ABSTRACT
This study investigated the quality attributes of ogiri produced from fluted pumpkin, egusi and castor oil bean seeds, using L. acidophilus, L. fermentum and Enterococcus sp. starter cultures. The total bacterial count, total coliform, and total fungi count of the starter culture inoculated ogiri samples were determined during storage using standard microbiological techniques. Proximate composition, minerals, anti-nutritional contents of the ogiri samples as well as the sensory evaluation of soups prepared from the ogiri samples was also determined. Bacterial count ranged from 8.4 x 103 to 1.36 x 107 cfu/g; castor oil bean ogiri inoculated with L.acidophilus recorded the lowest. Total coliform count ranged from 3.2 x 102 to 8.3 x 103, the lowest was recorded for fluted pumpkin ogiri fermented with L. acidophilus (FPL1). The fungi count ranged from 1.7 x 103 to 8.4 x 106 cfu/g, castor oil bean ogiri fermented with L. fermentum recorded the lowest. Results of proximate composition showed that dry matter (%) ranged from 65.20 to 86.50, moisture content (%) of the samples ranged from 13.50 to 34.80, protein content ranged from 12.60 to 27.98 mg/100g, ether extract content ranged from 5.01 to 10.04%. crude fibre ranged from 2.87 to 7.32%, ash content ranged from 2.12 to 4.77%, carbohydrate content ranged from 8.45 to 17.24%. The mineral compositions of the castor oil bean seed ogiri over a 9 day storage period are as follows: calcium (0.61-0.94 mg/100g), magnesium (0.29-0.63 mg/100g), sodium (0.02- 0.11 mg/100g), zinc (0.03-0.09), iron (0.05-0.13 mg/100g) and potassium (0.05-0.28 mg/100g). Calcium and magnesium occurred more abundantly in the LAB inoculated samples than in controls. The mineral composition of the egusi ogiri showed that calcium ranged from 0.52 to 1.03, magnesium 0.62 to 1.16 mg/100g, sodium 0.29 to 0.71 mg/100g, zinc 0.15 to 0.49 mg/100g, iron 0.26 to 0.52 mg/100g and potassium 0.12 to 0.35 mg/100g. Sensory scores of the soups prepared with ogiri samples ranged from 2.07 to 5.67, 2.54 to 6.40 and 3.15 to 6.41 for colour, aroma and general acceptability respectively. There was significant difference (p<0.05) in the mean sensory scores between the soups prepared with ogiri fermented with LAB isolates and the control samples. It was concluded that the use of LAB isolates enhanced nutritional, long shelf life and sensory qualities of ogiri products over the control samples.
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of Contents vi
List of Tables ix
List of Figures x
List of Plates xi
Abstract xii
CHAPTER 1: INTRODUCTION 1
1.1 Background of the Study 1
1.2 Statement of the problem 3
1.3 Justification of the Study 4
1.4 Objectives of the Study 5
CHAPTER 2: LITERATURE REVIEW
2.1 Food from Plant Sources 6
2.2 Food Fermentation 7
2.2.1 Traditional fermented condiments used in Nigeria 8
2.3 Sources of Ogiri Production 9
2.3.1 Melon seed 9
2.3.2 Castor oil bean seed 13
2.3.3 Fluted pumpkin 16
2.4 Lactic Acid Bacteria 18
2.5 Isolation and Identification of Lactic Acid Bacteria 27
2.6 Factors Influencing Growth and Bacteriocin Production of Lactic Acid
Bacteria 28
2.7 Lactic Acid Bacteria in Food Fermentation 29
2.8 Metabolites of Lactic Acid Bacteria Responsible for Food Preservation 35
