MICROBIAL QUALITIES OF FRUITS SOLD IN UMUAHIA METROPOLIS

ABSTRACT

This study evaluated the microbiological quality of fruits sold in Umuahia metropolis. A total of fifteen (15) sliced fruit samples consisting of 5 watermelon, 5 pawpaw and 5 pineapples were collected from five different markets. The samples were cultured on Nutrient Agar Medium, MacConkey Agar, and Sabauroud Dextrose Agar using pour plate techniques. A total of nineteen (19) bacteria were isolated and identified using morphological characteristics, pigmentation on media, microscopy, biochemical and sugar fermentation methods. The bacteria were Bacillus species, Escherichia coli, Staphylococcus aurues, Proteus species and Micrococcus species while the fungal isolates were Aspergillus niger, Aspergillus fumigatus and Rhizopus stolonifer. Ndioru had the highest aerobic plate count at 3.1x105, followed by Unuariaga (3.0x105), Orieugba (2.9x105), Gate six (2.4x105), while the least aerobic plate count was recorded at Ahieke (1.9x105) in that order. The total coliform plate count investigated reveals that Orieugba had the highest coliform plate count at (3.5 x105) while Ndioru and Umuariaga had the least total coliform plate count of (2.4 x105). The total viable fungal plate count reveals Gate six as having the highest viable fungi count at (4.5 x105), while Ndioru has the least viable fungi count at 2.3x105. The percentage occurrence and distribution of bacterial isolates revealed that Escherichia coli occurred most frequently with percentage occurrence of 6(20.0%) followed by Bacillus spp  and  Proteus spp at 4(13.3%) each, Staphylococcus aureus 3(10.0%), and Micrococcus spp 2(6.6%) respectively. Aspergillus niger was the most predominant with 5(16.6%), followed by Aspergillus fumigatus 4(13.3%) while the least was Rhizopus stolonifer at 2(6.6%).This study also revealed that Staphylococcus aureus showed high level of susceptibility to Amoxil, Erythromycin and Levofloxacin. Bacillus spp showed high level of resistance to Ciprofloxacin, Amoxill and Chloramphenicol while Escherichia coli showed high resistance to Norfloxacin. The presence of these microorganisms in the fruit juices is of public health significance. Therefore, regular monitoring of the quality of commercially available fruit juices for human consumption is recommended to avoid outbreak of food borne illness resulting from the organisms encountered in this study.

TABLE OF CONTENTS

Title Page                                                                                                                                 i

Certification                                                                                                                           ii

Dedication                                                                                                                              iii

Acknowledgements                                                                                                                iv

Table of Contents                                                                                                                   v

List of Tables                                                                                                                          viii

Abstract                                                                                                                                  ix

CHAPTER ONE

1.0       Introduction                                                                                                                1

1.1       Aim and Objectives                                                                                                    3

CHAPTER TWO

2.0       Literature Review                                                                                                       4

2.1       Microbiology Of Polyethylene-Packaged Sliced Watermelon

            (Citrullus Lanatus) Sold By Street Vendors in Nigeria                                             4

2.2       Microbiological Quality of Pre-Cut Fruits On Sale in Retail

            Outlets in Nigeria                                                                                                       5

2.3       Microbiological Quality of Sliced Fresh Fruits Sold In Bida Nigeria                        6

2.4       Bacterial Pathogens Associated with Fruit Contamination                                       7

2.4.1    Campylobacter                                                                                                           7

2.4.2    Pathogenic Escherichia coli                                                                                       8

2.4.3    Salmonella spp                                                                                                            8

2.4.4    Shigella spp                                                                                                                9

2.4.5    Staphylococcus                                                                                                           10

2.4.6    Vibrio                                                                                                                          10

2.4.7    Listeria monocytogenes                                                                                              11

2.4.8    Sporeformers                                                                                                              11

2.5       Sources of Contamination                                                                                          12

2.5.1    Production Environment                                                                                            12

2.5.2    Postharvest Handling                                                                                                  13

2.5.3    Human Hygiene                                                                                                          14

2.6       Pathogen Prevention                                                                                                   15

2.6.1    Processing Strategies                                                                                                  15

2.6.2    Handling Parameters                                                                                                  17

2.6.3    Alternative Technologies                                                                                           18

CHAPTER THREE

3.0       Materials and Methods                                                                                               20

3.1       Study Area                                                                                                                  20

3.2       Materials and Reagents                                                                                              20

3.3       Collection of Samples                                                                                                20

3.4       Sterilization of Materials                                                                                            21

3.5       Preparation of Culture Media                                                                                     21

3.6       Inoculation and Isolation                                                                                            21

3.7       Purification of Isolates                                                                                               22

3.8       Identification of the Isolates                                                                                       22

3.9       Gram Staining                                                                                                            22

3.10     Biochemical Test                                                                                                        23

3.10.1  Catalase Test                                                                                                               23

3.10.2  Indole Test                                                                                                                  23

3.10.3  Citrate Utilization Test                                                                                               23

3.10.4  Hydrogen Sulphide (H₂S) Production Test                                                                24

3.10.5  Starch Hydrolysis                                                                                                       24

3.10.6  Motility, Indole, Urease (MIU)                                                                                  24

