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EFFECT OF PROCESSING ON THE NUTRITIONAL VALUE OF COCOYAM (Colocasia Esculenta And Xanthosoma Sagittifolium)





        This project work was carried out to determine the composition, vitamins, minerals and Anti nutrients present in the different processed samples of Cocoyam (C. esutenta and X. sagittifolium) i.e fried and boiled.

          The samples were analyzed for proximate composition, mineral composition, vitamin composition and Antinutritional factors.

          The results revealed that there were significant difference in the moisture composition, ash content, crude protein, ether extract and crude fibre after the sample was processed (Boiled and Fried).

          The result of the vitamins and minerals gave a significant difference as they contain a lesser value of these vitamins and minerals when Boiled and Fried compared to the raw sample.        

          The result of the Antinutritive composition (phytic acid, Tannin, Trypsin Inhibitor & Oxalate) revealed that there is a large difference comparing the raw, Boiled and Fried sample as their content are reduced when processed.







Title page                                                                                i

Certification                                                                            ii

Dedication                                                                              iii

Acknowledgement                                                                  iv

Abstract                                                                                  v

Table of Content                                                                     vi

List of Tables                                                                          x



1.0           Introduction                                                          1

1.1           Aims and objectives                                              4



2.0           Literature Review                                                  5

2.1           Cocoyam Historical Background                         5

2.2           Varieties of Cocoyam                                            8

2.3           Toxicity                                                                  9

2.4           Taro (Colocasia esculenta)                                   10

2.4.1        Ecology                                                                  10

2.4.2        Structure                                                               10

2.4.3        Cultivation Practices                                             11     Propagation                                                           11     Husbandry                                                            11     Planting                                                                  12     Cultivation                                                             13     Harvesting                                                             14

2.4.4        Major Diseases and Pest                                      14

2.4.5        Utilization of Taro Cocoyam                                 15

2.5           Tannia (Xanthosoma Sagittifolium)                      16

2.5.1        Ecology                                                                  16

2.5.2        Structure                                                               16

2.5.3        Cultivation Practices                                             17     Propagation                                                           17     Husbandry                                                            18     Planting                                                                  19     Cultivation                                                             19     Harvesting                                                             19

2.5.4        Major Diseases and Pest                                      20

2.4.5        Utilization of Tannia Cocoyam                              20

2.6           Nutritional value of Cocoyam                               22

2.7           Processing of Cocoyam                                         24

2.8           Effect of processing on Nutritional Value            25

2.9           Storage of Cocoyam                                              28



3.0           Methodology                                                          31

3.1           Collection of Samples                                           31

3.2           Apparatus and Reagents for Analysis                 31

3.3           Proximate Analysis                                               38

3.3.1        Determination of Moisture Content                     39

3.3.2        Determination of Ash Content                              40

3.3.3        Determination of Crude Protein                           41

3.3.4        Determination of Crude Fibre                              43

3.3.5        Determination of Ether Extract                            45

3.3.6        Determination of Minerals                                    47

3.3.7        Determination of Vitamin C                                  48

3.3.8        Determination of Vitamin B1                               49

3.3.9        Determination of Vitamin B2                               50

3.4           Methodology for Antinutritional Factors             51

3.4.1        Determination of phytic acid                                51

3.4.2        Determination of Trypsin Inhibitor                      53

3.4.3        Determination of Tannin                                       54

3.4.4        Determination of Oxalate                                     55



4.0           Result and Discussion                                          57

4.1           Result of proximate analysis                                57

4.2           Result of mineral analysis                                    58

4.3           Result of Vitamins analysis                                  58

4.4           Result of Antinutritional Factors                         59

4.5           Discussion                                                             59

                 Recommendation                                                  62

                 Conclusion                                                            63

                 References                                                             64

                 Appendix                                                               66




Table 1       Phytic acid standard curve                                          52

Table 2       Tannin Standard Curve                                               55

Table 3       Proximate Composition of Cocoyam                           57

Table 4       Mineral Composition of Cocoyam                               58    

Table 5       Water Soluble Vitamin Composition of Cocoyam      58

Table 6       Antinutritive Composition of Cocoyam                       59




Human beings require food to carry out essential functions, which include growth, development and reproduction.  A balanced food must provide all the nutrients required for energy, body building, maintenance, and regulation of body processes.  The nutrients include carbohydrates, lipids, proteins, minerals, vitamins and water.


The major crops grown in Nigeria consist predominantly of carbohydrates.  Examples of such crops are roots and tubers which belong to the class of food that basically provide energy in the human diet such as cassava, potatoes, yam, cocoyam and grains such as maize, rice sorghum and millet.  Development of production practices of these crops have since evolved from shifting cultivation through various types of multiple cropping to permanent or continuous cropping (Coursey, 1976).

Root and tuber crops are abundant in rural areas of most developing countries and are often thought of as a cheap staple food.  In Africa, the tubers are grown and consumed extensively in the sub-saharan region, root and tuber crops rank next in importance to cereal grains in providing the major part of the daily calorie needs of the people in the tropics.  Cocoyam flour especially is important in areas where there is a seasonal famine because they are good substitute to other foods such as yam and potatoes etc. (FAO 1985).


It has been established by Okigbo (1978) that Africa has the highest per capital consumption of root crops, 60% of which is supplied by Cassava and 20% by Yam.  It was also estimated that in this region.  The per capital consumption of these tubers is about 182.4kg/year and is highest in Central Africa 417.5kg/year and West Africa, 196.8kg/year.


This however indicates that processing food productions from root and tuber crops is a major activity of people in this region.  Yet, the Food processing industry carried out at the family or village levels has been mostly traditional and inefficient.


Starch is the most prominent constituent of major crops, such as roots, tuber and cereal grains that are grown and processed in Nigeria into Food for human consumption.  Similarly, the by products or waste materials obtainable during local and industrial processing of these starchy crops into foods through diverse, may each be assumed to contain starch as a prominent component.


Cocoyam, a test material for this research work has been processed into many forms for utilization, it has been processed domestically into starches.


The Nigeria weather suit cultivation of Cocoyam but insufficient ways of utilizing them industrially have not encourage the large scale production.  It is unlikely however that Cocoyam will ever attain the status of major world crop.  In West Africa, where most of the world production occurs, Cocoyam suffers very stiff competition from yam (Oyenuga 1968).


Cocoyam are usually consumed after processing which tends to increase their palatability, digestibility, their keeping qualities and safety.  During processing the nutritional value may be adversely affected and in some cases anti-nutritional substances may be reduced or increased depending upon the processing method.



The aim and objective of this research work is as the name implies, to assess the effects of processing on the nutritional value of two cultivars of Cocoyam (Taro and Tannia).  The work will cover the physiochemical properties of Cocoyam starches, which is when boiled, and fried.



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