Evaluate The Cyanide Content Of Cassava Products Such As Garri And Fufu

ABSTRACT

The study is on “Evaluate the cyanide content of cassava products such as Garri and Fufu”. The study has three aims objectives. A particular variety of cassava was purchased from the faculty of Agriculture and veterinary medicine research center, Imo State University. The hydrogen cyanide of the samples were determined using the A.O.A.C. (1990) Method. Triplicate determination of the cyanide content of garri, fufu and abacha were done and the mean + SD calculated using the method of steel and Torrie (1960). The findings show that most of the biochemical changes required for the fermentation of cassava mash to produce “garri”, a roasted cassava mash and fermentation of cassava tubers to produce cooked fufu paste of acceptable nutritional and hydrogen cyanide content were achieved within four to five days of fermentation. The removal of cyanogenic glycosides through hydrolysis to hydrocyanic acid and the subsequent degradation and reduction of this to a low level was much pronounced within four to five days of fermentation, after which the hydrocyanic acid can be completely eliminated during the subsequent roasting to “garri” and cooking to get cooked fufu paste. The study therefore recommended among others that fermentation of cassava mash and cassava tubers for gari processing should be carried out for four to five days because all the biochemical processes required for development of necessary nutritional and anti-nutritional qualities desired for the product were optimally achieved within this period.

CHAPTER ONE 1.0     

INTRODUCTION

Cassava (Manihot esculanta crantx) is a versatile commodity with numerous uses and by products. Each component of the plant can be valuable to its cultivator. The leaves may be consumed as a vegetable or cooked as a soup ingredient or dried and fed to livestock as a protein feed supplement (Grace, 1971). According to the same author the stem is used for plant propagation and grafting while the roots are typically processed for human and industrial consumption.

Cassava (Manihot esculanta Crantx) when processed is an important food for many people in the tropics (Coursey, 1973). However, the roots contains the cyanogenic glycosides, linamarin, arid lotaustralinc, which upon hydrolysis produce free hydro cyanide acid (HCN) which is considered as one of the most powerful poisons known (Coursey, 1973). Hydrolysis occurs when the glucosides come in contact with the endogenous enzymes, linamarasc, present in the roots which is released upon crushing of the root or damage of the cellular structure. Hydrolysis can also be affected by acid in the digestive tract. Thus ingested glucosides which in itself may not be toxic could be hydrolysed in the digestive tract into HCN (Ajibola et al, 1987).

The most important requirement in the processing of cassava roots is its detoxification by the reduction of the total cyanide content (bound and free) to acceptable levels (Ajibola et al, 1987). Cyanogenic glucosides are referred to as bound cyanide while hydrocyanide acid is referred to as fee cyanide.

Cassava (Manihol esculanla Crantx) has been variously used hi ihe production of different types of food in Africa (Lasekkan et al, 2004). Some traditional cassava products include Fufu (Akpu), Lafun, Garri, Abacha and Tapioca. The product of interest in this research is Fufu, Garri and Abacha. In Nigeria, the consumption patterns vary according to ecological zones. Garri, a roasted granule is the dominant product and is widely accepted in both rural and urban areas. It can be consumed without any additives or it can be consumed with a variety of additives such as sugar, groundnut, fish, meat and stew [Nweke and Kormawa, 2004).

Table 1. Consumption pattern by zone and cassava product

    Zone                                                 Order of Importance

South. West                                      Garri, Lafun, Fufu/Akpu

South South                                     Garri. Akpu

South   East                                     Garri, Fufu/Akpu, Abacha

North Central                                   Garri, Fufu/Akpu, Starch

North East                                       Fufu/Akpu, Garri, Abacha

Source: Akinrele et al (1964)

Fufu a fermented wet paste from cassava is widely consumed throughout the country especially in the Southern Zones (Okafor, 1983). Most processors however complain that the wet paste and ready to eat forms (fufu) that are currently sold have a very short shelf life.

