ABSTRACT
This study investigated the changes in nutrients that occurred at room (26+2℃) and refrigeration (4℃) temperatures after fermentation of castor oil bean. A portion of locally made ogiri was used as inoculum for the production of ogiri which was fermented for 96 h. The “ogiri” produced was divided into two parts. One part was kept at room temperature (26+2°C) for 96 h, while the other part was kept in a refrigerator (4oC) for 96 h. Sub-samples were collected from the refrigerated sample and from the room temperature sample and analysed to monitor the changes in pH, TTA, TVC, proximate composition and amino acids contents every 24 h starting from 0 h after fermentation. The results obtained showed that the pH of the “ogiri” kept at room temperature increased significantly from 7.14 – 8.48 while the “ogiri” sample kept in the refrigerator did not show significant increase in pH (7.12 – 7.14) over the 4-day monitoring period. The TTA of the “ogiri” at room temperature decreased significantly (0.51- 0.27%) throughout the study period, whereas the TTA of “ogiri” in the refrigerator decreased slightly (0.51 – 0.49%). For the sample at room temperature, there was a slight decrease in moisture content (27.30 - 26.65) and a significant decrease in ash content (2.86 - 2.23%) respectively but fat content (47.25 – 53.16%) and protein content (22.17 – 27.66%) showed progressive increases respectively. There was also a significant decrease in the carbohydrate content (24.37 – 15.74%). Similar trends of nutrients changes were observed in the refrigerated sample but there was higher decrease in moisture content (27.30 - 26.04%) and a slight decrease in ash content (2.86 – 2.50%). The fat content increased from 47.25 - 48.63 and protein content increased from 22.17 - 26.62% while carbohydrate content decreased from 24.37 – 19.45%.All the essential amino acids (Leucine, Lysine, Isoleucine, Phenylamine, Tryptophan, Valine, Methionine, Histidine, Threonine) and non-essential amino acids (Proline, Arginine, Alanine, Glutamic acid, Glycine, Serine and Aspartic acid) in both samples showed progressive increase within the period of study. However, higher increase was obtained in the samples kept at room temperature than for the sample kept in the refrigerator. The mean total amino acid content (essential and non-essential) was lower than the FAO/WHO stipulated standard values. However, some amino acids in the samples were higher than their reference values.
TABLE OF
CONTENTS
Title page i
Declaration ii
Certification iii
Dedication iv
Acknowledgement v
Table of Contents vi
List of Tables xi
List of Figures xii
List of Plates xiii
Abstract xiv
CHAPTER 1: INTRODUCTION
1.1 Background Information 1
1.2 Statement of Problem 3
1.3. Justification 4
1.4. Objectives 5
1.4.1 Specific objectives 5
CHAPTER 2: LITERATURE REVIEW
2. 1 Food Condiments: Meaning and Uses
6
2. 2 Castor Oil Bean Plant: Botany, Morphology and Cultivation 7
2. 3 Varieties Of Castor Oil Bean
Plant 10
2.3.1 Varieties for ornamental purposes 10
2.3.2 Oil-producing varieties 10
2.4 Morphology of Castor Oil Seed 11
2.5 Chemical Composition of Raw Castor Oil Bean Seeds 14
2.6 Toxicants In Castor Oil Beans 16
2.7 Economic Importance of Castor
Oil Beans 18
2.8 Castor Oil Bean Seed As Food
Condiment 19
2.9
Ogiri as Food Condiment 19
2.10 Traditional Method of Processing Castor Oil
Seed into Ogiri 22
2.11 Unit
Operations Used In Processing of Ogiri 24
2. 12 Effects of Packaging Materials On The
Keeping Quality Of Ogiri 27
2.13 Other Seed Legumes Used As Raw Materials For
Processing Of Ogiri29
2.13.1 Melon seeds as raw material for Ogiri
production 31
2.13.2 Fluted pumpkin seeds as raw material for Ogiri
production 32
2.13.3 Prosopsis africana as raw
material for Ogiri production 32
2.13.4
African oil bean seeds as raw material for Ogiri production 32
2. 13.5
African locust beans as raw material for Ogiri production 33
2.13.6
Soybeans as raw material for Ogiri production 34
2.13.7
Cotton seeds as raw material for Ogiri production 34
2.13.8
Baobab seeds as raw material for Ogiri production 35
