Once or twice in your life, you have encountered mold on bread. The greatest dilemma that faces you is whether to do away with the whole bread or eliminate the affected area. Many people wonder if bread molds can affect their health. The need to be safe and less wasteful makes it hard to decide what to do with moldy bread. Sometimes you might not be sure whether the molds have affected the whole bread or a part of it. This blog will discuss what molds are, why they grow on bread in the first place, whether they are safe to eat, and how we can prevent them from growing on bread.

What are Molds?

Molds belong to the kingdom fungi. They require moisture and oxygen for them to grow. Molds can grow on any surface. The most favorable condition for them to survive is moisture. There are many types of molds with different colors. These colors include: white, blue, grey, yellow, and black. As they develop, these colors may change, making it hard to identify the type of mold. They reproduce fast through spores. Once the spores land on a moist surface, they grow into new molds. Within a short period, molds can spread on a whole bread. The most common type of mold that grows on bread is Rhizopus, Penicillium, and mucor.

Are Molds Safe?

Mold is not safe to eat. These are reasons why molds are unsafe. Inhaling molds can cause allergic reactions. Sneezing and difficulties in breathing characterize these reactions. Those with respiratory diseases such as asthma may show adverse reactions to inhaling mold. Once you notice a mold on a break, refrain from smelling it.

Molds can cause infections. People with a weak immune system are more vulnerable to such infections. Molds belong to the fungi family. Once inhaled, they may thrive in the breathing system as it is moist, causing infections. Moldy bread has a stale taste. The staleness may affect the digestive system leading to stomach upsets.

Molds can produce some poisonous substance known as mycotoxins. Consuming these mycotoxins can cause serious digestive diseases. The toxins interfere with the lining of the stomach. Little exposure to them may cause stomach upsets and nausea. Long-term exposure to such toxins has been linked to increased chances of getting stomach cancer. The mycotoxins accumulation in the body may also interfere with the functioning of the liver. It may later lead to liver failure. These toxins affect both animals and human beings. So, it would help if you did not give moldy bread to pets too. Molds might show in one area of the bread while other areas might look fresh. It is not a guarantee that other parts of the bread are safe. Mold roots are microscopic. They might go deep into the bread unnoticed. Therefore, it is safe to do away with the whole bread.

Why Molds grow on Bread

The survival and reproduction of molds require certain conditions that might e met by a bread. Moisture is one of the conditions. The outer part of the bread might seem dry. However, it might contain some moisture on the soft inner part of the bread. After baking, bread is usually packed in plastic bags. If it is packed without enough cooling, hot air may later condense, leaving moisture on bread. Poor storage at home may also attract some moisture into the bread. While slicing the bread, the knife used might be wet, introducing more moisture to the bread. This moisture would provide a suitable area for the survival of molds.

Living things require food for survival. Bread provides enough food for molds. It is rich in carbohydrates which are fed on by the mold. Availability of food leads to faster multiplication. The mold may spread on the whole read quickly. Room temperatures are best in the survival of mold. Molds can not survive at low or high temperatures. Storing bread in a polythene bag at room temperatures encourages the growth of molds.

How to prevent the growth of mold on  bread


Low temperatures inhibit the growth of mold. Freezing makes the bread maintain its original taste and prevent staling. Ensure you get it out of the freezer 30 minutes before eating the bread.

Check on the expiry date.

Ensure you finish your bread at least one day before the expiry date. Keeping the bread past the dates increases the chances of developing mold and staling.

Keep your bread dry

Plastic bags that store bread can clearly show any moisture inside. Ensure you change the packing bag once you notice any moisture. Mold can not survive on a dry surface.

Always keep it covered.

Covering bread prevents any spores in the air from landing on the bread. Spores later grow their molds after getting favorable conditions.

Vacuum seal it

Vacuum sealing of bread ensures no oxygen is needed for molds to grow. Once the bread is removed from the vacuum store, you should not restore it.

Use of chemical preservatives

Bread with no preservatives starts to develop molds within three days. Adding preservatives prolongs the period in which the bread can go without staling and developing mold.

The bottom line

Never eat moldy bread. A mold on one spot is an indication that the whole bread might be affected. Eating such bread may make you sick.  Poor storage of bread increases the chances of bread developing mold. Ensure you store your bread in a dry place. Cover the bread to prevent contact with spores. Freezing will also prevent mold. A piece of moldy bread is not safe for pets too. It should be disposed of in a place out of reach of children and pets.

In some places where bread is produced in large numbers, preservatives are added to inhibit mold growth.  Other companies use lactic acid in place of preservations to deter the growth of mold. Cinnamon, cloves, and vinegar are also used for this purpose. However, they are rarely used as they interfere with the taste of bread.


We would like to thank the below contributors who have helped us to write this article:

Guangzhou CN CNC Tools Co., Ltd

Marie Salbuvik

Dietician MS, Lund University, Sweden Nutrition plays an important role in human life. Eating habits are one of the factors that affect our health. There is often a misconception among people that nutritionists force a very restrictive diet, but that is not true. In fact, I don't ban any products, but I point out dietary mistakes and help change them by giving tips and new recipes that I've tried myself. I advise my patients not to resist change and to be purposeful. Only with willpower and determination can a good result be achieved in any area of life, including changing eating habits. When I don't work, I love to go climbing. On a Friday evening, you are most likely to find me on my couch, cuddling with my dog and watching some Netflix.