Working together to eliminate cyanide poisoning, konzo and tropical ataxic neuropathy (TAN).

Cassava Cyanide Diseases Network

Issue Number 8, December 2006

Processing, Cooking and Garri is a ready-to-eat product used Contents in different ways in the kitchen. One Cyanogen Reduction of method is to add boiling water with Processing, Cooking and Products in stirring until a sticky smooth garri Cyanogen Reduction of dough is produced. The dough is cooked and served with or Cassava Products in Nigeria1 as the main meal at any time Cassava is an important staple food of the day. Garri may also be Total Cyanogen Content of for 500-1000 million people in the dispersed in cold water, sweetened tropics. Nigeria leads the world in Gari from South-Eastern with sugar or salted and served as a cassava production (about 34m refreshing drink. Some people chew 1 Nigeria ……………………….2 tonnes ) and is the largest consumer garri along with roasted , of cassava as food. Nigerian smoked dried fish or palm kernel as Some Potentially Unsafe farmers grow sweet cassava with a a snack. low level of cyanogens and bitter Practices in Cassava Retting cassava with a high cyanide paste is a fermented cassava in Eastern Nigeria…………..3 2 content which is preferred for product. It is processed by peeling processing of “garri” and “fufu”. The the root, washing in potable water Wetting Method to Remove main food sources of cassava are and fermenting for 4-5 days to Cyanide from Cassava Flour the root and leaves which are soften in a pot or bowl. The ferment processed and cooked in diverse ………………………………..4 liquid is decanted, the roots are ways according to local customs and crushed by squeezing by hand in preferences. another bowl of water and sieved to PestNet…………………..….4 remove fibrous materials. The Some of the popular cassava sieved material is allowed to settle in 2,3 products in Nigeria include garri the water before decanting, to 1 1 cassava fufu paste, fufu flour, produce fufu paste. The thick paste 4 “lafun” (fermented chips), cooked is molded into large balls and CCDN Coordinator: 5 cassava slices or chips (wet or dry) cooked in boiling water for 15-20 Dr. J. Howard Bradbury 6 and cassava leaves. Garri is a minutes to produces thick fufu balls. School of Botany and Zoology gritty, starchy, fermented cassava The cooked balls are pounded in a Australian National University Canberra ACT 0200, Australia staple consumed throughout mortar with water to yield smooth Phone: +61-2-6125 0775 Nigeria. It is estimated that about sticky soft dough. The dough is E-mail: [email protected] 70% of cassava roots are processed eaten as small balls with soup or 7 Coordinating Group: into garri. Garri is processed by stew for lunch or dinner. The meal is Julie Cliff, Paula Cardoso, Humberto peeling the root, washing and very common among rural cassava Muquingue,Arnaldo Cumbana, Dulce grating to form a mash, followed by consumers rather than in urban Nhassico; fermentation for 2-3 days by tying in areas because of the characteristic Country Contacts: a hessian bag with occasional : E.E Agbor; D.R. Congo: odour from fermenting cassava. pressing to dewater the mash. The D.D. Ngudi; India: Bala Nambisan and cassava cake is sieved to remove K.T. Shenoy; Fufu flour is processed by peeling CCDN News is the Newsletter of the Cassava Indonesia:A.Hidayat;Mozambique:Ana fibrous material and heated in a the cassava root, washing in water Cyanide Diseases Network (CCDN). The metal dish with stirring over a fire to CCbDeNla Zias caraia s;f rNeeig, eriwa:o rMld.wNid.Ae dinndeutw ork and fermenting for 2 days in water. comanmde nP.ceNd. Oin kJaufnoer 2001, which is working produce garri. A small amount of It is crushed and ground to form a Website: palm oil is added during frying if paste, bagged in woven polythene www.anu.edu.au/BoZo/CCDN yellow garri is desired. bags and dewatered by pressing.

