Food Safety Issues/Botulism in banana bread?


QUESTION: Someone in my household made several loaves of banana bread yesterday afternoon. They stuck toothpicks in to check for doneness. After the loaves had cooled, they wrapped them quite tightly in foil and left them on the counter til tonight -- maybe 30 hours - then put them in the refrigerator.  I am feeling anxious about botulism after not finding any reassurance on the internet. Is there any possibility of botulism in the banana bread since it was poked and tightly wrapped and left in room temperature so long?  Should we eat it or toss it?


You do not need to be concerned with C. Botulinum as this organism only becomes an issue in foods with a pH above 4.6 and in low to no oxygen environments such as in a vacuum sealed can or jar.  Botulism does not occur in foods with a pH below 4.6 that are left on the counter, even when wrapped in foil.

Banana bread can be left at room temperature and does not require refrigeration. The main organism that can affect any bread after storage at room temperature is mold, but usually this takes several days or even a week before any sign of mold is seen.  The dryer the bread, the longer it takes mold to form.  Normally, quick breads have more moisture than other types of bread and therefore will mold faster. Notice that breads are sold at room temperature at the grocery store and bakery.

The only way botulism could be associated with bread is if it is canned.  This is why home canning of bread in jars is not recommended.

As long as the bread is not showing any signs of mold, it should be safe to consume.


---------- FOLLOW-UP ----------

QUESTION: I appreciate your prompt response. My concern is because I assume a moist bread product made with ripe bananas is above pH 4.6 and that foods snugly wrapped by hand could create a low or no oxygen environment -- since baked potatoes wrapped in foil and left out of refrigeration too long are a danger. Is there something wrong in my assumptions or is there another factor that explains why such bread would not be susceptible to botulism?

Hi Again,

The problem with baked potatoes and foil is that potatoes, which are grown in the ground where botulism spores are found, if not washed properly before baking could have spores on their surface.  If the potatoes are then baked wrapped tightly in foil and then left at room temperature after baking for several days, it is a possibility for the botulism spores to become active.  It is very rare...but it is possible.

Most food related botulism cases in the US are are related to improperly canned low-acid foods -- not foods wrapped in foil.

To my knowledge, there has never been botulism associated with baked goods such as bread. The key factor for botulism is contact with tainted soil and none of the ingredients used in baking bread has been associated with botulism.

Even wrapping banana bread tightly in foil would not give an oxygen free environment necessary for botulism spores to become active.  Banana bread has air holes as part of the texture. Couple that with ingredients that are not known to harbor botulism spores and you get a product that is not susceptible to botulism.


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Carol Schlitt


I can answer questions on home food safety, sanitation and home food preservation.


I am a former Extension educator, nutrition, wellness and food safety, having retired August 1, 2010. I am a food safety instructor for the Illinois Department of Public Health, a ServSafe Instructor/Proctor and have my own company, Safe & Savory Solutions, Inc -

National Extension Association of Family and Consumer Sciences (Past President and current Historian), St. Louis Culinary Society.

BS - University of Illinois MS - Southern Illinois University at Edwardsville

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