Design And Fabrication Of Yam Pounding Machine

Yam is another crop cultivated across Nigeria. It is a seasonal crop and very difficult to preserve as it tends to rot. Nearly all Nigerians consume yam on a regular basis and in large quantities particularly the Yoruba tribe in Nigeria. Nature allows yam to form a bond when it is pounded or beaten in a mortar, it is then consumed as a meal with a choice soup. Pounded yam is a staple food consumed by the indigenous process of pounding yam is very laborious. It requires physical pounding by one or more people.
Depending on the quantity in the mortar, in a bid to reduce the labour involved in yam pounding came the manufacturing of Herbert mixer, the Kenwood mixer and Hammermill in early 1975. These intended yam pounders failed due to some limitations in their operational functions. The Herbert and Kenwood mixers had almost the same operational principle and they had been identified for poor pounding due to the flapping (moving up and down) of their stirrer or mixer which is keyed to the electric rotating shaft. In addition to the poor pounding of both pounders, the Herbert mixer was found to heat excessively and as a result, the machine has to be stopped intermittently for cooling purposes.
1.1 Historical Background
Yam belongs to the class of carbohydrate type of food and had been one of the oldest recipes known to man. It has been a major food crop in many of the African/Caribbean countries such as Ghana, Ethiopia, Benin Republic and Nigeria in particular. Also, in some other parts of the world like Brazil, India, Oceania and Latin America, yam is a major source of food.
The word “yam” was derived from the Wolof word “nyam” which is a Portuguese name meaning “to taste”. Also, in other African languages, it can mean “to eat” e.g. in Hausa “nyam”. This perennial herbaceous crop is of different species such as white yam (Dioscorea-rotundata) yellow yam (Dioscorea-Acayenensis), water yam (Dioscorea alata) and trifoliate yam (Dioscorea-dumentorum). The fruit of yam consists of a membranaceous, three-wing capsule. The yam family is mostly of the weak-stemmed vines with large, underground food storage organs-tuber-rhizomes.
Yam has found its use in the preparation of steroid hormones by syntax synthesis of cortisone from yam extract. Also, its lower glycemic index than potato products accounts for its more sustainable energy and better protection against obesity and diabetes.
According to the food information network in 2008, it was estimated that the world production of yam in 1993 was at 28.1million tons of which 96% of this estimate is from the West African tropical regions and 71% from Nigeria. This figure was later reviewed in 1998 accounting for about 72.4% of the world's total production of 29.6million tonnes. Also, according to the Federal Office of Statistics, Nigeria is the world's largest producer of yams having the water yam (Dioscorea alata) and the yellow yam (Dioscorea rotumdata) as her most cultivated species of yam.
Yam is one of the most sumptuous meals that can be prepared in diverse ways. While the Yoruba tribe may prefer its dried, milled and then made into a slightly solid paste called “Amala”, the Igbos would prefer cutting the tuber into smaller blocks, or in bits, boiled and eaten in order to avoid the tedious nature of pounding the boiled yam which results to bond formation like Nigeria locally prepared fufu. However, the process of meshing or beating something into pulp or powder with repeated heavy blows is known as pounding.
Yam has remained one of the most highly regarded food products in West Africa and particularly Nigeria as virtually all her ethnic groups feed on it; hence its close integration into the sociocultural, economic and religious aspects of life such as marriage where some tubers of yam are presented to the bride family in accordance to the customs of the people. Also, there is the new yam festival which marks the harvest and eating of the newly harvested yams which are also used as sacrificial and appreciation items.
However, the background of this study originated from the desire of a Nigerian family of four who spent the majority of his career life in the United Kingdom (Bristol, England) in the medical field who came back home and needed to adapt to his home culture which he found pounded yam very sumptuous meal but the rigorous processes involved in the traditional method which he also observed to be unhygienic and the noisy effect of the process due to the number of strokes during pounding to be uncalled for.
1.1.1 Major Cultivated Species
Yam, a tropical crop in the genus Dioscorea, has as many as 600 species out of which six are economically important staple species. These are:
Dioscorea rotundata (white guinea yam), Dioscorea alata (yellow yam), Dioscorea bulbifera (aerial yam). Dioscorea esculent (Chinese yam) and Dioscorea dum etroum (trifoliarte yam). Out of these, Dioscorea rotundata (white yam) and Dioscorea alata (water yam) are the most common species in Nigeria. Yams are grown in the coastal region in rain forests, wood savanna and southern savanna habitats.
Yam is in the class of roots and tubers that are a staple of the Nigerian and West African diet, which provides some 200 calories of energy per capita daily. In Nigeria, in many yam producing areas, it is said that “yam is food and food is yam”. However, the production of yams in Nigeria is substantially short and cannot meet the growing demand at its present level of use. It also has an important social status in gatherings and religious functions, which is assessed by the size of yam holdings one possesses.