The recovered cake is spread on a clean surface and sun-dried to produce flour. Fufu flour is cooked Starch is another cassava product 7Olukunle, O.A. (1987) A comparative by dispersing the flour in cold water consumed in the Niger Delta study of large and small scale garri in a pot. It is heated with continuous Region. It is cooked to form a thick processing technology in Southern stirring until a sticky smooth dough gel which is eaten with soup or stew. Nigeria. MSc Thesis. University of Nigeria, Nssuka. is produced. The dough is served Cassava products are subjected to 8FAO/WHO (1999) Joint FAO/WHO Food along with soup or stew as with fufu processes that can reduce total Standards Prog., Codex Alimentarius paste. It is eaten as the main meal cyanogens. Although, data on Comm. XII., Supp. 4, FAO, Rome, p 12- at any time of the day, commonly cyanogen contents of products are 45. among urban and rural dwellers. scarce, it was reported that 9Uzomah, A; Ubaonu, C.N and Aniche, reduction of toxicity varies in degree O.K. (2001). Nigeria Food J. 19, 70-75. 10 Cassava chips (“lafun”) are of effectiveness during processing Delange, F. and Ahluwalia, R. (1983) processed by peeling the cassava into different products.5 Recent Cassava toxicity and thyroid. IDRC, Ottawa . root, cutting into pieces and washing studies on cassava products such 11Osuntokun, B. O., Olurawaju, J.E, Mc in water. The pieces are soaked in as garri in some localities revealed Farlare, H and Wilson, J. (1968). Brit. water for 3-5 days and sun dried. It that some contained hydrogen Med. J. 2, 647-649. is milled into flour when desired. The cyanide (HCN) levels higher than 12Lambein, F, Defort, B. and Kuo, Y flour is dispersed in water and 10ppm, the safe level for cassava (2004) . CCDN News, No. 3, 2-3. cooked with continuous stirring to flour8 and 20ppm for garri.9 M.N.Adindu produce a sticky dough. The dough Consumption of improperly Nigerian Stored Products Research is eaten as small fufu balls with soup detoxified cassava products were Institute, Port Harcourt, Nigeria [email protected] or stew. reported to cause health disorders M. N. A 10 such as goitre and cretinism, Ni Cooked cassava sliced (wet or dry) tropical ataxic neuropathy (TAN) Total Cyanogen Content is processed by peeling the root, 11and konzo.12 TAN occurs in washing in water and cooking for Nigeria, but so far there is no of Gari from South- about 20-30 minutes. It is evidence of occurrence of konzo in Eastern Nigeria dewatered and cut into thin slices. Nigeria. The slices are soaked over night in Gari is a common staple among the water in a pot or bowl. They are Emphasis in research appears to Ibo speaking people of South- washed several times with water to concentrate in the area of Eastern Nigeria, especially in Imo remove slimy material on the slices. production, developing new varieties State. It is obtained by processing They are sun dried on a flat surface that are resistant to mosaic disease cassava during which about 83% of and the dry slices are eaten with and are high yielding which is good its inherent cyanogenic glucosides palm kernel, coconut or roasted for food security. It is therefore are detoxified.1 As a result complete peanut depending on locality and suggested that research in diseases detoxification of the cassava is not preference. associated with consumption of possible when bitter varieties which cassava products and their contain more than 400 ppm total Cassava leaves6 are consumed in elimination through simple and cyanogens are processed. different forms in Nigeria. Fresh effective processing methods as Sometimes the amount of residual immature leaves are washed in done in other African countries be cyanogens in the finished gari may water, shredded by hand and extended to Nigeria. This is even be higher than the FAO/WHO squeezed in water to reduce toxic more important because Nigeria recommended safe level of 10 ppm.2 constituents. The vegetable material consumes more cassava products in This calls for concern because the is filtered out and cooked with very diverse forms compared to chronic, continuous ingestion of condiments. It is eaten in some other producing countries, and cyanogens may have serious health combination with cooked yam processing and cooking of cassava implications such as acute (Dioscorea sp.) as porridge. In products is mainly done by rural intoxication, goiter, konzo and TAN.3 another method fresh cassava women using obsolete The disease tropical ataxic leaves are washed in water, technologies.9 neuropathy (TAN) is endemic in shredded gently underwater by hand some parts of Nigeria.4,5 Its to remove toxic constituents such as References: 1 incidence can be up to 18 to 26 cyanide. It is then used to cook soup Oyebanji A. O. (2004). in: Williams J. O. persons per 1000 in villages where or stew for consumption of garri or & Olokesusi, F. (eds). Proc. Root & the diet is nearly all cassava. By fufu. In yet another preparation, Tuber Crops Post Harvest Handling. comparison in yam eating villages cassava leaves are cut like other August 2004. Nigerian Stored Prod. Res. Inst., Ilorin, Nigeria. there is no incidence of TAN. vegetables, blanched and squeezed 2 Adindu, M. N. and Aprioku, A.B.I (2006). In this work, 22 gari samples were by hand under water to remove toxic Nigerian Food Journal 24: No 1. 