Effects Of Calcium Carbide As A Ripening Agent On Heavy Metals, Macro And Micro Minerals In Selected Fruits In Ikwuano L.G.A, Abia State

ABSTRACT

This study was carried out to determine the macro elements (Ca, K, P, Mg, Na, N), micro elements (Zn, Fe, Al, Cu and Mn) and  heavy metals (Pb, Ni, As, Cd and Cr) in oranges, pawpaw and pineapples artificially ripened with different amounts of calcium carbide (0g/5kg, 10g/5kg, 20g/5kg, 30g/5kg) in Umudike, Ikwuano L.G.A, Abia State. The samples were digested using the wet acid multiple Nutrient Digestion Method, heavy metals were determined by the Atomic Absorption Spectrophotometer. It was found that Ca (30.37%) Pb (10.52 mg/kg), Mg (3.80 %), P (1.89 %) were the predominant elements in calcium carbide. The fruits treated with 30g/5kg calcium carbide/fruit were quicker to ripen, 2 days (48 hours) for pawpaw, 6 days (144 hours) for oranges and 7 days (168 hours) for the pineapples. The concentration of macro elements as Ca, Mg, K, P and Na, micro elements as Zn, Cu, and Mn, and all the heavy metals ( Pb, Ni, As,Cr and  Cd,) increased with increased amount of calcium carbide applied while N, Fe and Al decreased. The results of macro mineral in the artificially ripened fruits obtained showed highest concentration of  Ca in pineapple at 30g/5kg (8.40%), K in pawpaw at control (0.62%), Na in pineapples at 30g/5kg(0.60 %), P in pineapples at 30g/5kg (1.42%)  and N in unripe oranges (0.98 %). For the micro minerals, data obtained showed highest value for Zn in unripe oranges (4.44mg/kg), Cu in 30g/5kg pineapples (0.26 mg/kg), Fe in the unripe pawpaw (60.15mg/kg), Mn in pawpaw at 30g/5kg (2.86 mg/kg) and Al in pineapples at control (0.35 mg/kg). While for the heavy metals, data obtained showed highest value for Pb in 30g/5kg pawpaw (0.56mg/kg), Ni in 30g/5kg oranges (0.67 mg/kg), As in the 30g/5kg oranges (0.55mg/kg), Cr in the unripe oranges (0.12 mg/kg) and Cd in the 30g/5kg pineapples (0.16 mg/kg). The application of calcium carbide showed significant difference on the heavy metal, macro and micro minerals in the treated fruits at p<0.05.

TABLE OF CONTENTS

Title page                                                                                                                    i

Declaration                                                                                                                  ii

Certification                                                                                                                iii

Dedication                                                                                                                  iv Acknowledgements                                                                                                            v

Table of contents                                                                                                        vi

List of tables                                                                                                               ix

List of figures                                                                                                             x

List of plates                                                                                                               xi

List of Appendix                                                                                                        xii

Abstract                                                                                                                      xiii

 

CHAPTER 1:  INTRODUCTION

1.1   Background of the Study                                                                                     1                                                                                              

1.2   Statement of the Problem                                                                                   5

1.3   Justification of the Study                                                                                   6

1.4   Aim and Objectives                                                                                            7

1.5   Significance of the Study                                                                                   7

1.6   The Scope of the Study                                                                                      8

1.7   Definition of Terms                                                                                            8

CHAPTER 2:  LITERATURE REVIEW

2.1   Fruits and Human Health                                                                                    9        

2.2    Health Benefits of Some Common Fruits in Nigeria.                                         10

2. 3   Mineral Elements and Heavy Metals in Fruits.                                                    11     

2.4   Macro Minerals, Health Benefits, Deficiencies and Risks                                   13

 

2.5   Micro minerals Health Benefits, Deficiencies and Risks                                      15

2.6   Heavy Metals and their Toxicity                                                                          18

 

2.7   Fruit Ripening                                                                                                       20

2.8   Calcium Carbide for Fruit Ripening                                                                      21

 

2.9   Other Chemical Agents used in Artificial Ripening of fruits.                            22

 

2.10  Possible Health Hazards Associated with Calcium                                                             

         carbide as Fruits Ripening Agent.                                                                    23

 

2.11  National and International Laws and Legislatives                                            25

2.12  Critical Analysis on Fruit Quality and Nutritional Values                                26

2.13  The Right Fruits to Consume                                                                            27

CHAPTER 3: MATERIALS AND METHODS  

3.1    Study Area                                                                                                        29

3.2    Methods                                                                                                             32

3.2.1  Fruits Samples and Calcium Carbide Samples Collection.                               32       

3.2.2  Fruits Samples Preparation                                                                               32

3.2.3  Application of Calcium Carbide to the Selected Fruits                                    32

3.2.4  Ripening Process                                                                                               33

3.2.5   Calcium Carbide Sample Preparation and Digestion by

            Wet-Acid Digestion Method                                                                          34

 

3.2.6   Fruits Samples Digestion by Wet -Acid Multiple Nutrient

            Digestion Method                                                                                           34

3.2.7   Atomic Absorption Spectrophotometric (AAS) Determinations of the

Sample Digests                                                                                               35