2.13.9
Roselle as raw material for Ogiri production 35
2.14 Main Biochemical Modifications During
Alkaline Fermentation 36
2.14.1
Protein modification 36
2.14. 2 Carbohydrate modification 37
2.14.3 Lipid modification 39
2.14.4 Formation of aroma compounds during
alkaline fermentation 41
2.15 Use of Backslop As Inoculum In The
Production/Fermentation of
Condiments 43
2.16 Safety Of Alkaline-Fermented Condiments 44
2.17 Nutritional Properties Of Ogiri And Other
Alkaline-Fermented
Condiments 46
2.18. Physical Properties Of Alkaline-Fermented
Condiments 47
2.19 Alkaline-Fermented Condiments As
Functional Ingredients 47
2.20 Preservation 49
2.20.1
Preservation of fermented foods 49
2.20.2
Traditional methods of preserving fermented foods 50
2.20.3
Improved methods of preserving fermented foods 52
CHAPTER 3: MATERIALS AND METHODS
3.1 Source of Materials 55
3.2 Methods 55
3.2.1 Traditional
processing of Ogiri from castor oil
beans 55
3.2.2 Isolation of
microorganisms 55
3.3 Identification of
Microorganisms 56
3.4 Biochemical
Identification Tests 56
3. 4.1 Gram staining test 56
3.4.2 Catalase test 57
3.4.3 Citrate test 57
3. 4.4 Oxidase test 58
3.4.5 Starch hydrolysis test 58
3.4.6 Indole test 59
3.4.7 Hydrogen sulphide
production test 59
3.4.8 Gelatin hydrolysis test 59
3.5 Processing of Ogiri From
Castor Oil Beans Using Backslop As
Inoculum
60
3.6 Determination of Total
Viable Count 62
3.7 Determination of
Titratable Acidity 62
3.8 Determination of pH 63
3.9 Determination of Amino Acid Profile 63
3. 10 Defatting Sample 63
3. 10.2
Nitrogen determination 63
3.10.3 Loading of the hydrolysate into analyzer 65
3.1 Determination of Tryptophan 66
3.11 Proximate Analysis for Moisture Content,
Protein, Fat, Ash and Crude
Fibre 68
3.12 Statistical Analysis 73
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Morphological
and Biochemical Characteristics of Probable Bacterial
Isolates in the Backslop 74
4.2 Total
Viable Count During Fermentation/Production 77
4.3 Total
Viable Count After Production/Fermentation 79
4.4 Titratable Acidity and pH During The Fermentation of Castor Oil
Bean Marsh 81
4.5 Titratable Acidity and pH After Fermentation/Production
of Castor Oil
Bean Ogiri 83
4.6 Proximate Analysis 86
4. 7 Moisture Content 86
4. 8 Ash Content 89
4. 9 Fat Content 91
4.10 Protein Content 93
4. 11 Carbohydrate Content 95
4. 12 Amino Acids Profile 98
4. 13 Essential Amino Acids 98
4. 14 Non-Essential Amino Acids 105
CHAPTER 5: CONCLUSION AND
RECOMMENDATION
5.1 Conclusion 106
5.2 Recommendation 106
REFERENCES 108
APPENDICES 148
LIST OF TABLES
2.1 Chemical Composition of Raw Castor Oil Bean
seeds 16
4.1 Morphological And Biochemical Characteristics
Of Probable Bacterial
Isolates in
The Backslop 74
4.2 Changes in Total Viable Count During
Fermentation 77
4.3 Changes in Total Viable Count After
Fermentation 79
4. 4 Changes in Titratable Acidity and pH During
Fermentation Of Castor
oil bean
marsh 81
4.5 Changes In Titratable Acidity and pH After
Production of Castor oil bean
Ogiri 83
4.7 Changes in the Moisture Content of Ogiri After
Production 86
4.8 Changes in the Ash Content of the Ogiri After
Production 89
4.9 Changes in the Fat Content of the Ogiri After
Production 91
4.10 Changes in the Protein Content of Ogiri After
Production 93
4.11 Changes in the Carbohydrate Content of Ogiri
After Production 95
4.13 Changes in Essential Amino Acids Composition
of the Ogiri At Room And
Refrigeration Temperatures 98
4.14 Changes in Non-essential Amino Acids
Composition of Ogiri At Room And
Refrigeration Temperatures 101
LIST
OF FIGURES
2.1 Flow Chart for Traditional Processing of Ogiri 9
3.1 Flow Chart for Processing of Ogiri Using Castor
oil beans 61
LIST
OF PLATES
2.1 Castor Oil Bean Plant 8
2.2 Castor Oil Bean Seeds 12
2.3 Dehulled Castor Oil Bean seeds 13
2.4 Ogiri Condiment Made From Castor Oil Beans 21
CHAPTER 1
1.0 INTRODUCTION
1.1 BACKGROUND INFORMATION
Fermented
condiments remain the key component of diet throughout the world especially in
Africa and Asia (Sanni, 1993; Ogunshe et al., 2007).
