i

SOKOINE UNIVERSITY OF AGRICULTURE

COLLEGE OF AGRICULTURE

DEPARTMENT OF ENGINEERING SCIENCE AND TECHNOLOGY

B.Sc. BIO-PROCESS AND POST-HARVEST ENGINEERING

SPECIAL PROJECT REPORT

By

AMIR,martnine J.

Supervisor(s): Prof V.C.K. Silayo

Title: Design and fabrication of low cost Irish potatoes processing line: Potato peeler

A SPECIAL PROJECT PRESENTED TO THE DEPARTMENT OF ENGINEERING

SCIENCE AND TECHNOLOGY OF SOKOINE UNIVERSITY OF AGRICULTURE IN

PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF BIO-

PROCESS AND POST-HARVEST ENGINEERING

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ABSTRACT

For the processing of potatoes, removal of the peel is an important unit operation. Hence, a pedal

operated potato peeler was designed and developed. The main parts of the integrated machine

were peeling drum, water spraying unit. The peeling drum, with brushes on the inside surface,

rotated and detached the peel from the potatoes by abrasion. The water spraying unit washed the

potatoes and, simultaneously, the peel was removed from the drum through the peripheral

clearance of the drum along with the flow of water. The water pipe, shafts and chain drives were

significant parts of the machine. The machine worked at 102.75 rpm with a 43.2 kg/hr capacity

at average time of 1.25 minutes and flesh loss of 1%.

Potato peeling machine was fabricated and efficiency of 62.5% and with time of 1.25 minutes

was attained.

It is recommended that by designing a new system within the unit of peeling drum which will

increase the efficiency of peeling potatoes by placing brushes with protruding wires which are in

form of zig-zag and placing adjustable speed to determine the suitable speed of rotating the drum

during peeling process for improvement of the machine

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ACKNOWLEDGEMENTS

First and foremost I would like to thank my project supervisor Prof. V.C.K. silayo for his

guidance and support in this project, which enables the project to run smoothly. His teaching and

his encouragement had broadened my perspective towards the engineering world.

Besides that, I would also like to express gratitude to University of sokoine,

all lecturers from Department of Engineering, supporting staffs and to all my friends who

had also helped me either directly or indirectly in gathering information and opinion

provision.

Lastly, my "endless" thanks to my family for their love that have kept me going

and never giving up hope in me.

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TABLE OF CONTENTS

ABSTRACT.............................................................................................................................. ii

ACKNOWLEDGEMENTS .................................................................................................... iii

TABLE OF CONTENTS ........................................................................................................ iv

CHAPTER ONE .......................................................................................................................1

1.0 INTRODUCTION .............................................................................................................1

1.1 BACKGROUND...................................................................................................................1

1.2 Problem statement and justification .......................................................................................2

1.3 Objectives .............................................................................................................................2

1.3.1 Overall objective ................................................................................................................2

1.3.2 Specific objectives ..............................................................................................................2

CHAPTER TWO ......................................................................................................................3

2.0 LITERATURE REVIEW ...................................................................................................3

CHAPTER THREE ..................................................................................................................5

3.0 METHODOLOGY ..............................................................................................................5

3.1 Machine Design ....................................................................................................................5

3.1.1 Machine Components and Specifications. ...........................................................................5

3.2 Material Selection .................................................................................................................5

3.2.1 Wood .................................................................................................................................5

3.2.2 Mild Steel ...........................................................................................................................6

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3.3 CALCULATIONS BASED ON WORKING MECHANISM OF THE PEELING

MACHINE..................................................................................................................................7

3.3.1 Design calculations .............................................................................................................7

3.3.2 Number of brushes required to be fitted into the calculated number of wood pieces, ...........8

3.4. Wheel specifications .............................................................................................................8

3.4.1 Roller Chain Design for power transmission .......................................................................9

3.4.2Machine Capacity and Efficiency ...................................................................................... 11

3.4.2.1Machine Capacity ........................................................................................................... 11

3.5 Machine Efficiency ............................................................................................................. 11

3.6 TESTING OF THE MACHINE .......................................................................................... 11

CHAPTER FOUR ................................................................................................................... 14

4.0 RESULTS AND DISCUSSION ........................................................................................ 14

CHAPTER FIVE..................................................................................................................... 15

5.0 CONCLUSION AND RECOMMENDATIONS .............................................................. 15

5.1CONCLUSION .................................................................................................................... 15

