ABSTRACT
The study to evaluate the suitability of cocoyam (Colocasia esculenta) flour composites in cookies production was conducted. The functional and pasting characteristics of the different composites (0 - 40%) of cocoyam flour with wheat flour were determined. The proximate, mineral, antinutritional, physical and sensory properties of cookies produced from the composite flours were evaluated. The pasting properties were analysed using rapid visco-analyzer while sensory characteristics of cookies were evaluated by panelists (n=20) for taste, aroma, colour, texture and general acceptability. Results of the functional properties of the wheat-cocoyam composite flours differed significantly (p<0.05), with 100% wheat flour having the highest values in emulsion and foam capacities and in foam stability. The values ranged from 0.63 to 0.69 g/ml for bulk density, 0.95 to 1.75 g/g sample for water absorption capacity, 1.45 to 2.45 g/g sample for oil absorption capacity, 14.68 to 35.57% for foam capacity, 10.28 to 19.98% for foam stability, 34.44 to 43.58% for emulsion capacity, 1.14 to 1.34% for swelling index, 14 to 20% for gelation capacity, 68 to 78 °C for gelatinization temperature and 157.00 to 449.50cP for viscosity. The pasting properties including peak viscosity, peak time, trough breakdown, final viscosity and setback varied significantly (p<0.05) among samples, with no definite trend. Range of values obtained include 208.67 – 281.00 RVU (peak viscosity), 30.83 – 94.25 RVU (breakdown viscosity), 140.42 - 225.58 RVU (trough viscosity), 226.08 – 371.00 RVU (final viscosity), 80.08 – 220.33 RVU (setback viscosity), 70.33 – 83.66 °C (pasting temperature) and 4.93 – 5.61 min (peak time). Results of the proximate composition of the cookies were in the range of 3.10 – 5.30% (moisture), 7.00 – 11.33% (protein), 12.20 – 14.33% (fat), 2.00 – 2.70% (crude fibre), 2.10 – 2.75% (ash) and 61.33 – 71.10% (carbohydrate). Cookies from 100% wheat flour had higher contents of protein, fat and ash but lower contents of crude fibre, carbohydrate and moisture than the composite cookies. Cookies from 100% wheat flour had higher mineral contents than the composite cookies. Results of the physical properties showed that the composite cookies had higher values for diameter, spread ratio and cookies’ weight. The sensory characteristics showed no definite trend in the sensory qualities of the cookies and also showed no significant (p>0.05) difference among samples produced from the different composite flours and the control, indicating that the different cookies were favourably similar and comparable. Except for phytate, cookies from the flour composites had higher values than the 100% wheat flour cookies in the antinutritional properties studied. However, they were all below the safe limit thresholds of all the antinutrients. Therefore, wheat:cocoyam flour composites can be adopted for the production of good quality cookies.
