Abstract
Microbial quality of Shawarma sold in Umuahia metropolis; Twenty(20) shawarma sandwiches comprising of two categories, Beef Sharwama (B1-B10), and Chicken Sharwama (C1-C10), were analysed. From the study, the Total Heterotrophic Count (THC) has the highest count of 2.8x105 (cfu/g) (C2) and lowest count of 9.0x104 (cfu/g) (B5), the Total Coliform Count (TCC) has the highest count of 2.5x 104 (cfu/g) (C10) while the lowest count is 6.5x103 (cfu/g) (B6), the Staphylococcal count (SC) has the highest count of 2.3x104 (cfu/g) (B3) and lowest count of 4.0x103 (cfu/g) (B8), the Salmonella Count (SAC) has the highest count of 1.9x104 (cfu/g) (C6) while the lowest count is 5.4x103 (cfu/g) (B4), the Shigella count (SHC) has the highest count of 1.9x104 (cfu/g) (C1) and lowest count of 4.1x103 (cfu/g) (B4), the Escherichia coli count (EC) has the highest count of 1.7x104 (cfu/g) (C8) and lowest count of 4.0x103 (cfu/g) (B5), the Lactobacillus count (LC) has the highest count of 1.3x104 (C7) (cfu/g) while the lowest count is 2.6x103(cfu/g) (B3), the Total Fungal Count (TFC) has the highest of 1.0x104(cfu/g) (C2) while the lowest count is 3.9x103(cfu/g) (B5).The distribution of the isolates include; Salmonella spp 15 (75%), Escherichia coli 14 (70%), Staphylococcus aureus 11 (55%), Shigella spp 9 (45%), Lactobacillus spp 8 (40%), Bacillus spp 6 (30%), Rhizopus spp 7 (35%), Aspergillus spp. 2 (10%). The total heterotrophic count (THC) was further subjected to statistical analysis, and showed a significant difference (P< 0.05, P< 0.01) between the beef and chicken Sharwama varieties. Higher contamination rates were found in the chicken variety when compared with the meat variety. The presence of the isolated pathogens is of public health concern because some strains are capable of producing a heat-stable enterotoxin that causes food poisoning in humans, and should therefore be taken into account in risk assessment.
TABLE
OF CONTENTS
Title page
i
Certification ii
Dedication iii
Acknowledgement iv
Table of Contents v
List of Tables ix
List of Figures x
Abstract xi
CHAPTER ONE
1.0
Introduction 1
1.1
Aims and objective 4
CHAPTER TWO
2.0
Literature Review 5
2.1
Definition of Shawarma 5
2.2
History and Nature of Shawarma 5
2.3
Ingredients and condiments used in the preparation of Shawarma 7
2.4
Preparation of Shawarma 7
2.5
Popular dressings used in Shawarma recipes 8
2.6
Serving and packaging 8
2.7
Health and Nutritional facts about Shawarma 9
2.8. Microbiological changes in Shawarma 9
2.8.1
Contamination of meat 10
2.8.2
Microbiological changes of meat 12
2.8.2.1
Contamination of chicken 15
2.8.2.2
Microbiological changes of Chicken 17
2.8.3
General methods of meat preservation 21
2.8.4.
Contamination of vegetable 27
2.8.4.1
Microbiological changes of vegetable 29
2.8.4.2
Preservation of vegetables 31
CHAPTER THREE
3.0
Materials and method 35
3.1
Study Area 35
3.2
Sample collection 35
3.3
Experimental design 35
3.4
Sterilization of Materials 36
3.5
Media used and their preparation 36
3.6
Microbiological analysis of samples 36
3.6.1
Serial dilution 36
3.6.2
Isolation and enumeration 37
3.6.3
Detection of Salmonella spp 37
3.7
Characterization and identification of Bacterial isolates 38
3.7.1
Purification and storage of isolates 38
3.7.2
Colonial morphology 38
3.7.3
Motility test 38
3.7.4
Gram staining 39
3.7.5
Biochemical tests 40
3.7.5.1
Catalase test 40
3.7.5.2
Coagulase test 40
3.7.5.3
Indole test 40
3.7.5.4
Methyl red test 41
3.7.5.5
Voges proskauer 41
3.7.5.6
Citrate utilization test 42
3.7.5.7
Oxidase test 42
3.7.5.8
Urease test 42
3.7.5.9
Sugar fermentation test 43
3.8
Identification and characterization of fungal isolates 43
CHAPTER FOUR
4.1
Results 44
CHAPTER FIVE
5.1
Discussion 54
5.2
Conclusion 59
5.3
Recommendation 59
References 61
Appendices 70
LIST
OF TABLES
Table Title page
1.Effect of processing practices on
Microbiological Quality of Chicken Meat 20
4.1 Microbial
count of Shawarma samples analysed 45
4.2
Cultural, morphological and biochemical characteristics of the bacterial
isolates 46
4.3 Cultural
and Morphological characteristics of the fungal isolates 48
4.4 Shawarma sandwich samples,
microorganisms isolated and the incidence 49
of organisms in
different Shawarma samples.
4.5 Incidence and percentage
occurrence of microorganisms in each of the 50
Shawarma samples in Umuahia
4.6 Analysis
of T-test carried out 51
LIST
OF FIGURES
Figure
Title Page
1
Percentage(%) distribution of
microorganisms in each category of the 52 Shawarma sandwich
2
Percentage (%) distribution of microorganisms in the Shawarma sandwiches 53
.
