ABSTRACT
The study investigated the quality attributes of ugba (Pentaclethra macrophylla) produced using different boiling and fermentation periods. The African bean seeds were boiled at different time intervals (2, 3 and 4 h) and fermented at three respective time intervals (72, 96 and 120 h) to produce ugba. Proximate composition, mineral, anti-nutritional contents, microbial analysis and as well as sensory evaluation were carried out on the different ugba samples. Statistical analysis was done using analysis of variance to determine the significant difference at 95% confidence level. Proximate composition showed that the crude protein (33.48%), fat (18.47%), fibre (2.49%), ash (2.27%), moisture (24.81%) and carbohydrate (18.48%) were highest the in raw ugba seeds. Mineral analysis showed that raw ugba seed samples had the highest sodium concentration among all the elements analyzed and were found to be highest in all other elements analyzed in the order: Na (228.77 mg/100g) > K (190.27 mg/100g) >Ca (189.71 mg/100g) > P (177.20 mg/100g) > Mg (18.07 mg/100g) > Fe (16.00 mg/100g). The tannin content ranged from 0.07 – 0.34%, phy6uytate (0.02 – 0.23%), oxalate (0.01 – 0.19%) and alkaloid (0.02 – 0.27%). These low contents imply that the ugba samples could be beneficial for human consumption. The result of microbial analysis showed that the following microorganisms were involved in the fermentation of the ugba samples irrespective of the boiling time: Staphylococcus, Proteus, Pseudomonas, Bacillu, E.coli. Lactobacillus, Aspergillus, Penicillum, Fusarium, Rhizopus, Saccharomyces spp. but only Bacillus and Pseudomonas were persistent during fermentation with Pseudomonas disappearing at the later stages of fermentation (after 48 h). The general acceptability assessment showed that the ugba sample boiled and fermented at 72 h was found to be the best among others. This study concluded that ugba sample obtained with fermentation at 72h and beyond had desirable proximate composition and low anti-nutritional factors, which could be useful in enhancing human nutrition.
TABLE OF CONTENTS
Title Page i
Declaration ii
Dedication iii
Certification iv
Acknowledgements v
Table of Contents vi
List of Tables x
List of Figures xi
List of Plates xi
Abstract xiii
CHAPTER 1: INTRODUCTION
1.1
Background of the Study 1
1.2
Statement of Problem 2
1.3
Justification of the Study 3
1.4
Objectives of the Study 4
CHAPTER 2: LITERATURE
REVIEW
2.1 Fermented
Foods 5
2.2 Preparation of Ugba 6
2.3
Importance and Applications of African Oil Bean Seeds 8
2.4 Chemical Composition
of the African Oil Bean Seeds 9
2.5Toxicology of Ugba (Pentaclethra macrophylla) 14
2.6 Health Benefits of the African Oil Bean Seeds 14
2.7 Microorganisms Involved
During Fermentation 16
2.8 Biochemical Changes Accompanying Fermentation 17
2.8.1 Changes in amino acids 19
2.8.2 Changes in lipids 19
2.8.3 Changes in carbohydrates 20
2.9 Effect of
Fermentation on Quality Properties of African Oil Bean Seeds
(Ugba) 21
2.10
Nutritional Changes Associated with Fermentation of African Oil Bean Seed 22
2.11 Chemical and Biochemical Changes
Associated with Fermentation of African Oil Bean Seeds 25
2.12 Nutritional Value of
Fermented and Unfermented African Oil Bean Seeds (Ugba) 26
2.13.1 Fatty acid content 26
2.12.2 Vitamin and
mineral content 26
2.12.3 Carbohydrate
content 28
2.13
Microbiological Changes During Fermentation 29
2.14
Handling and Storage of African Oil Bean Seed 31
2.15 Organoleptic Properties of Ugba Fermented with the Starter Cultures of Bacteria Isolates 32
2.15.1 Colour 32
2.15.2 Flavour (aroma/taste) 33
2.15.3 Texture 33
2.15.4 Overall acceptability 34
2.16 Microbiological Safety of Fermented
African Oil Bean Seeds 35
2.17 Selection of Starter Cultures for
Controlled Fermentation of Ugba 35
CHAPTER 3: MATERIALS AND METHODS
3.1
Source of Raw Material 37
3.2
Experimental Design 37
3.3 Sample Preparation 37
3.4
Proximate Analysis 42
3.4.1
Moisture content determination 42
3.4.2
Ash content determination 42
3.4.3
Fat content determination 43
3.4.4
Crude fibre content determination 44
3.4.5
Crude protein content determination 44
3.4.6
Carbohydrate content determination 44
3.5
Determination of Mineral Content 45
3.5.1
Calcium and magnesium content determination 46
