Sources of Cereal Contamination STRENGTHENING/IMPROVING THE CAPACITY OF NIGERIAN RICE/MAIZE PRODUCERS ORGANIZATION Sources of Cereal Contamination

What is contamination?

Contamination is simply the action or state of making or being made impure by polluting or poisoning.

Grains/Cereals Contamination The exteriors of harvested grains retains some of the natural flora they had while growing plus contamination from air, dust, soil , & other sources.  Freshly harvested grains contain loads of a few thousand to million of bacteria. There are three major sources of grain contamination. Physical contamination Biological contamination Chemical contamination

Physical contamination 1. Rodents What connection does rodents and lassa fever have?

Physical contamination 2. Anthropod fragments

Physical contamination 3. Exuviae sloughed skin of an animal, especially of an insect larva

Physical contamination 4. Feaces Cat are proven biological control for rodents in grain stores

Physical contamination 5. Internally feeding insects Wheat weevil Rice weevil

Physical contamination 5. Internally feeding insects cont’d Maize weevil

Biological contamination Flies, cockroaches, silverfish, wasp, rodents disseminate more than 100 species of pathogenic viruses, bacteria and fungi. They increase occurrence of mycotoxins. This poses a considerable risk to human food and animal feed safety

Chemical contamination Bacteria and fungi cause microbiological contamination in cereals. They produce chemicals such as Heavy metal presence in grains Storage Pests produce volatile chemicals which are responsible for bad smell of infested grains Pesticides also contaminate grains in storage if not applied correctly (in dosage, active ingredient, concentration and quantity Microbiological contaminants: these are from living things that are not easily visible to the eyes except they come under microscope Aflatoxins Ochratoxins Moniliformin

No so visible

Aflatoxin: a chemical contaminant Quick Facts Aflatoxins are formed as a result of fungal growth They don’t go even after the fungi that introduces them dies Those who consume contaminated commodities have severe health injuries including hemorrhaging, acute liver damage, edema (swelling), digestive difficulties, and possibly death, usually within a week of exposure The biggest and best known health effect of aflatoxin is liver cancer You cannot see, smell, feel or taste aflatoxin in grains 25% of the food produced worldwide is contaminated with aflatoxins. Due to the increasing recognition of the impact of aflatoxins on human health, food regulatory authorities have set and enforced limits for aflatoxins in traded food.

Maize contaminated with aflatoxin

At what stages does aflatoxin contamination occur? It begins during pre-harvest and can be worsened by inappropriate harvesting, handling, storage, processing, and transport practices Droughts, high temperatures, low soil fertility, pest and other stresses that affect plant growth and vigor increase the likelihood of fungal infection as well as the levels of aflatoxins produced by the Aspergillus fungi.

How to prevent/handle aflatoxin contamination Aflatoxin contamination can be prevented by application of good agricultural practices in crop cultivation and good management practices in post-harvest food handling. Destroy or bury deep infected cobs or grains. Why? This is because they are so stable and stubborn they are not easily removed by cooking, washing, milling or other common food treatment

Other contaminants Hair Water Residue in containers/bags Metals from processing machines

Non-poisonous contaminants Physical Mixture of different types of grains Physical Mixture showing crop off-types This is common among maize and rice farmers. This is common among maize and cowpea farmers What is the consequence of this paddy mix-up?

Mungode