ABSTRACT
Six species of lactic acid bacteria Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus fermentum, Lactobacillus acidophilus, Lactobacillus brevis, Lactococcus lactis, was isolated from the various samples yoghurt, orange, kunu, MRS medium was used for the isolation for 48 hours at 37°C incubation temperature. The use of colony forming unit per quality of sample was adopted to attain the actual number of viable cells. The colonies obtained was further subcultured to get a pure culture. Identification, characterization and biochemical properties of isolates obtained was performed on the different species of lactic acid bacteria. Three species of the LAB isolated L. buglaricus, S. thermophilus and L. fermentum was further used as starter culture to produce yoghurt using powdered milk (Milksi).The quality parameters of the product was determined by laboratory analysis and compared within the different yoghurt sample produced from A-H (control) in terms of nutritional and sensory attributes. The result of the various fermented milk at 0 to 5 hours of production were noted, the result obtained showed that the initial pH of the yoghurt during fermentation were slightly acidic during fermentation, all the sample tended to be more acidic due to fermentation and had lower pH values even at different degree censius when pH of yoghurt sample where check (38°C, 39°C, 40°C).The other yoghurt produced had more protein 3.95%, ash 0.85% and moisture content 85.50% than the (control) protein 2.97%, ash 0.73, moisture content 86.39% . The value at (P<0.05 ) showed that there was a significant different in the values above. The optimal conditions for the production of yoghurt using these species of lactic acid bacteria (Lactobacillus bulgaricus, Streptoccus thermophilus and Lactobacillus fermentum) was found to be 40°C and pH 5.5. The result of the hedonic test of sensory properties showed that product has more sour taste, this indicates that the quality of the products was pleasant. It was therefore concluded that lactic acid bacteria could be sourced from yoghurt, orange, and kunu.
TABLE OF CONTENTS
Title page i
Certification ii
Dedication iii
Acknowledgement iv
Table of content v
List of tables viii
List of figures ix
Abstract x
CHAPTER ONE
1.1 Introduction 1
1.2 Aims and Objectives of study 3
CHAPTER TWO
2.0 Literature Review 4
2.1 Lactic acid bacteria 4
2.1.1 Sources of lactic acid bacteria 5
2.1.2 Conditions that favours the growth of lactic acid bacteria 5
2.1.3 Classification of lactic acid bacteria 8
2.1.4 Uses of lactic acid bacteria 8
2.2.1 Yoghurt and its components 9
2.2.2 Milk and its constituents 11
2.2.3 Yoghurt starter cultures 16
2.2.4 Other components of yoghurt 17
2.2.5 Selection of pure culture 17
2.2.6 Classification of yoghurt 17
2.2.7 Nutritional quality of yoghurt 19
2.2.7.1 Health benefits effects of yoghurt 19
2.2.8 Uses of yoghurt 21
CHAPTER THREE
3.0 Materials and methods 23
3.1 Sample collection 23
3.2 Lactic acid bacteria culture preparation 23
3.3 Isolation of lactic acid bacteria 23
3.4 Determination of bacteria load at suitable temperature using direct plate count 24
3.5 Identification and characteristics of bacterial isolates 24
3.5.1 Macroscopic examination 24
3.5.2 Gram staining reaction (microscopic examination) 25
3.5.3 Motility Test 25
3.5.4 Biochemical Reaction 25
3.6 Measurement of pH 28
3.7 Determining of titratable acidity 28
3.8 Proximate analysis 28
3.8.1 Determination of moisture content 29
3.8.2 Ash content determination 29
3.8.3 Determination of protein 30
3.8.4 Determination of carbohydrate 31
3.8.5 Determination of fat content 31
3.9 Sensory properties of youghurt samples 32
CHAPTER FOUR
4.0 Results 33
CHAPTER FIVE
5.0 Discussion, Conclusion and Recommendation 53
5.1 Discussion 53
5.2 Conclusion 57
5.3 Recommendation 57
References
Appendix
LIST OF TABLES
Identification, characterization and biochemical properties of lactic acid bacteria isolated from yoghurt, orange and kunu. 36
The total viable count of bacteria load of colonies obtained from isolates. 37
Effect of time on the pH of the samples during fermentation of yoghurts using 38 different species of lactic acid bacteria.
Effect of temperature on the pH of the yoghurts. 39
The quality parameters (proximate analysis) of the produced yoghurts. 40
The quality parameters of result on total titratable acidity of samples. 41
Result of Hedonic test for sensory properties of (colour, texture, taste, flavour, 42 general acceptability).