2.9 Mechanism of Food Fermentation by Lactic Acid Bacteria 38
2.10 Importance of Fermentation 39
2.11 Biochemical Changes Accompanying Fermentation 44
2.12 Anti-Nutrients of some Foods 47
CHAPTER 3: MATERIALS AND METHODS 50
3.1 Sample Collection 50
3.2 Isolation and Characterization of Lactic Acid Bacteria 50
3.2.1 Culture media preparation 50
3.2.2 Isolation of microorganisms 50
3.2.3 Culture preservation 51
3.2.4 Characterization of isolates 51
3.2.4.1 Gram’s staining 51
3.2.5 Biochemical test 51
3.3 Technological Properties of Lab Isolates (for Selection of Suitable-
Isolates) 53
3.4 Preparation of Ogiri 55
3.5 Inoculation of Ogiri with Chosen Lactic Acid Bacteria 60
3.6 Microbiological Analysis 60
3.7 Determination of Proximate Analysis 61
3.8 Determination of Minerals 66
3.9 Determination of Anti-Nutritional Factors 67
3.10 Sensory Evaluation 70
3.11 Statistical Analysis 70
CHAPTER 4: RESULTS AND DISCUSSION 71
4.1 Morphological and Biochemical Characteristics of Isolates 71
4.2 Technological Properties of the Isolates 74
4.3 Bacterial Count of Ogiri During Storage 79
4.4 Total Coliform Count of the Ogiri Samples 81
4.5 Total Fungi Count of the ogiri Samples 83
4.6 Proximate Compositions of the Ogiri Samples 85
4.7 Mineral Composition 91
4.8 Mineral Composition of the Seeds 102
4.9 Anti-Nutritional Composition of Ogiri 103
4.10 Sensory Evaluation 107
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS 109
5.1 Conclusion 109
5.2 Recommendations 109
References 110
LIST OF TABLES
2.1. Major divisions within the genus lactobacillus based on Phenotypic
characteristics 26
2.2: Lactic acid bacteria and its fermentable products 32
4.1: Morphological and biochemical characteristics of isolates 72
4.2: Technological properties of the Isolation 73
4.3: Bacterial load of Ogiri samples fermented with lab isolates 78
4.4: Total coliform count of the Ogiri samples during storage 82
4.5: Total fungi count of the Ogiri samples during storage 84
4.6: Proximate composition of Ogiri samples 88
4.7.1: Mineral composition of castor bean oil Ogiri 94
4.7.2: Mineral composition of egusi Ogiri 96
4.7.3: Mineral composition of fluted pumpkin Ogiri 97
4.9: Anti-nutritional properties of the Ogiri 106
4.10: Sensory evaluation of the soups prepared with Ogiri condiment 108
LIST OF FIGURES
3.1: Flow chart for the preparation of Ogiri 59
4.1: Bar chart of the mineral content of the seeds (unprocessed seeds) 101
LIST OF PLATES
1: Castor bean oil seeds (undehulled) 57
2: Blended castor oil bean seeds 57
3: Fluted pumpkin seeds (undehulled) 57
4: Blended fluted pumpkin seeds (dehulled) 57
5: Egusi seeds (undehulled). 58
6: Blended raw egusi seeds 58
7: Prepared Ogiri sample 58
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND
OF THE STUDY
‘Ogiri’ is a traditionally fermented oily
paste produced mainly from melon seeds and consumed within the West African
countries (Odunfa, 1981a). The process of production is still a traditional
family art and the fermentation is by chance inoculation (Odunfa, 1985). ‘Ogiri’ is used as a cheap soup condiment
particularly among the poor rural dwellers. In the South-East Nigeria, ‘ogiri’ can also be produced from castor
oil seeds Ricinus cummunis
(Enujiugha, 2003) and
fluted pumpkin (Telfairia occidentalis)
(Odibo et al., 1990;
Omafuvbe and Oyedapo, 2000).
