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The Design, Fabrication And Performance Evolution Of Cashew Nut Cracking Machine. Diction

 

Chapter One

Introduction

1.1 Background of the Study

Cashew (AnacadiumOccidentale) is an ever green tropical tree, which originated from Northeast Brazil, which is now widely grown in tropical regions, Vietnam and Nigeria being one of the major producers, in addition to India, the Ivory coast and Indonesia (FAO 2004) The cashew tree produces nuts in a kernels with economic importance and it is widely consumed as snacks all over the world. World production and consumption has rapidly increased and cashew nut ranks third among the edible tree nuts of the world with a current output of about 700, 000 metric tonnes nuts in shells (FAO, 2004) .The cashew nut is kidney shaped and it consists mainly of a nutshell (pericarp) and a kernel, which is the main product of the cashew. The pericarp consists of a hard shell (epicarp), a honey combed structure (mesocarp), in the cells of which is contained a useful but toxic natural resin, known commercially as Cashew Nut Shell Liquid (CNSL) and a hard and brittle inner shell (endocarp) which protects the kernel (Thivavarnvongs, 1995). There is a covering of thin membrane on the kernel known as testa or peel, which protects the kernel. The kernel seed is made up of two developed kidney shaped cotyledons and an embryo. The average weight of a whole fruit varies from 5 to18 g according to variety and cultivation (Pechnick and Gulmaraes ,1969). Generally the kernel accounts for about 22-24% of the whole fruit. The processing of cashew nut involves series of unit operations before it finally gets to the consumer. These operations are cleaning, sorting, roasting, shelling and packing. But the two main unit operations in cashew nut processing are the removal of the cashew nut shell liquid (CNSL), which is an irritant that could contaminate the nut and blister Human skin if not handled properly, andshelling the nut to remove the kernel (Olaoye, 1992).

The shell of the cashew nut is toxic, which is why the shell must be removed before it is sold to consumers. The cashew nut can also be harvested in its tender form when the shell has not be hardened and is green in colour. The shell is soft and can be cut with a knife and the kernel extracted, but it is still corrosive at this stage, so gloves are required. Cashew nut may be sold raw or as processed kernels and may be further processed into value-added product such as fried, roasted or chocolate-coated kernels and confectioneries etc.

International market price is generally influence by certain quality standard (e.g kernel size and percentage of broken kernels) in accordance with the specifications of the international organization for standardization (AFI, 1990, Nouwligbeto and Jerome, 2003).

However, in view of the low capacity for cashew nut processing in Nigeria (Ogunsina and Odugbenro, 2005), bulk of the harvested nuts goes to India and other countries in Asia where the processing capacity is large (Adetunmbi, 2001). Local consumption and demand by importing countries for cashew kernels continue to increase, providing opportunities for expansion of the industries world wide (Ohler, 1988).

 

1.2 Statement of problem

It is expected that the kernel should remain intact and whole but in most mechanical system, 25%-40% of the kernels get broken, whereas whole kernel reaches 90% with traditional method. As a result of this problem, the cashew nut processing has been limited to a cottage industry for decades. One major problem is how to produce a machine that will crack with minimum damage to the kernel

 

1.3 Objectives of the Study

i) To design and fabricate a cashew nut cracking machine

ii) To crack the nuts of different moisture contents and evaluate the performance of the cracking machine.

ii) To analyze results and make recommendations.

 

1.4 Scope of the Study

 

This project is not limited to cashew nut only but to other nut which has similar

physical and mechanical properties as cashew nut. Though Cashew nut processing equipment is not new but since the kernels are expected to remain intact and whole but in most mechanical system, 25%-40% of the kernels get broken, whereas whole kernel reaches 90% with traditional method. This work focused on improving the efficiency of mechanical system to 80%. It shall range from drying of the nut to cracking and hence cracking efficiency.

 

1.5 Significance of the Study

Cracking is perhaps the greatest bottleneck along the processing line of cashew nut. Local shelling is carried out by hand with a hammer or using mortar and pestle. This cracking. Machine can be employed by cashew nut processing industries rather than the local methods, which usually are tedious in their performances, and in few cases use of complex and expensive shelling machinery, which are usually imported. This project will play a major role in large scale processing of cashew nut for commercial, domestic and industrial use. This will also help to promote the market values for cashew farmers, that is increasing the supply and reducing the cost of purchase of cashew nut.

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