LIST OF FIGURES
Flow chart of yoghurt production 28
Effect of time on the pH of sample A and H during fermentation of yoghurts 43
Effect of time on the pH of sample B and H during fermentation of yoghurts 44
Effect of time on the pH of sample C and H during fermentation of yoghurts 45
Effect of time on the pH of sample D, E, F and H during fermentation of yoghurts 46
Effect of time on the pH of sample G and H during fermentation of yoghurts 47
Effect of time on the pH of all sample of yoghurt A-H during fermentation of yoghurts 48
Effect of temperature on the pH of yoghurts 49
Showing all samples of yoghurt produced from A-H 50
Showing samples of yoghurt produced A,B,C 51
Showing samples of yoghurt produced D,E,F 52
CHAPTER ONE
1.1 INTRODUCTION
Lactic acid bacteria are industrially important organisms used for the production of milk and milk products like yoghurt and cheese butter milk. The species of the lactic acid bacteria belong to numerous genus under the family of Lactobacillaceae. They represent as potential microorganisms and have been widely applied in food fermentation worldwide due to their well known status as generally recognized as safe microorganisms. The species used for these applications typically belong to the group of gram- positive bacteria including the genera Lactobacillus, Lactococcus, Leuconostoc, Pedicoccus and Streptococcus. They are recognized for their fermentative ability and thus enhancing food safety, improving organoleptic attributes, enriching nutrients and increasing health benefits (Panesar, 2011; Liu et al., 2011; Sharma et al., 2012; Steele et al., 2013).
Due to the characteristics of milk that is highly perishable, the main purpose of milk fermentation using lactic acid bacteria is to prolong its shelf- life as well to preserve the nutritious component of milk. It is also recognized that fermentation of milk using lactic acid bacteria will undoubledly produce good quality of products with highly appreciated organoleptic attributes. Recently, there is a growing interest to develop a variety of fermented milk products for other beneficial purposes, particularly for health purposes and preventing of toxins produced by food- borne pathogens and spoilage bacteria that enter human body (Shah, 2007; Ali, 2010; Panesar, 2011; Sharma et al., 2012).The beneficial effects of fermented milk products are produced by a variety of bioactive compound of lactic acid bacteria (Griffiths and Tellez, 2013).
Lactic acid bacteria represent as the most extensively studied microorganisms for milk fermentation (Olson, 1990; Marakoudakis, et al., 2006). The presence of lactic acid bacteria in milk fermentation can be either as spontaneous or inoculated starter cultures. Milk itself is known as one of the natural habitats of lactic acid bacteria (Wouters, et al., 2002; Delavenne, et al., 2012). Although under spontaneous fermentations the growth of lactic acid bacteria cannot be predicted or controlled, but this procedure has been practiced and carried out traditionally for years. A procedure called as back slopping is often used. There are some examples of fermented milk by lactic acid bacteria produced under this procedure such as those of artisanal cheese. In general, the technology of milk fermentation is relatively simple and cost effective.
On the other hand, standardized fermented milk products are produced and manufactured in large-scale production under controlled conditions and become an important industrial application of lactic acid bacteria as starter cultures. There are some important features of lactic acid bacteria starters in fermented milk products. A single potential starter culture will dominate and reduce the diversity of micro organisms in fermented milk products compared to that of products under natural fermentation. Using lactic acid bacteria in milk fermentation and preservation is indispensable to improve milk palatability and quality. However, there is a limitation to reviewing these and other related information and thereby to delivering such synthesized and summarized data to the beneficiaries.
Yoghurt production is based on lactic acid bacteria ability to ferment sugars, especially glucose and galactose, so to produce lactic acid and aroma substances that give typical flavour and tastes to fermented products. Lactic acid bacteria also release antimicrobial metabolites so called bacteriocin, which are considered safe and natural preservatives, with great potential to be used on their own, or synergistically with other methods in food preservation. Therefore, reviewing sensible findings on lactic acid bacteria function in milk fermentation and preservation seems to be a milestone area to deliver combined information to the beneficiaries. Based on this outlined background, the objective of this paper was to review lactic acid bacteria function in milk fermentation and preservation and thereby to deliver combined information for beneficiaries. A number of studies on the development of food fermentation process based on the use of cereal and vegetable substrates have been reported (Demir, et al., 2006). Microbial growth on these substrates depends on environmental factors such as PH, temperature and accumulation of metabolic end products. However as natural fermentation rely on microbial populations present in the raw material, these products exhibits substantial variations in flavour and quality (Giraud, et al., 1998). The good adaptation of LAB in cereals and vegetables suggests that the utilization of a potentially probiotic strain as starter culture in these substrates other than milk would produce a fermented food with defined and consistent characteristics and possibly health promoting properties. This is focus base on the potential role of lactic acid bacteria in milk fermentation based on their properties that support the development of fermented milk products.
1.2 AIMS AND OBJECTIVE
The objectives of this study were;
i. To determine the optimum conditions for the production of yoghurt from powdered milk
ii. To isolate, identify and characterize the microorganisms (LAB) capable of being used as probiotic strains.
iii. To study the key factors, influencing the growth and metabolic activity of the strains.
iv. To use these isolated organism as starter cultures to produce yoghurt probiotic food.
Click “DOWNLOAD NOW” below to get the complete Projects
FOR QUICK HELP CHAT WITH US NOW!
+(234) 0814 780 1594
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