ABSTRACT
The effects of inclusion of different proportions of germinated and ungerminated pearl millet flour on the chemical composition, glycemic index and sensory properties of garri samples fermented for 24 hours and 48 hours were investigated. The garri and pearl millet samples were in ratios of 100:0, 70:30 and 50:50. Results of the proximate content analysis on the samples showed that germination increased the protein content of those samples with pearl millet; however it led to decrease in the fat and carbohydrate content of these samples. Increase in fermentation time of the garri samples led to increase in their protein and fat contents and a corresponding decrease in the carbohydrate content of these samples. The starch characteristics of the samples were also affected by germination of pearl millet and increase in fermentation time of cassava. The amylose and resistant starch content of the samples increased with germination of the pearl millet and increase in fermentation time. Dietary fibre components of the samples which include: soluble dietary fibre, insoluble dietary fibre and total dietary fibre all increased with germination of the pearl millet samples; they also increased with an increase in fermentation time of the garri samples. The 100% garri sample fermented for 48 hours was the most acceptable sample in terms of all the sensory properties scored by the panelists. The least preferred samples were the ones with 100% germinated and ungerminated pearl millet samples respectively. Other sample blends were moderately acceptable and preferred to the 100% germinated pearl millet sample. Sample blends such as the sample with 70% garri fermented for 24 hours with 30% ungerminated pearl millet, the sample with 70% garri fermented for 48 hours with 30% ungerminated pearl millet, the sample with 70% garri fermented for 48 hours with 30% germinated pearl millet had a close range in acceptability when compared to the 100% garri samples which were the most preferred. The glycemic index of all the samples containing pearl millet decreased with germination and the glycemic index of those containing garri (cassava) decreased with increase in fermentation time. Hence based on sensory acceptability and the glycemic indices of the samples, the sample blend recommended is the sample with 70% cassava fermented for 48 hours and 30% germinated pearl millet; this sample had an estimated glycemic index of 53 which is considered a low glycemic index food.
TABLE OF
CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgement v
Table of Content vi
List of Tables x
List of Plates xi
Abstract xii
CHAPTER
1: INTRODUCTION
1.1
Background of the Study 1
1.2
Statement of Problem 4
1.3
Justification of the Study 5
1.4
Objectives of the Study 5
CHAPTER
2: LITERATURE REVIEW
2.1
Fermentation 6
2.2 Germination 7
2.3 Pearl
millet 8
2.3.1 Nutrient composition of pearl millet 9
2.3.2 Food uses of pearl millet 10
2.4 Cassava 10
2.4.1 Origin of cassava 11
2.4.2
Cassava cultivation and distribution 11
2.4.3
Cassava varieties 12
2.4.4
Description of cassava root and composition 12
2.4.5
Cassava Production, yield and utilization 13
2.4.6 Cassava processing and uses 14
2.4.7
Garri 15
2.5 Glycemic Index 16
2.5.1
Glycemic index and fermentation 21
2.6 Particle
Size Distribution 21
2.7 Diabetes Mellitus 21
2.8.1
Starch (amylose and amylopectin) 22
2.8.2
Resistant starch 25
2.9 Dietary Fibre 27
CHAPTER 3: MATERIALS AND METHODS
3.1 Materials 31
3.2 Preparation of Germinated Pearl Millet 31
3.2.2 Processing of garri 33
3.2.3
Formulation of blends 35
3.3 Experimental
Design 36
3.4 Proximate
Composition Analysis 36
3.4.1 Moisture Content
Detemination 36
3.4.2
Crude protein determination 36
3.4.3
Determination of fat content 37
3.4.4 Ash
content determination 38
3.4.5
Determination of crude fiber 39
3.4.6
Determination of carbohydrates 40
3.4.7
Dietary fibre determination 40
3.5 Particle Size Distribution Analysis 41
3.6 Starch
Profiling 41
3.6.1
Resistant starch 41
3.6.2
Total starch determination 42
3.6.4
Amylose and amylopectin content analysis 42
3.7 Sensory
Evaluation 43
3.8
Glycemic Index Measurement 43
3.8.1 Ethics approval 43
3.8.2 Glycemic index determination 43
3.8.3
Determination of blood glucose response 44
3.8.4 Glycemic index calculation 44
3.9 Statistical Analysis 45
CHAPTER 4: RESULTS AND
DISCUSSION
4.1 Proximate Content and Energy Value 46
4.1.1
Moisture content and dry matter 46
4.1.2
Crude protein content 46
4.1.3
Fat content 47
4.1.4
Crude fibre content 48
4.1.5 Ash content 49
4.1.6 Carbohydrate content 50
