Friday, July 18, 2008

Aspergillus

Aspergillus species is commonly found in the corn. The species that is closely associated with the corn is the Asp.flavus and A.parasiticus. The mycotoxin formed by these 2 species is Aflatoxins.[1]

Aflatoxins is then classify B and G. In maize Aflatoxins B is present in it and this might remain in the flour as the maize under minute processing treatment when milled into flours.

Source of Aflatoxigenic mold and Aflatoxins
Aspergillus Flavus and parasiticus occur naturally. They can invade the crops before harvesting. In corn, the molds can enter when the crops are damage by insect or during the development of the ear of the corns. Both the species are usually found in peanuts, oilseed, cottonseed and corn. A. flavus can also be discovered in cereals and spices.

Detection and Identification of Aflatoxigenic molds
The medium used to detect the Aflatoxigenic molds is Aspergillus Flavus and parasiticus agar. This agar is specifically made to detect this toxin. The agar is then incubated at 30°C for 48 to 72 hours. The Asp.flavus and A.parasiticus then will produce an orange-yellow colony reverse in which it can be easily being recognized and detected.

Hazards of Aflatoxins
Aflatoxins can result in acute health hazards which include lung, liver cancer and teratogenesis. In addition, it will lower the human immune system and affect the production of the antibodies in the body. Thus, this result the bodies to be prone to infectious disease.

Detection of toxins
The samples are extracted with solution consisting of the organic solvent (methanol and chloroform) and small amount of water. The presence of food composition such as protein, fats or pigment will interfere the effectively of the extraction. In this cause, solvent such as the hexane can be employed to separate these interference from the sample.

The extracts are then undergoes clarification whereby the extracts are concentrated and cleaned up to remove or filter out any possible food particle residue. Lastly, the extract are then separated by thin-layer chromatography or HPLC. The Aflatoxins will be visible under the UV light and are quantified by fluorimetry or by the comparison with the known standard concentration, if thin-layer chromatography is being used.

Immunoassay techniques such as ELISA and dipstick tests can also be used for the detection. Whereas, rapid technologies like the use of biosensors, PCR can commercial test kits are also available for detecting the toxin.








References for above info and data:

1. ICMSF. 2005. Micro-organisms in Foods 6; 2nd Edition. Klumer Academic/ Plenum Publishers; USA. Accessed on 10 July 2008.

2. (mostly from)

Michael P.Doyle and Larry R. Beuchat. Food Microbiology: Fundamentals and Frontiers; 3rd Edition. ASM Press; United States of America. Accessed on 16 July 2008.






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