5.2 RECOMMENDATION ....................................................................................................... 15

REFERENCES ......................................................................................................................... 17

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LIST OF TABLES

Table 1: Showing Peeling Efficiency of machine (P.E) (%) ....................................................... 11

Table 2: Showing peeling efficiency (P.E %) under constant number of potatoes ...................... 12

1

CHAPTER ONE

1.0 INTRODUCTION

1.1 BACKGROUND

In Tanzania, potatoes (Solanum tuberosum) are sometimes called "Irish potatoes" or "European

potatoes" (Viazi Ulaya in Swahili). Irish potato is one of mankind’s most valuable food crops in

the world with annual production volume of 347 metric million tones, produced in an estimated

area of 18.9 million hectares (FAOSTAT, 2004). It ranks fourth in the world as food crop after

maize, rice, and wheat (FAOSTAT, 2004). Among root crops Irish potato ranks first in terms of

volume produced and consumed followed by cassava, sweet potato and yams, and provides

roughly half of the world’s annual output of all roots and tubers, making it the largest non cereal

food and cash crop worldwide (FAOSTAT, 2004). It contributes energy and substantial amounts

of high quality protein and essential vitamins, minerals and trace elements to the diet (Horton,

1987). A single medium-sized Irish potato contains about half the daily adult requirement of

vitamin C, very low in fat (about 5 percent of the fat content of wheat), more protein, and twice

calcium than maize (Horton, 1987; Dean, 1994; McGlynn, 2007). The health benefits of potatoes

have been widely acknowledged and research is continuously finding new health benefits of

potatoes, such as a flavonoid called quercetin (Suszkiw, 2007).

Ludaladio et al (2010). project that in the future, world potato production is expected to grow at

a rate of 2.5% per year, thereby presenting opportunities for expanded utilisation and opening up

new market segments. To realise the full potential of this crop, developing countries must

address both supply and demand side constraints. (Lutaladio et al. 2009, 11.) Potatoes are a

traditional food crop, which refers to widely used diversification between a food crop and an

export/cash crop. The FAO (2006) publication states that while potato output has declined in

Europe, growth is so strong in developing countries that global production has nearly doubled

over the last 20 years.

Irish potato was introduced in Tanzania during 1920s by German mission in the Southern

Highlands (SH) of Tanzania where local farmers began its cultivation in small scale gardens

(Jakobsen and Mallya, 1976; Macha et al., 1982), it is becoming an important cash and food crop

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(Kelly, 2006). Since its introduction, production trends have been increasing positively

(FAOSTAT, 2007).

Potatoes will have growing demand in the future. The reasons for expected growth in demand are

a lack of substitute crops, an increasing population, urbanization, an improving road network,

and changing eating habits. Demand for processed products like French fries and crisps are

expected to grow. This lead to the demand of good harvesting, handling, and processing

practices

1.2 Problem statement and justification

In East Africa, Tanzania in particular, there are many constraints on the spread and adoption of

potatoes processing line, including availability of affordable processing kits and technologies. In

developing countries, street Venders use mostly women and children to peel, slice and clean

potatoes. Low cost potatoes processing line can fill an important technology gap for the street

vender who makes French fries. Street venders are able to benefit from this processing line

because they can be adapted to small and medium production. Low-cost processing line retains

the benefits of conventional processing line while removing the factors that prevent their uptake

by small venders. Using this processing line will save time and the overall workload of women

and children will also significantly be reduced. There will also be a notable improvement in

income generation from use of low-cost processing line by small venders.

1.3 Objectives

1.3.1 Overall objective

The overall objective is to design and fabricate pedal driven potatoes processing line for small

vendors.

1.3.2 Specific objectives

The specific objectives include:

(i) To design and fabricate paddle potatoes peeling machine.

(ii) Peeling a potato

(iii) Design a suitable peeler machine for vendors.

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CHAPTER TWO

2.0 LITERATURE REVIEW

Potatoes have been processed in the U.S. since 1831 when the first starch plant was established.

Potato chips are also reported to have been first prepared during the mid-19th century, but

remained on a small commercial scale until World War II when improved peeling and frying

techniques were developed. The freezing industry was also launched in the 1940’s.

The growth in potato processing has been phenomenal. Prior to 1960, reports on potato

utilization did not differentiate between snack foods (chips and shoestrings) and fresh

consumption. By 1970, U.S. processed utilization was nearly equal to that of fresh. Major

processing uses of potatoes now are chips, dehydration, and freezing. By the late 1980s, these

three uses accounted for about 98 percent of all processing in the U.S.