4.1.7 Energy value 51
4.2 Starch Characteristics of Garri/Pearl
Millet Flour Samples 54
4.2.1 Amylose 54
4.2.2 Amylopectin 55
4.2.3
Resistant Starch 55
4.2.4
Total Starch 56
4.3 Dietary Fibre Content of Garri/Pearl Millet
Flour Samples 58
4.3.1
Soluble dietary fibre 58
4.3.2
Insoluble dietary fibre 58
4.3.3
Total dietary fibre 59
4.4 Particle Size 62
4.4.1
Particle size distribution of garri/pearl millet flour blends 62
4.5 Sensory Properties of Garri Sample 64
4.5.1
Color 64
4.5.2
Smoothness 64
4.5.3
Flavor 64
4.5.4
Taste 65
4.5.5
Consistency 65
4.5.6
Moldability 65
4.5.7
Swallowability 65
4.6 Glucose Responses 69
4.7 Glycemic Indices of Garri/Pearl Millet Eba Blends 69
4.7.1
Glycemic load 72
CHAPTER 5: CONCLUSION AND RECOMMENDATION
5.1 Conclusion 74
5.2 Recommendations 75
References 76
LIST
OF TABLES
3.1 Sample
Formulation 35
4.1 Proximate
Content and Energy Value of Pearl Millet/Garri
Flour
Samples 52
4.2 Starch
Characterization of Garri Supplemented with
Raw
Germinated Pearl Millet Flour Blends 57
4.3 Dietary Fibre Content of Garri/Pearl Millet
Flour Samples 61
4.4 Particle Size Distribution of Garri/Pearl Millet
Flour Samples 63
4.5 Sensory Scores of Garri/pearl Millet Eba Blends 67
4.6 Glucose
Response of Garri/pearl Millet Eba
Sample at
Various
time Interval (mg/dl) 68
4.7 Glycemic Indices of Garri/Pearl Millet Eba Samples 71
4.7.1 Glycemic
load of eba samples 73
LIST
OF FIGURES
3.1 Processing of Germinated and Fermented Pearl
Millet Flours 32
3.2
Processing of Garri Samples 34
CHAPTER
1
INTRODUCTION
1.1 BACKGROUND OF STUDY
Cassava (Manihot
esculenta) is reported to be the major source of carbohydrate for more than
500 million people in tropical Africa, South-America and Asia; providing 37%,
12% and 7% dietary energy in these areas, respectively (Agbara and Ohaka, 2018). Garri which is a common
popular food for Nigerian dwellers is normally produced after cassava has been
fermented and subjected to other processing techniques (Elijah, 2014).
Nigeria, the largest producer of cassava in the world,
harvests 36.8 million tonnes from 3.13 million hectares with an average yield
of 11.7 tonnes/ha (Babatunde, 2012). Local varieties of cassava produce an
average of 12 tonnes/ha while improved varieties produce up to 25 tonnes/ha
(Tarawali et al., 2012). The commonly
available white cassava lacks some basic micro nutrients hence, considering the
important role of cassava in the diets of Nigerians, National Root Crops
Research Institute (NRCRI) Umudike and International Institute of Tropical
Agriculture (IITA), Ibadan jointly developed cassava varieties that has been
bio-fortified in order to complement government’s efforts to check certain
nutritional deficiencies such as malnutrition and other nutritionally
implicated ailments in the country (Adeola et
al., 2017). These bio-fortified varieties however may not be readily
available and accessible to the local farmer in villages due to a high demand,
cost and/or ignorance of their availability by these farmers.
Millet (Pennisetum
glaucum .l) is capable of growing in harsh climatic conditions like less
rainfall, no fertilizer availability or any other facilities. So, they are
frequently recommended for farmers dealing with difficult circumstances (Soumya
et al., 2016). Out of all varieties
of millet (kodo, finger, foxtail, proso, barnyard, little millets, ETC), pearl millet
occupies cultivated area of greater than 29 million hectare but is restrictedly distributed
geographically within Africa and Asia with 15 million and 11 million area
respectively.
According to Ekta and Sarita (2017), pearl millet (Pennisetum glaucum .l) is rich in
calcium, iron, zinc, lipids, amino acids such as lysine, threonine, tryptophan;
fatty acids such as omega-9, omega-6 and omega-3; phytochemicals such as
tannins and phytates acting as antioxidants. Pearl millet has low glycemic
index and may render therapeutic effects in some health problems like anaemia,
constipation, diarrhea, diabetes, cardiovascular diseases, celiac diseases, cancer
(Truswell, 2002; Vanisha et al., 2011;
Gupta et al., 2012). As a result of
some of the phytochemicals (anti-nutrients) present in pearl millet,
digestibility is poor and it is unpleasant to taste leading to a subsequently
reduced use of the product. In order to increase the use of millet, certain
food processing methods such as milling, soaking, cooking, malting,
germination, ETC are applied to improve digestibility, nutrients
bioavailability and decrease anti-nutrients (Choudhury et al., 2011; Ekta and Sarita, 2017).