Traditionally
fermented food condiments have constituted a significant proportion of the diet
of many people as they give pleasant aroma to soups and sauces in many
countries, especially in Africa and India where protein calorie malnutrition is
a major problem (Sarker et al.,
1993). They have been considered a great potential key protein and fatty acid
sources, and are good sources of gross energy (Achinewhu et al., 1991; Omafuvbe et al.,
2004). In Africa, many proteinaceous oily seeds are fermented to produce food
condiments (Sanni and Ogbonna, 1991; Baird-Parker, 1994). These condiments are
basic ingredients for food supplementation and they have been named according
to the substrate or raw materials employed (Odunfa, 1985) which may include “ogiri ugu” produced from fluted pumpkin
seeds (Telferia occidentallis) and “ogiri
egusi” produced from melon seeds (Citrullus
vulgaris) and ogiri from castor bean
seed.
Ogiri is a food condiment produced
from fermented oil seeds such as egusi seeds (Citrullus vulgaris), castor oil seeds (Prosopis Africana) and fluted pumpkin seeds. Ogiri okpei has a very strong aromatic smell that sets the whole
house on a high pitch once it jumps into the soup pot. Ogiri has a history from West Africa, precisely Igbo part of
Nigeria and it is characteristically dark-brown in appearance. Many parts of
Nigeria have different names for ogiri;
Yoruba’s call it Iru while the Hausas call it Dawadawa, a seasoning native to Nigeria, and West Africa at large.
Many types of ogiri exist but the most common
varieties are Ijebu, Igbo, and Nwan. The names were coined out from the region
of origin. Ogiri Ijebu is from Ijebu in Western Nigeria and gotten
from fermented Egusi seeds. Egusi has many names from Agushi, Egushi to Egusi;
its seeds are from West African melons whose fruit is bitter and inedible. The
seeds are covered with a light brown shell, which is always removed prior to
cooking. When de-shelled, the seeds have a creamy white appearance and it is
ground into a powder that has a consistency of breadcrumbs (Eke, 1996). Melon
seeds (Yoruba, Egusi) belong to two family varieties; Cucumis melo and Cucurbitaceae, they are mostly cultivated in the southern part of
Nigeria and is usually inter planted with yam and cassava where it serves as a
cover crop. It may account for up to 80% dietary protein and has been used as
the only source of protein for some groups of people. Melon seeds have been
reported to contain 3.3% moisture, 15.5% crude fibre, 10.3% crude protein, 8.2%
carbohydrate, 52% oil and 3.6% ash (Omafuvbe et al., 2004). This being
the case, other forms of utilizing melon seeds is adjudged useful. Ogiri made from melon seeds is one of
such (Achi, 2005).
Ogiri being a flavouring
condiment, is prepared by traditional methods uncontrolled solid-state
fermentation of melon seeds (Citrullus vulgaris) (Achi, 2005). The
handling of Ogiri before, during, and
after fermentation is crucial since a lot of flavor and aroma emanates (Achi,
2005). Use of chance fermentation coupled with unhygienic practices make the
fermentation difficult to control and results in contamination of the product
with pathogens or other microorganisms capable of producing toxins or odourous
compounds that can cause off-flavours (Ramos et al., 1984).
Castor
oil bean seed is a small annual plant; it ranges from one to seven meters in
height and has well developed roots, with green and reddish stems, which become
hollow with age. The fruit is a spherical capsule with small grey seeds with
brown spots. Castor bean is cultivated for the seeds, which yield viscous, pale
yellow, non-volatile and non-drying oil. It has been used for industrial and
medicinal purposes (Ogunniyi, 2006; Ramos et al., 1984). It has been
widely used as a human laxative-cathartic agent, particularly in cases of radiological
examinations, which require prompt and thorough evacuation of the small
intestine (Stubiger et al., 2003; Duke, 1983). The botanical name is Ricinus communis L of the family Eurphorbiaceae, a plant indigenous to
many parts of the world and has been used in the production of ogiri condiment (Akpan et al., 2006).
