ABSTRACT
Exopolysaccharides were determined from lactic acid bacteria isolated from fermented foods. Foofoo, Ogiri, Ugba, and Yoghurt were the fermented foods used. Five lactic acid bacteria including species of Lactobacillus, Streptococcus, Bacillus, Micrococcus and Leuconostoc. The occurrence of the isolates were Lactobacillus (78%), Leuconostoc (50%), Micrococcus (66.7%), Streptococcus (50%) and Bacillus (66.7%). The distribution of the isolates in the fermented foods vary significantly. Tests on EPS production shsow that the quanitity of EPS produced by the different lactic acid bacteria vary between the organisms. The yield was highest 486.67 mg/l from Lactobacillus, and least 130.0 mg/l in Leuconostoc while Streptococcus, Micrococcus and Bacillus yielded 413.3 mg/l, 133.3mg/l, 320.0 mg/l respectively. Test on optimization of conditions for maximum EPS production show that temperature, pH and fermentation time affected the production of EPS but the optimum conditions show that fermentation at pH 5.0 at 40°C for 96 hours yielded the best results in all the test lactic acid bacteria. Although variations were needed in the preferences of the isolates which includes Bacillus, Streptococcus, and Lactobacillus were used in the optimization test which gave the same result irrespective of the organisms involved. It was recorded that EPS production should be conducted at the above found optimum conditions for maximum yield.
TABLE OF CONTENTS
Title
page i
Certification ii
Dedication
iii
Acknowledgement iv
Table
of Contents v
List
of Tables vii
List
of Figures viii
Abstract ix
CHAPTER ONE
1.1 Introduction
1
1.2
Objective of study 2
CHAPTER TWO
2.0 Literature Review 3
2.1 Exopolysaccharides 3
2.1.1
Exopolysaccharides from Lactic acid bacteria 3
2.1.2
Application of Exopolysaccharides in foods 4
2.2. Lactic acid bacteria 5
2.2.1
Application of Lactic acid bacteria 5
2.3 Fermented foods 6
2.3.1
Purpose and benefits of food fermentation 7
2.3.2
Nutritional benefits of food fermentation 7
CHAPTER THREE
3.0 Materials and methods 9
3.1 Sources of materials 9
3.2 Sample preparation and media preparation 9
3.2.1
Preparation of sample 9
3.2.2
Media preparation 9
3.2.3
Preparation of MRS media 10
3.3 Isolation of lactic acid bacteria 10
3.4 Identification of isolates 11
3.5 Screening for exopolysaccharide Production 11
3.6 Extraction of exopolysaccharide 12
3.7 Optimization of EPS production 12
CHAPTER FOUR
Results 14
CHAPTER FIVE
Discussion 24
Conclusion 26
References 26
LIST OF TABLES
Table Title Pages
1: Characterization and
identification of bacterial isolates from samples 16
2: Occurrence
of lactic acid bacteria in test samples 17
3: Preliminary test for EPS
yield by isolates 18
4: Optimization of EPS
production by pH 19
5: Optimization of EPS
production by Temperature 20
6: Optimization of EPS
production by fermentation time 21
LIST
OF FIGURES
Figure Title Pages
1.
Formation of mucoid
colony 22
2. Exopolysaccharide
determined after drying 23
CHAPTER ONE
INTRODUCTION
1.0 BACKGROUND OF THE STUDY
Lactic
acid bacteria are associated with many fermented foods; particularly milk based
products such as curd, yoghurt, sour cream, cheese and buttermilk where they
contribute to develop taste, flavour and shelf life of fermented food (Shah and
Prajapati 2013).
Most of the lactic acid bacteria producing
exopolysaccharide belong to the genera Streptococcus, Lactobacillus,
Lactococcus, Leuconostoc, and Pediococcus. Lactic acid bacteria are
able to produce mainly two types of polysaccharides according to their location
in the cell, intracellular polysaccharides and extracellular polysaccharides
(Deegest et al., 2001).
Exopolysaccharide impart highly desirable
rheological changes in the food matrix such as increased viscosity and improved
texture (Badel et al., 2011).
Exopolysaccharide may induce positive
physiological responses including lower cholesterol levels (Levrat-Verny et al., 2000) reduced formation of
pathogenic biofilms, (Kim 2009) modulation of adhesion to epithelial cells
(Ruas-Madiedo et al., 2006)
The beneficial effects of bacteria to human health, with
respect to the development of functional food, have largely been attributed to
its exopolysaccharides. Some of these bacteria are referred to as probiotics; a
concept Salminen et al. (1998) describes as live microbial food
ingredients which are of benefit to human health. The health promoting effects
of probiotics has been attributed partly to exopolysaccharides. Antitumor,
antiulcer, immunomodulatory, antiviral and cholesterol lowering activities
(Ruas-Madiedo et al., 2002) are some
of the health benefits attributed to these exopolysaccharides. Lactobacillus
lactis sub specie cremoris, enjoys wide application in dairy industries for
yogurt production due to the special rheological properties that it impacts on
products; however, this same organism is thought to possess some
health-promoting properties.
Looking at the various utility of exopolysaccharide from
lactic acid bacteria, it is essential to raise the yield and improve efficiency
of exopolysaccharide. A crucial strategy to achieve this will be to precisely
understand the interaction between different exopolysaccharide producing lactic
acid bacteria and the best condition the optimum yield. Lactic acid bacteria
cannot bulk synthesize the exopolysaccharide without altered fermentation
conditions. Screening the spontaneous diversity in lactic acid bacteria will
increase the chances of picking genetically stable strains of lactic acid
bacteria and discover the ones capable of providing large quantities of
functionally efficient exopolysaccharide (Monsan et al., 2001).
1.1 Objective
Of Study
a) To determine the exopolysaccharide
productivity of selected lactic acid bacteria
b) To determine the growth condition
necessary for the optimum yield of exopolysaccharide by the selected lactic
acid bacteria.
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