Soaking and Drying of Cassava Roots Reduced Cyanogenic Potential of Three Cassava Varieties at Jimma, Southwest Ethiopia

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1 World Journl of Agriculturl Sciences 7 (4): , 20 ISSN IDOSI Pulictions, 20 Soking nd Drying of Cssv Roots Reduced Cynogenic Potentil of Three Cssv Vrieties t Jimm, Southwest Ethiopi Amslu Neiyu nd Esulew Getchew Deprtment of Horticulture nd Plnt Sciences, Jimm University, Ethiopi Astrct: Detoxifiction of three cssv vrieties (NR-44/72, NW-45/72 nd NW-44/72) y trditionl methods of processing to produce cssv flour ws investigted t the college of griculture, Jimm University during Ferury-My, Totl HCN quntittive determintion in cssv flour ws crried out using simple enzymtic picrte pper method developed y Dr. Hwrd Brdury. Results showed tht vrieties, soking time nd their interctions highly significntly reduced (P<0.0) totl HCN content (ppm) in the flour. Soking of cssv chips in wter for out 24 hours prior to sun drying reduced the HCN from to 0.83 ppm (reduced y 90 %), from to 3.33 ppm (reduced y 79.94%) nd from to 5.0 (reduced y %) for vrieties NW-44/72, NR-44/72 nd NW-45/72, respectively. It ws noted tht totl HCN content in cssv flour cn e sustntilly eliminted (y more thn 80%) y soking of cssv chips in wter. The present study highlighted the importnce of soking of cssv chips for t lest 24 hours prior to sun drying for sfe level of HCN in the flour. However, it is lso importnt to develop new nd improved processing techniques to reduce HCN sustntilly. Key words: Cssv flour Soking Totl HCN INTRODUCTION Consumption of cssv nd its products is thought to cuse cynide poisoning with symptoms of vomiting, Cssv (Mnihot esculent Crtz) is one of nuse, dizziness, stomch pins, wekness, hedches the most importnt food crops in Afric. It is the nd dirrhe nd occsionlly deth [5]. Cynide intke third most importnt food in the tropics, fter rice from cssv cn worsen goiter nd cretinism in iodine nd mize. It derives its importnce from the fct deficient res nd is lmost certinly the cuse of konzo tht its strchy, tuerous roots re vlule source of in estern, centrl nd southern Afric [6, 7]. Konzo is n chep clories, especilly in developing countries where irreversile prlysis of the legs of sudden onset tht clorie deficiency nd mlnutrition re widespred. occurs prticulrly in children nd women of child ering Cssv lone provides the mjor source of dietry ge [8]. Tropicl txic neuropthy is chronic condition clories for out 500 million people, mny of them in of grdul onset tht occurs in older people who consume Afric []. repetitive cssv diet. It cuses loss of vision, txi of Cssv contins the potentilly toxic compounds git, defness nd wekness [9, 0]. These medicl like the cynogenic glycosides. Both roots nd leves conditions cused y cynide overlod could e contin cynogenic glycosides, primrily s linmrin prevented y considerle reduction in the per cpit which lierte hydrogen cynide (HCN) upon hydrolysis cynide intke [0]. It is therefore crucil to develop etter [2]. These compounds cn cuse cute cynide poisoning strtegies to reduce the cynide content in cssv sed nd deth in humns nd nimls when consumed in products. sufficient quntities. There re over 5000 known One of the strtegies to reduce cynide content of phenotypiclly distinct cssv cultivrs which ll processed cssv is to improve processing methods contin vrying concentrtions of the cynogenic used for conversion of roots to storle cssv products glycosides [3]. The cynogenic potentil of known such s flour. A numer of processing methods or cssv cultivrs rnges from less thn 0 mg kg to comintion of them (peeling, slicing, soking, retting, more thn 500 mg kg s HCN on fresh weight sis [4]. fermenttion, oiling, drying, rosting, pounding, Corresponding Author: Amslu Neiyu, Deprtment of Horticulture nd Plnt Sciences, Jimm University, Ethiopi. Tel: , Fx:

