ABSTRACT
Production and quality evaluation of whole grain agidi was studied. The maize slurry was subjected to functional and physiochemical analyses while the agidi samples were analyzed for proximate, physiochemical mineral and sensory properties. Significant differences (p<0.05) exist on the functional properties of the slurry samples with mean values ranges of 87.50 to 93.00% dispersibility, 61.29 to 76.25 oC gelation temperature, 4.43 to 5.85% swelling power, 3.94 to 5.67% solubility and 71.07 to 78.18% syneresis. The physiochemical mean values ranged from 20.78 to 21.60% total solid, 0.02 to 0.03 % TTA, 3.82 to 3.97 pH, 2.22 to 3.92 foam capacity and 51.45 to 69.46% foam stability. The proximate composition values of the agidi samples ranged from 39.88 to 46.16% moisture, 0.15 to 0.96% ash, 1.62 to 1.76% fat, 1.68 to 6.56% protein, 0.23 to 0.64% fiber and 44.77 to 56.05% carbohydrate. Significant differences (p<0.05) exist on the mineral composition of the mineral composition with mean values range of 3.65 to 7.21 mg/100g calcium, 3.57 to 4.58 mg/100g magnesium, 10.79 to 13.36 mg/100g iron, 325.50 to 613.63 mg/100g sodium and 2.21 to 3.50 mg/100g zinc. The physiochemical properties of the agidi samples ranged from 3.59 to 4.35 pH, 53.85 to 60.13 % total solid, 0.01 to 0.02 % TTA, 0.20 to 1.68 % foam capacity and 38.79 to 47.50 % foam stability. The sensory scores of the agidi samples ranged from 5.15 to 7.45 appearance, 4.90 to 7.65 taste, 5.05 to 7.90 consistency, 5.40 to 7.80 mouthfeel, 4.85 to 7.50 texture and 5.20 to 8.00 general acceptability. The study revealed that Blending maize starch with maize offal in the ratio of 90 % maize starch:10 % maize offal in agidi production should be encouraged for increased nutritive value and sensory acceptance.
TABLE OF CONTENTS
Title
page i
Declaration
ii
Certification
iii
Dedication iv
Acknowledgements v
Table of contents vi
List of tables x
List of figures
xi
List of plates
xii
List of appendices xiii
Abstract xiv
CHAPTER ONE: INTRODUCTION
1.1 Background to the study 1
1.2 Statement
of problems 3
1.3 Justification
of study 3
1.4 Objectives
of the study 4
CHAPTER TWO: LITERATURE REVIEW
2.1 Cereals:
Overview 5
2.1.1 Whole grain cereals 6
2.1.2 Nutritional contents of whole grain cereals 6
2.1.3 Health benefits of cereals 9
2.2 Maize: Production and classification 9
2.2.2 Advances in Global Maize Production 10
2.3 Nutritional value of maize 11
2.3.1 Phytochemical value of maize 13
2.3.2 Carotenoids 13
2.3.3 Phenolic compounds 13
2.3.4 Phytosterols 14
2.4 Health Benefits of Maize 14
2.5 Approaches to improving the nutritive value of maize 16
2.6 Utilization of maize 17
2.7 Food enrichment 19
2.8 Micro nutrient deficiency 19
2.8 Other quality parameters 20
2.8.1
Proximate composition 20
2.8.2 Minerals 20
2.8.3 Sensory evaluation 21
CHAPTER 3: MATERIALS AND METHODS
3.1 Source of raw materials 22
3.2 Sample preparation 22
3.2.1 Production
of whole maize slurry and starch 22
3.3 Formulation
of blends 22
3.4 Production
of Agidi (corn jellos) 22
3.5 Proximate
analysis 29
3.5.1 Moisture
content determination 29
3.5.2 Ash content determination 29
3.5.3 Determination crude fiber 30
3.5.4 Fat determination 31
3.5.5
Crude protein determination 31
3.5.6
Carbohydrate determination 32
3.6 Determination
of the energy value 32
3.7 Mineral
analysis 32
3.8 Physicochemical
properties 33
3.8.1 Determination of pH 33
3.8.2 Determination of total titratable acidity 33
3.8.3 Determination of total solid 34
3.9 Functional
properties 34
3.9.1 Gelatinization
Temperature 34
3.9.2 Solubility 34
3.9.3 Dispersibility
determination 34
3.9.4 Swelling power of
flours/meals 35
3.9.5 Syneresis
determination 35
3.10 Sensory
evaluation 36