3.5.2
Potassium and sodium content determination 47
3.5.3 Phosphorus content
determination 47
3.5.4
Iron content determination 48
3.6 Anti-nutritional Factors Analysis 48
3.6.1 Oxalate content determination 48
3.6.2 Alkaloid content determination 50
3.6.3 Tannin content determination 50
3.6.4 Phytate content determination 51
3.7
Microbial Analysis 51
3.7.1 Preparation of diluents and
media 51
3.7.2 Microbiological analysis of
samples 51
3.7.3 Enumeration of microbial
population 52
3.7.4 Characterization and
identification of microbial isolates 52
3.8
Sensory Analysis 52
3.9
Statistical Analysis 53
CHAPTER
4: RESULTS AND DISCUSSION
4.1
Proximate Composition of Ugba Samples
Produced by Different Processing
Conditions
54
4.2
Mineral Composition of Ugba Samples
Produced by Different Processing
Conditions 58
4.3
Anti-nutritional Composition of Ugba Samples
Produced by Different
Processing Conditions 61
4.4:
Microbial Characteristics of the Ugba Samples
64
4.4.1
Total microbial count of ugba samples
produced by different processing
conditions 64
4.4.2
Occurrence of microbial isolates in ugba
samples produced by different
processing conditions 67
4.5:
Sensory Evaluation of Ugba Samples
Produced by Different Processing
Conditions 73
CHAPTER 5: CONCLUSION
AND RECOMMENDATION
5.1
Conclusion 77
5.2
Recommendation 77
References 79
Appendices 91
LIST OF TABLES
Page
2.1: Uses of African oil bean tree (Pentaclethra macrophylla) in West Africa. 10
2.2: Amino acid content
(g/100g protein) of African oil bean seed 11
2.3: Fatty acid
composition of African oil bean seed. 13
2.4: The medicinal uses of African oil bean seeds
plants (Pentaclethra
macrophylla) 15
2.5: Major microorganism
encountered in fermentation of sliced oil bean seed
(per gram) 18
2.6: Vitamin and mineral content of unfermented
and fermented ugba. 27
4.1:
Proximate composition of ugba samples
produced by different processing
conditions 55
4.2:
Mineral composition of ugba produced
by different cooking time and
fermentation periods 59
4.3:
Anti-nutritional composition of ugba samples
produced by different
processing conditions 62
4.4:
Total bacterial and fungal counts of ugba
samples produced by different
processing conditions 65
4.5:
Occurrence of bacteria isolates in ugba samples
produced by different
processing conditions 68
4.6:
Occurrence of fungi isolates in ugba samples
produced by different
processing conditions 69
4.7:
Percentage occurrence of microbial isolates in the ugba samples produced
by different processing conditions 70
4.8:
The result of sensory evaluation of ugba samples
produced by different
processing conditions 74
LIST OF FIGURE
Page
3.1:
Flow chart for production of ugba
(fermented)
39
LIST OF PLATE
Page
3.1:
Raw African oil bean seeds (Pentaclethra macrophylla) 40
3.2: Fermented ugba 41
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
The
seed of African oil bean also known as “ugba”
and “ukpaka” in Igbo language is a popular food delicacy in Nigeriaespecially
among Igbo ethnic group. The seed is also called “ukana” by the Efiks in
southern part of Nigeria (Njoku and Okemadu, 1999). The method of preparation
varies from producer to producer or community to community resulting in a
non-uniform product (Njoku and Okemadu, 1999). The seeds that have been
fermented for more than three days are taken as a delicacy. The fermented
product is a rich source of protein and can be obtained by a solidstate
fermentation of the boiled, shredded seed of African oil bean tree (Pentaclethra
macrophylla). Well-fermented bean seeds are added as flavouring to soup. Also they have been used as food condiment
which are prepared as cubes from well fermented ugba seeds (Odunfa and Oyeyiola, 1985)
The
fermented product is largely consumed in Eastern States of Nigeria with
tapioca, stock fish and garden eggs and leaves. Also, it can be eaten with
bitter kola (Garcina kola) or kola
nuts (Cola acuminateand Cola nitida), and when prepared with garden
egg leaves, it is used to eat yam and cocoyam (Okafor et al., 1991; Mbajunwa et al.,
1998). The fermented ugba is of
primary importance and rich in protein for people in developing countriesof
theworld and Africa whose staple foods are deficient in proteins (Obeta, 1993).
