EFFECT OF GINGER AND GARLIC ON THE MICROBIAL LOAD AND SHELF-LIFE OF ZOBO DRINK (HIBISCUS SABDARIFFA)

ABSTRACT

Zobo drink is a non-alcoholic beverage which is consumed in most part of Nigeria, mostly in the northern part of Nigeria It is produced from the dried calyces of the Roselle plant Hibiscus Sabdariffa(Malvaceae)by boiling and filtration. Microbial and sensory attribute of Zobo drink treated with ginger and garlic was investigated. Zobo drink was produced by hot extraction and filtration. The drink obtained was treated with different quantities of ginger and garlic and their effects evaluated during the period of 4 days of storage. A five- fold serial dilution of both treated and control drink samples were carried out for enumeration of microorganisms on appropriate media. The sensory evaluation of the samples was determined using standard methods. Different values of bacterial and fungal counts of both treated and control Zobo drink samples were obtained during the period of monitoring but the total viable bacterial count ranged from 4.11 x 106 – 3.62 x 107 cfu/ml while the fungal count ranged from 4.0 x 106– 3.59 x 107cfu/ml. Similarly, different values of the sensory evaluation of Zobo samples were obtained during the storage period. However, the samples containing ginger and/or mixture of both were better rated in terms of the parameter tested. Shelf-life (based on sensory overall acceptability) of the samples varied with the treatments. The ginger-treated sample showed to extend the shelf-life by 1 day whereas other treated samples showed marginal enhanced shelf-life of 3days. However, untreated control sample exhibited remarkably high microbial loads than the treated samples.

TABLE OF CONTENTS

Certification                                                                                                               i

Dedication                                                                                                                  ii

Acknowledgements                                                                                                    iii

Table of Contents                                                                                                       iv

List of Tables                                                                                                              vi

List of Figures                                                                                                             vii

Abstract                                                                                                                       viii

CHAPTER ONE

1.0Introduction                                                                                                                       1

1.1       Aim and objectives of the research                                                                           2

            CHAPTER TWO

2.0       Literature review                                                                                                       3

2.1       Nutritive values                                                                                                         5

2.2       Economic values                                                                                                        6

2.3       Properties of garlic and ginger                                                                                  6

            CHAPTER THREE

3.0       Materials and methods                                                                                                9

3.1       Collections of samples                                                                                                9

3.2       Preparation of Zobodrinks                                                                                         9

3.3       Treatment of the Zobodrinks with ginger and garlic                                    9

3.4       Microbiological analysis of samples                                                                          10

3.5       Enumeration and characterization of bacteria and fungi                                           10

3.5.1    Microscopic examination                                                                                          10

3.5.2    Gram staining                                                                                                            10

3.5.3    Biochemical tests                                                                                                        12

3.5.3.1 Catalase test                                                                                                               11

3.5.3.2 Coagulase test                                                                                                            12

3.5.3.3Indole test                                                                                                                    12

3.5.3.4 Citrate utilization test                                                                                                 12

3.6       Motility test                                                                                                                13

3.7       Sensory evaluations                                                                                                    13

            CHAPTER FOUR

4.0       Results                                                                                                                         14

            CHAPTER FIVE

5.0       Discussions                                                                                                                 20

5.1       Conclusions                                                                                                                21

5.2       Recommendations                                                                                                      22

            References                                                                                                                  23

            Appendix I                                                                                                                  30

            Appendix II                                                                                                                 31

            Appendix III                                                                                                               32

LIST OF TABLES

Table       Title                                                                                Page

1.     Effect of garlic and ginger on the total viable bacterial counts (cfu/ml) of Zobo

            drink during storage                                                                                                    15

2.     Effect of garlic and ginger on the total viable fungal counts (cfu/ml) of Zobo                                  drink during storage                                                                                              16

3.     Biochemical characteristics of bacteria isolates                                             17

4.     Identification of fungal isolates                                                                      18

5.     Sensory evaluation of different samples of Zobo drink                                 19

LIST OF FIGURES

Figure       Title                                                    Page

1.              Flow chart for the production of Zobo drinks                                                5

CHAPTER ONE

1.0 INTRODUCTION

Drinks and beverages are consumed for their nutritional value, thirst quenching properties, stimulating effect or for their medicinal values (Adegunloye et al., 1996;Elmahmood and Doughari, 2007). Zobo drink is a non-alcoholic beverage which is consumed in most part of Nigeria, mostly in the northern part of Nigeria (Osuntogun and Aboaba, 2004).It is produced from the dried calyces of the Roselle plant Hibiscus Sabdariffa(Malvaceae)by boiling and filtration. At present, the production process is neither standardized nor mechanized. Roselle also known as Jamaican sorrel is probably a native of West Africa and has been cultivated throughout India and part of Asia for centuries. Currently, it is grown throughout the tropics especially in Indonesia, central Eastern Java, India-Bangladesh, Sri Lanka, the Philippines and the West Indies. Different ethnic groups call the vegetable plant various names. The Yorubas call the leaves ‘Amukan’, while the flower is called ‘Isapa’. The Igbos call it names like ‘ojo’, ‘Akwaroazo’, while the Hausas call the fleshy calyx names like ‘Yakuwa’, ‘Sure’ or ‘Gurguzu’ (Arthney and Dennis, 1991).

            The economic and religious situation in Nigeria has made the Zobo drink gain wide acceptance in different occasions and being consumed by several millions of people from different socio-economic classes and background. It is used as refreshment, entertainment in parties or as appetizers before the main dish is served and it is also sold in market to various consumers (Onuorahet al., 1987). Zobo drink has been shown to be a good source of natural carbohydrate, protein and vitamin C which constitutes the basic reason for consuming soft drinks and juices (Ogiehor and Nwafor, 2004).

            Many parts of the roselle including the seeds, leaves, fruits and roots are used in various foods. Among them, the fleshy red calyces are the most popular (Yadenget al., 2005).

1.1 AIMS AND OBJECTIVES OF THE RESEARCH

·       To identify and characterize microorganisms associated with Zobo drink.

·       To determine the effect of ginger and garlic on the shelf-life of locally produced Zobo drink.

·       To evaluate the sensory attributes of the Zobo drink during storage.

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