TABLE
OF CONTENTS
Title i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
List of Tables ix
List of Figures x
Abstract xii
CHAPTER 1: INTRODUCTION
1.1 Background of the Study 1
1.2 Statement of Problem 4
1.3 Justification 5
1.4 Objectives 5
CHAPTER 2: LITERATURE REVIEW
2.1 Cookies 7
2.1.1 Brief history of cookies (or
biscuits) 9
2.1.2 Classification of cookies (or
biscuits) 10
2.1.3 Decoration of cookies/biscuits 14
2.2 Cocoyam: Its Consumption and
Utilization 14
2.3 Composite Flour Technology in
Cookies Production 15
2.3.1 Production of cookies from blends of wheat and cocoyam flours 18
2.3.2 Importance of cocoyam flour as
a pastry food source 20
2.3.3
Some factors affecting the consumption of cocoyam 20
2.4
Physicochemical Content of Varieties of Cocoyam and the Anti-Nutritional Factors
of Cocoyam Cookies 21
2.4.1
Proximate composition of varieties of cocoyam 21
2.4.2
Anti-nutritional factors of
cookies
from varieties of cocoyam 22
2.5 Oxalate Control in Cocoyam
Processing 23
2.6
Functional, Pasting and Nutritional Properties of Flour 23
2.7 Effects of Functional Properties
on the Potential Behaviour of Cocoyam Flour 25
2.7.1 Bulk density 26
2.7.2 Water absorption capacity 27
2.7.3 Swelling index 28
2.7.4 Solubility in water 28
2.7.5 Foam capacity/foam stability 29
2.7.6 Wettability 29
2.7.7 Gelation property 29
2.7.8
Viscosity 30
CHAPTER 3: MATERIALS AND METHODS
3.1
Sources of Raw Materials 31
3.2
Preparation of Cocoyam Flour 31
3.3
Experimental Design 33
3.4
Formulation of Sample Blends 33
3.5
Preparation of Cookies 33
3.6 Determination of Functional Properties of
Wheat-Cocoyam Flour 36
3.6.1 Bulk density 36
3.6.2 Water and oil absorption capacities 36
3.6.3 Foam capacity and stability 37
3.6.4 Emulsion capacity 37
3.6.5 Gelation capacity 38
3.6.6 Gelatinization temperature 38
3.6.7 Wettability 38
3.6.8 Swelling index 39
3.6.9 Viscosity determination 39
3.6.10 Determination of pH 39
3.7 Determination of Flour Pasting Properties 39
3.8
Determination of Proximate Composition of Cookies 40
3.8.1
Determination of moisture content 40
3.8.2
Determination of crude protein 40
3.8.3
Determination of ash content 41
3.8.4
Determination of fat 41
3.8.5
Determination of crude fibre 42
3.8.6
Determination of carbohydrate 42
3.9
Determination of Physical Properties of Cookies 42
3.10
Mineral Composition Analyses 43
3.11 Anti-Nutritional
Factors Analyses 44
3.11.1 Phytate analysis 44
3.11.2 Determination of
tannin 45
3.11.3 Determination of
alkaloid 46
3.11.4 Determination of saponin
content 47
3.11.5 Determination of
oxalate content 47
3.11.6 Determination of
hydrogen cyanide content 48
3.11.7 Determination of
trypsin inhibitor 49
3.11.8 Quantitative determination of steroids 50
3.12
Determination of Sensory Properties of Cookies 50
3.12
Statistical Analysis 51
CHAPTER 4: RESULTS AND
DISCUSSION
4.1 Functional Properties of
Wheat-Cocoyam Flour 52
4.1.1 Bulk density 52
4.1.2 Water absorption capacity 54
4.1.3 Oil absorption capacity 54
4.1.4 Foam capacity and foam
stability 55
4.1.5 Swelling index 55
4.1.6 Emulsion capacity 56
4.1.7 Wettability 56
4.1.8 Gelatinization temperature 57
4.1.9 Viscosity 57
4.1.10 pH 58
4.2 Pasting Properties of
Wheat-Cocoyam Composite Flour 58
4.3 Proximate Composition of
Wheat-Cocoyam Cookies 62
4.3.1 Moisture content 62
4.3.2 Crude protein 64
4.3.3 Crude fibre 64
4.3.4 Ash 64
4.3.5 Fat 65
4.3.6 Carbohydrate 65
4.4 Mineral Content of Wheat-Cocoyam
Cookies 66
4.4.1 Sodium 66
4.4.2 Magnesium 68
4.4.3 Calcium 68
4.4.4 Phosphorus 68
4.4.5 Potassium 69
4.4.6 Iron 69
4.5 Physical Properties of
Wheat-Cocoyam Cookies 70
4.5.1 Diameter 70
4.5.2 Thickness 72
4.5.3 Breaking strength 73
4.5.4 Weight 74
4.6 Sensory Attributes of
Wheat-Cocoyam Cookies 75
4.6.1 Aroma 75
4.6.2 Taste 75
4.6.3 Appearance 78
4.6.4 Texture 79
4.6.5 General acceptability 79
4.7 Anti-Nutrient Content of
