ABSTRACT
Tomato and pepper are rich source of vitamins and also rich source of minerals which makes it an essential component of food. The microorganisms associated with the spoilage of physical damaged tomatoes (Lycopersicon esculentum) and pepper obtained from three markets ( Isi gate, Ubani and Orie-ugba) in Umuahia, Abia State, Nigeria were evaluated. This analyses was conducted at two(2) days interval for a period of six days, using standard microbiological techniques. A total of five species of bacteria were isolated and identified as Staphylococcus, Salmonella, Klebsiella, Bacillus and Lactobacillus species, while the fungal isolates isolated were Aspergillus and Penicillium species. The most prevalent bacteria isolated was Staphylococcus species with 27.3% in tomato and was found in all the samples while Klebsiella and Lactobacillus species was the least prevalent isolate with 9.1%. The most prevalent bacteria isolate in pepper was Bacillus species with 22.2% while Staphylococcus and Salmonella species were the least prevalent isolate with 11.1%. The most prevalent among the fungal isolate was Aspergillus with 27.3% in tomato and 33.3% in pepper. The microbial count of the physically damaged tomato and pepper fruit was higher compared to the count observed for fresh tomato and pepper fruit which was used as the control sample. Findings from this work revealed that the intake of spoilt tomatoes and pepper could be dangerous, since these organisms produced spores and toxins that could cause severe food poisoning that will result in disastrous outcome.
TABLE
OF CONTENTS
Title page i
Certification iii
Dedication iv
Acknowledgements v
Table of contents vi
List of tables ix
List of figures x
List of Plates xi
Abstract xii
CHAPTER ONE
1.0 Introduction 1
1.1 Aims and Objectives 3
CHAPTER
TWO
2.0 Literature
Review 4
2.1 General description and scientific
classification 4
2.1.1 Description
of Tomato 4
2.1.2 Description of Pepper 5
2.1.3 Classification of Tomato 7
2.1.4 Classification and taxonomy of Pepper 8
2.2 Origin 9
2.2.1 Origin of Tomato 9
2.2.2 Origin of Pepper 10
2.3 Varieties 10
2.3.1 Varieties of Tomato 10
2.3.2 Varieties of Pepper 11
2.4 Diseases and Pests 12
2.4.1 Diseases
and Pests of Tomato 12
2.4.2 Diseases
and Pest of Pepper 13
2.5 Nutritional
Value 14
2.5.1 Nutritional
Value of Tomato 14
2.5.2 Nutritional
Value of Pepper 15
2.6 Medicinal
Uses 15
2.6.1 Medicinal Uses of Tomato 15
2.6.2 Medicinal Uses of Pepper 17
2.7 Health
Benefits 17
2.7.1 Health
Benefits of Tomato 17
2.7.2 Health
Benefits of Pepper 21
2.8 Spoilage
22
2.8.1 Microorganisms
associated with spoilage of tomatoes and pepper 22
2.9 Prevention
of spoilage 24
CHAPTER THREE
3.0 Materials
and Method 25
3.1 Sample
Collection 25
3.2 Preparation
of media 25
3.3 Preparation
of samples 25
3.4 Isolation
and enumeration of microorganism 26
3.5 Purification
and maintenance of pure isolates 26
3.6 Characterization
and identification of bacterial isolates 26
3.7 Biochemical
tests 27
3.7.1 Gram stain 27
3.7.2 Indole test 27
3.7.3 Methyl red (MR) 27
3.7.4 Voges proskauer (VP) 28
3.7.5 Hydrogen sulphide test (H2S) 28
3.7.6 Citrate test 28
3.7.7 Urease test 29
3.7.8 Catalase test 29
3.7.9 Coagulase test 29
3.7.10 Motility Test (Stab method) 29
3.7.11 Sugar fermentation test 30
3.7.12 Starch test 30
3.8 Fungal Characterization 30
3.9 Statistical Analysis 31
CHAPTER FOUR
4.0 Results
32
CHAPTER FIVE
5.0 Discussion, Conclusion and
Recommendations 46
5.1 Discussion 46
5.2 Conclusion 49
5.3 Recommendations 50
References 53
Appendix 60
LIST
OF TABLES
4.1 Total
viable count of the tomato samples at different days intervals 33
4.2 Total
viable count of the pepper samples at different days intervals 35
4.3 Morphological identification, Biochemical Identification, Gram
Reaction
and Sugar
Utilization Profile of isolates from the tomato and pepper samples 37
4.4 Cultural Morphology and Microscopic Characteristics of the Fungal
Isolates
from the tomato
and pepper samples sold in Umuahia 39
4.5 Percentage occurrence of the isolates
from the tomato samples 41
4.6 Percentage occurrence of the isolates
from the pepper samples 43
4.7 Distribution of
isolates from the tomato and pepper samples 45
LIST OF FIGURES
1 Picture
showing spoilt tomatoes 60
2 Pictures
of some displayed fresh tomatoes and pepper in the market 60
LIST
OF PLATES
1 Showing
Salmonella in SSA agar 61
2 Showing S. aureus in MSA agar 61
CHAPTER
ONE
1.0 INTRODUCTION
Food spoilage refers to various
changes in which the food becomes less palatable or even toxic to consumers;
these changes may be accompanied by alterations in taste, smell, appearance or
texture. Numerous microbial defects of tomatoes and pepper are characterized by
the types of microorganisms responsible for their deterioration (Akinmusire,
2011). Tomato (Lycopersicon esculentum)
is a perishable vegetable widely cultivated and consumed worldwide (Agrios,
2005). It is rich in nutrients, vitamins dietary bres, and phytochemicals
(Mariga, 2012). Tomato has long been used as food both in cooked as well as raw
form. The deep red colouration of ripened tomato fruit is due to the presence
of lycopene, a form of β- carotenoid pigment which forms the precursor of
vitamin A and hence is of great nutritional value. It is a rich source of water
and its composition includes 95%. Today, with an increased number of ailments
of vision, these fruits rich in carotenoid pigment forms prime importance to
minimize the problems related to vision. Also, tomato forms a major food
component because of its wide distribution and application in a number of food
stuff, they are eaten fresh in salads or processed and can be stewed, fried,
baked and also used to produce soup, or used as juice.