135- purchased from markets in Imo constituents. It is used as a 138. State. The total cyanogen content of vegetable in cooking soup for 3Adindu M. N., Olayemi, F.F. and Nze- the samples was determined in consumption of garri or fufu. Finally, Dike, O.U (2003). J. Food Comp. Anal. triplicate using kit B2 with the colour young cassava shoots are washed, 16,121-124. 4 chart supplied.6 The mean values for shredded and placed in boiling water Adetuyi, & Nwankwo, (2002) Nigerian J. total cyanogen content ranged from and stirred for a few minutes. The Stored Prod. Res. 1, No 1, 82-86. 5Sokari, T. G and Wachukwu, C. K. 5 to 43 ppm with an average value cooking water is decanted and the (1993) Trop. Sci.. 33, 145-151. of 21 ppm (SD 10). 82% of the mean vegetable recovered for cooking 6 Metre, T.K (2006) CCDN News, No 7,p values were above10 ppm, the soup for garri consumption. 3. 2 CCDN News FAO/WHO safe level,2 which various types of products such as would have been eliminated during indicates that most of the processing “fufu” 2 in Nigeria, and “ kivunde” 3 in washing of the dough. On the other was inadequate. Tanzania. Fufu is obtained by further hand, the amounts in the control This is quite alarming because some pressing out water until the dough and treated samples of trona authors have reported cases of becomes firm. Retting takes about (bicarbonate) were 3660 and 4880 cyanide poisoning after consumption three to four days, which cassava ppm and of iron were zero and 87 of meals that contain cyanogenic processors today consider to be too ppm respectively. The high level of glucosides and no free cyanide, eg long. bicarbonate in the control sample is cooked dewatered lima beans, In Nigeria, practices, which include due to the hardness of local water cassava products etc. It has been the addition of chemicals not supplies. suggested that the enzyme required permitted in foods during retting, The results show that addition of for the hydrolysis of linamarin was have been adopted by local these chemicals to water for retting supplied by the microbial flora of the processors to shorten retting time4. cassava may render fufu unsafe for 4 intestine. This seems to be the These chemicals are used in the consumption. Trona, (NaHCO3) is an reason for the reported cases of mistaken belief that they will alkaline salt that greatly reduces the TAN in Nigeria, since TAN occurs as accelerate retting. Microorganisms activity of linamarase, an enzyme a result of prolonged ingestion of are known to have roles in the with maximum activity at pH 5.5 – inadequately processed cassava. chemical processes occurring during 6,7 which therefore resulted in fufu It is important to educate processors retting including the detoxification of with unacceptably high levels of on the correct methods to use. cyanogenic glycosides2,4. An cyanide. Disease consequences During processing there must be alteration of chemical conditions associated with consumption of food sufficient time for the linamarase during retting may affect the growth containing cyanogenic compounds enzyme to contact linamarin and of these microbes thereby are well known. Residues of trona break it down. There is also the compromising the detoxification (bicarbonate) and iron resulted from need to mount regular checks by process. In addition, a carry over of insoluble compounds that these governmental agencies to guard added chemicals into the finished chemicals formed during retting, that against the activities of product may constitute a health were trapped within the mash. unscrupulous processors. hazard on consumption of such Ingestion of trona may cause retted cassava foods. This report gastrointestinal disorders. It is also a References: investigates these risks in fufu, a suspected carcinogen because it 1 White, Garson, McMahon and Sayre popular cassava meal in eastern contains 0.4% silica.8 The (1998) Plant Physiol. 116, 1219-1225. Nigeria. presence of iron in the fufu is also a 2 FAO/WHO, 1991. Joint FAO/WHO Bitter cassava roots (2 years old) potential danger. Iron overload due Food Stand. Prog., Codex Alimentarius containing about 300 ppm cyanide, to excessive dietary intake among Comm. XII, Supp. 4, FAO, Rome. 3 Cliff, CCDN News 1, (2003), p 3. were steeped in water for 4 days African Bantu resulted in high