Wheat-Cocoyam Cookies 80
CHAPTER 5: CONCLUSION AND
RECOMMENDATIONS
5.1 Conclusion 83
5.2 Recommendations 84
References
Appendices
LIST
OF TABLES
3.1: Quantity of ingredients for
cookies production 34
4.1: Functional properties of
wheat-cocoyam flour 53
4.2 Pasting properties of
wheat-cocoyam flour 59
4.3:
Proximate composition of wheat-cocoyam cookies 63
4.4: Mineral composition of
wheat-cocoyam cookies 67
4.5: Physical properties of
wheat-cocoyam cookies 71
4.6: Sensory attributes of
wheat-cassava cookies 77
4.7: Anti-nutrient content of
wheat-cocoyam cookies 81
LIST
OF FIGURES
3.1: Flowchart for the production of cocoyam flour 32
3.2: Cocoyam (Colocasia esculenta) corms 32
3.3:
Flowchart for the production of cookies 35
4.1: Samples of
cookies baked with 100% wheat flour 76
4.2: Samples of
Wheat-Cocoyam cookies 76
CHAPTER
1
INTRODUCTION
1.1 BACKGROUND OF THE
STUDY
Baking is the prolonged cooking of food by the
application of dry heat acting by convection and by radiation, normally using
an oven but also in hot ashes or hot stones. It is a dry heat cooking method
primarily used for preparing snacks such as cakes, breads, biscuits, doughnuts,
chin-chin, wafers, pastries, pies, tarts, quiches and cookies
(http://www.wikipedia.com/baking,
May, 2009). Around the world, snacks are principal foods which
provide more nutrient than any single food source (Kay, 1987). Types of snacks
consumed vary widely from country to country. Thus we do meet such names as
French, Spanish, Iranian and Egyptians snacks (Mayhew and Penny, 1988).
Cookies are examples of snacks. They are small, flat
sweet baked good, usually containing flour, eggs, sugars and either butter,
cooking oil or another oil or fat. Some cookies can also be named after their
shapes such as date squares or bars. In most English speaking nations, cookies
are called biscuits, except in the US and Canada (BIRT, 2010). The major
ingredient in the production of cookies is the flour because it contains a fraction
of protein which is responsible for paste formation, which is one of the
characteristics of good snacks (Mayhew and Penny, 1988).
Conventionally, baking flour is the powder made from
cereals. However it can equally be produced from other starch based products
such as cassava, maize, yam, nuts and others. Flour is the major ingredient in
baked goods production and most especially bread, which constitutes a staple in
many countries’ diet. The availability and sufficient supply of flour has often
been an important economic and political issue (Adeleke and Odedeji, 2010).
Wheat which is the chief raw material in the
production of wheat flour cannot thrive or survive well in Nigeria soil and
weather conditions prevalent in our regions (Akubor and Obiegbuna, 2014).
Therefore, wheat has to be imported for wheat flour production. The importation
has led to the relatively high price of the commodity with the overall effect
on the price of baked goods. Attempts to incorporate composite flours into
wheat flour resulted in net savings of income and reduced cost of baked goods (Adeleke
and Odedeji, 2010). Supplies of wheat come from temperate countries such as
Canada, U.S.A, Argentina, USSR, and others. In this regard, the continuous
importation of wheat must be paid for by poor tropical, non-wheat producing
countries with scarce foreign currency. It would be to the advantage of these
countries if there is a reduction or even elimination of this importation by
making snacks with wheat blended with local materials such as cocoyam, cassava,
maize, sorghum, rice flour as well as groundnut meal, respectively (Dendy et al., 1970; Olatunji and Akinrele,
1978; Olatunji et al., 1982; Tindall,
1983). Such flour blends are generally referred to as composite flour.
Cocoyam (Colocasia
esculenta) is among the major staple crops for a majority of West Africans.