1.1.2 National Value
Yams are primary agricultural commodities and major staple crops in Africa, where yam cultivation began 11,000 years ago. In West Africa, they are major sources of income and have high cultural value. They are used in marriage ceremonies, and a festival is held annually to celebrate its harvest.
Consumers’ demand for yam is generally very high in this sub-region and yam cultivation is very profitable despite high production costs.
1.2 Problem Statement
The edible yams are root crops groomed on a field scale for the tubers. They provide staple carbohydrate food in the yam zone of West Africa, where daily consumption is 0.5, 1.0kg yam need a great deal of labour for their cultivation and to prepare them for food and they are usually expensive to buy for normal human consumption, the field or peel, sometimes after partial boiling in West Africa, they are usually eaten as pounded yam which is prepared by peeling cut-up yam and boil before pounding them in a wooden mortar to produce a glutinous dough (pounded yam).
The chemical composition of yam tuber is as follows:
Water 70%
Starch 25%
Sugar 1%
Protein 1.2%
• Justification Of Project
The most important justification for this project is as follows:
• The machine is being operated electrically
• The safety of the user comes first when constructing the machine
• The operation is hygienic and the machine can be cleaned with water after being used
• Lubrication of the adjacent moving part is made possible through a channel to reduce frictional resistance
• The need to improve the country’s economy for if the machine is produced in large number they could be exported thereby improving our foreign trade and hence, earning of more foreign exchange.
o Aims And Objectives
The aims and objectives of the project were:
• To design and develop a mechanical device that with the rotary motion of the beaters perform the pounding operation which will be more efficient, less time consuming, with less human effort and of greater hygienic processing.
• To make the beaters detachable for easy maintenance

The aim of this research work is based on the design and development of a motorized yam pounder for pounding yam. This research was considered because of the importance of pounded yam in Africa particularly in Nigerian and because of the time and energy wasted using the traditional mortal and pestle method of yam pounding. The research work aimed at eliminating the labour involved in the traditional method of pounding. Through this improvement, the possibility of food contamination by sweating while pounding will be controlled. This project work sought to design a yam pounder that pounds yam right from the peeled cooked stage in a pounding bowl with the help of an electric motor that transmits power through rotary motion together with the help of a shaft. The pounding blades function at the pestle. The machine is to be operated by electricity and it consists of a shaft, electric motor, yam beaters or pounding blades, bowl and the frame. Metal Rod for shaft; 0.30mm, Angle Bar for Frame; 40O, Stainless Steel Sheet; 0.2mm, Flat Mild (Pan); 2mm (Thickness), Prime mover; 1horse power, Bolts and Nuts; M8, Belt; V-belt, V-35, Screws; Cap Screw. Low-cost materials were used so as to make the machine affordable for the average. Nigerian homes, thereby improving the standard of living. In order to avoid food contamination, stainless materials were also incorporated for smooth and clean pounding before consumption.

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