Rice is a cheap source of carbohydrates and is a staple throughout the world. So, it’s very frustrating to go to your store cupboard only to find your meal plans have been scuppered because the rice you were going to use has become moldy.
Why has it become moldy in the first place, is it still safe to eat and how can you prevent this from happening again?
In this article, we will be answering all of these questions plus a bunch more, covering everything you should be aware of when dealing with moldy rice, so keep reading!
Mold on rice presents itself as a black, green, or white, powdery substance on the surface of dry or cooked rice. The most common mold that grows on rice is called Aspergillus oryzae. This mold strain can cause gastrointestinal discomfort if eaten, so moldy rice is best discarded.
Does rice get moldy?
Both dry and cooked rice can become moldy if the conditions are correct for it to grow.
Mold needs specific circumstances in which to thrive, which are:
- A lack of natural sunlight
- Humidity levels greater than 55%
- An ambient temperature between 60 and 80 degrees Fahrenheit
- A source of nutrients
In most homes, you will find rice stored in just these circumstances, as dry rice is often stored in the kitchen which has high levels of humidity, usually in a cupboard where there is no natural sunlight, and in a heated home that provides just the kind of temperatures it needs.
Of course, in most cases, dry rice is kept in a container that prevents the rice from becoming moist, but if water were to find its way into this container, mold could certainly begin to grow.
This is the same for cooked rice, as this should be stored in a refrigerator. Humidity levels are high in most fridges, however, the low temperature should usually delay the growth of mold and bacteria. The problem arises only when a faulty thermostat or broken gasket causes temperature fluctuations, causing the rice to be stored at a temperature where mold can begin to form. There are also strains of mold that can not only survive but thrive in colder environments.
Can you get sick from moldy rice?
If mold has been allowed to form on rice for a long enough period, it may have begun to produce mycotoxins. Rice is highly susceptible to something called fungal secondary metabolites (also known as aflatoxins), which are capable of causing gastrointestinal discomfort, vomiting, diarrhea, and even liver damage and cancer.
It is not uncommon for both mold and bacteria to be growing on cooked rice, as a strain of bacteria is present within the rice grain and can survive the cooking process. If left to cool at room temperature, the bacteria can begin to multiply and become a threat.
A combination of both mold and bacteria growth on cooked rice can cause great Illness including food poisoning which presents as vomiting, diarrhea, chills, muscle fatigue, and stomach cramps.
What kind of mold grows on rice?
The strain of mold that commonly grows on rice is Aspergillus Oryzae, which is also sometimes called kōji mold. This form of mold is actually used in Japan to saccharify the rice, and other carbohydrates to create sake and shōchū.
Aflatoxins have been detected in basmati, jasmine, and long-grain varieties of rice. These are cancer-causing toxins that are produced by Aspergillus flavus and Aspergillus parasiticus mold strains commonly found throughout parts of the world with high humidity.
In lower doses, the toxins produced by these strains of mold can cause gastrointestinal discomfort, nausea, headaches, and breathing difficulties if the spores produced are inhaled by those sensitive to them.
Can uncooked rice go moldy?
Whilst it’s much more common to find mold growing on cooked rice, dry rice can still develop mold.
As long as dry rice is kept in a dry environment, it has a very long shelf life, and should not develop mold on its own. The issue arises when moisture finds its way into the container the rice is stored in.
Mold spores float through the air and can land on the surface of the rice, without moisture these spores will not be able to gestate. However, in the presence of moisture, mold will be able to grow and use the rice as a source of nutrition. If you notice patches of green, white, or black patches of mold on your uncooked rice, you should throw it away, as eating the rice after this point could cause potentially serious illness.
How to prevent rice from going moldy
Dry rice
Store dry rice in an air-tight container to prevent moisture and spore buildup. Keep this container in the area of your kitchen with the lowest humidity levels. These tend to be areas away from cooker hoods, stoves, microwaves, etc.
Try to find a storage place such as a cupboard as far away from these items as possible to reduce the humidity levels your rice is under. It may be better to store your rice in another room of the house with lower humidity (such as a bedroom), if you live in a smaller apartment or house, as this will reduce the humidity the rice is exposed to.
