ABSTRACT
Vegetables are important protective food and highly beneficial for the maintenance of health and prevention of diseases. This study was aimed at identifying and classifying the microorganisms (bacteria and fungal) associated with rotten onions bulb. With the following objectives which are to isolate the Microorganisms found in rotten onions bulb, identify the Microorganisms in rotten onions bullb. Ten (10) samples of rot onion bulbs used for this study were obtained from onion sellers at popular markets which are Amawon market, Ahiaeke market, and Ndoro market in Ikwuano L.G.A, Umuahia, Abia State. The onions were purchased in batches and brought to the laboratory for Microbiological analysis. The sample was processed by standard bacteriological method. From the result it shows that bacteria load of rotten onions sample 1.0 x104 to 6.0 x101 while the fungal ranges from 1.5 x103 to 1.5 x101 . The result also shows the bacteria and fungi isolated from rotten onions bulb samples which were identified by morphological characteristics on media, microscopy, biochemical and sugar fermentation methods. These reveals the major bacterial isolates to belong to Bacillus species, Escherichia coli, Proteus spp and Non-haemoltyic streptococcus and fungi isolates are Rhizopus spp, Candida spp and Mucor spp. The result also shows the occurrences of bacteria, Non-hemolytic streptococcus (41.17%) followed by E. coli (23.52%) has the highest percentage occurrences, while the bacteria isolates with the lowest percentage occurrence are Proteus spp. (17.64%) and Bacillus spp. (17.64%), fungi isolates Candida spp. (55.55%) has the highest percentage occurrence followed by Mucor spp. (33.33%), while the fungi isolates with the lowest percentage occurrence is found in Rhizopus spp. (11.11%). Rotten onion bulbs harbor a wide range of bacteria and fungi species. The pathogenic microorganisms implicated in the rotten onion bulbs samples are of public health importance. It was also noted that some of the bacteria and fungi isolates have history of pathogenicity which some fungi involved are to deposit mycotoxins which are inimical to health.
TABLE OF CONTENT
Title page i
Certification ii
Dedication iii
Acknowledgements iv
Table of contents v
Lists of table’s viii
Abstract ix
CHAPTER
ONE
1.0
Introduction 1
1.1
Aim of Study 3 1.2 Objectives 3
CHAPTER TWO
Literature
Review 4
2.1 Onions 4
2.2 Species
of Onions 5
2.3 Composition
of Raw Onions 6
2.3.1 Nutrient 6
2.3.2 Phytochemicals 7
2.4 Spoilage
of Vegetables 8
2.5 Spoilage Organisms in Vegetables 9
2.5.1 Yeasts 10
2.5.2 Molds 11
2.5.3 Bacteria 13
2.5.4 Other
Bacteria 15
2.6 Factors
Affecting Food Spoilage and Shelf Life 16
2.6.1 Vegetables 17
2.7 Control
of Spoilage Microorganisms 18
CHAPTER THREE
3.0 Material and Methods 20
3.0.1
Study Area 20
3.1
Methods 20
3.1.2
Sample Collection 20
3.1.3
Sterilization of Glass Wares 21
3.1.4
Media Preparation 21
3.1.5
Microbiological Serial Dilution 21
3.2 Isolation
of Bacteria and Fungi 21
3.3.2 Inoculation
and Incubation 21
3.4 Microbial
Colony Count 22
3.5 Identification of Fungi 22
3.5.1 Macroscopy
and Colonial Identification 22
3.5.2 Microscopy 22
3. 6 Gram Reaction 23
3.6.1 Characterization
of Bacteria (Biochemical Tests) 23
3.5.1.1 Motility Test 23
3.6.1.2 Catalase Test 24
3.6.1.3 Indole Test 24
3.6.1.4 Citrate Utilization Test 24
3.6.1.5 Methyl Red (MR)
3.6.1.6 Coagulase Test (Slide Test) 25
3.6.1.7 Voges- Proskauer (VP) Test 25
3.6.1.8 Sugar Fermentation Test 25
CHAPTER FOUR
4.0. Results 27
CHAPTER FIVE
5.0. Discussion, Conclusion and Recommendation 38
5.1. Discussion 38
5.2. Conclusion 39
5.3. Recommendation 40
Reference 41
LIST OF TABLES
TABLE TITLE PAGE
4.1. The sources of
samples 29
4.2 The percentage
occurrence of the bacteria isolates 30
4.3 The percentage
occurrence of the fungal isolates 31
4.4. Morphological and biochemical
characteristics of bacterial isolates 32
4.5 Morphological
characteristics of fungal isolates 33
4.6 Distribution of
bacteria isolates from rotten onion sample 34
4.7 Distribution of bacteria isolates from rotten
onion sample 35
4.8. Bacterial load 36
4.9 Fungal load 37
CHAPTER ONE
1.1 INTRODUCTION
Generally,
vegetables are considered as the leafy outgrowth of plants or plants shoot used
food. These include those plants or plant part used in making soup or served as
an integral part of main meal (Yusuf et
al., 2004). Vegetables can also be regarded as the edible component of
plants, such components includes leaves, stalk, roots, tubers, bulbs, flowers
and seed (ICMSF, 1998). Vegetables are important protective food and highly
beneficial for the maintenance of health and prevention of diseases. They contain
valuable food ingredients, which are essential for the proper function of the
body. Pathogenic
bacteria contribute to a worldwide crop loss of roughly 10-15% annually (FAO
2005; Strange and Scott 2005). Plant pathogenic bacteria affect innumerable and
valuable agriculture crops, causing hundreds of millions of dollars in damage
each year. Pathogenic bacteria affecting plant health are a major and chronic
threat to food production and ecosystem stability worldwide (Ste’phane et al., 2005; Abd-Alla and Bashandy
2008; Abd-Alla et al., 2010).
