Aflatoxin in Peanut Butter
What is aflatoxin?
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Aflatoxin is a naturally occurring mycotoxin produced by certain fungi (Aspergillus flavus and Aspergillus parasiticus) which can grow on crops such as peanuts. Aflatoxins are known human carcinogens and can remain in the liver for long periods of time, sometimes resulting in suppression of the immune system as well.
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What is a fluorometer?
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A fluorometer is a device composed of four parts:
1. Keypad, 2. Readout device, 3. Sample holder, and 4. Detection, which can be used to quantify the level of toxins in a particular sample of food after completing the processes of extraction, dilution, filtering, and eluting through an affinity column. |
Purpose of Experiment:
To utilize the Aflatest AOAC Fluorometer procedure to quantify the concentration of aflatoxin present in a sample of commercially sold peanut butter.
Procedure:
The fluorometer was first calibrated using Mycotoxin calibration standards. 25 g of the JIF peanut butter sample was weighed out on a piece of weigh paper using an analytical balance. That sample was then blended with 125 mL 70% methanol: 30% water solution and 5 g NaCl (also weighed out on the analytical balance) at high speed for 2 minutes. The extract was poured into fluted filter paper; filtrate was collected in a clean glass beaker. 15 mL of the filtered extract was transferred to a second beaker and diluted with 30 mL distilled water. The dilute extract was filtered through a microfiber glass filter into a syringe barrel using the marking on the barrel to measure out 15 mL. The 15 mL of twice-filtered dilute extract was passed through the Aflatest column at a rate of 1-2 drops/second, then followed by two 10 mL washes of distilled water at a rate of 1-2 drops /second. The Aflatest column was then eluted with 1.0 mL HPLC grade methanol at a rate of 1-2 drops/second to collect all 1 mL of sample eluate in a glass cuvette. 1 mL freshly prepared Aflatest Developer was mixed with the eluate in the cuvette before measuring fluorescence in the calibrated fluorometer. After 60 seconds, the provided readout of aflatoxin concentration was recorded.
Results:
Our sample of JIF peanut butter contained 1.7 ppb aflatoxin, well below the 20 ppb limit set by the AOAC.
Conclusion/ Improvements:
Because the aflatoxin reading generated by the fluorometer came out to be 1.7 ppb, below the 20 ppb limit set by the AOAC, our sample of peanut butter was confirmed to be safe for human consumption. Because the aflatoxin content of the peanut butter sample was found to be below the limit, the fungal metabolite should not pose any significant threat to human health. Though aflatoxin is known to accumulate in the liver, at this level, where it is considered to be an “unavoidable contaminant” by the FDA, it should not increase risk of liver cancer or cause notable suppression of the immune system.