ABSTRACT
The Cyanide Content of four varieties of Cassava: (Tropical Manihot Selection; TMS 01/1638), (Tropical Manihot Selection; TMS 01/1412), (Tropical Manihot Selection; TMS 419), and (Tropical Manihot Selection; TMS 98/0505), from National Root Crop Research Institute (NRCRI), Umudike were studied using Picrate method. The Cyanide contents were: TMS 01/1638 (0.424 ) mg/kg, TMS 01/1412 (0.443 ) mg/kg, TMS 419 (0.557 ), AND TMS 98/0505 (0.518 ) mg/kg. The Cyanide content of the Yellow Root Cassava was found to be low compared to the White Root Cassava. The results of the Cyanide Content in the Current study were found to be within the acceptable unit as recommended by WHO.
TABLE OF CONTENTS
Cover
Page
Title
Page i
Declaration ii
Dedication iii
Certification iv
Acknowledgements v
Table
of Contents vi
List
of Figures ix
List
of Tables x
Abstract xi
CHAPTER 1: INTRODUCTION
1.1 Background of the Study 1
1.2 Statement of the Problem 3
1.3 Aims and Objectives of the Study 4
1.4 Significant of the Study 4
1.5 Scope of the Study 5
CHAPTER 2: REVIEW OF RELATED LITERATURE
2.1 Cassava Plant (Manihot esculenta crantz) 6
2.1.1 History of the cassava plant 7
2.1.2 Production/economic impact of cassava 7
2.2 Cassava Toxicity 8
2.3 Cassava Products and Varieties 9
2.3.1 Fermentation of cassava and its products 9
2.4 Cyanide 10
2.4.1 History of cyanide 11
2.4.2 Forms of cyanide 11
2.5 Sources of Cyanide 14
2.5.1 Production and synthesis of cyanide 14
2.5.2 Application and uses of cyanide 15
2.5.3 Cyanide Poisoning 16
2.5.4 Effect of cyanide poisoning 17
2.5.5 Cyanide poisoning detection 17
2.5.6 Cyanide poisoning treatment 18
2.5.7 Cyanide irreversible toxicity and inhibition 19
2.5.8 Toxicity of cyanide 19
2.5.8.1 Acute toxicity 20
2.5.8.2 Mechanism of acute cyanide poisoning 20
2.5.8.3 Chronic toxicity 21
2.5.8.4 Neurological effects 21
2.5.8.5 Tropical ataxic neuropathy (TAN) 22
2.5.8.6 Konzo 22
2.5.9 Technique analysis of cyanide reduction 23
2.5.10 Removal of cyanide constraints from cassava 23
2.6 Enzyme Inhibition 24
2.6.1 Form of inhibition 24
CHAPTER 3: MATERIALS AND METHODS
3.1 Sample Collection 30
3.2 Sample Preparation 30
3.3 Methods 30
3.3.1 Preparation of alkaline picrate solution 31
3.3.2 Preparation of the stock solution for the
concentration 31
3.4 Determination of Cyanide Content 31
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Results 34
4.2 Discussion 39
CHAPTER 5: CONCLUSIO N AND RECOMMENDATION
5.1 Conclusion 40
5.2 Recommendation 41
References 42
LIST
OF FIGURES
Figure
4.1 Absorbance reading of the Samples 33
4.2 Diluted Samples with 100 ml of Distilled
Water 34
4.3 Not Diluted Samples with 100 ml of
Distilled Water 34
LIST OF TABLES
Table
4.1 Absorbance Reading of the Diluted Stock
Solution 31
4.2 Absorbance Reading of the Non-Diluted
Stock Solution 32
4.3 Results of Cyanide Content 33
4.4 Results of Diluted Sample with 100 ml of
Distilled Water 34
4.5 Results of Non-Diluted Sample with 100 ml
of Distilled Water 35
CHAPTER 1
INTRODUCTION
1.1
BACKGROUND
OF THE STUDY
Cyanide,
a toxic contaminant, occurs naturally in most plants but has high concentration
in cassava and bamboo shoot. It is released into the environment through
volcanoes and natural biogenic processes from higher plants, bacteria, algae
and fungi (ATSDR, 1997) burning biomass, discharges from industries, waste
water, tobacco smoke, wood smoke, smoke from burning plastics, vehicular emission,
inadequately processed cassava products e.t.c (ATSDR, 1997). Exposure to small
amounts of cyanide can be deadly regardless of the route of exposure. Cyanide
is very poisonous, it stops cellular respiration by inhibiting an enzyme in
mitochondria called cytochrome c. oxidase in the body.
Various poisonous substances that
affect human metabolism have been identified in some edible plants. One of such
poisonous substances is linamarin, a cyanogenic substance that is highly
concentrated in cassava (Gari, 2002). Cassava (Manihot escilanta, crantz)
constitutes one of the major stable foods for an estimated 500 million people
in the tropical world and 700 million people worldwide (Kaur et al., 2009). The high carbohydrate
content makes cassava a major food item especially for the low income earners
in most tropical countries especially Africa and Asia (Li et al., 2001). The main food source is the starchy roots while the
leaves are processed and used as sources ofprotein in Africa (ATSDR, 1997). The
tubers are processed into gari, fufu, chips and flour for baking bread and biscuits
(Robert et al., 2000). Thus, cassava
serves as a major source of dietary energy but deficient in protein (Ano et al., 2007).