2 milling etc) re ville tht ttempt to remove the Cssv chips of the pproprite size were mde from the poisonous principle s much s possile. In Afric, the sliced tuers nd then sujected to four different soking mjor methods of flour mking from cssv roots periods nd sun drying tretments s follows: involves sun drying of peeled roots followed y crushing in pestle nd mortr nd sieving. This method ws Sun drying with out socking proved to retin 25-30% of the originl linmerin present 2 hours socking nd sun drying [0]. Another method like hep fermenttion is lso known 24 hours socking nd sun drying to remove twice s much linmrin s does sun drying, 36 hours socking nd sun drying ut still 2-6% of linmrin is retined []. Brudury[] descried tht, in order to produce cssv flour of the Following ech of the ove tretments, cssv WHO sfe level (0 mg HCN equivlent per kg flour), flour ws mde using lortory grinder/mill. 500 grms cssv roots contining less thn 32 ppm linmerin of the flour ws used for the experiment. The lortory would e needed. experiment ws lid out in 3x4 fctoril rrngement (3 In view of the importnce of cssv s mjor vrieties with 4 soking periods s indicted ove, A-D) source of food to the locl people in Ethiopi, fer of HCN in Completely Rndomized Designed with three toxicity still exists y these people. Hence, serching for replictions. nd ppliction of different post hrvest prctices tht cn significntly reduce HCN will hve gret role in Anlysis of Totl HCN: Totl HCN (ppm) in the flour ws promoting the wider production nd consumption of nlyzed using the enzymtic picrte pper kit developed cssv in Ethiopi. Although vrieties hve een y Brdury et l. (999). The sornce of the solution improved for root yield, their cynogenic potentil nd the produced y immersing the exposed picrte ppers to the quntity of HCN retined fter processing is not known. smple in 5 ml distilled wter for 30 minutes ws mesured The ojective of this experiment ws therefore to exmine t 50 nm using spectrophotometer ginst the lnk the effects of soking nd drying of cssv roots on solution otined y immersing picrte pper without totl cynide content of cssv flour of three vrieties. exposure to the smple. The totl HCN content in ppm ws clculted s totl HCN content (ppm) = 396 x MATERIALS AND METHODS sornce. The Study Site: The experiment ws conducted in Sttisticl Anlysis: Totl HCN ws sujected to posthrvest physiology lortory of the deprtment of nlysis of vrince. The significnt tretment mens were Horticulture t Jimm University College of Agriculture compred using Duncn s Multiple Rnge Test [?] (955) nd Veterinry Medicine (JUCAVM), Ethiopi during t P<0.0. MSTAT-C sttisticl softwre pckge ws Ferury-June, used for the nlysis. Experimentl Mterils, Tretments nd Procedures: Cssv tuers were hrvested, twelve months fter plnting, from three vrieties (NR-44/72, NW-45/72 nd NW-44/72) grown t Jimm Agriculturl Reserch Center which re known to e high yielding ut with high Cynogenic Potentil (CNP) (50-00 ppm totl HCN kg of fresh tuers) (Tle ). The tuers were peeled, immeditely wshed with tp wter nd sliced. RESULTS The different soking periods resulted in highly significnt (P<0.0) differences in the totl HCN content in ech of the vrieties tested. Totl HCN rnged etween ppm (Tle 2). The lowest totl HCN (0.83 ppm) in the flour ws otined when cssv chips were soked in wter for out 24 hours prior to drying nd Tle : Chrcteristic fetures of the test vrieties t Jimm Vriety Yield potentil (tones h ) CNP (ppm) Stem color Origin/ source Yer of introduction NR-44/ red Nigeri 972 NW-45/ ple Nigeri 972 NW-44/ ple Nigeri 972 Source: Amslu et l. [8] 440

3 Tle 2: Effect of Vriety nd soking time on the totl HCN (ppm) content of cssv flour of three different vrieties Vrieties Drying without soking Socking for 2 hours Socking for 24 hours Socking for 36 hours Vriety men NR-44/72 cd* NW-45/ d NW-44/ d 0.83 c men CV(% ) =2.64 * Mens followed y the sme letter re not significntly different from ech other Tle 3: Men percent reduction of totl HCN in three cssv vrieties Vrieties CNP (ppm) Men HCN fter processing (ppm) % reduction of HCN NR-44/ NW-45/ NW-44/ LSD Soking time (hours) Fig. : Effect of soking time on men totl HCN (ppm) content of three cssv vrieties 40 Fig. 2: % Totl HCN (ppm) reduction of three cssv vrietiet t different soking milling in the vriety NW- 44/72 followed y NR-44/72 nd chips drying in the sun with out soking resulted in.6 NW-45/72 which resulted in 3.33 nd 5.00 ppm, ppm totl HCN in NR-44/72 followed y 6.67 nd respectively. The commonly used method of cssv ppm totl HCN in NW-44/72 nd NW-45/72, respectively. 44

