MICROBIAL EVALUATION OF SLICED CITRULLUS LANATUS (WATER MELON) AND ANANAS COMOSUS (PINEAPPLE) SOLD BY HAWKERS IN UMUDIKE, MOUAU

ABSTRACT

Fresh fruits may harbour a wide range of microbial contaminants due to several factors which may be of public health significance. This study was conducted to evaluate the microbial quality of sliced watermelon and pineapple sold in Umudike, MOUAU. Evaluation of the possible bacteria and fungi on the fruit samples was carried out based on standard microbiological methods. A total of seven species of bacteria and five species of fungi were isolated from twenty samples of fresh cut pineapple and water melon fruits analyzed. This work revealed the Total Viable Count (TVC) and Total Fungal Count (TFC) for both Pineapple and Watermelon collected from different locations. 5.2×108 and 1.1×107 (CFU/ml) represented the highest and lowest Total Viable Count (TVC) respectively while 2.4×107 and 0.2×107 represented the highest and lowest Total Fungal Count (TFC) respectively for Pineapple. The Total Viable Count (TVC) and Total Fungal Count (TFC) for Watermelon collected from different locations were 5.2×107 and 1.0×107 (CFU/ml) representing the highest and lowest Total Viable Count (TVC) respectively while 5.5×107 and 0.1×107 represented the highest and lowest Total Fungal Count (TFC) respectively. It was observed that almost all the fruits examined had bacterial counts above the acceptable limit and is therefore microbiologically unacceptable. Pineapple appeared to have the highest bacterial count which may be due to its high carbohydrate content needed for the growth of bacteria. From this, the percentage occurrence of the different bacterial isolates for both Pineapple and Watermelon, S. epidermidis had the highest percentage occurrence (31.9%) followed by Staphylococcus aureus 19.1%, Bacillus sp 17%. Pseudomonas aeruginosa 14.9%, Enterobacter 8.5%, Proteus 6.4% while E. coli had the lowest percentage occurrence (2.1%). The percentage occurrence of fungal isolates revealed that Aspergillus sp had the highest percentage occurrence (40%) followed by Mucor sp 25%, Botrypdiplodia sp 15%, while Fusarium sp and Penincillum sp had the lowest percentage occurrence (10%) respectively. The commonest genera of fungi that were isolated and identified included Aspergillus sp, Mucor, Penicillum sp, Fusarium sp, and Botrypdiplodia sp. There is need for urgent improvement in the hygienic condition of preparation and handling of fresh cut fruits, especially when organisms like S. aureus, E. coli, and Bacillus species occur in high numbers. E. coli count in fruits is widely used and accepted as indicators of feacal contamination.

