, many strains of mold will be invisible to the naked eye. Only after several days under the correct circumstances will they grow large enough colonies, able to be seen by the naked eye.
Many strains will begin life as a circular patch of growth, white, brown, gray, or black that slowly spreads and becomes powdery or velvet-like in texture.
Over time these patches can change color from white to blue, blue-green, olive, yellow, brown, or black.
Generally, penicillium
has blue or green coloration, with Botrytis cinerea presenting in gray, and Aspergillus and Rhizopus stolonifer tending to appear with darker, brown, and black colorations.
To get a good idea of what a moldy kiwi fruit looks like, take a look at this short video which shows it happening. Around day 7, you’ll start to notice small white patches appearing, it gets pretty unappetizing after this point.
What type of mold grows?
The most common strains of mold found growing on Kiwis are Botrytis cinerea (Gray Mold), Penicillium spp, aspergillus, Rhizopus stolonifer (Black Bread Mold), Alternaria spp, and Mucor spp. These strains all grow under similar circumstances to those outlined above, and so poor storage is again the main cause of their accumulation.
The most common of these strains found growing on kiwis is Botrytis cinerea, or “gray mold” as it is often referred to. This strain not only affects kiwi fruits but can cause devastation to many types of plant crops. It not only makes the fruit look unappealing but can also rapidly decrease its shelf-life by causing patches of soft rot.
What is the white mold on kiwi fruit?
The white mold that can be found on the outer skin of kiwi fruit is often Sclerotinia rot. This strain of mold forms a white flurry mold with dark spots in its interior.
This pathogenic fungus is also known as cottony rot, watery soft rot, and stem rot, and it can contain toxins that are hazardous to human health if inhaled or ingested.
Sclerotinia can infect many types of fruits, vegetables, and other types of crops, so it is certainly not only kiwis that are affected by this strain. It grows most favorably under cool moist conditions, so storage in high-humidity areas is the main culprit for finding white patches of mold on a kiwi.
What are the other signs that your kiwi has mold?
Other than seeing obvious patches of growth on your kiwi, you may also spot that the fruit has become a loft softer to the touch, the skin may have darkened and there might be a musty scent coming from it.
If any of these signs are present, it is a good indicator that your kiwi may have already begun to grow mold or will do so shortly.
Is the mold dangerous?
Yes, all three of the mentioned molds can produce a toxic substance known as mycotoxins as a defense mechanism whenever they feel threatened.
These mycotoxins can cause allergic reactions in those with allergies and serious health complaints in those with weakened immune systems.
With frequent exposure, even otherwise healthy individuals can suffer from a variety of symptoms, which can include:
- Headaches
- Nausea
- Breathlessness
- Coughing
- Skin irritation
This is only a small list of the reported symptoms of mold exposure. It is important to note, however, that the quantities of mold that would be growing on a kiwi fruit will be very small and unlikely to cause many of these symptoms. If you do have any allergies or a suppressed immune system, you should still be very careful when dealing with any type of mold, as they can cause serious reactions in some.
Can you still eat a kiwi with mold?
It is not a good idea to try to eat moldy kiwi fruits, as it is possible that spores could be inhaled, leading to breathing difficulties in some people.
The second reason is that mold frequently grows on fruit that has begun to go bad, and so if you were to try to eat the fruit, it would usually be past its best, resulting in a poor, slightly acidic taste and a soft, squishy texture.
There is also a slight chance of allergic reactions in people sensitive to mold growth that can cause any of the symptoms listed above, such as breathing issues, skin irritation, and nausea.
Can you cut the moldy parts off and eat the rest?
You might think that if you find only a small patch of mold on your kiwi, you can simply cut it off and eat the rest, resulting in no kiwi being wasted.
Unfortunately, this is not the case, as when mold grows, it produces roots or threads called hyphae, which burrow down deeper into the fruit.
If mold is allowed to grow for some time, these roots can grow deep into the fruit, meaning that even if you were to cut off the moldy parts, mycotoxins could already be within the remainder of the fruit.
Again, by the time mold has become established, the fruit is more than likely already turning bad, so even if you were to remove the moldy parts, the rest would still be unpleasant to eat.
If one kiwi is moldy in a pack, should you throw the rest out?
There’s truth to the phrase “one bad apple can spoil the bunch”, and in this case, it’s also true for Kiwis.
If you find mold growing on one kiwi, there is a very good chance that spores could have spread from the infected fruit onto others in the pack.