4 In the present study, the test vrieties differed since the HCN levels re very ner to the WHO sfe level significntly (P<0.0) in their totl HCN content. NR-44/72 of 0 ppm. Tivn nd Bvochor [3] lso reported tht ppered to show the lowest totl HCN men vlue (4.38 cssv flour with 25 ppm HCN my e used to prepre ppm) over the four processing methods followed y NW- cssv flour mel without disorder to humn helth, 44/72 nd NW-45/72 which resulted in 6.04 nd which is in greement to the present findings. ppm, respectively (Tle 3). Although different countries hve different sfe In ddition, the men performnce of the different levels of HCN, the WHO hs set sfe level of cynogens soking periods over the three vrieties ws lso highly in cssv flour s 0 ppm [7]. For exmple, the significnt (P<0.0). Socking of cssv chips in wter for cceptle limit in Indonesi is 40 ppm [0]. In the present out 24 hours gve the lowest totl HCN men vlue of study, this ws pprent for the vriety NW-44/72 which 3.06 ppm over the three vrieties followed y soking for resulted in 0.83 ppm fter socking for 24 hours. The 2 hours which resulted in ppm (Fig. ). present investigtion highlighted the importnce of Anlysis of percentge totl HCN reduction in the socking cssv chips for t lest 24 hours prior to sun present study indicted lso highly significnt (P<0.0) drying during cssv flour mking. However, it is quite rnge of vritions under ech of the soking periods. It importnt to develop further processing techniques to rnged etween 3.77 to 90% totl HCN reduction (Fig. 2). reduce totl HCN in the product. Moreover, men totl HCN reduction of the vrieties ws highly significnt. It vried from 52.38% in NW-45/72 to ACKNOWLEDGMENTS 85.20% in NR-44/72 (Tle 3). Due pprecition is given to the Horticulture division DISCUSSION of Jimm Reserch center for kind provision of the cssv vrieties. Dr. Hwrd Brdurry of the Ntionl The considerle reduction in totl HCN content of University of Austrli is duly cknowledged for his kind the cssv flour recorded in this experiment might e provision of the cssv cynide kits free of chrge. Bye explined s result of enhnced hydrolysis process of Mitiku, Henok Alemyehu, Sisy Aer nd Solomon cynogenic glucosides y the enzyme linmrse. The Amre re lso cknowledged for dt collection in the significnt contriution of socking of cssv chips in l. The uthors lso extend their due pprecition to the wter for 24 hours ws pprent to induce hydrolysis. Reserch nd Puliction Office of the College of Similr results were reported previously y Muluget nd Agriculture, Jimm University for finncil support. Eskinder [2], Tivn nd Bvochor [3], Kemedirim et l. [4], Kowil et l. [5]. The prole justifiction for REFERENCES totl cynide reduction y hydrolysis in sliced nd socked cssv chips could e due to cteri produced. Yeoh, H.H., T. Ttsum nd N. Oym, 998. linmrse [5]. According to Kowil et l. [5], Monitoring the cynogenic potentil of cssv: the Lctocillus spp. is most of the time found ssocited trend towrds iosensor development. Trends with cssv tuers nd hence it might hve significntly Anlyticl Chem., 7: contriuted to the oserved totl HCN reduction in the 2. White, W.L.B., D.I. Aris-Grson, J.M. McMhon present study s well. nd R.T. Syre, 998. Cynogenesis in cssv: the On the other hnd, cutting of cssv tuers into role of hydroxynitrile lyse in root cynide smll pieces (chips) might crete esy ccess for contct production. Plnt Physiol., 6: etween the enzyme nd cynogenic glycosides resulting 3. Hque, M.R. nd J.H. Brdury, 999. Simple method in higher hydrolysis. Similr results were lso reported y for determintion of thiocynte in urine. Clinicl Gomez et l. [6] who otined reduction of 70-80% fter Chemistry, 45: hours of sun drying,while,tivn nd Bvochor [3] 4. O Brien, G.M., C.C. Whetley, C. Iglesis nd otined 95.4% reduction y hep fermenttion followed N.H. Poulter, 994. Evlution, modifiction nd y sun drying. Although hep fermenttion is importnt comprison of two rpid ssys for cynogens in in reducing HCN, levels were reported to e ove the cssv. J. Sci. Food Agric., 65: WHO sfe level [7]. The present investigtion pointed 5. Akintonw, A., O. Tunwshe nd A. Onifde, 994. out tht the retined HCN level in the flour otined Ftl nd non-ftl cute poisoning ttriuted to fter processing is very sfe for humn consumption cssv-sed mel. Act Horticulture, 375:

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