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Mold on foods

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  • Mold on foods

    A question was received that asked what are the recommendations for preserving foods that have mold on them or visible "rot"?

    The vast majority of rot causing microorganisms are simply spoilage and have no ability to cause food borne illness. In fact most spoilage microorganisms outgrow, out-compete, and overrun foodborne illness causing microorganisms. There are no yeasts that cause food borne illness. There are no molds that cause food borne infections. There are a very few molds that produce toxic byproducts. Ergot is an example. This chemical is produced by mold spoiling grains in moist environments in the field or in storage. Some blame ergot for causing the hallucinations that led to the Salem witch trials. Some other mycotoxins include aflatoxin, ochratoxin, and patulin. Commercial foods that are known to be a potential for mycotoxin contamination are tested by food ingredient suppliers and food manufacturers to protect the public.

    IF” a mycotoxin producing mold were present on a food the toxin causes illness when consumed in very large quantities. For example, aflatoxins are associated with certain grains and nuts. They grow extensively on them for a length of time in the field or storage. This accumulates high levels of aflatoxin. As people eat more and more of the same item, they can become ill. Encountering a single mold or rot on a fruit or vegetable is a little different. First, it is usually a spoilage bacteria that invades the tissue of a fruit or vegetable. This wounds the “skin”. The wound then is colonized by a spoilage mold or yeast.

    Recommendation: For firm fruits and vegetables remove and discard 1/2 to 1 inch around the visible rot. Use the remaining fruit or vegetable for preserving. For fruits or vegetables that have free flowing juices (soft), discard the entire item (e.g. cucumbers and tomatoes). Be aware that mycotoxins are NOT destroyed by cooking temperature. Boiling water canning temperatures might lead to a small reduction and pressure canning temperatures may destroy some or all of the mycotoxins (depending on type, time, food, etc).
    Dr. Brian Nummer, PhD
    USU Extension Food Safety Specialist