Nigeria ranked first among major
producers of cassava in the world, producing about 33 million metric tons of
cassava in 1993 (Ugwu et al., 2011).
Over 95% of cassava produced in Nigeria is used as food for the country’s
teeming population, being one of the countries staple foods (Alloway, 1995).
However, the presence of cyanogenic glycosides (linamarin) in cassava has
greatly affected utilization of cassava as food source. The cyanogenic
glycosides form effective biological system to deter predators (Ugwu et al., 2011). Cyanide binds to the
enzyme, cytochrome oxidase which negatively affects respiration. Akintonwa et al., (1994) had earlier reported
cases of consuming cassava diets containing high levels of dietary cyanide.
Non-fatal doses of cyanide have been associated with such symptoms like
dizziness, headache, stomach pains, vomiting and diarrhea which appear four or
more hours after consuming poorly processed cassava. In some cases, excessive
consumption of cassava due to improper preparation has been linked to such
ailments like goiter, ataxia (a neurological disorder affecting the ability to
walk) (Pope et al., 2001), chronic
pancreatitis (Hahn and Keyser, 1985) and even death. Toxic levels of cyanogenic
glycosides have been used as the basis for categorizing cassava varieties. The
less toxic varieties are designated as sweet cassava (Manihot palmate)
while the more toxic varieties are designated as bitter cassava (Manihot utilissima).
The bitter variety is widely cultivated because of its high yield and economy although,
has high concentration of cyanogenic glycoside (100-500 mg/kg fresh weight), and
is distributed throughout the tuber. The sweet variety has low concentration of
cyanogenic glycoside (less than 100
mg/kg) which is confined mostly to the peels (Philips, 1983). Cyanide level of
less than 50 mg/kg is slightly poisonous, 80-100 mg/kg is toxic and levels
above 100 mg/kg are fatal especially in grated cassava (Stone, 2002). In most
cases, the cyanogens in fresh cassava roots are detoxified during processing
into edible products (Wyllie et al.,
1984). The processing of cassava roots commences with the peeling of the
tubers, which contains higher cyanide content than the pulp. Removal of the
peels therefore reduces the cyanogenic glycoside content considerably (Tewe,
1983). Thus, the selection of cassava species to be grown is very important.
This study aimed at determining the cyanide content of varieties of cassava
grown in NRCRI Umudike, of Abia State, Nigeria. This will assist farmers in
their choice of cassava for cultivation.
1.2
STATEMENT
OF THE PROBLEM
Cassava
(Manihot esculenta crantz) is a staple food in most tropical
regions, and is grown over a range of climates and altitudes and on a wide
variety of soils. The estimated total world cassava production in 2012 was 256
million tonnes according to FAO (2013), which is an increase of 40% since 2000.
Africa represents the continent with the largest cassava production of more
than
50%
of the annual world production. The crop is one of the most important staple
food with about 93% of the production used for human consumption (Nweke et al., 2002). The roots of this
important carbohydrate source are eaten both fresh and as processed products
(Westby, 2002). However, in its tissue, cassava contains cyanogenic glycosides,
mainly linamarin, that are enzymatically hydrolysed to glucose, acetone and
hydrogen cyanide during cell rupture (Conn, 1994). The released cyanide is
highly toxic for humans and is a threat to the cassava consumer (Rosling,
1988). The presence of cyanogenic glycosides in cassava tissues is related to
illnesses that occur in populations where cassava is the staple food. These
illnesses include tropical ataxic neuropathy, epidemic spastic paraparesis,
also known as konzo (Cliff et al.,
2011). These problems have been reported in the Democratic Republic of Congo,
Nigeria, Tanzania and Mozambique (Ciglenecki et al., 2011).
1.3
AIM AND OBJECTIVES OF THE STUDY
The major aim of this research work
is to determine the cyanide content in yellow root and white root cassava tuber
(Manihot esculanta, crantz).
The specific objectives of this
research work are outlined as follows:
1.
To determine the cyanide content
of the cassava varieties in the study area
2.
To determine the of level of Cyanide of released new cassava
varieties in breeding programs in the study area.
1.4
SIGNIFICANCE
OF THE STUDY
Due to the evidence of the toxicity
of cassava, it is of utmost importance to ascertain the level of cyanide
present in cassava varieties in the study area especially in new varieties of
cassava programs bread at NRCRI.
1.5
SCOPE
OF THE STUDY
This study is limited to the analysis
of cyanide content of different varieties of cassava bread at National Root
Crops Research Institute Umudike in Abia state.
Click “DOWNLOAD NOW” below to get the complete Projects
FOR QUICK HELP CHAT WITH US NOW!
+(234) 0814 780 1594
Login To Comment