It is for this reason that you are best off throwing away the entire pack if you discover mold. Much as this may seem wasteful when it comes to health, it is better to be safe than sorry.
How to store kiwi fruits to prevent mold growth
Poor storage conditions are the number one reason for fruits and vegetables becoming moldy, so, follow the guidelines outlined below to keep your kiwis fresh and mold-free for the longest time possible.
Keep them at 32-35 degrees Fahrenheit
Most fruits will be unripe when you first take them home, this prevents them from being overly ripe by the time you are ready to consume them.
To keep your kiwis mold-free whilst they ripen, store them in a refrigerator between 32-35 degrees. This is below the temperature at which many strains of mold can grow at their most rapid (although some can still grow at refrigerated temperatures).
Ensure there is airflow
Do not pack your kiwis too tightly together, and certainly do not wrap them in any kind of plastic, as this will allow moisture to condense around the fruit, giving mold a source of hydration.
Each time you open and close the fridge door, fresh air enters the unit, removing excess humidity, so this will create plenty of airflow.
Keep the humidity levels low
Check the humidity levels of your refrigerator regularly if you find fruits and vegetables rotting quickly.
Mold requires a humidity level of 60% to grow at its fastest rate, so, aim to keep your unit between 30-50%. You can use a hygrometer to keep check of the moisture percentage, and if you find it difficult to keep the moisture levels low, remember to cover liquids such as sauces in a container and do not store items in a fridge whilst they are still warm.
Store them in an airtight container
Much as the fruits require adequate airflow, as long as there is plenty of room for the air to flow around the fruit, water should not condense on the skin, which would occur if they were tightly wrapped in plastic.
Storing your kiwis in an airtight container protects them from temperature fluctuations, and increased moisture from other items within the fridge, and prevents mold spores and bacteria from finding their way onto the fruits in the first place.
Place them on the bottom shelf of your fridge or salad crisper
As heat rises, it brings moist air with it, resulting in the top shelves of a refrigerator having the highest humidity.
Store your kiwis and other fruits on the lower shelves of your fridge to keep them as dry as possible. Placing them as far towards the back of the fridge as possible (without touching the walls), will further protect them from temperature fluctuations whenever the door is opened or closed.
If you have one, a salad crisper is the perfect location to refrigerate kiwi fruits, as the moisture level is always lowest in these drawers, they are fully protected from temperature changes and prevent cross-contamination with other items.
Why do Kiwi fruits get moldy?
Fruits are highly susceptible to the growth of fungi because they provide everything they need to grow successfully.
Mold is a type of fungi, and as such, is a complex organism. Its needs, however, are fairly basic. All it requires are nutrients, hydration, and oxygen. As long as these three components exist, and there is an acceptable environment for them, mold can not only grow but thrive.
The nutrition mold needs comes directly from the fruit itself, it consumes these by releasing enzymes that break down the macro and micronutrients of the fruit and then absorb them, in a manner that is not too dissimilar from the way humans digest food.
Hydration comes from the high water content of the fruit which is stored within its flesh, as well as the possibility of the fruits being stored in humid conditions, especially in tropical climates.
Oxygen, of course, is everywhere, and fungi only need small amounts of it to “breathe”, but the other important factor, is its environment.
In what type of environment does mold grow on kiwis?
Fungi prefer to grow in moist environments that preferably have little airflow and minimal exposure to sunlight. This is because the UV radiation emitted by the sun will kill both mold and its spores, and airflow with remove moisture from the air surrounding it.
This is why storage is such an important factor to consider when discussing mold growth on Kiwi fruits, if they are stored improperly in a warm, dark, and moist warehouse in a tropical climate, for example, the chance of mold growth becomes very high.
How quickly does mold grow on a kiwi?
Mold can begin to grow exceptionally quickly under the correct circumstances. If you have stored your kiwis in a warm, high moisture area of a property, and mold spores find their way onto the fruit, it could start to grow within only two hours. After only a few days, visible patches of mold growth would be visible to the naked eye which would then begin to rapidly spread across the rest of the fruit as it spoils further.
Conclusion
Kiwi fruits are susceptible to mold due to their high water content. If stored in improper conditions, fungi will be able to form within only a few hours, so, to protect them from mold, store them between 32-35 Fahrenheit on the bottom shelf of a fridge, or, if possible, within a salad crisper. A ripe kiwi fruit will last under these conditions for several days, and unripe fruits can last up to one month.
