DETERMINATION OF HYDROGEN CYANIDE IN CASSAVA

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ABSTRACT

Cassava is one of the major dietary stable for a large percentage of the population of tropical Africa and other parts of the world, and is likely to remain the biggest single source of calories for the poor in the continents. An important drawback to increase cassava use for human and animal feeding is its cyanogenic potential, or ability to generate hydrogen cyanide, a well – known poison with potential acute and chronic metabolic effects in human.
This project work deals with the determination of hydrogen cyanide (HCN) concentration in cassava tubers (using the bitter varieties) collected from Institute of Management and Technology (IMT) premises with respect to four days fermentation period using Atomic Absorption spectrophotometer (AAS).
The result shows that the concentration of hydrogen cyanide (HCN) decreases with increase in fermentation period, and based on the safe limit given by the us food and drug administration (FDA) and others, a safe fermentation period for cassava before processing it to produce garri is deduced.
TABLE OF CONTENT
CHAPTER ONE
Introduction 1
1.1 Hydrogen Cyanide 2
1.2 Aims and Objectives of The Study 4
1.3 Statement of Problem 5
1.4 Hypothesis 5
1.5 Scope of Study 5
CHAPTER TWO
Literature Review 7
2.1 Chemical and Physical Properties of HCN 9
2.2 Entry of Hydrogen Cyanide into the Body and
Its Exit from the Body 11
2.3 Effect of Cyanide on Health 14
2.4 Symptoms of Cyanide Poisoning and Treatment 18
2.5 Safety Factor and Procedures for Cyanide Identification 21
2.6 Cassava and Cyanide Concentration 25
2.7 Factors Affecting Cyanide Toxicity 27
2.8 Sources and Control Methods for Hydrogen Cyanide 28
2.9 Uses of Cassava 32
CHAPTER THREE
Methodology 34
3.1 Materials for the Analysis 34
3.2 Method of Analysis 35
3.3 Personal Hygiene Procedures 36
3.4 Sample Collection and Fermentation Process 37
3.5 Sample Fermentation 38
3.6 Sample Preservation and Storage 39
3.7 Acid Distillation 40
3.8 Distillation Procedure 40
3.9 Calibration Standard Preparation 42
CHAPTER FOUR
Result and Discussion 43
4.1 Concentration 44
4.2 Safe Fermentation Period 46
4.3 Cassava Processing Technique 46
4.4 Innovation to Cassava Processing 48
4.5 Seasonal Influence on Cyanide Content of Cassava 50
CHAPTER FIVE
5.1 Conclusion 52
52 Recommendation 52 References 54
Appendix I 56
Appendix II 56
Appendix III 57
CHAPTER ONE

INTRODUCTION
Cyanide, is usually found in compounds. It can interact with metals and other organic compounds. Cyanide refers to all of the cyanide compounds that can be determined as the cyanide ion, CN. The cyanide ion is a conjugate base of a weak acid, hydrogen cyanide, which is an extremely poisonous gas with an almond odor. Other forms of cyanide compounds are sodium cyanide (NaCN) and potassium cyanide (KCN). Cyanide can be produced by certain organism (e.g bacteria, fungi and algae), and equally present in plants. Cyanide ion is one of the most rapidly working po isons. Lethal doeses taken orally act in minutes, cyanide, poisons by asphyxiation, as does carbon monoxide, but the mechanism is different. Instead of preventing the cells from getting oxygen, cyanide interferes with oxidative enzymes, such as cytochrome oxidize, which is vital to every cell in use of oxygen. Oxidizes are enzymes containing metal usually iron or copper. Cyanide binds tightly to the enzyme cytochrome C and forms stable cyanide complexes with Fe3+ ion and inactivates the enzyme system.
Much of the cyanide in soil, water and air comes from industrial processes gold mining, waste waters from starch industry. The major source of cyanide in water are discharges from metal mining processes, other sources include exhaust, release from certain chemical industries, municipal waste burning and use of pesticides containing cyanide. Underground water can be contaminated by cyanide present in landfills. In other body, cyanide can combines with plants foods including almonds, millet sprouts, lima beans, soy spinach, bamboo shoots and cassava roots, cyanide occurs as part of naturally occurring sugars or other complex organic compounds.

1.1 HYDROGEN CYANIDE
Chemical formular: HCN
Synonyms: Hydrocyanide acid, prussic acid,
forminitrile, carbon hydride nitride
Hydrogen cyanide (HCN) was discovered by scheele in 1982. He made it by heating sulphuric acid with Prussian blue; hence the old name was prussic acid. HCN occurs in nature as glycoside amygdalin in some plants, for almonds, cassava etc. Hydrogen cyanide together with sodium cyanide and potassium cyanide are the most of cyanide likely to be found in the environment as a result of industrial activities. Its presence could be found in air, water, soil, and even in gaseous state (present in solution in cassava root), with a faint, bitter, almond like odour. It is a potential metabolic poison present in some food crops and other plants.
Hydrogen cyanide is a small molecule composed of a carbon, hydrogen and nitrogen atom joined together by a stable triple bond. This poison is best known for its inhibition of many enzymes that are important in animal metabolism. Enzymes are proteins that act as catalyst in biochemical reaction.
It could be made to act as an anti-herb ivory compound to discourage plant consumers (pests). Most often, it attaches itself to other molecules in the form of cyanogenic glycosides. In example of one such compound is amygdalin (from stems of cherry, apricot etc). In this form, cyanide is non-toxic to the plant, only in the breakdown of cyanogenic glycosides, during animal consumption or digestion, is hydrogen cyanide released. For example, cows feeding on some species of grasses containing cyanogenic glycosides became ill as they chew on the grass, in this fashion, it is hypothesized that cyanide in non lethal does effectively deters herbivory.
Some cyanide containing plants are listed below (plants and relative cyanide level):
– Cassava (+ + + +)
– Lima beans (+ + +)
– Sorghium (+ +)
– Millet (+ +)
– Bamboo Shoots (+ +)
– Sweet Potatoes (+)
– Maize (+)

1.2 AIMS AND OBJECTIVES OF THE STUDY
The aim of this project is to determine the effect of fermentation period (time) on hydrogen cyanide concentration in cassava tubers and to suggest safe and efficient processing technique of cassava in order to reduce hydrocyanic acid concentration thereby enhancing the consumption of cassava without health hazard.
1.3 STATEMENT OF PROBLEM
Since high concentration of hydrogen cyanide is fatal to human and other life species especially when consumed and is lethal to the