Many agricultural products are susceptible to contamination by a group of fungi that produce toxic secondary metabolites known as mycotoxins. Among these, aflatoxins are the most studied due to their harmful effects on human health, poultry, and livestock.
Aflatoxins are mainly produced by two species of fungi: Aspergillus flavus (predominant in Asia and Africa) and Aspergillus parasiticus (mainly found in the Americas). These fungi can contaminate a wide range of food products. One of the most dangerous forms, aflatoxin M1, can even be found in the milk of animals that have consumed contaminated feed, such as peanut cakes or small immature pods attached to the plant.
- Carcinogenic: Aflatoxins are known cancer-causing agents, especially linked to liver cancer.
- Synergistic with Hepatitis Viruses: They increase the risk of infection and disease progression in individuals exposed to hepatitis B and C.
- Immune Suppression: Aflatoxins weaken the immune system, making the body more vulnerable to infections.
- Child Growth Impairment: In regions like Africa, aflatoxins are linked to growth stunting and childhood cirrhosis, particularly in India.
- Impact on Livestock and Poultry: Symptoms include reduced appetite, weight loss, lower egg production, and contamination of milk and other animal products.
Post-Harvest Factors
- Delayed harvesting
- Mechanical damage to pods during harvest
- Storing pods with moisture content above 10% or under humid conditions
- Insect infestation during storage
- Storing plant residues (haulms) with small or immature pods, which are more susceptible to aflatoxins
- Delayed pod cleaning after harvest
- Re-wetting of stored pods due to ground moisture or leaky roofing
Pre-Harvest Factors
- Presence of Aspergillus flavus in soil and air, capable of infecting groundnuts at any stage
- Use of susceptible varieties
- Extended drought (over 20 days) at the end of the crop cycle
- Soil temperatures between 28–31°C around pod zones
- Pod cracking and physical damage due to growth stress or mechanical injury
- Pod damage by termites or pod borers
- Plant death caused by stem, root, or pod rot diseases at pod maturity
- Nematode infestations attacking pods
Different Pod Sizes
Pre-Harvest Measures
- Use aflatoxin-resistant groundnut varieties
- Select healthy seeds and treat them before sowing
- Apply organic manure or compost at 5–10 tons/ha
- Apply Trichoderma at 1 kg/ha
- Maintain an optimal planting density (33 plants/m²)
- Apply gypsum at 400–500 kg/ha during flowering
- Irrigate during late-cycle drought if possible
- Manage leaf diseases using Kavach with 1–2 sprayings
- Remove dead plants before harvesting
- Harvest the crop at full maturity
Post-Harvest Measures
- Avoid pod damage during harvest by placing the plough blade below pod zones
- Dry harvested pods for 3–5 days using a line-drying method facing the wind
- Ensure moisture content drops below 8%
- Shell or thresh pods immediately after drying to avoid rehumidification
Pods Damaged by the Plough
- Use appropriate sieves on mechanical threshers to eliminate unripe pods
- Discard damaged pods
- Separate large, fully mature pods (for consumption) from others (for oil extraction)
- Do not mix cleaned pods with unclean ones
- If needed, re-dry pods to maintain moisture below 8%
- Store jute bags filled with pods on wooden platforms in well-ventilated, dry areas
- Prevent insect infestation during storage
Cracks on Groundnut Pods
- Remove immature pods attached to the haulms
- Cereals: maize, sorghum, millet, rice, wheat
- Oilseeds: groundnut, soybean, sunflower, cottonseed
- Spices: chili, black pepper, saffron, coriander, ginger
- Nuts: almonds, pistachios, coconuts
- Milk and dairy products
- Cause visible deterioration of grain quality due to fungal growth, rendering them unfit for consumption or sale.
- Lead to poor seed quality, including seedling death and root rot.
- Severely impact the export value of groundnuts and their by-products.