As long as you keep your rice in as dry a condition as possible, it should have a shelf-life of up to two years (for white rice) and 6 months for brown rice varieties.
Cooked rice
Cooked rice needs to be treated carefully to prevent harmful bacteria and molds from growing.
Cooked rice should be served immediately, with any leftovers being rapidly cooled in cold water before being stored in the fridge.
Cooked rice should not be stored in the fridge for more than 3 to four days before being reheated, as bacteria can begin to rapidly grow after this point which can cause food poisoning.
Some strains of mold can live in colder temperatures, such as those found in refrigerators, so you may be slowing down the growth of bacteria, but mold can still find its way into your rice if left for long enough.
Mold can begin to grow within 24 hours under the correct circumstances, but bacteria is more of a concern for cooked rice. If you do see any black spots on your cooked rice, it is most likely mold and it should be thrown out immediately.
Can moldy rice be saved?
You might be tempted to scrape off the top layer of rice that has a little mold growth on it to save the rest of the packet.
The problem with doing this is that if the mold has been established for long enough, it may have begun producing spores. These spores are released when disturbed, and even gently touching or moving air around the mold can release the spores into the air.
The act of scraping mold off the top layer of rice will release spores into the rest of the packet and potentially cause additional breakouts of mold deeper within it. If you spot patches of any color variation of mold on your rice, you will need to throw the whole packet away, as it cannot be safely consumed.
What color is mold on rice?
There are three main color variations you will be most likely to find growing in rice varieties.
- Black
- White
- Green
Although there are many variations of mold that are harmless, certain strains of mold, including those mentioned above have the potential to release toxins that can be hazardous to human health so are best avoided.
There are also less common color variations of mold that can be found growing on food, including red, pink, and orange molds. It is more common for these types of molds to release toxins, so any signs of these on either dry or cooked rice means it should be thrown away immediately.
Black mold on rice
If you find patches of mold on either cooked or dry rice, you should throw the rice away immediately. There are several strains of black mold that can produce mycotoxins that can be very harmful to human health, and so should not be eaten.
White mold on rice
White mold, (commonly Aspergillus, Cladosporium, and penicillium strains), can also be found in any location where there are sufficient nutrients, warmth, and moisture levels. Whilst not all strains of white mold are toxic, there are several that can still produce aflatoxins which can cause harm to the body, so no risk should be taken with these either.
Green mold on rice
One of the three most common colors of mold found on rice and food, in general, is green mold. As you can probably tell, green mold is no better to eat than other strains, as it can still cause gastrointestinal discomfort, nausea, headaches, and shortness of breath if released spores are inhaled.
As a general rule, there is no color of mold that grows on rice that can be safely consumed. If you are not sure of exactly the strain you are dealing with, it is certainly not worth the risk to try to still eat any form of rice, with any color of mold living on it.
Why does my rice smell moldy?
Mold growth isn’t always detectable to the naked eye. In rice, the mold could in fact be growing a few inches from the surface, so you would not initially see any formed patches.
What you would be able to notice, however, is a decidedly musty odor when you open up the packet. Some people compare the smell of mold to used gym socks or a cave or basement.
If you notice this smell, your rice is bad and it should not be consumed and should be thrown away.
What is pink mold on rice?
There are several mold strains that when grown have a pink hue to them, these are Aureobasidium and Fusarium.
Whilst you may automatically assume that the pink formation you see on your rice is mold, the two strains mentioned above grow more commonly on meat and dairy products. What you are more likely to be seeing is a form of bacteria called Serratia Marcescens.
If you spot any signs of pink formations growing on your rice, it should be thrown away and not eaten. Serratia Marcescens is known to cause several types of infections in humans, such as UTI, respiratory, conjunctivitis, and keratitis.
Conclusion
By the end of reading this article, you will have learned a great deal about why mold forms on rice, whether or not it’s still safe to eat, what kind of mold grows, and whether moldy rice can be saved.
In the case of rice, It’s important to remember the old adage, “If in doubt, throw it out”. Much as no one likes wasting food, in some circumstances, your health could be put at risk if you try to eat around mold just to save on buying another packet. It’s not worth the risk for a small saving.