4 Agency for Toxic Substances and and then processed into fufu as hepatic iron stores in a substantial

Diseases Registry (ATSDR). described above. Kerosene (a thin part of the population and a high Toxicological Profile for Cyanide. Atlanta, oil distilled from petroleum), sodium prevalence of liver cirrhosis9. GA, Department of Health and Human bicarbonate (Trona, Solvay Therefore the use of these Services, (1997), 3 p. Chemicals Inc.) and common iron chemicals during retting, should 5 Cliff, CCDN News 2, (2003), p.4. 6 nails were added to steep water be strongly discouraged. Bradbury, Egan and Bradbury (1999) along with the cassava roots, at the J.Sci.Food Agric. 79, 593-601. rate of 0.5 mL kerosene/L, 1 g References: N. Onuegbu 1 Department of Food Science & trona/L and 10 g nails/L in separate FAO/WHO (1991). Joint FAO/WHO Technology, Federal University of trials. Total cyanides were Food standards programme, Codex Technology, Owerri, Nigeria determined on dried (500C) samples Alimentarius Commission XII, Supp. 4. of fufu using a picrate paper kit B25. Rome. 2Okafor, N., Ijioma, B. & Oyolu, C. Stored Products Research Institute Residues of added chemicals in fufu (1984). J. Appl. Bacteriol. 56: 1-13. Some Potentially Unsafe were determined by comparison 3Kimaryo, V.M., Massawe, G.A., Practices in Cassava between quantities in the test Olasupo, N. A. and Holzapfel, W. H. samples and control samples6. (2000). Int. J. Food Microbiol. 56: 179 – Retting in Eastern Trona was estimated by determining 190. Nigeria bicarbonates (method No. 33.076). 4Ogbo, F.C. (2006). African J. To determine iron, 10g of dried Biotechnol. 5 (9): 775 – 777. 5Bradbury, M.G., Egan, S.V. & Bradbury, samples were dry ashed and iron Retting is a simple traditional J.H. (1999). J. Sci. Food and Agric. 79: measured using a method for processing cassava 593-601. spectrophotometer (Spectronic 21 6 tubers, which usually yields products AOAC. (1974). Official methods of UVD), see method No. 14.013. th with cyanide levels within the Analysis.12 Edition. Association of Samples of cassava retted with Official Analytical Chemists, Washington, FAO/WHO safe level of 10 mg U.S.A. 1 kerosene and nails contained 9 and HCN/kg cassava (ppm). During 7 8 ppm of cyanide respectively. Cooke, R.D., Graham, G., Blake, W. and retting, roots are steeped in water However, samples retted with trona, Battershill, J.M. (1978). Phytochem. 17: and after they have softened are contained 20 ppm cyanide, which 381 - 383. mashed, washed, sieved and then 8Trona: T – 50. Material Safety Data exceeded the FAO/WHO 10 ppm dewatered into a dough, which may Sheet (MSDS) No. T50 – 1103. URL safe level for total cyanides. Since subsequently be processed into http://www solvaychemicals us1.800 765 kerosene is not miscible with water it 8292/html. CCDN News 3 9FAO/WHO Expert Committee. (1983). Humedecimento da farinha de Njia ya kuldwanisha ili kuondoa Technical Report Series No. 696: pp. mandioca com agua para sumu ya “sianaidi” katika unga

203-219. World Health Organization, remover cianeto (Portugues) wa muhogo (Swahili) Geneva, Switzerland. Introduz-se a farinha de mandioca Unga wa muhogo unawekwa