The chipping industry is more evenly spread. Chipping plants can be found in every region. The

fragility of potato chips and the high cost of shipping low-density products make long distance

shipping undesirable. As a result, chipping plants tend to be located near heavily populated areas.

The market for processing potatoes exhibits some characteristics that are quite different from the

fresh market. Since French fry processors are concerned about finished product quality,

processing contracts place emphasis on those raw product characteristics that influence finished

product quality. Specific gravity is of particular concern and processors pay premiums for high

specific gravity and penalize for low specific gravity. Other characteristics, such as tuber size

and grade, have also generated premiums. Contract provisions have changed over time in

response to changes in processing technology, production practices and the appearance of new

quality factors in individual growing areas. The processing industry is a major and expanding

market for potatoes which benefited both the producer and the consumer. (Joe Guenthner, 18)

Most potatoes in Tanzania are consumed as food at household level and through food service

outlets such as restaurant and street food vendors. It has been established that significant

volumes of ware potato in major urban centre’s are consumed as French fries (chips) through

food service outlet and mainly street food vendors (SAGCOT, 50).

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The processing of potatoes in Tanzania is still very small-scale and undeveloped; currently it is a

common scene to find unsorted and poor packaged potatoes in the market and groups of women

at the market place peeling potatoes for street vendors and restaurants that make French fries.

This indicates that people who make French fries are ready to pay a little bit more for peeled

potatoes.

In the research made by Mwakasendo et al. (2007), found that the only company in Tanzania

with a cold store chain was the French fries Company Bright Choice Company Ltd. The firm

imports frozen French fries and does not use local (fresh) products because of the low quality

and infrequent inconstant supply. (Mwakasendo et al. 2007, 43.). However, demand for French

fries in hotels and restaurants is constantly increasing, forecasting growth for the whole potato

industry.

Low cost potatoes processing line (pedal driven potatoes washer, peeler, sorter and slicer

machines) technology is appropriate for small venders who cannot afford conventional

processing line because of high initial investment costs, this will help them to copy with the

increase in demand of snacks food that keep on growing due urbanization and changes in life

style.

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CHAPTER THREE

3.0 METHODOLOGY

The objective of this project is to design paddle driven peeling machine for small vendors. The

concept is developed based on the cost, ergonomics and easy handling of the equipment. The

following steps are designing the machine, material selection, machine fabrication, performance

analysis.

3.1 Machine Design

3.1.1 Machine Components and Specifications.

Singh(1995) describes the a power-operated batch type potato peeler that includes a peeling

drum (670 mm in length and 450 mm in diameter) And water- spraying units. The following are

main components of the paddle driven peeling machines.

1. Feeding - this is feed party in which the potatoes feeder into the drum. The feeder part

was designed in such a way that allows a person to open during feeding and removing

potatoes after being peeled.

2. Bearings and its shaft- are used to rotate the drum during peeling process.

3. The peeling drum- the peeling drum fitted with brushes (40mm) on the inside surface

removes the skin from potatoes by means of abrasions as drum rotates. The drum was

constructed by using wooden slats of 80mm length and 60mm in which the brushes was

fitted on it using screws.

4. Bicycle paddle – is one of the component used for rotating the drum unit.

3.2 Material Selection

Material selections is most important criteria during processing and handling of the food crops as

some of the materials are causing corrosion to the food and also in terms of cost some of them

are very expensive. Proper selection of material also can reduce product failure or increase

product life time. Working environment are also important issues and is taken into consideration

during material selection. The following are materials used for the design of paddle driven peeler

machine.

3.2.1 Wood

Wood materials were used in the construction of the peeling drum.

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The wood material was used in the design of machine due to the following factors:

1. Availability of wood is cheap and at low cost compared to steel and aluminum sheet.

2. Suitable for handling as materials does not undergo rusting and corrosion.

3. Wood manufacturing processes are not expensive compared to other materials like steel

and aluminum sheet.

4. The strength of wood materials is very hard and durable(high strength to weight ratio)

5. water resistant

3.2.2 Mild Steel

The machine frame is made up of mild steal materials. Uncoated mild steel can easily form

corrosion. Therefore, all surfaces for the frame have been coated with oil paint. The components

made up of mild steel are body frame, stand, rotating shaft, bearings and the gearing system.