The quantity of ugba produced every
year is not yet known because the seeds are collected by individuals and sold
in the market to ugba producers.The processing
of these seeds involves boiling, removal from pod, shredding or cutting
intoslices, further boiling, sieving, wrapping in banana or plantain leaves and
fermentation.
Heat
treatment induces a resultant rise in nutrient bioavailability and seed digestibility.
Enujiugha and Akanbi (2005) reported that the unprocessed seeds of African oil
bean are bitter and possess anti-nutritional factors amongst which are pancine,
cyanide, oxalates, saponin, phytic acid,
phytate and tannins. More so, Enujiugha and Ayodele-Oni (2003) also
opined that processing ugba seeds
drastically reduces the levels of the anti-nutritional compounds mentioned
above while increasing iron, calcium, potassium, thiamine and riboflavin
levels.
1.2
STATEMENT OF PROBLEMS
African
oil bean has been underutilized as a food crop despite all its rich potential
to serve as important food supplement in most of the diet of many traditional
communities in Africa. Its production in Nigeria is still on a small scale
level involving production at the household level where there is little or no
consideration for good manufacturing practices (GMP) and sanitation (Olasupo et al., 2002;
Gadaga et al., 2004).
Also,
despite the rich nutritional value of African bean and its role in bridging the
prevailing protein energy malnutrition (PEM), the quality of its final products
have been affected by not having specific processing conditions that will yield
fermented ugba products with optimum
nutritional value and organoleptic attributes. The fermentation period is
chosen according to human judgment and varies from one manufacturer to the
other. Lack of standardization in the production process often results in
product inconsistency and quality variation.
Lastly,
fermented ugba products have very
short shelf-life and it has restricted its usage, availability and overall
microbial safety. Additionally, poor hygiene of handlers, lack of portable
water, poor packaging and quality and maturity level of raw materials often
introduce spoilage and pathogenic microorganisms which contributes to the short
shelf-life of the fermented ugba
products (Olasupo et al., 2002;
Gadaga et al., 2004).
1.3
JUSTIFICATION
Standardizing
the conditions for the production of fermented ugbawill help to make the quality of the products consistent and
also encourage its production in industrial level where good manufacturing
practices (GMP) are required and specific production method documented for easy
implementation. Standardization of process conditions will also enable food
engineers to design automated processing units that will enhance the production
of fermented ugba with high quality
and in larger scale. It will also serve as guide to individuals, communities
and cultures who are not conversant with the processes involved in producing
fermented ugba of high quality but
desires to do so.
Implementing
proper hygiene, using raw materials of high quality, portable water and proper
packaging will help in extending the shelf-life of fermented ugba products which has been within 5
days to longer period without the product being unsafe for consumption.
Lastly,
researching on how to improve the quality of products from African oil bean and
new ways of utilizing this important food crop will go a long way in solving
the problem of under- utilization and enable food scientist to fully utilize
this important food crop as one of the indigenous crops that will help in
solving the problem of protein energy malnutrition common to Africa and other
developing countries.
1.4 OBJECTIVES
OF THE STUDY
The
main objective of this study was to evaluate the quality attributes of ugba (Pentaclethra macrophylla)
produced using different boiling time and fermentation periods.
The
specific objectives were to:
i.
determine the proximate composition of the raw, boiled and fermented ugba samples at
various time intervals.
ii.
determine the mineral contents of the raw, boiled and fermented ugba samples at various
time intervals.
iii.
determine the anti- nutritional content of the raw, boiled and fermented ugba samples at
various time intervals.
iv.
assess the microbial characteristics of the ugba
samples at various time intervals.
v.
determine sensory attributes of the fermented ugba samples at various time intervals.
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