 

3.2.8   Potassium and Sodium Determination   using the Flame

Photometric Method                                                                                       35

 

3.2.9   Heavy Metal Determination by the Atomic Absorption

Spectrophotometer                                                                                          35

 

3.2.10. Phosphorus Determination by Vanado Molydbate Yellow Method                         36

 

3.3       Standards                                                                                                        36

3.4       Quality Assurance.                                                                                          36

 

3.5         Experimental Design and Statistical Data Analysis                                                 37

 

 

CHAPTER 4   RESULTS                                                                                                  

                                                                                                                                                                 4.1:             The Chemical Characteristics of the Calcium Carbide (CaC₂) used for

Ripening of the Selected Fruits.                                                                     39                                                                               

4.2:      Ripening Time and Shelf Life of Artificially Ripened Oranges, Pawpaw

and  Pineapples with Calcium Carbide at Different Inclusion Levels.           41

 

4.3:      Macro Elements Levels in the Selected Fruits before and after Application

of Calcium Carbide.                                                                                        43

 

4.4:      Micro Elements Levels in the Selected Fruits before and after Application

of Calcium Carbide.                                                                                        46

 

4.5:      Heavy Metals’ Levels in the Selected Fruits before and after Application

of Calcium Carbide.                                                                                        49

 

CHAPTER  5.

5.1:       Discussion                                                                                                      52

5.2 :     Conclusion                                                                                                      56

5.3:      Recommendation                                                                                            57

REFERENCES                                                                                                       

APPENDICES

 

 

 

 

 

 

LIST OF TABLES

 3.1:     Showing the 1-7 Scale Common in the Fruit Industry                                  33

 

 4.1:     Mean ± SD: The Chemical Characteristics of the Calcium

            Carbide (Cac₂) used for Ripening of the Selected Fruits.                              40

 

 4.2:     Ripening Time of Artificially Ripened Fruits at Different

Inclusion  Levels.                                                                                            42

 

 4.3:     Mean of Macro Minerals Levels in the Fruits Samples before

           and after Application of Different Levels of Calcium Carbide                     45

 

 4.4:     Mean of Micro Minerals Levels in the Fruits Samples before

            and after Application of Different Levels of Calcium Carbide.                    48

 

4.5:      Mean of Heavy Metals levels in the Fruits Samples before

            and after Application of Different Levels of Calcium Carbide.                    51

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LIST OF FIGURE

 

1.         Map Showing Umudike, the Study Area                                                       31

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LIST OD PLATES  1:  Citrus sinensis (oranges) before Ripening                                         38  2: Citrus sinensis (oranges) after Ripening                                                       38  3: Carica papaya (pawpaw) before Ripening                                                    38  4: Carica papaya (pawpaw) after Ripening                                                     38

 5:  Ananas  comosus (pineapples) before Ripening.                                           38

Plate 6: Ananas  comosus (pineapples) after Ripening                                        38

Plate 7: Rocky Calcium Carbide.                                                                         38

Plate 8: Crushed Calcium Carbide                                                                       38

 LIST OD APPENDICES

 

 1a:      Profile Plot Showing Ca (%) in the Selected Fruits before and

after CaC₂  Application.                                                                                 

 

 1b.      Profile Plot Showing Mg (%) in the Selected Fruits before and

after CaC₂  Application                                                                                              

 

 1c.      Profile Plot Showing K (%) in the Selected Fruits before and

after CaC₂  Application                                                                                              

 

 1d.      Profile Plot Showing P (%) in the Selected Fruits before and

after CaC₂  Application                                                                                              

 

 1e.      Profile Plot Showing Na (%) in the Selected Fruits before and

after CaC₂  Application.                                                                                 

 

 1f.       Profile Plot Showing N (%) in the Selected Fruits before and

after CaC₂  Application.                                                                                 

 

 2a.      Profile Plot Showing Zn (mg/kg) in the Selected Fruits before

and after CaC₂  Application                                                                           

 

 2b.      Profile Plot Showing Cu (mg/kg) in the Selected Fruits before and

after CaC₂  Application.                                                                                 

 

 2c.      Profile Plot Showing Fe (mg/kg) in the Selected Fruits before and

after CaC₂  Application.                                                                                 

 

 2d.      Profile Plot Showing Mn (mg/kg) in the Selected Fruits before and

after CaC₂  Application.                                                                                 

 

 2e.      Profile Plot Showing Al (mg/kg) in the Selected Fruits before and

after CaC₂  Application.                                                                                 

 

 3a.      Profile Plot Showing Pb (mg/kg) in the Selected Fruits before and

 after CaC₂  Application.                                                                                

 

 3b.      Profile Plot Showing Ni (mg/kg) in the Selected Fruits before

 and after CaC₂  Application.                                                                         

 

 3c.      Profile Plot Showing As (mg/kg) in the Selected Fruits before

and after CaC₂  Application.                                                                          

 

 3d.      Profile Plot Showing Cr (mg/kg) in the Selected Fruits before

and after CaC₂  Application.                                                                          

 

 3e.      Profile Plot Showing Cd (mg/kg) in the Selected Fruits before and

 after CaC₂  Application