Microbiology and Plant Pathology
Aflatoxin in Peanuts and Peanut Butter

Project background and rationale
Food safety is the assurance that the food will not cause harm to the consumer when it is prepared and/or eaten according to its intended use (1). Food safety refers to all hazards, whether chronic or acute, that may make food injurious to the health of the consumer (2). In general, there are extensive groups of food safety hazards, including chemicals, natural occurring toxicants, food additives, pathogenic microorganisms, tampering and nutritional defects (3). Of these hazards, microbiological hazards are the major cause of foodborne illnesses worldwide. Although not regarded as foodborne pathogens, fungi producing toxic metabolites known as mycotoxins can also affect the health of humans.

Mycotoxins such as aflatoxin are a group of secondary metabolites produced by fungi that are natural contaminants of agricultural products such as peanuts. Aflatoxin is the name for a group of toxins (poisonous chemical components) that are produced by two fungi called Aspergillus flavus and Aspergillus parasiticus (4). This two species are more problematic during storage (especially in warm and humid silos). These toxins occur naturally and have been found in wide range of commodities (including peanuts) used for animal and human consumption. Depending on the levels, the toxins (B1 – AFB1in particular) can severely affect the liver and they are known human carcinogen (i.e., causes cancer). Aflatoxin is a major health risk to humans and animals in developing countries due to the high levels of contaminated product consumed. According to a study done a few years ago, eating peanut butter that contains an average level of only two parts per billion of aflatoxin once every 10 days could present a cancer risk of seven times in one million (5). Although the risk seems small, it is higher than the estimated risk of cancer from pesticides. The levels of aflatoxins in peanut butter differ from brand to brand (6). The minimum aflatoxin level required is 15 ppb (parts per billion).

In South Africa, high levels of aflatoxin were allegedly found in peanut butter in 2001 given to school children in the Eastern Cape (7). In subsequent studies conducted by the government, levels of aflatoxin in certain cases exceeded the legal limits. Consequently, an Aflatoxin Project was established and consists of the most significant stakeholders – Department of Health and Agriculture and the Peanut Forum (7). Although there were no deaths reported in all the studies conducted, the findings strongly suggested the need for rigorous inspection of peanuts and peanut butter before they reach the shelves.

The main objective of this study is to evaluate existing levels of mycotoxins in peanuts and peanut butter.

Project objectives

References

Participants