Moldy Peanuts: Safe to boil?

by Jessica
(Columbia, South Carolina)

I got a bag of boiling peanuts at the grocery store and let them sit on the counter for a few days. By the time I went to boil them, many were moldy. Should I throw the whole bag out, or can I safely cook the ones that weren't moldy?

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Oct 12, 2012
Mold on Peanuts
by: Bret

Jessica,
Throw them all out. Aspergillus flavus, and Aspergillus parasiticus can be present on peanuts. These 2 molds produce aflatoxin, which is toxic for humans and animals.

Green peanuts typically have between 35% and 50% kernel moisture content (KMC). Green peanuts should be stored in the refrigerator or freezer if you are not immediately boiling them.

The FDA regulates the acceptable food levels of aflatoxin to 20 parts per billion for human consumption.

According to the Agricultural Experiment Station/Auburn University paper (1977), "Aflatoxin Formation in Peanuts by Aspergillus Flavus",

"The A. flavus group of species is a normal constituent of the microflora in air and soil, and is found on or in living or dead plants and animals throughout the world. It has been found associated with peanut soils and peanuts wherever they are grown. Aspergillus flavus is an important storage fungus associated with the deterioration of wheat, corn, rice, barley, bran, flour, soybeans, and other seeds. It has also been reported as a pathogen of man and animals and as a plant pathogen" (p. 4).

"High mold counts were correlated more often with high initial moistures of peanut kernels than with any other factor. Mold counts were consistently high in peanuts placed in storage with kernel moisture contents 12 1/2 percent" (p. 6).

"Under tropical conditions, peanuts that were free of toxin at digging contained detectable toxin in 48 hours" (p. 8).

"The longer the crop was in the field before artificial drying, the greater was the amount of aflatoxin. Other field studies showed that contamination of kernels with aflatoxin occurred at least 5 to 6 days after lifting" (p. 8).

"It is difficult and probably arbitrary to separate the interrelationships of temperature and time from that of RH or moisture. Aspergillus flavus has cardinal growth temperatures as follows: minimum 6 to 8 C, optimum 36 to 38 C, and maximum 44 to 46 C. Minimal and maximal temperatures for growth are affected by moisture, oxygen concentration, availability of nutrients, and other factors" (p. 11).

"Limiting conditions that prevent aflatoxin production by the fungus were demonstrated to 83 percent relative humidity or lower (peanut KMC of 10 percent or lower) and temperatures of 12 C or lower and 41 C or higher" (p. 43).

"Harvesting at maturity with minimal damage to pods followed by rapid drying and storage in a low moisture environment will reduce aflatoxin development to a minimum. Cold air can be used to aerate farmers stock peanuts in storage. The use of refrigerated storage for shelled peanuts is common" (p. 44).

Jul 17, 2014
Mold on boiled peanuts
by: Anonymous

I boiled some peanuts, and the plug got kicked out, and mold formed on top. I skimmed it off, and reheated the nuts. Will it hurt them?


Aug 14, 2017
boiled peanuts
by: Anonymous

Is it safe to eat peanuts after u boiled them.

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