These
condiments are usually fermented from seeds of legumes which account for up to
80% of dietary proteins for some groups of people within the society
(Olanbiwoninu and Odunfa, 2018). Ogiri is one of such traditional condiment
products of alkaline fermentation of Castor Oil Seeds (Ricinus communis)
widely consumed as food condiment in Eastern Nigeria (Ojinnaka et al.,
2013). Ogiri can also be processed from
other popular legumes like melon (Colocynthis citrullus) or Fluted
pumpkin (Telfairia occidentalis) (Omafuvbe and Oyedapo, 2000; Ogueke and
Nwagwu, 2007). It is used as a seasoning agent or condiment for local
delicacies like Oha soup (ofe oha)
and bitter leaf soup (ofe onugbu).
Soups
are the main source of proteins and minerals for the Igbos and one of
the ways to improve their diet is to improve the nutrients in the soup using
fermented condiments made from legume seeds (Achi, 2005). The condiment can
also be used to season tapioca (abacha), akidi and other local
delicacies consumed by the Igbos of
southeastern enclave of Nigeria particularly those ones who are the original
indigenes of states like Anambra, Ebonyi, Enugu and Imo.
Ojinnaka
et al. (2013) reported that Ogiri is a protein-rich meat substitute,
hence, its wide consumption by the Igbos
in Eastern Nigeria has led to economic empowerment of the people, mostly women
who take up the production and merchandize of the condiment as a source of
livelihood. Ogiri is added in fairly small quantities as it not only enhances
the sensory properties of food, it also improves nutritional value providing
fiber, energy, minerals and vitamins (Kolapo et al., 2007). Ogiri is
processed by traditional methods of uncontrolled solid substrate fermentation
resulting in extensive changes of protein and carbohydrate components through
hydrolysis (Achi, 2005). The fermentation involves continuous nutritional,
physical and organoleptic modification of the starting material by
microorganisms (Aidoo, 1994). The fermentation which yields Ogiri is carried
out in a moist solid-state involving contact with appropriate assorted
microorganisms more of Bacillus sppand
it is aided or accomplished by the natural temperature of the tropics
(Olanbiwoninu and Odunfa, 2018). The actual desired state of the fermentation
of the condiment during processing is indicated by the formation of mucilage
coupled with ammonia produced as a result of breakdown of amino acids during
fermentation (Odunfa, 1985).
Fermentation
has been considered as one of the foremost technologies for the processing of
food products with desirable qualities such as extended shelf-life, improved
nutritional and organoleptic properties (Smid and Hugenholtz, 2010). During the
production of Ogiri by fermentation, proteolysis is the most important reaction
that occurs leading to the degradation of proteins to peptides and amino acids.
The breakdown products and amino acids not only have a considerable influence
on the nutritional values but also contribute directly to the desired
organoleptic properties in some cases serving as fundamental aromatic
substances or precursors of aromatic products (Kiers et al., 2000; Han et
al., 2004). Fermentation enhances the nutrient content of Ogiri through
biosynthesis of vitamins, essential amino acids and proteins by improving
protein and fiber digestibility and by so doing, degrades the antinutritional
factors and other toxicants such as ricin inherent in the vegetable substrate
and develops compounds that might impart flavor to the condiment (Mensah et
al., 1990). On account of the indispensable roles which fermentation plays
in Ogiri production, it holds promise as a food processing method that can be
used to diversify and increase the utilization of some under-exploited plant
foods like castor oil bean seeds.
