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TOXINS IN POTATO

Sunday, July 11, 2010

GLYCOALKALOIDS
-naturally occurs in potatoes and are pest resistant.
-found in mainly potato sprouts & the peel of potatoes that taste bitter. but usually found low in levels.
-produced by the plant in response to stress such as microorganisms, UV light, and damage such as bruising.
-Concentration of toxin may vary because of fungal or bacterial infection & usually increase in response to wounding, as a defense mechanism against potential diseases.
-Amount of toxins produce also depends on the type of potato and their growing conditions. -glycoalkaloid poisoning can cause severe stomach ache and even death as it is an inhibitor of choline esterase that can cause hemorrhagic damage to the gastrointestinal tract as well as to the retina. however, this is very unlikely
-glycoalkaloids are not destroyed by cooking temperatures as its decomposition temperature is about 243ºC
-it is very important that the sprout of the potato, any greening due to sunlight exposure or damage parts of the potato and the skin of the potato are remove adequately before cooking to prevent consumption of such toxins by the consumers.
-it is recommended that potatoes are to be stored in dark, cook and dry places, as levels of glycoalkaloids increases when the potatoes are exposed to bright light for long period of time and storage under 10ºC. (New Zealand Food Safety Authority, n.d.; S.S. Deshpande, 2002; FAO Corporate Document Repository, n.d.)

ARSENIC
-occurs in our food in both organic and inorganic forms.
-groundwater that are from areas with geothermal activity and rocks that are rich with arsenic will contain extremely high levels of arsenic.
-Arsenic is also naturally present in all soils, thus the arsenic content of plants is usually determined by the arsenic content of the soil, water, air, fertilizers and other chemicals.
-Arsenic level in the plant can also be affect by the use of pesticides that may contain arsenic.
-If arsenic containing water is being use accidently to water the plants, the potatoes may contain high levels of arsenic that will increase the risk of consumers getting cancers. (Zealand Food Safety Authority, n.d.)

AFLATOXIN
-a mycotoxin that has been found in many foods of animal & plant origin.
-produced by 4 species of Aspergillus: A. flavus, A. parasiticus, A. nomius & A. pseudotamarii that contain metabolites that have been implicated in carcinogenicity, mutagenicity, teratogenicity, hepatoxicity & aflatoxicosis.
-Aflatoxicosis is the major syndrome associated with aflatoxins and the liver is the primary target of the toxin.
-Moderate to high consumption of the toxin will fatty, pale & decolorized livers, derangement of normal blood clotting mechanisms, resulting in hemorrhages, reduction in total serum proteins of the liver, accumulation of blood in the gastrointestinal canal, glomerular nephritis & lung congestion. (Heredia, N., Wesley, I., Garcia, S., 2009)

PROTEINASE INHIBITOR
-protects the potato against insects and microorganisms but are not toxic because they are destroyed by heat.
-Lectins or haemogglutenins are also present in potato. These toxins are capable of agglutinating the erythrocytes of humans, but are of no significant issue as they can be destroy by heat. Thus, it is important that the potatoes are adequately cooked. (FAO Corporate Document Repository, n.d.)

New Zealand Food Safety Authority. (n.d.). Arsenic and the food we eat. Retrieved on 1st June 2010, from NZFSA. Website: http://www.nzfsa.govt.nz/consumers/chemicals-nutrients-additives-and-toxins/arsenic/
Heredia, N., Wesley, I., Garcia, S. (2009). Microbiological Safe Foods. U.S.A., New jersey: John Wiley Sons, Inc.
FAO Corporate Document Repository. (n.d.).Toxic substances and antinutritional factors. Retrieved on 1st July 2010, from FAO. Website: http://www.fao.org/docrep/T0207E/T0207E08.htm#Potato