3.11 Statistical analysis and experimental design 36
CHAPTER 4: RESULTS
AND DSICUSSION
4.1 Functional properties of raw maize slurry
samples 37
4.2 Physicochemical properties of maize slurry
40
4.3 Proximate composition of gelled agidi samples 43
4.4 Mineral composition of the
agidi samples 47
4.5 Physicochemical properties of gelled agidi samples 50
4.6 Sensory evaluation of the agidi samples 52
CHAPTER 5: CONCLUSION AND
RECOMMENDATIONS
5.1 Conclusion
54
5.2. Recommendations 54
REFERENCES 55
LIST OF
TABLES
Table 2.1:
Composition per 100 g of edible portion of maize 12
Table 3.1: Formulation of blends for agidi (corn jellos) Production 25
Table
4.1 Functional properties of maize slurry samples 38
Table 4.2 Physicochemical properties of maize
slurry 41
Table 4.3 Proximate composition of agidi samples 44
Table 4.4 Mineral
composition (mg/100g) of the agidi
samples 48
Table 4.5 Physicochemical properties of agidi samples 51
Table
4.6 Sensory scores of the agidi
samples 53
LIST
OF FIGURES
Fig. 3.1: Flow chart for production of whole
maize slurry and starch 24
Fig. 3.2: Flow chart for production of agidi (corn jellos) 27
LIST OF PLATES
Plate 3.1:
Whole grain slurry 26
Plate 3.2:
90 % maize starch:10 % offal slurry 26
Plate 3.3:
85 % maize starch:15 % offal slurry 26
Plate
3.4: 70 % maize starch:30 % offal
26slurry
Plate 3.5:
50 % maize starch:50 % offal 26
Plate 3.6:
Whole grain agidi 28
Plate 3.7: Agidi from 90 % starch:10% offal 28
Plate 3.8: Agidi from 85 % starch:15% offal 28
Plate 3.9: Agidi from 70 % starch:30% offal 28
Plate 3.10: Agidi from 50 % starch:50% offal 28
LIST OF APPENDICES
Appendix 1: Anova
for functional properties of maize slurry 63
Appendix 2: Anova
for Physicochemical properties of maize slurry 64
Appendix 3: Anova
for Proximate composition of maize agidi 65
Appendix 4: Anova
for mineral composition of maize agidi
66
Appendix 5: Anova
for Physicochemical properties of maize agidi
67
Appendix 6: Anova
for sensory properties of maize agidi
68
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND TO THE
STUDY
Cereals are an important form of the human
diet as they provide starch and carbohydrate (dietary fiber), thus providing
with the demands of energy and nutrient intake of humans (Serere et al., 2016). Major cereals grown in
Africa include maize, rice, sorghum, and millet (Abiodun and Adedayo, 2018).
Cereals are more widely utilized as food in African countries, than in the
developed world. Cereals account for as much as 77% of total caloric
consumption in African countries (Mkpado, 2013), and contribute substantially
to dietary protein intake in a number of these countries. A majority of
traditional cereal-based foods consumed in Nigeria are processed by natural
fermentation. Fermented cereals are mostly used as weaning foods for infants as
well as dietary staples for adults in most of Africa (Mkpado, 2013).
The diets of most Nigerian households are
maize-based because maize is considered the staple diet. Nigeria is the tenth
largest producer of maize in the world, and the largest maize producer in
Africa, followed by South Africa (Cadoni and Angelucci, 2013). It is the fourth
most consumed cereal during the past two decades, below sorghum, millet, and
rice (Abiodun and Adedayo, 2018). However, it is the most frequently consumed
food staple in Nigeria (IITA, 2003).
Maize (Zea mays) is a source of starch,
protein, fiber, and micronutrients for millions of people in sub-Saharan Africa
(Onyango, 2014) though it is low in protein content (9.4%) and micronutrients (Serere
et al., 2016). Maize is an important
cereal and is used together with other cereals to reduce food insecurity
problems and thus promote survival in rural areas (Afoakwa et al, 2010).