Onions belongs to the Allium genus and have been used
as an herbal remedy for a wide range of ailments, due to their association with
many pharmacological effects (Lanzotti,
2006; Yin and Cheng, 2008).
Biological effects attributed to onions have been commonly ascribed to the
volatile sulfur-containing compounds, such as thiosulfinates, mainly
responsible for the characteristic taste, aroma and lachrymatory effects (Krest and Keusgen, 2002).
These compounds are formed from cysteine sulfoxide precursors and the effect of
the enzyme alliinase, which is released from cell vacuoles when tissues are
damaged (Ioku et al.,
2001). However, these
volatile products are highly unstable and recently, attention has been focused
on the effects of phenolic compounds, such as flavonoids, which are more stable
(Fossen et al., 2008). Onion is known for
being a good natural source of flavonoids mainly represented by the flavonols -
quercetin and kaempferol, which are present as their glycosides (Viuda
and Fernández, 2008).
Protection of food from pathogens and spoilage organisms has been traditionally
achieved by chemical methods, but during recent years there has been an
increase in consumer interest in developing Onion, which contain a low level or
are free of chemical preservatives (Xu and Lee, 2001). The emergence of pathogens,
which are resistant to classical preservatives, has also created an urgent
necessity to find alternative antimicrobial agents (Grohs and
Kunz, 2000). In consequence,
the food industry is interested in developing natural components for the
partial replacement of synthetic antimicrobials (Navas et al., 2006). Onions can be considered as a good
source of natural additives to retard food deterioration (Uzeh et al., 2009). Numerous benefits have been attributed
to onions including prevention of cancer and cardiovascular disorders,
reduction in the blood levels of cholesterol, reduction in osteoporosis (Adebajo
and Diyaolu, 2003).
Reduction in stomach ulcers, inhibition of the proliferation of cultured ovarian,
breast and colon cancer cells, inhibition of platelets-mediated thrombosis,
prevention of inflammatory processes associated with asthma, treatment of
fever, common cold, cough, sore throat and its use as an antimicrobial agent (Tyson and Fullerton, 2004).
Onions are packed locally in baskets and jute bags.
These packaging materials come from palm, bamboo and fibrous jute trees. However,
these materials provide no barriers of dust, and can easily be crushed which
might lead to damage of the onions. During storage, some losses occur due to sprouting,
drying and rotting (Muhammed et al., 2004). Bulb rots are a common cause of onion
loss during storage. They are caused by microorganisms particularly fungi. The
black mould disease caused by Aspergillus
niger is a limiting factor in onion
production worldwide (Raju and Naik, 2006). Aspergillus
niger has been reported to survive
between onion crops as a soil saprophyte in or on bulbs in field or storage and
is ubiquitous in nature. The fungus invades bulbs of onions in field or storage
whenever they find injured tissues by producing various enzymes or toxins (Samuel
and Ifeanyi, 2015).
Association of Aspergillus niger with onion seeds produced in hot
climates and their transmission from soil and naturally-contaminated seeds to
onion seedlings cause 30-80% loss or spoilage of onion bulbs (Federal
Republic of Nigeria, 2006).
1.2 OBJECTIVES THE STUDY
The
aim of the present study is to evaluate the spectrum of Microorganism associated
with rotten onions bulbs
Specific
Objectives include to;
1. To isolate and identify the Microorganisms responsible for causing
onions spoilage
2. To determine the microbial load associated with spoilage
Buyers has the right to create
dispute within seven (7) days of purchase for 100% refund request when
you experience issue with the file received.
Dispute can only be created when
you receive a corrupt file, a wrong file or irregularities in the table of
contents and content of the file you received.
ProjectShelve.com shall either
provide the appropriate file within 48hrs or
send refund excluding your bank transaction charges. Term and
Conditions are applied.
Buyers are expected to confirm
that the material you are paying for is available on our website
ProjectShelve.com and you have selected the right material, you have also gone
through the preliminary pages and it interests you before payment. DO NOT MAKE
BANK PAYMENT IF YOUR TOPIC IS NOT ON THE WEBSITE.
In case of payment for a
material not available on ProjectShelve.com, the management of
ProjectShelve.com has the right to keep your money until you send a topic that
is available on our website within 48 hours.
You cannot change topic after
receiving material of the topic you ordered and paid for.
Login To Comment