Moldy food, fruits & vegetables – safe to eat?

Our busy daily life sometimes hinders us from properly managing our fruit & vegetable supplies. At times, we’re late in eating or cooking them, and mold appears!

Moldy foods, quick facts

Hard foods – chop mold off & cook
Soft foods – throw them out
All cooked foods – throw out

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Now, the question: Is it safe to eat food after removing the mold?

The answer is both yes and no depending on which food items we are talking about. For that, a little background information is needed.

What are molds?

Molds are a type of microscopic fungi that are mostly multi-cellular, thread-like organisms.

They thrive on plant and animal matter, forming colonies. When they grow large enough, they can be seen by the human eye.

Molds produce spores that can be white, grey, black or green in color. They form in spore-sacs that burst open when ripe. These spores are like seeds. Air, water, and even insects carry the spores from one place to the other.

There is no exact number how many species of fungi there are. What’s clear is that it’s an amazingly high number. The lowest estimates are of no less than a few hundreds of thousands of species!

  • Fungi, including molds, are experts at breaking down organic matter.
  • On growing plants, they actively attack live materials.
  • Molds tend to specialize. Each species becomes an expert in infecting a specific plant, food, or other organic material.
  • As an example, check out this list of Septoria species.

Are yeasts and molds the same?

  • Yeast is a type of mold. Both are types of fungus.
  • With a powerful microscope, scientists can tell the difference between yeast and mold by counting the cells in an organism.
  • Yeast only has a single cell. This cell “does everything”: finds nutrients, reproduces itself, etc.
  • For molds, a single individual will be made up of multiple cells. Each cell type has a different function within the individual (reproductive cells, digestive cells, etc).
  • Bacteria are completely different, they are not even a type of fungus.

Where do molds usually grow?

Molds love food just as much as we do!

The perfect environment for mold is a warm and moist organic matter. This is exactly what food provides. Mold can grow on almost any food, be it raw or cooked.

  • Entire plants and live animals have an active immune system.
  • This continuously fights mold off to keep away infection.
  • Food is usually deprived of this immune system, since it’s cut away from the rest of the plant or has already been cooked.
  • Food harvested and brought inside is more vulnerable to mold than complete, live organisms.

When food is fresh, it has a particularly high water content.

  • High moisture makes it prone to having molds grow on it.
  • Warmth also triggers mold germination and spread, hence the importance of refrigeration.

What food can be eaten after cutting the mold out?

Mouldy food such as bread, apple, cheese.It’s important to know that if the layer of mold is thick, whatever the food, discarding it is the only option. But when there’s only a speck of mold or a very thin layer, two main groups of food can be distinguished.

Foods that are safe when a bit moldy – hard foods such as raw carrots, squash and hard cheese

Foods that are NOT safe when even a bit moldy – soft cheese, any food that has been cooked, and soft fruits and vegetables such as tomato.

Last but not least, you can influence how fast mold appears!

How to tell if food is moldy

Smell and taste

Moldy food has a peculiar smell and taste. It is not that horrible but it is surely not pleasant either. It usually tastes like wet dirt or dust.

The quantity involved in tasting a mold (a dab of a finger or small lick of the tongue) is very small. Even if toxic compounds are present, it’s rarely enough to be dangerous or even to trigger an allergy.

Soft layer of white, blue, or gray

Most molds are white or gray in color. Sometimes, more surprising hues appear, like blue or green.

How to keep mold from appearing

With most processed food, to reduce growth of molds, preservatives are added to food. They can be as simple as sugar, vinegar or salt. Sometimes more elaborate chemicals are used.

Preservation techniques like sterilizing, freezing, drying, smoking or pickling are also practiced.

  • Each of these uses a different way to make sure molds and other organisms that spoil food cannot grow.

However, it is good to remember that molds are also present on all things, indoors and outdoors. Even when they’re not actively developing, spores are there, waiting for the right conditions to germinate.

Moldy food can cause health problems

Here’s a nice quote to remember:

An important point to keep in mind is that mold is like an iceberg. What we see is not all that there is.

Mold sends out “roots” and “branches” that grow beyond what is visible on the food. A layer of thick mold on food can be expected to have a matching depth of roots deep beyond the top surface.

In most cases, if mold is present, so is bacteria.

  • Bacteria not only looks awful, it’s also more dangerous to health.
  • Visible mold often is a signal that dangerous, invisible bacteria might also be present.

Some molds (and many bacteria) develop and spread toxins (specifically, “mycotoxins”). These are chemical compounds that the mold uses to break through plant cells to get to the nutrients inside. These toxins are the main reason molds are dangerous. They induce health problems like allergic reactions and respiratory problems.

  • Some species develop potent “mycotoxins” which can lead to severe health issues.

What makes it difficult is that quite often, toxins are heat-resistant. This means cooking the moldy food will kill the mold, but it won’t destroy the dangerous chemicals that are left behind.

Waste not! – A new paradigm

Should moldy food always be thrown out?

Mold (or mould, in British English) clearly shows that rotting has begun. Not wanting to waste food, we don’t want to throw it all away.

  • Usually, we slice the bad part off.
  • If what’s left still looks okay, we keep it and toss it in our recipe.

Not only does it save effort and expenses, but, increasingly, it answers a deeper motivation.

  • That moldy piece of food is the result of both nature and persons working together for us.
  • Finding a way to keep and use it is an active, concrete way to show respect and honor towards nature and the work of others.

Mold in the wild

In the wild, mold is an essential part of the ecosystem. In forests, mold breaks down fallen trees and autumn leaves. Decaying animal carcasses also are recycled back into nutrients thanks to molds.

  • In forestry, mold and fungi play a critical role: the faster fallen leaves are broken down, the healthier the soil.
  • A healthy forest is a forest with only extremely few of last year’s leaves.
  • A thick layer of leaves is a sign that molds and bugs in the soil aren’t degrading dead plant material fast enough.
  • It’s quite unexpected, since we often recommend to use dead leaves for mulch in thick layers. In a garden, the goal is to trigger mold and bug activity, hence the overload!

Some animals, such as forager ants, have actually specialized in cultivating mold for food.

Usually, mold attacks and degrades dead organic matter. In the case of some fungal diseases such as sooty mold, even live plants are targeted.

Smart tip about moldy food

Take two minutes to look up the local food poisoning center. Create a contact on your phone with the name “Food poisoning” and add the address and emergency number for that center. Also, write this up on two notes that you can set on the fridge and near the main door to your house.

Moldy food on social media

Click to open the post in a new tab on the relevant social media site. Follow us there, comment, and share!
Create or join a topic on our food growers forum, too.

Picture related to the article overlaid with the Facebook logo.Picture related to the article overlaid with the Pinterest logo.

Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Molding tomato by Rosalyn & Gaspard Lorthiois, own work
Good & bad moldy food by Marco Luzi under Pixabay license
Moldy tomatoes and Moldy food on plank (on social media) by Rosalyn & Gaspard Lorthiois, own work