Owing to the presence of the cyanogenic glucoside various methods which bring about a reduction in the toxicity of the roots are employed during the processing. However most of these method are tedious, having long fermentation period and ends up yielding products with repulsive odour and moderate level of HCN although the HCN level (20-50mglkgj reported by some workers (Okpokiri et al, 1985, and Onwueme, 1978) may be within the standard organization of Nigeria (SON) (1985) standard. The cumulative effect due to its continuous consumption as a staple food may still lead to chronic cyanide toxicity (Maduagwu, 1978). The traditional and improved methods commonly used are targeted at encouraging natural imamarase to cause- hydrolysis of cyanogenic glucoside, hence the long fermentation could be due to microbial enzyme activity which is usually reduced during fermentation (Ejiofor et al, 1984; Okafor, 1983).

One risk associated with the consumption of cassava products is the presence of glucosides which are converted to hydrocyanide a very harmful compound to the body. Purseglove (1991) reported that the bitter cassava varieties have a high level of cyanogenic glucoside distributed throughout the root tuber while sweet varieties have low levels mainly found in the peel. These cyanogenic compounds are mainly reduced to residual amount by the various processing methods like as fermentation. Acute cyanide toxicity rarely occurs, but chronic toxicity may occur in population where under processing is common.

Onabolu et al, (2001) concluded that consumption dependence on cassava products almost exclusively can lead to onset of several neurological syndromes seen in the tropics such as atoxic neuropathy (TAN); tropical amblyopic and konzo which are attributed to cyanide released when cassava products are eaten. Remedy lies in improving overall nutrition with elaborate processing and rigorous assessment of cyanide content of final products before they are consumed.

This research work is designed to evaluate the cyanide content of cassava products (fufu, garri) produced at different fermentation time (72, 96 and 120 hours). Therefore assessment of the cyanide (cyanogenic glucoside) and nutrient content of the cassava products will help to ascertain the effectiveness of the processing given to such products and hence their safety.

1.1      STATEMENT OF PROBLEM

Cassava contained the cyanogenic glucosides linamarin and lotaustralin (White et al, 1998), but the quantity depends on the type of cassava, the age and the environment where it was cultivated. These compounds (linamarin and lotaustralin) are broken down by endogenous enzymes in cassava to release cyanide in the product (white et al, 1998). In Africa, improperly processed cassava is a major problem. Its associated with a number of cyanide related health disorders, particularly among people who are already malnourished (Okafor et al, 1998).

The toxicity of HCN can either be acute or chronic depending on the level of intake and the severity of the symptoms. The habitual ingestion of small quantities of HCN results into chronic effects while very large doses can cause acute poisoning and death within a short time. (Onigbinde, 2005). The lethal dose of HCN for man is 0.5-3.5mg/kg body weight when orally consumed as a single dose. Also when very high amounts (up to 200ppm) of cyanide are ingested, it could lead to-” insistence death due to respiratory failure (ATSDR, 1997).

In population where cassava is a staple food, endemic disease related to chronic ingestion of cyanide are prevalent. This include weight loss, goiter, nerve damage, Konzo (paralysis of the limb) etc. (Harm, 198; ATSDR,” 1997). It is therefore expected that continuous consumption of inadequate processed cassava products such as fufu, and abacha may result in such disease.

1.2     JUSTIFICATION OF THE STUDY.

In Nigeria, cassava is a staple food to the majority of the populace and its consumption is almost on a daily basis. It is the main source of affordable energy by individual and population group. Unfortunately the cyanogenic glucoside content is a serious drawback to its consumption safety. Significant and trace amount taken over time may impose a health hazard that neither the consumer nor the seller are aware of.

Individual and population groups who consume these cassava products may subconsciously be exposed to unexplored risk of ataxic neuropathy, cretinism, goiter and other mental health conditions common in people consuming cyanide containing food products. The extent of exposure to these dangers is currently unknown. As the producer and the consumer of these cassava products may be ignorant of the cyanide content of the products, determination of their cyanide content will help to ascertain the safety of these products and the processing method that should be encouraged. 

1.3     AIMS AND OBJECTIVES

The purpose of the study was to evaluate the cyanide content of cassava products such as garri and fufu.

SPECIFIC OBJECTIVES

The specific objectives were to

1. To determine the processing methods used to produce cassava
2. To evaluate the level of nutrients and cyanide in these cassava products.
3. To compare the nutrient and cyanide level of the cassava products with different fermentation time.
   

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   Pages:  48

   Category: Project

   Format:  Word & PDF        

   Chapters: 1-5                                 

   Material contains Table of Content, Abstract and References.