TABLE OF CONTENT

Title Page i

Certification ii

Dedication iii

Acknowledgement iv

Table of Contents v

List of Table viii

Abstract ix

CHAPTER ONE

1.0 Introduction 1

1.1 Aim and Objectives of the Study 3

1.1.1 Aim of the Study 3

1.1.2 Objectives of the Study 3

CHAPTER TWO

2.0 Literature Review 5

2.1 Water Melon (Citrullus Lanatus) 5

2.2 Pineapple (Ananas Comosus) 9

2.2.1 Nutritional Value 11

2.3 Pathogens of Greatest Concern in Fruits 13

2.3.1 Shigella Species 13

2.3.2 Escherichia Coli 14

2.3.3 Campylobacter Species 15

2.3.4 Yersinia Enterocolitica 15

CHAPTER THREE

3.0 Materials and Methods 17

3.1 Sample Collection 17

3.2 Media Used 17

3.3 Sterilization 17

3.4 Enumeration of Bacteria 17

3.5 Identification and Characterization of Isolates 18

3.5.1 Gram Staining 18

3.5.2 Spore Staining Technique 18

3.5.3 Motility Test 19

3.6 Biochemical Cultural Characteristics 19

3.6.1 Catalase Test 19

3.6.2 Coagulase Test 19

3.6.3 Citrate Test 19

Indole Test 20

3.6.5 Oxidase Test 20

3.6.6 Urease Test 20

3.6.7 Methyl Red Test 21

3.6.8 Voges-Proskaeur Test 21

3.7 Sugar Fermentation Test 22

3.8 Identification of Fungi 22

CHAPTER FOUR

4.0 Results 23

CHAPTER FIVE

5.0  Discussion, Conclusion Recommendation 30

5.1 Discussion 30

5.2 Conclusion 33

5.3 Recommendations 34

REFERENCES

CHAPTER ONE

1.0        INTRODUCTION

Raw and minimally processed fruits and vegetables are an essential part of people’s diet all over the world. Where land is available, families grow fruits and vegetables for their own use. (Daniyan and Ajibo, 2011). Some of these frequently consumed fruits include water melon and Pineapple. Water melon (Citrullus lanatus) is usually produced in the Northern states in Nigeria and brought to the markets where it is bought and usually sliced, packed in transparent white polythene bags and sold in the market. It is difficult for one to attest to the hygiene of the processing and the sanitary conditions at the point of preparation. (Mbata et al., 2016). Pineapple is highly perishable and seasonal. Mature fruit contains 14% of sugar; a protein digesting enzyme, bromelin, and good amount of citric acid, malic acid, vitamin A and B (Barro et al., 2007). Pineapple juice's composition varies depending on geography, season, process and time of harvest. Its balance of sugar and acid contributes to the fruit's refreshing flavour (Eni, et al., 2010).

Sliced fruits refer to fruits that have been cut open, sliced into bits, but remain in the fresh state and displayed for sale in retail outlet for consumption. (Nwachukwu and Osuocha, 2014). These freshly sliced fruits are processed by peeling, slicing or trimming with or without further processing or cooking before consumption. Sliced fruits have been on the increase in many developing countries due to lack of formal jobs for the working age groups. Sales of sliced fruits can contribute significant income for households and at the same time providing a source of inexpensive nutritious meal (Nwachukwu and Osuocha, 2014). Also, the significant increase in the consumption of sliced/ ready-to-eat fruits in Nigeria especially among students is largely due to the fact that they are easily accessible, convenient, and most importantly, cheaper than whole fruit. However, despite their nutritional and health benefits, outbreaks of human infections associated with the consumption of fresh or sliced fruits have increased in recent years. Studies have already confirmed that sliced/ ready to eat fruits might be contaminated with Salmonella, Listeria monocytogens and high count of Staphylococcus aureus. (Allamin et al., 2015).

Fruits are known to carry natural non-pathogenic microflora (Chukwu et al, 2010) however, cutting and slicing can eliminate the protections and microbes can invade the internal tissue. This is due to the fact that fruits and vegetables are widely exposed to microbial contamination through contact with soil, dust and water and by handling at harvest or during postharvest processing. They therefore harbour a diverse range of microorganisms including plant and human pathogens. (Eni et al., 2010). Moreover, the case is worsened by the fact that the sliced water melon vending is done without adequate storage conditions, thereby exposing the sliced water melons to flies and other disease causing agent. Outbreaks of Salmonellosis have been associated with the consumption of cut watermelon in the United States of America (Oranusi and Olorunfemi, 2011). Salmonella spp has been reported to survive and grow rapidly on water melon held at room temperature and the level of contamination did not change when the melon was stored at refrigeration temperature (Brooks, 2014). Differences in microbial profiles of various fruits result largely from unrelated factors such as resident microflora in the soil, application of non-resident microflora via animal manures, sewage or irrigation water, transportation and handling by individual retailers (Iyoha and Agoreyo, 2015).

Although, water supplemented with varying concentrations of organic acids, such as acetic, citric and ascorbic acids, has been shown to reduce microbial populations on fruits and vegetables. Previous studies revealed that a vinegar dip resulted in a 3 to 6 log10 decrease in the number of aerobic bacteria on parsley leaves, depending on vinegar concentration used and incubation time. (Eni et al., 2010).

Freshly sliced fruits are usually prepared in such ways that doesn’t require extra processing and as such are termed as ready to eat. These fruits are mostly purchased due to their convenience of purchase and ease of accessibility in terms of price and other factors. Also, the nutritional value of these fruits promulgate their constant demand and hence the continued existence of sliced ready to eat fruits albeit their processing.

Many of these fruits have been implicated in the outbreak of diseases associated with consumption of these fruits. This may be due to the method of processing by the street vendors or the state of hygiene of these vendors. Worrisome also is the issue of storage of these fruits which may also be a contributing factor to the contamination of these fruits and also owing to the fact that these fruits require little or no processing.

This research evaluates these issues and tries to identify plausible cause of these contamination.

1.1 Aim and Objectives of the Study

1.1.1 Aim of the Study

This research is aimed at evaluating the microbial quality of freshly sliced fruits consumed by students and staff of Umudike as well as the local natives around the environs of the study location.

1.1.2 Objectives of the Study

i. To isolate, characterize and identify the microorganisms present in freshly sliced Water melon and Pineapple.

ii. To determine the total count of fungi and bacteria

iii. To determine the percentage occurrence of the bacteria isolates

To determine the percentage occurrence of the fungi isolates

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