CHAPTER ONE
1.0 INTRODUCTION
Fast
food or Ready-to-eat ( RTE) food is a term given to food or meal that can be
prepared and served for immediate consumption with low preparation time and can
be consumed at the point of sale without further treatment (Tsang, 2002). According
to Gilbert et al. (2000), ready-to-eat
foods are foods that are consumed in the same state as they are sold and do not
include nuts in the shell, whole raw fruits, vegetables, and meats that are
intended for hulling, peeling or washing by the consumer. RTE are mainly
referred to food sold in restaurants, sold along the streets by food vendors
and served to customers, packaged in a take-away (Maturin and Peeler, 1998). In
western culture, RTE are seen as a type of food not meant to be eaten as a main
meal of the day like breakfast, lunch or dinner but rather to assuage a
person’s hunger between meals by providing a brief supply of energy for the
body (James, 2005).
RTE
foods can be divided into continental and local snacks (Liyide, 2010).
Continental fast foods include Shawarma, hotdogs, meat pie, salad, hamburger,
kebabs, while the local snacks include roasted corn, roasted plantain (booli),
plantain chips, fried maize and so on. These foods can serve as meal or in
between meals for adults and children (Olumakaiye and Ajayi, 2008). Mensah et al. (2002) reported that young children and adolescents do a
good deal to RTE while parents supplement their baby’s diet with it. These
types of foods are cheap, tasty, and easily available. Mainly people from low
socioeconomic bracket and students are most popular consumers of street foods (Chauliac et al., 1998; Oladipo, 2010),
especially the local snacks while the high income earners go for the
continental snacks.
The
major problem associated with RTE is the frequent incidence of contamination.
Due to the nature of these snacks and their methods of preparation involving
extensive handling, they are usually prone to contamination from water, air,
storage/distribution facilities, environment and human activities (food
handlers and vendors) (James et al.,
2005; Oranusi et al., 2011).
Earlier
studies on the assessment of microbial contamination have reported poor
knowledge practiced in food handling (FAO, 1995). Furthermore, like many other
processed foods, snacks are subjected to physical, chemical and microbiological
spoilage by such organisms as Escherichia
coli, Salmonella, Clostridium, Staphylococci, Listeria, Bacillus spp. and moulds of several
genera like Rhizopus, Aspergillus and Penicillium (Annan-Prah et
al., 2011; Odu and Akano, 2012: Smith et
al., 2004).
According
to Coda et al. (2011), the major
problem of long-term shelf life of snacks is contamination with fungi mostly of
the genera Eurotium, Aspergillus, Monilia, Mucor, Cladosporium, Fusarium and Rhizopus.
The implication of consuming contaminated snacks is the risk associated with
ingestion of mycotoxins and other allergens produced by these contaminants.
These
microorganisms varied according to the method of the manufacture, utensils, quality
of used ingredients and contamination level during the processing chain,
packaging and storage (Narasimba and Rameshi, 2000).
In
processed meat, microbes respond to the environmental changes during processing
and storage. The carcasses are likely to support the growth of these
microorganisms at any subsequent stage of processing (Stern et al., 1995; Stern et al., 2007).
According
to Abd El Rahman et al. (2011),
Shawarma, is one of the mostly consumed delicious continental meat products
served at fast food restaurant chain. It is a type of grilled meat loaf
prepared from chicken meat, beef, vegetables, spices and bread, which have a
high protein and carbohydrate value (Abdalhamid et al., 2013).
Staphylococcus aureus have been discovered to play a great role in bacterial contamination of
processed meat meal (Shawarma) because workers during preparation and
processing may touch Shawarma which are eaten without further cooking or
heating (Soliman, 1998).
Microbiological quality problems
of Ready-to-eat foods like Shawarma depends greatly on the following factors:
i.
Low quality of raw meat and other
ingredients
ii.
Inefficient cooking process
iii.
Improper sanitary practices of personnel, and cooking or processing
utensils (Kayarardi et al., 2006).
One or several of these factors
mentioned may lead to health hazard for humans (Evan et al., 1999; Harakeh et al.,
2005).
According to WHO (1989), food handling play a major
role in ensuring food safety through the
chain of food production and storage. Mishandling and disregard of
hygienic measure on the part of food vendors may enable pathogenic bacteria to
come into contact with and in some cases multiply in sufficient numbers to
cause illness in the consumer.
Trivader (2003) highlighted the increasing prevalence of eating in restaurants where the
use of partly or fully cooked food items were not regulated, they operated
hazardly without any monitoring of what
they prepared and how they prepared it
(Abdalla et al.,2008a; Abdalla et al.,2008b; Abdalla et al.,2009; Ekanem, 1998).
Studies by FAO (1995) recorded
poor knowledge practised in food handling in the assessment of microbial
contamination. Therefore the primary goal of food service programmes is to
protect the consumers from any food contamination or at least reduce the effect
of any health hazard , although it is difficult to prevent the contamination by
different microorganisms which are found
everywhere (Monteny and Gould, 1988).
Evans
et al. (1999) reported that during July 1995, an outbreak of Salmonella in South Wales
was linked to the consumption of döner kebabs, the investigations pointed to
cross-contaminated relishes and dressings as well as under-cooked meat as
potential vehicles.
While Richardson
and Stevens (2003), mentioned that there were significant
associations between bacteriological quality and temperature of storage. There
was a lack of information about the incidence of foodborne diseases related to
Shawarma in addition to the absence of microbiological standards for this food
product (Nemati, et al., 2008).
1.1 AIMS AND OBJECTIVES OF STUDY
i.
To isolate, identify and characterize the microbial consortium
constituting the microbial load of Shawarma sold in Umuahia metropolis.
ii.
To evaluate the microbiological quality of
Shawarma sold in Umuahia metropolis
iii.
To highlight the public health implications of consuming heavily
contaminated Shawarma.
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