Aflatoxins are toxic compounds produced by specific types of molds, posing a food safety concern. These toxins are particularly relevant to peanuts, a globally important crop. This article explains how aflatoxins contaminate peanuts and their health implications, ensuring the safety of this widely consumed food.
Understanding Aflatoxin
Aflatoxins are produced by certain fungi, primarily Aspergillus flavus and Aspergillus parasiticus. These molds are commonly found in soil and decaying vegetation, thriving in warm, humid regions with temperatures typically ranging from 82 to 98°F (28 to 37°C) and relative humidity exceeding 85%. While their presence doesn’t always mean aflatoxins are present, it indicates a significant risk. Aflatoxin B1 is the most potent carcinogen, produced by both A. flavus and A. parasiticus.
How Peanuts Are Contaminated
Peanuts can become contaminated with aflatoxins at multiple stages: in the field before harvest, during harvesting, or throughout storage. In the field, factors like high temperatures, drought stress, and insect damage increase susceptibility to fungal growth and toxin production. For example, severe drought can lead to poor pod development and increased A. flavus growth.
After harvest, improper drying contributes to contamination; peanuts not dried immediately or failing to maintain a safe moisture level allow fungal growth. During storage, high moisture content (above 8%), elevated temperatures (exceeding 77°F or 25°C), and insect activity create environments conducive to aflatoxin production. Peanuts stored in conventional metal warehouses, for instance, have shown higher temperatures and moisture, correlating with increased insect infestations and aflatoxin levels.
Health Risks of Aflatoxin Exposure
Consuming aflatoxin-contaminated peanuts leads to health issues, with severity depending on dose and duration of exposure. Acute, high-dose exposure, though less common due to regulatory controls, causes severe liver injury and may be fatal, especially in children. Acute toxicity symptoms include nausea, vomiting, and abdominal pain.
Chronic, low-level exposure is more prevalent and results in long-term health consequences. This includes liver damage, such as cirrhosis, and immune system suppression. Aflatoxins are classified as human carcinogens, strongly linked to hepatocellular carcinoma. The risk of liver cancer is elevated, up to 30 times greater, for individuals with chronic hepatitis B virus infection who are also exposed to aflatoxin.
Ensuring Peanut Safety
Minimizing aflatoxin exposure in peanuts involves industry practices and regulatory oversight. Farmers employ methods such as timely irrigation to reduce drought stress and proper harvesting at optimal maturity to prevent fungal growth. After harvest, rapid drying of peanuts to a moisture content of 7% or less inhibits mold development.
The peanut industry also implements post-harvest measures, including storage at controlled temperatures and humidity (e.g., 77-81°F and 70% relative humidity for up to a year) and sorting to remove damaged or discolored kernels. Regulatory bodies, like the U.S. Food and Drug Administration (FDA), set action limits for aflatoxin in food products. While the FDA’s action limit for total aflatoxins in peanuts for human consumption is 20 parts per billion (ppb), the industry often adheres to a stricter self-imposed limit of 15 ppb. Consumers can contribute to safety by purchasing peanuts from reputable sources, storing them in cool, dry conditions, and discarding any peanuts that appear moldy or discolored.