Being among the primary food staples, maize
consumption is widespread across the country and among households of different
wealth. It is widely used in the preparation of traditional foods.
Agidi (corn
jellos), a popular food in Southeastern and Southwestern Nigeria; is a gel-like
traditional fermented starchy food item produced from maize, millet, and
sorghum (Adebola et al., 2016). Its
color depends on the cereal used. It is cream to glassy white from maize, light
brown from sorghum, and grey to greenish color from millet. It is known by
different names in different localities such as Eko (Yoruba), Akasan (Benin), Kamu
(Hausa), and Agidi (corn jellos) (Ibo) (Zakari et al., 2010). It is becoming very
popular, with acceptability cutting across the various multi-ethnic groups and
socioeconomic classes. The ease of consumption, alone or with soup, stew, beans
cake (Akara), moi-moi, as light meal especially amongst post-operative patients
and other patients in the hospitals makes it very popular (Ogiehor et al.,
2005). The traditional production process involves soaking maize grains in cold
water for 1-3 days after which the water is decanted. The soaked grains are wet
milled and sieved and the filtrate is fermented for 2-3 days to yield wet
‘ogi’, which is sour, white starchy sediment and then boiled into a thick
porridge, ‘Agidi (corn jellos)’ (Adebola et al., 2016). Spices and seasonings may be added to improve taste,
and for the rich ones, minced meat may be added (Zakari et al., 2010). The production varies from one locality to another
resulting in a non-uniform product, non-specified quality indices, unknown
shelf life, and lack of safety indices, thus limiting product acceptability to
immediate locality (Adebola et al., 2016).
Furthermore, ‘Agidi (corn jellos)’ deteriorates rapidly in storage
(2-3 days), warranting repetition of the cumbersome and time-consuming
production cycles to keep the product available (Ogiehor et al., 2005).
According to Ukegbu et al. (2015), ‘Agidi (corn jellos)’ has very little nutritive value
and the nutritional losses have been reported in the wet milling method of
preparing it. As a result of
this, many attempts have been made to improve the nutrient content,
particularly protein to reduce the high prevalence of protein-energy
malnutrition among infants.
1.2 STATEMENT OF PROBLEMS
In developing countries, the low-income
groups who constitute the bulk of the population are particularly at risk of
malnutrition as their source of food is basically either from cereals or roots
and tubers. These staples, which are low in some of the essential nutrients,
are usually subjected to different processing methods and as such, most of
these nutrients are denatured or leached out. The traditional method of ‘Agidi
(corn jellos)’ processing is
accompanied by severe nutrient losses, leaching during soaking and fermentation
as well as during sieving to get the needed starch for its processing. Also,
the fermentation and sieving processes of ‘Agidi
(corn jellos)’ preparation make it
very cumbersome for those who solely depend on it to make a living. Hence,
there have been several attempts at improving the nutritional quality of ‘Agidi (corn jellos)’. The strategies used
include the addition of high-protein material such as legumes or the incorporation
of fruits and vegetables. However, no attempt has been made to prepare ‘Agidi (corn jellos)’ from whole fermented grains
such as maize. This, when done, will reduce much nutrient loss and the burden
involved in the preparation of ‘Agidi (corn jellos)’. Also, the maize offal usually
discarded after sieving may now contribute and improve the dietary fiber
content of the food.
1.3 JUSTIFICATION OF STUDY
There is no information yet on the
preparation of ‘Agidi (corn jellos)’ from whole grains such as
maize. The development of these maize-based foods through value-added processes
will establish appropriate and optimum conditions for improving nutrient and product
quality. The study if successful will reduce nutrient loss as well as the tedious
process of preparing ‘Agidi (corn jellos)’. This research work is in line
with national policies of food security and upgrading traditional food
processing techniques, thus adding value to Nigerian local staple foods.
1.4 OBJECTIVES OF THE STUDY
This study was aimed at evaluating the
quality attributes of ‘Agidi (corn jellos)’ prepared from whole fermented
maize grains.
The specific objectives of the study were to:
i.
Produce ‘Agidi (corn jellos)’ from fermented whole grains
(maize).
ii.
Determine the physicochemical, proximate, and mineral composition of ‘Agidi (corn jellos)’ samples.
iii.
Evaluate the functional properties of the sample
iv.
To evaluate the sensory properties of the samples.
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