Germination is a biochemical process which involves
the transition of a seed from dormant state to vital active state; leading to
an increase in properties like protein content, mineral bioavailability,
dietary fibre and decrease in anti-nutirents such as tannin, phytic acid content
and polyphenols (Ghavidel and Prakash,
2007; Ekta and Sarita, 2017 ).
Fermentation of cassava is the most important and
widely used means of cassava processing. Fermentation enhances the nutrient
content of cassava through biosynthesis and enhanced bioavailability of
vitamins, essential amino acids, proteins and fibre digestibility. It also aids
in the degradation of anti-nutritional factors (Obueh and Kolawole, 2016).
According to Ihediohanma (2011), an increase in the length of fermentation (24,
48, and 72 hours) of a cassava specie (Manihot
utilisima) caused a decrease in dietary fibre and subsequent increase in
the glycemic index (62, 67, and 73) respectively of the garri produced.
Indicating that garri made from the 24 and 48 hours fermentation was an
intermediate GI food and that from the 72 hours fermentation a high GI food.
The rate at which food is able to increase the blood
glucose is called the glycemic response while the glycemic index (GI) is the
measurement of the food’s glycemic response as compared with the glycemic
response of a standard food (glucose GI=100, bread GI=71) by same subjects
(Ihediohanma, 2011). High glycemic index foods elicit, calorie for calorie,
higher insulin levels and C-peptide excretion than low GI foods (Wolever and
Bolognesi, 1996; Omoregie and Osagie, 2008). Reductions in dietary GI may also
lower the risks for various conditions associated with hyperinsulinemia such as
diabetes mellitus (Salmeron et al., 1997;
Omoregie and Osagie, 2008) and cardiovascular diseases.
In Nigeria, a majority of the adult population
preferably eat foods made from tubers such as cassava (Manihot Spp) and locally grown cereals such as rice, maize or
millet (Pennisetum typhoides). The
powdered form of these crops are usually reconstituted in hot water to form
solid pastes (commonly known as swallow) and eaten with soups.
1.2 STATEMENT OF
PROBLEM
Cassava is the staple food for over one (1) billion
people in the world especially in Asia and Africa; due to its high moisture and
cyanide content it undergoes series of processing techniques and is transformed
into various forms such as garri- a starchy staple (convenient) food high in
calorie; commonly sold and consumed in Nigeria (Ebeye, 2018). Garri is cheap,
available all through the year in every part of Nigeria and is ready-to-eat on
purchase.
In a study by Egwim and Gajere (2017), consumption of
food low in glycemic load led to increased satiety, a delayed return of hunger
and decreased food intake while a regular ingestion of high glycemic foods was
found to lead to an increased susceptibility to obesity which is a potential
factor favoring hyperglycemia, hyperinsulinemia, reduced insulin sensitivity,
hyperglyceridemia and a decreased blood HDL-cholesterol concentration.
According to Ahmed et
al. (2013), Nigeria is the third country that grows the highest quantity of
millet grain in the world (at 59,994tons/annum) after India and Niger
respectively. Millets have been found to be of high nutritional standard
comparable to rice and wheat. Pearl millet for instance is rich in resistant
starch, soluble and insoluble dietary fibre, minerals, essential amino acids
and phytochemicals. This study however, highlighted that millets only serve as
a major food specifically among the non-affluent segments of many African and
Asian countries; hence this crop is considered to be highly underutilized.
1.3 JUSTIFICATION
OF THE STUDY
In Nigeria, most indigenous staple foods available are
based on starchy foods that are high in glycemic index. However, more than just
a low glycemic index food, a fortified diet is more appropriate for diabetics
and combating malnutrition across several socio-cultural and economic groups
without modifying cultural habits (Asinobi et
al., 2016). With the assertion above in mind, this work was focused on the
possibility of developing blends of garri grits and pearl millet as a meal
recommended for diabetic patients. The choice of food blend was informed by the
fact that pearl millet has been found to be both rich in essential nutrients
and low in glycemic index (Vanisha et al.,
2011) and garri a meal preferred by a great percentage of the Nigerian
population is cheap, available all through the year in every part of Nigeria
and is ready-to-eat on purchase (Ebeye, 2018).
1.4 OBJECTIVES OF
THE STUDY
The main objective of this study was to investigate
the effects of inclusion of pearl millet flour on the chemical composition, glycemic
index and sensory properties of garri.
The
specific objectives were to:
1. Evaluate
the effect of inclusion of germinated pearl millet and the effect of fermentation
time on the Chemical composition and starch properties of garri.
2. Determine
the sensory properties of the composite garri.
3. Evaluate
the effect of inclusion of germinated pearl millet and the effect of
fermentation time on the glycemic index of the composite garri
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