CHAPTER ONE
1.0 INTRODUCTION
Human
generation need recipe of various varieties to get energy to perform their
daily activities and also to survive, then there is need for consumption of
energy giving food like yam, cassava. Cassava is originated from latin America
and was later introduced to Asia in the 17th century and to Africa
in about 1558, in Nigeria, cassava is mostly plant by subsistence farmers,
usually intercropped with vegetables, plantation crop, yam, sweet potatoes,
melon,beans, and maize etc. Cassava is propagated by 20-30cm long cutting of
the tree stem, space between plants is usually 1-1.5m. Intercropping with
beans, maize, and other annual crops is produced in young cassava plantations.
1.1
Varieties
of Cassava
Cassava
is classified as either sweet or bitter, like other roots and tubers, both
bitter and sweet varieties of cassava contain auto nutritional factors and
toxins with the bitter varieties containing much larger amounts. They must be
properly prepared before consumption, as improper preparation of cassava can
leave enough residual cyanide to cause acute cyanide intoxication, goiters, and
even ataxia or partial paralysis, (Fao,
2001)
The more toxic varieties of cassava
are a fall-back resource (a “food
security crop”)
in times of famine in some places. Farmers often prefer the bitter varieties
because they defer pests, animals and thieves.
1.2 Importance of Cassava
No
continent depends as much on root and tuber crops in feeding its population as
does as Africa. Cassava, yams and sweet potatoes is an important source of food
in the tropics. The importance of cassava to many Africans is epitomized in its
name for the plant, e.g ege, paki, agble. The production rate world-wide is
positive for cassava over the last years, and the production increase by 12.5%
between 1988 and 1990 with Nigeria becoming the largest cassava producer in the
world. (Bamiro,
2006)
Cassava
and yams also occupy an important position in Ghana,niger republic, Benin
republic,Cameron agricultural economy and contribute about 46% of the
agricultural Gross Domestic product (GDP). Cassava accounts for a daily intake
of 30% in Ghana and is grown by meanly every farmer’s family. Cassava is the most favoured
among all Tuber crops and even all food crops by Ghanaian consumers. ( Bamiro, 2007 )
1.3 Uses of Cassava
Cassava
is a staple crop and food source for millions of people in Nigeria, Ghana and
other parts of Africa. It has many uses in addition to producing nutrition to
humans. The leaves can be eaten as a vegetable or cooked as a soup. They can
also be dried as hay and given as feed stuff to animals for extra protein.
The tubers can be processed into many
things
i.
Cassava can be processed into flour.
The flour can be used to produce most of our local food and even foreign food.
ii.
Cassava can be processed into chips.
Cassava chips can be used for animal feed.
iii.
Cassava can be processed into ethanol.
The ethanol produced from cassava can be used as bio-fuel when combined with
additives.
iv.
Cassava can be processed into
fructose. Fructose is used in industry for sweetening fizzy drinks.
v.
Cassava can be processed into starch.
The starch can be used in textiles industry.
Cassava is usually grown for human
consumption. Fufu is a traditional way to consume cassava. There are 14 steps
to the process making fufu including peeling grating and washing so its time
consuming and labour consuming. Garri is another traditional way of eating
cassava. The cassava is grated and put into porous sacks for the water to drain
out and for the cassava to ferment slightly.Amala is another way of consuming cassava
which includes fermentation,drying,grinding and sieving processes . Cassava
flour has been turned into variety of snack foods. You can purchase cassava
snack that are promoted as “healthy
snacking”
in the UK in a variety of flours.
1.4 Method of Peeling Cassava
There are several methods of peeling
cassava, which have been adopted. They include manual, chemical, steaming and
mechanical methods. Each has its own advantages and disadvantages
1.4.1 Manual Method
The
manual method of peeling cassava is primitive and cumbersome. It’s unhygienic, time wasting and
requires more time of producing small quantities. Also, it’s carried out by hand peeling of
cassava using a sharp edged object like knife.
Advantages of manual peeling
1. It require no money
2. No chemical involved which may lead
to poison when react with tuber
Disadvantages of manual
peeling
1. So cumbersome and slow
2. Doesn’t encourage peeling of large quantity.
1.4.2 Chemical Method
Chemical
method is often adopted in the industries, factories and food processing
companies. It involves chemical actions and thermal shock which leads to weaken
and loosening of the skin using caustic soda (NaOH).
The disadvantages
of this method of peeling cassava include;
ØCost of acquiring caustic soda.
ØThe difficulty in controlling the penetration of chemical in the
cassava tuber.
ØThe difficulty in the removal of chemical traces as it may be
poisonous.
Advantages
Øit is easy and encourage
large quantity peeling
Øit required little human effort.
1.4.3
Steaming Method
The tubers are subjected to high steam
pressure over a short period of time to avoid partial cooking (or eventual
cooking). The disadvantage is that the tubers could be subjected beyond the
time.
1.4.4
Mechanical Method
This
includes mechanized means of peeling, aimed at peeling a large number or a
batch at a time. Many mechanisms have been devised for this purpose, this
includes the continue process, abrasive belt conveyors and batch abrasion types
among others.
These methods of peeling have not been
yielded the desired results. Hence, the continued research in this area. An
extensive literature research was conducted to determine the state of the art
in cassava processing.
1.5 Justification of Study
Presently in Nigeria, the products
of cassava are usually locally consumed and exportation is low due to reason
that the products do not always meet the international standards for healthy
foods. Thus, the need to encourage the small scale(home production) of cassava
product to ensure quality of products and good hygienic values.
From the research carry out, it was discovered that most of the
cassava graters machines in the research area are usually corroding (reducing
service life) due to the acidic nature of the cassava fluid and materials used
for the fabrication. To ensure all cassava products is free from any taste,
odour, or infected by iron content of parts (food poisoning) which may affect
the quality of their contents (Giews, 2001) hence
need to modify the design and use appropriate materials for fabrication.
Now, the
government has also started campaign for production of bread using cassava
flour to reduce more concentration on wheat.
1.6 Aim and objectives
The sole aim of this project is to design and
fabricate improved cassava grating machine.
1.6.1
Objectives:The objectives
of this project are as follow:
i.
To modify the
design of the existing cassava grater (dimensions) to the home use-small scale
sizes.
ii.
Ensuring proper
grinding performance thereby eliminating vibrating shifter/sieving since the
cassava products can be re-grinded to finer particles after pressing and frying
to ensure no wastage.
iii.
To save time
and cost of processing
cassava products by the average family.
1.7 Scope of study
The scope of the project
is to design and fabricate a viable motorized cassava grater which would be
useful for home-use, retailers and small scale farmers and ;
i.
To obtain some data or information
that will be required and that are suitable in the design and fabrication of
cassava grater.
ii.
To select suitable materials based on
the result of the analysis for the fabrication of the machine.
iii.
To prepare a neat and detailed working
drawing for the fabrication process.