3.10.7  Coagulase Test                                                                                                           25

3.10.8  Oxidase Test                                                                                                               25

3.11     Identification of Fungal Isolates                                                                                 25

3.11.1  Colonial Morphology                                                                                                 25

3.11.2  Yeast Viability Staining                                                                                             26

CHAPTER FOUR

4.0       Results                                                                                                                        27

CHAPTER FIVE

5.0       Discussion and Conclusion                                                                                        34

5.1       Discussion                                                                                                                   34

5.2       Conclusion and Recommendation                                                                             37

LIST OF TABLES

CHAPTER ONE

1.0       INTRODUCTION

Fruits are an extraordinary dietary source of nutrients, micronutrients, vitamins and fiber for humans and are thus vital for health and wellbeing. Well balanced diets, rich in fruits and vegetables, are especially valuable for their ability to prevent vitamin C and A deficiencies and are also reported to reduce the risk of several diseases (Daniel et al., 2014). Fruits product are known to carry natural nonpathogenic micro flora; however, contamination with pathogens from humans or animals source can also occurs sporadically at various stages along the production. Globalization of fresh fruits potentially increase human exposure to a wider variety of food-borne pathogens and has resulted in a potential increased risk of food-borne illness outbreak associated with the consumption of these raw commodities. These pathogens may invade the inner surface of the fruits during slicing or peeling. Studies have already confirmed that pre-cut fruits might be contaminated with Salmonella, Listeria monocytogens and high count of Stapyylococcus aureus (Eni et al., 2010). Consumption of sliced products has been on the increase locally and globally. This is so because they are more convenient, easily accessible, and most especially cheaper than the whole fruits (Nwanchukwu et al., 2008). The increase in the consumption of sliced fruits has been linked with parallel increase in food-borne illnesses (Estrada-Garcia et al., 2004; Eni, et al., 2010). Sliced fruits commonly consumed in Borno state include pawpaw pineapple and watermelon. Pawpaw pineapple and watermelon are process and sold by street vendors with poor education levels and untrained in food hygiene (Barro et al., 2006). The consumption of sliced pawpaw and watermelon may have potentially increase the risk of food-born disease caused by variety of pathogens, cross contamination of fruits, unsanitary processing and use of dirty trays for display of fruits further increases the risk of contamination. Another major source is the water used in washing those cut fruits (Estrada-Garcia et al., 2004). Bacteria causing gastrointestinal infection can contaminate the sliced fruits thus exposing the consumer to greater risk (Eni, et al., 2010).

In Nigeria, fruits are popularly displayed completely exposed for sales in shopping malls, along busy and major streets and hawked by street food vendors in motor parks and on busy roads with heavy traffic, security check points or at bad spots on the highways where motorists are forced to slow down. Fruits are often purchased as ready to eat and thus usually consumed without washing. The sliced fruits such as pawpaw, pineapple and watermelon could become contaminated with foodborne bacteria in the process such as processing utensils in adequate hygienic conditions, as they are left uncovered, trays left open in unsuitable places for buyers and irregular hand-washing by the vendors. The consumption of sliced pawpaw pineapple and watermelon may have potentially increased the risk of food-borne disease caused by variety of pathogens. To investigate the quality of those consume fruits sold at road side is of great concern (Eni, et al., 2010). The increased consumption, coupled with the associated risk of disease to which consumers may be exposed, is a matter of great concern. It is difficult for one to attest to the hygiene of the processors or to the sanitary conditions at points of preparation (Barro et al., 2006). Moreover, the case is worsened by the fact that sliced fruit street vending is done without adequate storage conditions, thereby exposing the sliced fruits to flies and other disease-causing agents. The sliced/peeled fruits are processed and sold by unlicensed vendors with poor education levels and untrained in food hygiene (Barro et al., 2007). The consumption of sliced/peeled fruits may thus potentially increase the risk of food-borne diseases caused by a wide variety of pathogens (Oranusi et al., 2004). There are different sources of microbial invasion of sliced produce. Pathogens may invade the interior surfaces of the produce during washing, peeling, slicing, trimming, packaging, handling and marketing. The use of dirty utensils, as well as the open display of street food produce encourages sporadic visits by flies, cockroaches, other insects, and dust (Chukwu et al., 2010). Holding of sliced fruits that requires no further processing before consumption at ambient temperatures during retail maintains the produce at optimum temperatures for proliferation/invasion by pathogenic mesophiles (Barro et al., 2006). Bacteria like Salmonella spp., Shigella spp., Campylobacter spp. and Escherichia coli can contaminate sliced fruits through contact with sewage and contaminated water (Oranusi et al., 2004). Fruits have been associated with outbreaks of food-borne disease in many countries. Organisms involved include bacteria, fungi, viruses and parasites (Chukwu et al., 2010).

1.1       AIM AND OBJECTIVES

The aim of this study is to evaluate the microbiological quality of fruits sold within Umuahia metropolis, while the specific objectives are;

·       Determination of total aerobic bacteria plate count and total fungal count.

·       Isolation and identification of bacteria and fungi contaminants from different vended fruits within Umuahia.

·       Determination of the percentage frequency distribution of the microbial isolates on the vended fruits.

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