Machine frame

This is the main skeleton of the machine as it supports all parts of the peeler. The frame is

rectangular in shape made of squire pipes. Squire pipes are held by welding joints to support the

drum and for stability of the machine.

Table no.1 showing materials used in design and fabrication of the machine

components Materials

standard

Reasons Manufacturing process

Peeling drum Wood

(80*60*30mm)

Available,

cheap

Sawing,cutting,fitting,drilling,finishing

Bicycle chain Mild steel Available,

cheap

-

sprocket Mild steel available -

Quarter pins aluminum available -

Bicycle pedal Mild steel available -

Squire pipes Mild steel

(40*40*3mm)

Available,

cheap

Welding and cutting

Shaft Mild steel Easy to

manufacture

Cutting into size

Bearings Mild steel available -

Bolts & nuts M8*8,M10*4 Available,

cheap

-

screws Mild steel available -

freewheel Mild steel available -

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Selection of Manufacturing Process

Many techniques were employed in order to manufacture the machine parts and components

during designing and fabrication of this machine. These include; machining, joining and

finishing, Mechanical fastening and finishing includes coating and painting.

Fabrication

The peeling drum fitted with brushes was fabricated according to design specifications.

Joining Processes

Are quite important in the design and fabrication, these include; welding, jointing, fitting

Painting/Coating

Painting process is only applied on mild steel surface that tends to suffer from oxidation.

Because of its decorative and functional properties such as environmental protection, low cost,

relative ease of application and the range of available colors, paint is chosen to use as a surface

coating.

3.3 CALCULATIONS BASED ON WORKING MECHANISM OF THE PEELING

MACHINE.

3.3.1 Design calculations

Calculations of the peeling drum design;

Diameter of the drum (D) = 400 mm

Calculate total circumference = 3.142*D

=1256.64 mm

From the design, given the length of piece of wood 800mm and 60mm,

Calculating the number of wood required to round the drum / circle and spaces between the

wood pieces.

Number of wood = 16

From

Total space occupied by wood pieces = 16*60 width

= 960mm

Total space between the wood piece =1256-960

= 296mm

Number spacing =16 mm

Calculating average spaces between wood piece and another is;

= 296/16

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=18.5 mm

= 1.85cm

3.3.2 Number of brushes required to be fitted into the calculated number of wood pieces,

From;

Number of wood pieces = 16

One brush cover = 250mm

In one piece of wood contain = 3 brushes

Total brushes in the drum = 3*16 = 48 brushes

3.4. Wheel specifications

Sprocket/free, wheel Diameter

D=

Or P= ΠD/N

Where; D = Sprocket diameter (mm), P= Chain pitch (mm) and N=Number of teeth in the

sprocket/freewheel.

In preliminary calculation the following measures are given from different sources for reliability

purpose P=13mm, so using N= 47 for sprocket and N=16 for freewheel, and crank length (L

Crank) =170mm, D can be calculated as;

D sprocket =13/sin (180/47) = 194.63mm

D freewheel =13/sin (180/16) =66.64 mm

Chain Length

L chain = 2C+ (D sprocket + D freewheel)/2

L chain = 2C + (194.6+66.64)/2

L chain = (2C+130.62) mm, for C = 600mm

L chain=1330.62

Chain links

L=

Where; L=Chain length in links

P=Pitch (mm)

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C= Centre distance (mm)

N1= Number of teeth of free wheel

N2=Number of teeth of sprocket

L =

Chain links =124

Chain Velocity (V)

Assuming it provide a constant velocity ratio as result of neither slippage no creep. Has ability of

driving single drive

V=

Where; D= diameter (194.63mm) and assuming pedaling produce speed (N) of (60-80rpm)

V=

V = 45.86

Velocity Ratio

VR=

VR = 47/16 = 2.97

3.4.1 Roller Chain Design for power transmission

Power, force and torque delivered by chain

Assumptions

Pitches are evenly distributed

Centre distance doesn’t vary

There is no slippage and creep

To calculate force and torque

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Force exerted on crank (W)

Assuming the average force a man can exert is equal to 1/10 of his / her own weight. Assuming

average man having weight of 65kg.

W= mg where m=mass, g=acceleration due to gravity and W= weight/force

=65kg*9.81m/s2

=637.65N*0.1

Force exerted on the crank is about 63.765N

Torque produced by crank.

