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Can Tea Bags Grow Mold? (And How to Prevent It)

Can Tea Bags Grow Mold? (And How to Prevent It)
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Mold is a form of fungi. Fungi spores exist all around us. Given the right conditions, these spores can bloom and grow into mold.

Mold can occur on any organic material and can even grow on and in tea bags.

How Do Tea Bags Grow Mold?

Your tea collection can become a potential greenhouse for mold. Mold growing within your home can form on the tea bags, given the proper growing conditions, or the tea bags may have been contaminated with mold before they even made it into your grocery cart.

Contamination of tea bags can occur from mold entering the tea itself or through the material of your tea bag. Fungal contamination of the tea can occur at almost any stage of its production.

The subtropical conditions that enable the growth of the Camellia sinensis plant also create an environment that fungi flourish in. Fungal pathogens can grow on the plant, its leaves, and even on the roots of the Camellia.

The potential for mold growth is also present in tea additives like valerian root, ginger, echinacea, and flavored oils.

Once the tea leaves are harvested, they are in further danger of contact with fungi. Fungi can be present on crops growing in the same field, crops that were previously harvested using the same equipment, and in the air during transit.

All traditional tea is made from the leaves of the Camellia sinensis plant. The difference between black, green, white, and other variations of the tea is the amount of oxidation that occurs in the leaves.

During oxidation, the chlorophyll in the tea leaves breaks down and darkens. Put simply, the leaves are dried out through various techniques. Leaves for white tea can take up to 26 hours to fully oxidize. In that period of time, mold spores can blossom and begin growing on the leaves.

Herbal tea is formed in the same manner. The fruit, leaves, or spices are allowed to dry slowly post-harvest. These materials also carry the same risks of pre- and post-harvest fungi contamination that Camellia leaves do.

The bag holding your tea leaves is a potential culprit for mold production too. Materials commonly used to make tea bags are filter paper, food-grade plastic, silk, and muslin.

Each of these materials can become a breeding ground for mold. Bleached filter paper poses the least risk of these choices but it is the least-popular choice among tea connoisseurs.

Perhaps the tea you purchased from a big chain grocery store or your local farmer’s market is completely free from fungi spores. Once you bring your tea home and decant it, the door for mold to enter is opened again.

Mold can grow nearly anywhere that water is present. Even without a water source, mold can derive its hydration from humid environments. Humidity above 60% in a home encourages the growth of mold.

Oxygen is also vital to mold growth and can be found in the air at any given time. Mold prefers temperatures above 60 degrees Fahrenheit but it will grow at any temperature above freezing and below boiling.

Lack of light is the last ingredient in the mold growing recipe. Ultraviolet light from the sun kills mold so it tends to blossom in locations with little to no sunlight.

All of these elements sound exactly like a cabinet, the most common place of storage for tea in anyone’s home. Mold can also invade your tea through the water it is brewed in.

Mold does not typically grow in water pipes but it can be found around sink taps and in water filters. Always use purified boiling water to brew your tea.

A Little Mold in My Tea Won’t Hurt Me

While most healthy individuals can be around small amounts of mold and experience no ill effects, this is not the case for everyone. Those who are allergic to mold can experience uncomfortable symptoms such as:

  • Sneezing and nasal irritation
  • Conjunctivitis
  • Hives
  • Coughing
  • Wheezing
  • Swelling of the lips, tongue, and face

Particular strains of mold produce secondary metabolites called mycotoxins. Research has found evidence of mycotoxins occurring in tea. Aflatoxins are a subset of mycotoxins produced by the fungi Aspergillus.

Aflatoxins are commonly found on goods grown in the tropics and subtropics. Aflatoxin B₁ is the most toxic of this group.

This strain is widely known as a cause of liver cancer. Chronic exposure to this type of aflatoxin can result in impaired immune function, liver damage, and malnutrition due to decreased appetite related to symptoms of exposure, such as nausea.

How Can I Tell If My Tea Bags Are Moldy?

Mold can grow on the individual tea bag or the container housing them. If you find mold growing on the inside of your tea storage container, it is best to discard all of the tea bags in that container.

Be sure to fully disinfect the container prior to storing anything else in it.

Mold spores can be present on the exterior and/or interior of your tea bag. Fungi can take on many different appearances. If you open your tea container to find a fuzzy, velvety substance that is white, black, blue, or yellow in color, you have found mold.

A mold infestation limited to the interior of the tea bag will present differently. The mold inside will typically be damp and you will see it begin to seep through your tea bag. This will give the appearance of a used tea bag despite its freshness.

When mold is present, the moisture of the growth will cause the tea leaves to clump together within the bag. Hold your tea bag up to a light source and give it a gentle shake. If the individual tea leaves are freely moving about in the bag, this tea is safe for consumption.

However, if the leaves are stuck to the interior of the bag or clustered together, it is best to toss the bag. Moldy tea bags that are in contact with other tea bags warrant a check of the other bags present in the container.

Your sense of smell can detect an infestation of mold as well. You should never intentionally sniff a known source of mold. Doing so will cause the mold spores to become airborne and enter your nasal passages and lungs, leading to irritation of those systems.

However, if you open your tea tin to discover a musty, dank, earthy smell that is not associated with the type of tea you purchased, discard the tea. It is either moldy or has expired.

The power of taste is another indicator of healthy tea. If your tea tastes unusually earthy or pungent, it may have been moldy. Discard the cup and any tea bags that were in contact with the contaminated batch.

What Can I Do to Prevent Moldy Tea Bags?

Your first line of defense against moldy tea bags is evaluating the type of tea you’re purchasing.

Herbal teas are the most likely to be contaminated by mold since the variety of ingredients varies widely and the process by which the organic materials are dried does not definitively kill fungal pathogens.

Purchasing organic tea also leaves your tea susceptible to fungi because organic crops are grown without pesticides or fungicides. Commercial-grade tea that is not grown organically is the least likely to have any pre-harvest mold contamination.

Loose-leaf tea varieties are packaged wholly without a tea bag. Investing in loose-leaf tea eliminates your risk of mold spores that may occur on traditional tea bag materials. Buying teas in leaf-only form with no added roots, oils, or herbs also nixes a factor where mold may be introduced to your tea.

Proper storage is the most important (and easiest to control) factor in preventing your tea bags from molding. The humidity of your home should be above 30% but below 50%. This percentage can vary from room to room.

Laundry rooms, bathrooms, and kitchens tend to be the most humid rooms in any given home. The humidity can be controlled through proper ventilation and dehumidifiers.

The easiest way to mitigate high humidity in small spaces is with desiccant dehumidifiers. Decreasing the humidity of your planned tea storage area will reduce the chances of mold growing on your tea bags.

The container in which you store your tea bags is just as important as the environment surrounding it. While darkness is ideal for mold, it’s also ideal for tea.

Choosing a canister that is opaque will protect your tea from light. Sunlight will degrade the tea’s quality and deprive it of flavor over time.

The ideal storage container for your tea bags should be airtight. This can be achieved by using a container with a hardy seal and ensuring that the container is proportionate to the volume of tea.

You wouldn’t store just a few tea bags in a gallon-sized jar. Doing so would trap copious amounts of oxygen and potentially mold spores in with your tea bags.

Excess oxygen would enable spore growth and would cause your tea to become stale more quickly than it normally would.

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Bill Redican

Thursday 27th of October 2022

Would it do any good to zap the teabags before use/storage in the microwave or oven to kill the fungus spores? I seem to have a problem after I brew the tea: Tossing the teabags in the trash or small collection bowl unleashes a glorious opportunity for the fungi to flourish.