Q.49 The aflatoxin found in post-harvested grains is injurious to health due to
(A) Aspergillus (B) Alternaria (C) Fusarium (D) Phytopthora
Aflatoxin in Post-Harvest Grains: Health Hazard from Aspergillus
Aflatoxins are potent carcinogenic toxins contaminating post-harvest grains like maize, peanuts, and rice under warm, humid storage. These mycotoxins cause liver cancer, immune suppression, and acute toxicity. The fungus responsible thrives in improperly stored crops, making identification crucial for food safety.
Correct Answer
(A) Aspergillus. Species like Aspergillus flavus and A. parasiticus produce aflatoxins B1, B2, G1, G2 in stored grains, leading to health risks including hepatocellular carcinoma.
Aflatoxin Toxicity
Aflatoxin B1, the most dangerous, binds DNA after metabolic activation in the liver, causing mutations. Chronic exposure (<20 ppb) leads to kwashiorkor-like symptoms; acute (>1000 ppb) causes liver failure. Grains turn toxic post-harvest during improper drying/storage.
Fungal Characteristics
Aspergillus spp. are storage molds forming greenish-yellow colonies. They grow at 12-40°C, 85%+ humidity, invading oil-rich seeds. Unlike field pathogens, they dominate post-harvest decay.
Option Analysis
| Option | Fungus | Correctness | Reason |
|---|---|---|---|
| (A) | Aspergillus | Correct | Primary aflatoxin producer (A. flavus) in stored grains; B1 causes liver cancer . |
| (B) | Alternaria | Wrong | Produces alternariol (weaker toxins); field blight on tomatoes/grains, not aflatoxin. |
| (C) | Fusarium | Wrong | Makes fumonisins/zearalenone in maize; causes fusarium head blight, not aflatoxins. |
| (D) | Phytophthora | Wrong | Oomycete causing late blight (potato/phytophthora root rot); no mycotoxin production. |
Prevention Tips
Dry grains to <13% moisture, store <15°C, use airtight silos. Monitor with ELISA kits (limit: 20 ppb). Biocontrol with non-toxigenic A. flavus strains reduces contamination by 90%.
