The project dealt on the production of yam flour from yam chips. The yams were peeled and washed, 100grams samples coded sample A to G were subjected to two different drying conditions. Some were dried using the sun drying method while the others were dried through oven drying method kept at constant temperature of 500C, sodium bi-carbonate was added to some of the samples, all these were done to obtain a flour with the best colour and texture quality. From the results obtained, it was observed that sample B (yam boiled with sodium bi-carbonate and dried with oven) gave the best result and quality when tested with hot water, this was as a result of the drying condition used, the constant temperature maintained and the presence of the sodium bi-carbonate used which helped in achieving the result. Generally, the samples dried through the oven drying method at 500C gave better colour and result of the yam flour when tested with hot water more than other samples dried by sun drying and this was due to the stability in temperature in the oven drying method used.

 

Title page - - - - - - - - - - i

Certification - - - - - - - - - ii

Dedication - - - - - - - - - - iii

Acknowledgement - - - - - - - - iv

Abstract - - - - - - - - - - v

Table of content- - - - - - - - - vi

CHAPTER ONE

1.0 Introduction - - - - - - - - - 1

1.1 Background of study - - - - - - - 1

1.2 Statement of problems - - - - - - - 2

1.3 Objective of the study - - - - - - - 4

1.4 scope of the work - - - - - - - - 5

CHAPTER TWO

2.0 Literature Review - - - - - - - - 6

2.1 Yam   - - - - - - - - - - 6

2.1.1 Origin and Cultivation of yam - - - - - 6

2.1.2 Water yam  - - - - - - - - 7

2.2 Agronomic characteristics of yam - - - - - 9

2.3 Component of yam - - - - - - - 9

2.4 Utilization and processing of yam -- - - - - 11

2.4.1 Processing of yam flour - - - - - - 11

2.5 Flour  - - - - - - - - - - 12

2.5.1 Etymology - - - - - - - - - 13

2.5.2 History - - - - - - - - - 13

2.5.3 Composition - - - - - - - - 13

2.5.4 Bleached and unbleached flour - - - - - 14

2.6 Types of flour - - - - - - - - 14

2.6.1 Yam flour - - -- - - - - - - 15

2.6.2 How to buy flour -- - - - - - - 16

2.6.3 How to store flour - - - - - - - 16

2.7 Drying - - - - - - - - - - 18

2.7.1 Drying behavior - - - - - - - - 19

2.7.2 General principle - - - - - - - 20

2.7.2.1 External conditions - - - - - - - 22

2.7.2.2 Internal conditions- - - - - - - - 23

2.7.2.3 Drying Mechanism - - - - - - - 24

2.7.3 Drying techniques and dryers - - - - - 25

2.7.4 Modeling of drying curve - - - - - - 29

2.7.4.1 Mathematical modeling of drying curves- - - - 31

2.8 Weighing Machine - - - - - - - 33

CHAPTER THREE

3.0 Methodology - - - - - - - - 34

3.1 Materials and Reagents - - - - - - - 34

3.2 Equipments Used - - - - - - - - 34

3.3 Procedure  - - - - - - - - - 35

3.4 Determination of Moisture Content - - - - 37

CHAPTER FOUR

4.0 Result and discussion - - - - - - - 38

4.1 Effect of total time on drying yam samples - - - 38

4.2 Effect of batch size on the drying temperatures - -- 40

4.2.1 Rehydration characteristics - - - - - - 41

4.3 Colour -- - - - - - - - - - 41

CHAPTER FIVE          

5.0 Conclusion and recommendation - - - - - 44

5.1 Conclusion - - - - - - - - - 44

5.2 Recommendations - - - - - - - 45

Reference -- - - - - - - - - - 47

Appendix A: Nomenclature and definition - - - - 48

Appendix B: Calculation of moisture content  - - - 50

Yam (dioscorea spp.) is a multi-species crop that originated principally from Africa and Asia before spreading to other parts of the world (Hahn et al.,1987). It belongs to the family of dioscoreae within the genus dioscorea and serves as a staple crop in west Africa.(Asiedu et al., 1992). There are many cultivars of yam, though only six are important as staple foods in the tropics. the economically important species grown are Dioscorea rotundata(white yam),D.alata (yellow yam),D.bulbifera (aerial yam), D.esculenta (Chinese yam) and D.dumenterum (trifoliate yam). Yam tubers which is the most important part of the plants can be stored longer than other root and tuber crops. This ensures food security even in times of general scarcity. Yam is the third most important tropical root and tuber crop after cassava and sweet potato (fu et al., 2005). West Africa is the leading producer of yam and grows over 90% of the worldwide production (40 tonnes fresh tuber/year) followed by the west Indians where Jamaica is the leading producer (FAOSTAT,2004). Nigeria is the world’s largest producer of yams followed by Ghana, ivorycoast and togo (FAO,2003). Both fresh tubers and yam flour are now exported from Ghana and Nigeria to developed countries such as united kingdom and united states of America. These are mostly patronized by emigrants from growing regions according to the Nigerian export promotion council (NEPC) Nigeria realized N56 billion in 2007. Sustainable production and utilization of yam are important steps in enhancing food security and alleviating poverty particularly in west Africa where it is estimated to provide more than 200 dietary calories each day for over 60 million people (Nweke et al.,1991., FAO 2002).

Yam is consumed in different forms,mainly boiled,fried or baked.tubers are often dried and milled into flour for various product,boiled yams,poundes yams and amala are the forms of yam mostly consumed in west Africa especially Nigeria and benin (Akissoe et al.,2001). Yam production faces many constraints among which are production cost (mainly planting material and labour cost),post-harvset losses(low yields). Water yam (Dioscorea alata) posses a higher multiplication ratio and tuber yields as well as better storability than the preferred indigenous species such as D.rotundata, D.alata is popular and prevalent abakaliki agro ecological zone of ebonyi state Nigeria where it is called ‘Mbala or Noula’ (igbo names) (Udensi et al.,2008) even though D.alata is also eaten boiled,it is less preferred to D.rotundata varieties. D.alata can also be processed into flour and reconstituted into fufu though generally D.alata contains less sugar and has an extended shelf-life (Raemackers,2001) which ensures availability in times of scarcity.it is also known for its high nutritional content,with crude protein content of 7.4%,starch content of 75-84% and vitamin C content of ranging from 13.0-24.7mg/100g (Osagie.1992).breeders are therefore kein to improve the food quality of the species as it has good agronomic characteristics.