ABSTRACT
Hibiscus
sabdariffa
L. Malvaceae is a tropical plant of considerable economic importance. In most
part of Nigeria, it is prepared into a traditional non-alcoholic beverage known
as Zobo. However, microbial contamination has been an issue with the production
and consumption of this product. This research
was carried out to determine the level of bacteriological contamination in Zobo
drinks consumed in Umuahia, Abia state. Ten (10) zobo drinks were bought from random retailers and vendors across
five (5) different markets in Umuahia; two (2) samples from each market. After
serial dilution, total bacterial count was determined by pour plate technique
using standard methods. The identification of microorganisms was based on; Gram
staining, Colonial morphology, Cell morphology, and Biochemical analysis.
Biochemical tests carried out included; motility test, indole test, coagulase
test, oxidase test, and catalase test. Data were collected on the pH of the
zobo drinks, total bacterial count (cfu/ml), cultural characteristics of bacterial
isolates, biochemical characteristics of bacterial isolates, and percentage
occurrence of the different isolates in each sample. The pH of the samples ranges from 2.9 to 3.1. All the
zobo drinks samples were contaminated with varying levels of bacterial count,
Ubani 1.7x102 to 2.7x103, Orieugba 1.0x102 to
4.9x103, Ahiaeke 4.6x102 to 3.6x103, Ahiukwu
olokoro 1,2x102 to 5.0x103, and Afor Ibeji 2.6x102
to 3.2x103. Sample Ahiaukwu Olokoro I, showed a high bacterial count
of 5.0x103, while Sample Orieugba II was the least affected area
showing a bacterial count of 1.0x102. E. coli, Staphylococcus aureus, Streptococcus spp, Bacillus spp and Proteus vulgaris were the organisms obtained from the different
culture plates. Streptococcus spp showed
a 30% occurrence, which is the least across the sample areas, Bacillus spp had 40% occurrence, Staphylococcus aureus was the highest
occurring isolate with a 80% occurrence across the sample areas followed by E. coli with 70% occurence while Proteus had a 40% occurrence in all
samples inoculated. Results obtained in this study have
shown a high contamination of zobo drink. This is of public health importance.
TABLE
OF CONTENTS
TITLE
PAGE i
CERTIFICATION ii
DEDICATION iii
ACKNOWLWEDGEMENT iv
ABSTRACT v
TABLE OF CONTENTS vi
LIST OF TABLES viii
CHAPTER
ONE: INTRODUCTION
1.1
Background information 1
1.2
Microbial spoilage of food products 2
1.3
Justification 3
1.4
Aim and objectives 3
CHAPTER
TWO: LITERATURE REVIEW
2.1 Economic
importance of zobo drink 5
2.2 Microbial
contamination of zobo drink 6
CHAPTER
THREE: MATERIALS AND METHODS
3.1 Location
(Study site) 8
3.2 Source
of sample 8
3.3 Sample
collection 8
3.4 Sterilization
of materials 8
3.5 Culture
media preparation 9
3.5.1 Preparation
of nutrient agar 9
3.5.2 Preparation
of blood agar 9
3.6 Microbiological
analysis of samples 9
3.7 Isolation
of bacteria 10
3.8 Identification
of bacterial isolates 10
3.8.1 Gram
staining 10
3.8.2 Biochemical
analysis 11
3.9 Data
collection and analysis 12
CHAPTER FOUR: RESULTS AND
DISCUSSION
4.1 pH
of the zobo drinks 14
4.2 Total
bacterial count (cfu/ml) 14
4.3 Cultural
characteristics of bacterial isolates 14
4.4 Biochemical
characteristics of bacterial isolates 19
4.5 Percentage
occurrence of the different isolates in each sample 19
4.6 Discussion 19
CHAPTER FIVE: SUMMARY,
CONCLUSION AND RECOMMENDATION
5.1 Summary 23
5.2 Conclusion 23
5.3 Recommendation 24
REFERENCES` 25
LIST
OF TABLES
1: pH of zobo drink samples 15
2: Total bacterial count on sample plates 16
3: Cultural characteristics of bacterial
isolates on nutrient agar 17
4: Cultural characteristics of bacterial
isolates on blood agar 18
5: Biochemical properties of bacterial
isolates 20
6:
Percentage occurrence of the different isolates in each samples 21
CHAPTER
ONE
INTRODUCTION
1.1
Background
information
Hibiscus
sabdariffa L. Malvaceae is a tropical plant of considerable
economic importance (Faye and Neela, 2004). The main edible part is the fleshy
sepal, called a calyx surrounding the seed. The calyx is bright red and closely
resembles the cranberry (Vacinium spp) in flavour (Morton, 1987; Faye
and Neela, 2004; McCaleb, 1996). In the West Indies, Sorrel is a prized drink
during the Christmas holidays (McCaleb et
al., 1996), and calyces can be chopped and added to fruit salad (Morton et al., 1987).