T = Force* Perpendicular distance

T crank=W*Lcrank

T crank=63.765*0.17=10.84Nm

Angular speed of sprocket ( )

The most powerful muscles in body in the most suitable motion (a smooth rotary motion) at the

most convenient speed 60-80rpm (Makungu 1995).

Making average of 70rpm

Let 1=70rpm

From the relation,

N sprocket sprocket = N freewheel freewheel

Freewheel =47*70/16 =205.625rpm

Then, angular speed can be calculated by;

W = (2Π )/60

W1 = (2Π sprocket)/60

= (2Π*70)/60=7.33 rad/sec

W2 = (2Π* freewheel)/60

= (2Π*205.625)/60=21.53rad/sec

Power

It is calculated by the following formula;

P=TV =F* L crank V=

Where P= Power

T=Torque

V=Velocity

D=Diameter

= *0.19463*10.84*70RPM*/1000

Power = 0.464 W approximately

= 0.5 W

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3.4.2Machine Capacity and Efficiency

3.4.2.1Machine Capacity

It is usually given as mass per unit time, can be either be measured as the through put capacity,

which is equal to the total weight of the material handled per hour or as material capacity which

is equal to the weight of material cleaned per time. Calculations involve measuring weight and

time.

Through put capacity=Total material handled by machine (kg)/ (Total time taken)

3.5 Machine Efficiency

Machine efficiency= (no. of peeled potatoes)/ (total number of potatoes)

3.6 TESTING OF THE MACHINE

During testing of machine the following data are determined;

1. Efficiency of the machine (%)

2. The output capacity (kg/h)

3. Peeling losses (kg/h)

SAMPLING PROCEDURES AND SELECTION PROCESS

Testing procedures

1. Arranging samples into different groups or numbers as shown in the table 1 and 2

2. Testing time arrangement

3. Testing the samples according to time shown

4. Data collection after testing (peeled and unpeeled potatoes)

5. Calculating the efficiency of machine (%)

6. Calculating its capacity (kg/hr)

7.

TABLE OF RESULTS

Table 1: Showing Peeling Efficiency of machine (P.E) (%)

Speed of

rotation (rpm)

Duration of

peeling (min)

N0 N1 N2 (P.E %)

75 1 6 4 2 67

80 1 10 8 2 80

74 1 15 7 8 46

59 1 20 11 9 55

Mean speed of

rotation = 72

mean 62

Where

N0 = total number potato before peeling

N1 = number of peeled potato

N2 = number of unpeeled potato

From table 1

Peeling efficiency = (no. of peeled potatoes)/ (total number of potatoes)

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Sample 6

P.E % = 4/6×100%

= 67%

Sample 10

P.E % = 8/10×100%

= 80%

Sample 15

P.E % = 7/15×100%

= 46%

Sample 20

P.E % = 11/20×100%

= 55%

Table 2: Showing peeling efficiency (P.E %) under constant number of potatoes

Speed of

rotation (rpm)

Duration of

peeling (min)

N0 Weight of

samples(g)

N1 N2 (P.E

%)

48 0.5 10 900 2 8 20

65 1 10 6 4 60

139 1.5 10 9 1 90

162 2 10 8 2 80

Average

speed= 102.75

Average time=

1.25

mean 62.5

Where

N0 = total number potato before peeling

N1 = number of peeled potato

N2 = number of unpeeled potato

From table 2

Peeling efficiency = (no. of peeled potatoes)/ (total number of potatoes)

Sample 10 at time 0.5min

P.E % = 2/10×100%

= 20%

Sample 10 at time 1min

P.E % = 6/10×100%

= 60%

Sample 10 at time 1.5min

P.E % = 9/10×100%

= 90%

Sample 10 at time 2 min

P.E % = 8/10×100%

= 80%

From the sample analyzed, 10 number of samples = 900g

Machine capacity = mass (kg)/time taken

= 0.9 (kg)/1.25 min

13

=0.72 (kg)/min×60min/hr

= 43.2 (kg)/hr

Graph of peeling efficiency against time of peeling used

PEELING LOSSES EFFICIENCY

The efficiency of peeling losses was determine by measuring the weight of potatoes before

peeling and after peeling the potatoes but the results was showing the same as before, this might

have been caused by a machine which removes the skin of potatoes only, the flesh loss can be

approximately 1% when you compare to manual peeling, the machine saves more than ten times

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CHAPTER FOUR

4.0 RESULTS AND DISCUSSION

Results obtained from table 1 indicates the peeling efficiency of the machine under constant time

of one minute but with variation of number of potatoes, the data shows that as the number of

potatoes increases the efficiency of machine decreases i.e. number of unpeeled potatoes was

increasing, an overall efficiency of 62 percent results with time of one minutes, during

collection of data as number of peeled increased to beyond 25, the machine was not able to

function properly, so the maximum of 20 potatoes should be suitable for this peeler machine.