Tomato is one of the widely consumed
fresh fruit worldwide since it contributes to a healthy well balanced diet
which is rich in vitamins such as vitamin, B, C, and E. Carbohydrates such as
fructose and glucose; and trace elements like iron, copper, zinc, and dietary
fiber ( Faostat, 2010). It is known to be a very protable crop that provides
high returns for small scale farmers in most developing countries (Lemma et al., 2014). Due to its nutritive
value, taste, affordability, and accessibility, there has been an increase in
demand by consumers (Behravesh et al., 2012). However, isolation
and identification of microorganisms that are associated with spoilage of
tomatoes have gained some research focus. In most developing countries,
microbial infestation of tomatoes can occur during the harvesting period, post
harvesting, handling, storage, transportation, and processing by customers
(Yeboah, 2011 and Barth et al., 2009), but there is a huge loss of
tomato across the globe due to microbial spoilage. Since it is composed mostly
of water, microbes grow best using it as its substrate. Baiyewu et al. (2007) have also reported that
another means of bacterial contamination is by exposing them on benches and
baskets in the open markets for customers. The proliferation of bacteria more
especially in damaged tomatoes could be considered to be more harmful when such
contaminated tomatoes are consumed in improperly cooked food (Valadez et al., 2012). Some studies have been
carried out on bacteria associated with tomatoes and tomato products in some
countries.
The fruits of pepper is drupe and
when dried, it is a pepper corn. It is grown in soil that is neither too dry
nor susceptible to flooding, moist, well drained and rich in organic matter.
Although, peppers are used as spice all over the world, their flavour and
pungent smell vary widely just as their content of the major active ingredient,
Capsicum and Capsaicinoid analoques vary(Dorantes et al., 2000). Pepper
play substantial roles and occupy an important nutritional consequences.
Peppers are also good sources of nutrients -
Vitamins A, C, K, and B6, calcium, iron, zinc, and fiber. The nutrient and
other phytochemical composition of peppers vary with color and/or maturity
stage (Deepa et al., 2007). The wide
variability in capsaicin and nutrient content of peppers allows more breeding
to be undertaken for improvement. Since peppers are easy to grow, harvest,
process and utilize, efforts should be undertaken by extension workers,
nutrition and health promoting specialists to disseminate and promote improved
varieties.
The biological structure of tomato
and pepper when disrupted (during harvesting, transportation and storage or by
insect) can serve as a route of entry for opportunistic pathogen (Salik et al., 2008). Due to their soft textures
the fruits, are easily bruised through harvesting and other postharvest
handling operations such as packaging, transportation and storage (Sani and
Alao, 2007). Tefera et al. (2007) states that due to poor storage
conditions, resistance of fruits and
vegetables to natural disease usually decline, leading to infection by
pathogens.
1.2 AIM AND OBJECTIVE
The aim of the study is concerned
with isolation and identification of pathogenic bacterial and fungi agents
associated with tomatoes and pepper(fresh and spoilt) sold in three central
markets in Umuahia.
Objectives
The specific objectives are to;
1. Isolate
and characterize microorganisms (bacteria and fungi) from fresh healthy
(unspoilt) and physically damaged (spoilt) tomatoes and pepper sold in Umuahia
market.
2. To
determine the average microbial load of tomato and pepper (spoilt and
unspoilt).
3. To
determine the percentage occurrence of the microbial isolates in the spoilt
tomatoes and pepper.
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