In
Africa, they are frequently cooked as a side dish eaten with pulverized peanuts
for stewing as sauce, for making a fine-textured sauce or juice (zobo), syrup,
jam, marmalade, relish, chutney or jelly. The seeds are somewhat bitter but
have been grounded to a meal for human food in Africa and have also been
roasted as a substitute for coffee.
Zobo
drinks are traditional non- alcoholic beverage which is consumed in most part
of Nigeria, mostly in northern part of Nigeria (Osuntogun et al., 2004). The economic and religious situation in Nigeria has
made the zobo drink gain wide acceptance in different occasions. It’s used as
refreshment, entertainment in parties or as appetizers before the main dish is
served and it is also sold in market to various consumers (Onuorah et al., 1987). The zobo drink is a red
liquid drink and taste like fruit punch, served as a fair source of vitamin A,
riboflavin, niacin, calcium and iron, and is low in sugar content (Qi et al., 2005).
This
drink also contains anthocyanin and Vitamins C, among others and it is used in
curing minor stomach ailments, sore throat and strengthening the heart among
other uses (Olawale et al., 2011).
1.2
Microbial
spoilage of food products
Microbial
spoilage is damage or waste caused by microorganisms like bacteria and fungi
(including yeast) in general due to their invasion. Various members of these
groups may cause changes in the character of the food, which may be classified
as “positive” or “negative.” The products of positive microbial transformation
include cheese, yoghurt and wine, which can be seen as increasing the
nutritional value or keeping quality of products with a short shelf life.
Negative effects of microbial growth including food poisoning, is mainly caused
by different and less widespread bacteria. As they grow, microorganisms release
their own enzymes to the liquid surrounding them and absorb the products of
external digestion. This is the main basis of microbial spoilage which lowers
nutritional value of the product. As a result, products develop undesirable flavours,
odour, appearances or textures via microbial action. Bacteria and moulds may
also produce waste products, which act as poison or toxins, thus causing the
renowned ill effects.
Fruits
and vegetables are normally susceptible to infection by bacteria, fungi and
viruses (Pelczer et al., 1986, 1993).
Deterioration of raw vegetables and fruits may result from –physical factors,
action of their own enzymes, microbial action, or combination of all of these
(Frazier and Westhoff, 1978). Frazier and Westhoff, (1978) reported the variety
of microorganisms present in deteriorating fruits and vegetables. They are;
Pseudomonas, Yeast, Rhizopus, Streptococcus, Bacillus, Erwinia, Aspergillus,
Chromobacteria, Penicillium, Fusarium, Flavobacterium, Xantomonas,
Enterobacter, etc. The character of the spoilage will depend upon the
product attacked and the attacking organism.
1.3
Justification
Zobo
drink serves as a source of Vitamin A, Riboflavin, Niacin, Calcium, Iron, and
it is also low in sugar content, which makes it suitable for diabetic patients
(Qi et al., 2005). The drink also
contains Anthocyanin and Vitamin C, which is useful in curing minor stomach
ailments, sore throat and strengthening the heart (Olawole et al., 2011).
The
safety of street drinks and food has remained a major public health concern
globally, especially in Nigeria where the regulation of these products is
extremely poor and inadequate, hence making street food and drinks a hazardous
source of nutrition (Oyeyi et al.,
2008).
Therefore,
there is need to evaluate the bacteriological quality of street-sold
locally-made zobo drink. The findings from this study will subsequently be made
available to NAFDAC or other the food safety authorities to ensure adequate
regulation, and also to educate the manufacturers on safety practices, such as
adding preservatives, as well as improving their production facilities.
This
will minimize the risk of food poisoning and other health challenges arising
from the consumption of food and drinks exposed to microorganisms, as well as
improving the quality and safety of locally made zobo drinks.
1.4
Aim
and objectives
The
aim of this research was to study the presence of bacteria associated with the
contamination of zobo drinks sold in Umuahia, Abia State.
The
specific objectives were to:
-
Evaluate the level of bacterial
contamination of the zobo drinks.
-
Isolate and identify the bacterial
organisms associated with the contamination of zobo drinks.
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