Table 2 presents the results for peeling efficiency of machine with constant number of potatoes

while varying the time of peeling, from these results the efficiency increases as time of peeling is

increased, from the table overall peeling efficient of 62.5 percent was obtained with capacity of

43.2 kg/hr. This is probably due to the fact that an increase in the speed of rotation increases the

rate of contact of the abrasive surfaces rubbing against the potato such that, sides of the potato

was peeled over and over until the prescribed time elapsed, but maximum time should not be

more than two minutes because it causes more severity on the surface of the potatoes and

damages

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CHAPTER FIVE

5.0 CONCLUSION AND RECOMMENDATIONS

5.1CONCLUSION

The fabricated potato peeling machine at the speed of 72 revolutions per minute had an average

peeling efficiency of 62 percent .However, when the speed was raised to 102.75 revolutions per

minutes there was an average peeling efficiency of 62.5 percent. Hence, high speed of rotation

of the peeling machine will increase the peeling efficiency and an average time of 1.25 minutes

and the peeling process is easier to control.

5.2 RECOMMENDATION

1. Design of new system within the unit of peeling drum which will increase the efficiency

of peeling potatoes by placing brushes with protruding wires which are in form of zig-zag

2. Due to heavy weight of the machine, the weight may be reduced by designing a machine

using stainless steel material especially on the peeling drum

3. Placing adjustable speed to determine the suitable speed of rotating the drum during

peeling action

4. The wood used to fasten the brushes should be fitted inside the round drum to increase

its strength because if the machine subjected under high load, the wood fastened using

screws might separated apart

5. Construction of a frame cover to protect the spread of water and designing of suitable

discharge of water during operation of the machine

6. The feeding and discharging chute should be designed in such a way it doesn’t create an

increase in weight on one side of the peeling drum (maintaining equal balance of the

drum )

7. Design of stainless steel material in a unit fastened to limit the potato from moving

together with peeling drum

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Figure 1: showing the data collection analysis

17

REFERENCES

Cromme, N., Prakash, A., Lutaladio, N. & Ezeta, F. (Eds.) 2010. Strengthening potato value

chains. Technical and policy options for developing countries. Rome: FAO.

FAO 2006. Agriculture, Biosecurity, Nutrition and Consumer Protection Department Buried

Treasure: The Potato. Retrieved jolly 1, 2015 from

http://www.fao.org/ag/magazine/pdf/ 0611-1.pdf

FAOSTAT (2004). Agricultural Data. Provisional 2003 Production and indices data Crop

primary [http://apps.fao./default.jsp] site visited on 1/7/2015.

Horton, D. (1987). Potatoes production, marketing and programs for developing countries.

[http://www.cipotato.org] site visited on 2/7/2015.

Jakobsen, H. (1976). Potato Production in Tanzania. In: Regional Workshop on Potato Seed

Production and Marketing, Nairobi, October, 1976. 4pp

Kelly T. (2006). Tanzania potato production. [http://research.cip.cgiar.org] site visited on

1/7/2015.

Macha, C.A. (1976). Report of participants on Potato Production in Tanzania. In: International

Potato Course on Production, Storage, and Seed Technology. International

Agricultural Center, Wageningen, the Netherlands. 340pp.

McGlynn, A. (2007). Re- Inventing the potato. A marketing approach for 21st century In:

National potato conference and Trade show. Glen Royal Hotel. 14TH Feb. 2007;May

Rooth, Co. Kildare. 44 pp.

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Mwakasendo, J.A., Mussei A. N., Kabungo C.D., Mende D. H. and Gondwe B. J. (2007). Market

for Fresh and Frozen Potato Chips in the ASARECA Region and the potential for

Regional Trade: The Case of Tanzania Mbeya, Tanzania. 46pp.

SAGCOT. Value Chain and Market Analysis. Retrieved July 1, 2015 from

http://www.sagcot.com/pdf

Suszkiw, Jan. 2007. Phytochemical Profilers Investigate Potato Benefits. Agricultural Research

Magazine. 55 (8): 20–21.