Ogiri ugu is another type of ogiri condiment, its production is still a traditional family art
done on household basis and its quality is as unpredictable as regards to the varying
environments and techniques used (Iwuoha and Eke, 1996). The fermentation
process is purely natural involving many microorganisms whose functions are not
necessarily involved (Barber and Achinewhu, 1992).
1.2 STATEMENT OF THE PROBLEM
Despite
the huge potential nutritional values and availability of local seasonings, some
developing countries like Nigeria require more information on the need for
increasing their utilization. Most of the consumers are not aware of the
nutritional values; therefore use them as functional ingredient in foods for
the purposes of tastes or aromatic characteristics. Hence strong emphasis on
the nutritional values of “ogiri” are
required in Nigeria so as to reduce the intake of artificial seasoning such as
maggi. However, fear of the unknown in the components of maggi is the major
factor that inhibits its maximum usage in Nigeria. Recently in Nigeria, there
has been series of controversial publications and debates over the use of maggi
and pure monosodium glutamate as a cancer inducing seasoning. Ijabadeniyi and
Omoya (2006) observed that brain lesions, obesity and other disturbances were
observed in mice treated with monosodium glutamate which might be detrimental
to health. Some other reports even asked for the ban of maggi because they
contain monosodium glutamate while some maintain that the amount of monosodium
glutamate in maggi is negligible, so it is safe. However, many Nigerian still
use artificial food seasonings such as maggi more than the natural food
seasonings such as “ogiri” as flavor
enhancer, their nutritional differences notwithstanding. This work was carried
out as a result of inadequate information on regard to the nutrient content of
these natural seasonings. The question will be whether the inoculation of
specific lactic acid bacteria isolates could enhance the quality attributes of
“ogiri” produced from different sources (fluted pumkin, egusi, and castor oil bean
seed) for preparing of meals in Nigeria, which might replace the constant use
of artificial food seasonings.
1.3 JUSTIFICATION OF THE STUDY
Local seasoning such as Ogiri” are used to enhance the flavor of food. Therefore a number
of benefits will be derived from the controlled fermentation of “Ogiri” by specific microbes. The result
of this study will be beneficial to homemakers, Home Economists, health worker,
nutritionist, dietitians, public, and the government. The findings will be of
great value to consumers by bringing to their awareness the nutritional values
of “Ogiri” from different sources.
With these findings, consumers from different states of Nigeria will know the
best source in which “ogiri” can be
prepared from and this could be achieved through seminar/workshops or women
conference such as August meeting and demonstration Programme in any state.
Further, the finding of the study will help food scientist through extensive
research programs where a food scientist could possibly commercialize the
production of ogiri on industrial scale. Secondly, food scientist will have the
opportunity to educate the people on the poisonous or harmful nature of “Ogiri” when they are not properly
fermented. Fermented ogiri are rich in live
cultures like probiotic microbes, which help the immune system by introducing
good, healthy bacteria. This study will also help the nutritionist and the dietitians to know
the nutritional value of “Ogiri” which
includes presence of probiotic microbes, antioxidant properties, treatment of
respiratory infections; this will form a base of recommendation for people that
lacks some nutrient in the body and to the people that have health problems.
1.4 OBJECTIVES OF THE STUDY
The
main objective of this study is to determine the effect of lactic acid bacteria
fermentation on the quality attributes of ogiri produced from three botanical
sources; castor oil bean, melon (egwusi) and fluted pumpkin seeds.
The
specific objectives of this study are;
1.
To isolate and characterize lactic acid bacteria from Ogiri.
2.
To select suitable strains of LAB as starter culture for Ogiri production.
3.
To Produce Ogiri by controlled
solid-state fermentation.
4.
To evaluate the effect of LAB starter culture on the anti-nutritional
and mineral composition of Ogiri.
5.
To determine the effect of storage on the mineral contents of the ogiri
sample.
6.
To evaluate the sensory attributes of the produced ogiri in soup.
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