F. Ogbu, P. Nwakpu, , E. Keka & C. num recipiente e marca-se na kwenye chombo cha uwazi na kimo Ihedioha, Department of Food Science & parede deste o nível do volume que chake kiwekewe alama nje ya Animal Production & Technology, Ebonyi ocupa. Adiciona-se água chombo. Maji yamiminwe taratibu State University, Abakaliki, Nigeria. (vagarosamente) e mistura-se kwa kuchanganya na unga mpaka [email protected] profundamente até que o nível do ujazo wa unga ulio lowa ufikie kimo volume da “pasta” que se obtém cha chombo. alcance a marca no recipiente. Unga uliolowa utolewe nje na Wetting method to remove Estende-se a “pasta” assim obtida kuwekwa kwenye trei (tray) au cyanide from cassava flour numa peneira ou bandeja, numa kikapu wazi na unene wa (English) espessura não superior a 1 cm e msambazo wa unga usizidi unene deixa-se na sombra por cerca de 5 wa sentimita moja (1). Kwa unene Cassava flour is placed in a horas. O tempo não deve ser inferior uachwe kwenye kivuli (shade) kwa container and its height marked on a 5 horas. Este é o tempo kacibi masaa 5 (matano). Muda the side of the container. Water is necessário para a degradação do usipunque masaa 5 (matano). Huu added slowly with thorough mixing composto que contém cianeto muda unahitajiwa kwa kuuua dutu until the wet flour volume comes up (linamarina) pelo enzima linamarase kwa kutumia mmengenyo uliomo ili to the mark on the container. para produzir cianeto de hidrogénio kuzalisha gesi ya hydrojeni sianide The wet flour is spread out on a (gás) que escapa para o ar. A ambayo hupotea hewani. Unga basket in a layer no thicker than 1 farinha tratada por este método uliolowa lazima utumike kupikia sila cm thick and left in the shade for deve ser cozida e consumida no hiyo ili kuzuia mehacho (spoilage) about 5 hours. This time is needed mesmo dia para evitar a putrefacção ambao ungetokea kama unga for breakdown of the cyanide que pode ocorrer quando deixada ungelala bila kupikwa. Maji kidogo compound by the enzyme present to para o dia seguinte. Esta “pasta” yanahitaji wa kwa kutengeneza give hydrogen cyanide gas that necessita de pouca água para wa kienyeji (luku) kwa unga uliolowa escapes. The wet flour is used for preparar a massa tradicional kuliko unga uliomkavu, bila hivyo cooking the same day to prevent (“ugali”, “luku”) comparada com a mapishi ni yaleyale. spoilage which may occur if it is left farinha seca, mas o procedimento The editor thanks those kind people who overnight. Less water is needed to (cozedura) é o mesmo. translated this text into the various languages. produce the traditional porridge Metodo humedo para remover el (“ugali”, “luku” ) from wet flour than cianuro de la harina de yuca PestNet from dry flour, but otherwise the (Español) PestNet is a forum to discuss issues cooking is the same. Colocar la harina de yuca en un concerning plant protection and Methode de mouillage pour recipiente y marcar la altura sobre quarantine. Although set up for the eliminer le cyanure de la farine du un lado del recipiente. Agregar agua Pacific and Asia, it welcomes manioc (Francais) lentamente, mezclando totalmente, members from anywhere in the De la farine de manioc est placee hasta que el volumen de la harina world. dans un recipient et sa taille húmeda llegue a la marca realizada PestNet allows members to marquee du cote du recipient. L’eau sobre el recipiente. exchange messages on quarantine, est ajoutee lentement en Esparcir la harina húmeda en un biological control, pest management, melangeant completement jusqu’a cesto o en una bandeja con una pest outbreaks, and to send images ce que le volume humide de farine capa no más gruesa que 1 cm de of pests for identification. It has 675 atteigne la marque sur le recipient. espesor y luego almacenar en la members in 60 countries and during La farine humide est étalée sur un oscuridad por cerca de 5 horas. El the 6 years it has been in existence panier ou un plateau sur une couche tiempo de almacenamiento no debe PestNet has exchanged more than pas plus profond que 1 cm ser menor de 5 horas. Este tiempo 4000 messages. Join by sending a d’épaisseur et laissée à l’ombre es necesario para la degradación de blank e-mail to pestnet- pendant environ 5 heures. Le temps los compuestos cianogenicos [email protected]. ne devrait pas être moins de 5 (linamarina) por la enzima presente heures. Ce temps est nécessaire CCDN News is the Newsletter of the Cassava Cyanide (linamarasa) para producir el acido pour la dégradation du composé de Diseases Network (CCDN). The CCDN is a free, cianhídrico (gas) el cual se libera al worldwide network commenced in June 2001, which is cyanure (linamarin) par l'enzyme working towards the elimination of konzo, TAN and aire. (linamarase) pour produire le gaz de other cassava cyanide diseases. La harina húmeda debe ser CCDN News will consider for publication short articles cyanure d'hydrogène qui s'échappe and letters (1-3 pages A 4 double spaced) written in cocinada el mismo día, para evitar à l'air. La farine humide doit être English. Because CCDN News is a newsletter, full- la pudrición que puede ocurrir si size original papers or reviews cannot be considered employée pour faire cuire le même for publication. esta se almacena durante toda la jour afin d'empêcher la détérioration CCDN News is published every 6 months and sent by noche. e-mail to about 70% of members and by air mail to qui peut se produire si elle est those who do not have e-mail. Material published in Es necesaria una menor cantidad de laissée durant la nuit. Moins d'eau CCDN News may be freely reproduced, but please agua para producir la tradicional always indicate that it comes from CCDN News. est nécessaire pour produire le Please send all correspondence to the CCDN papilla (“ugali”, “luku”) a partir de gruau traditionnel ("ugali", "luku") à Coordinator, Dr J Howard Bradbury, School of Botany harina humeda que si se utiliza and Zoology, Australian National University, Canberra, partir de la farine humide que de la ACT 0200, Australia. harina seca, pero de una u otra farine sèche, mais autrement la manera la coccion es la misma. préparation est identique. 4 CCDN News

Harcourt, N

M. N, Nigerian Stored Products Research Institute Port Harcourt, Nigeria [email protected]

CCDN News 5