Meanwhile, irrespective of the huge promise
that ogiri holds in terms of serving as a natural condiment coupled with its
wholesome chemical composition, yet, it has not attained a global commercial
and acceptability standard and status probably owing to its low keeping
quality, antiquated packaging material, stickiness and its characteristic
putrid and noisome odour (Arogba et al., 1995). Moreover, Achi (2005a)
reported that fermented condiments have a stigma attached to them; as they are
often considered as food for the poor. However, a better understanding of the nutrients
changes in Ogiri after production is required and the onus is on food
scientists to investigate the trends of nutritive values and amino acid
profiles of Ogiri when subjected to various conditions.
1.2 STATEMENT OF PROBLEM
There
are some indications that some nutrients and organoleptic qualities of
fermented foods may increase or improve few days after processing (Underdal et al., 1976). Barber and Achinehwu
(1992) while describing the methods of processing of ogiri stated that after
the four-day fermentation of Ogiri, the traditional condiment is left near
hearth (fireplace) for few days until the unique aroma of the condiment
develops. Post-production changes in nutrients of fermented condiments are
caused mostly by microbial activities, hence, Achi (2005a) pointed out that
fermented condiments are deficient in Ascorbate and some fat-soluble vitamins
due to fermentation. The problem of food insecurity is not just that of the
conceptual dearth or inadequate food supply but it is also a problem of loss of
salient nutrients occasioned by inherent microbes through nutrients changes
(Kumar and Kalita, 2017). Hence, Ojimelukwe et al. (2011) reported that
lime and sodium chloride were used to selectively inhibit the growth of
microorganisms. These antimicrobials are most often used with other techniques
such as refrigeration to slowdown the growth of microorganisms which bring
about tremendous nutrients changes leading to food spoilage (Ademola et al.,
2011). Ojinnaka et al. (2013) have improved the fermentation of ogiri
from castor oil bean using Bacillus subtilis as starter culture. This
research seeks to monitor the nutrients changes that occur in freshly processed
ogiri when kept at room and refrigeration temperatures. It is necessary to find
out the effect of fermentation on the trends of nutrients changes in ogiri at
these different temperatures so that consumers of this fermented condiment will
be better informed about the post-production changes in the nutrients of this condiment
and the best method that could be used to enhance its keeping quality.
1.3.
JUSTIFICATION
Traditionally
fermented foods and condiments consumed by people over a long period play
important role in establishing local identity, culture and custom and they
transfer cultural heritage from generation to generation (Albayrak and Gunes,
2010). Ogiri is one of such traditionally fermented food products and several
researchers have claimed that fermented condiments such as Ogiri are wholesome
and good sources of amino acids and micronutrients apart from their primary use
which is enhancement of food taste. There is need to evaluate the changes in
quality parameters and nutrients in the condiment days after production to
ascertain its use as a source of nutrients because researchers of this
traditionally fermented condiment have dwelt so much on the events that occur
in ogiri during production with little emphasis on the changes in nutrients of
ogiri as a result of biochemical events that transpire within its ecological
matrix after production, hence, a succinct and scientific information about the
trends in the nutrients changes in ogiri is very much needed so that consumers
will know the trends of its nutrients indices under different temperature
conditions.
1.4.
OBJECTIVES OF STUDY
The
main objective of this study is to evaluate the effect of fermentation
(inherent microbial activities) on the nutrients and quality parameters of
castor oil bean condiment (ogiri) at room and refrigeration temperatures.
1.4.1 The specific
objectives are to;
produce
ogiri from Castor oil bean seeds using the backslop as inoculum.
evaluate
the pH, TTA and Total viable count of castor oil bean Ogiri sample.
monitor
and compare the changes in total viable count, physicochemical properties,
proximate compositions and the amino acid profile of Ogiri during the
short-term monitoring at room temperature (26+20C) and at
refrigeration temperature (4°C).
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