They are usually referred to collectively as ‘Taro’ (Lyonga and Nzeitchueng, 1986).
The variety, Xanthosoma sagittifolium (Tannia) is hard and high
in starchy, which makes it easily amenable for use in the preparation of
pounded fufu while the variety Colocassia esculenta (Taro) with a
softer tuber is often prepared and consumed like yam. It also produces a more
flouring starch suitable for application in flour composite mixtures for food
productions. There are also indications that the Colocasia flour can be used effectively in baking and confectionary
because of its pentosans content (Ihekoronye and Ngoddy, 1985).
Composite flours quite differ from the ready mixed
flours well known to millers and bakers. Whereas ready mixed flours contain all
the non-perishable constituents of the recipe for a named or specific baked good,
composite flours are only a mixture of different vegetable flours with or without wheat flour,
rich in starch or protein, prepared and used for certain groups of bakery products
(http:/www.wikipedia.com/composite flour, 2009). This flour has been
incorporated with wheat flour in production of baked goods including cookies,
bread, cake and many others. Through this, incorporation, diversified and
acceptable products can be produced at much reduced cost (Abbey and Ibeh, 1988;
Adeyeye et al., 1994).
Compositing wheat flour with locally available cereals
and root has been reported to be desirable (Oyerekua and Adeyeye, 2009).
Composite flours have those properties that enhance their wide utilization. These
include water and oil absorption capacities, foaming capacity and stability,
bulk density, gelation capacity, emulsion capacity and others, which are
referred to as functional properties (Abbey and Ibeh, 1988; Adeyeye et al., 1994).
Functional properties have been described as those
physicochemical properties that influence the behaviour of proteins in food
systems during processing, storage, cooking and consumption (Adeyeye et al., 1994). Functional properties are
important in determining the quality, including the nutritional, physicochemical
and sensory properties of the final products and in facilitating processing,
such as improving the machinability of cookie dough or slicing of processed
meat (Abbey and Ibeh, 1988).
Functional properties of food proteins play important
roles in food processing and food product formulation (Wu et al., 2009). These properties, however, vary with the type of
food products. For example, protein with high binding capacities are desirable
for use in sausages, meats, bread and cakes, while proteins having high
emulsion and foaming capacities are good for salad dressings, frozen desserts,
soups, sausages, bologna, confectionary and cakes (Ahmedna et al., 1999).
On the other hand, pasting properties of starch depend
on the physical and chemical characteristics of the starch such as amylose/amylopectin
ratio, mean granule size, granule size distribution and mineral content
(Boruch, 1985; Wiesenborn et al.,
1994). Pasting properties are defined as the phenomenon following starch
gelatinization, involving swelling granules, exudation of molecular components
from the granules and eventually, total disruption of the granules (Atwell et al., 1988).
1.2 STATEMENT OF PROBLEM
The availability and adequate supply of flour has
often been a major economic and political issue .Wheat which is the chief raw
material in the production of wheat flour cannot thrive or survive well in
Nigerian soil and weather conditions prevailing in tropical regions. Therefore,
wheat flour has to be imported. The importation has led to the relatively high
price of the commodity with the overall effect on the price of baked goods.
Therefore, the use of local crops like cocoyam, cassava, etc., in partial
substitution of wheat flour is important.
However, cocoyam has high water content and the
presence of irritants which cause irritation and itching in the mouth, throat
and body, has been the major drawback in attempts at increasing the utilization
potentials of cocoyam as a food or its utilization as flour in baking
process. Despite the nutritional value
of cocoyam, it is still regarded by many as food mainly for the poor. This
misconception has lingered for so long and the numbers of people who depend on
cocoyam for their main meal are not appreciated. Most of the utilization of
cocoyam in Nigeria has been its use as an adjunct either as a thickener for
soups or mixed with yam, banana or plantain, beans and vegetables as main dish.
Using cocoyam as composite flour ingredient in the production of cookies is
therefore a compelling necessity worthy of thorough investigation.
1.3 JUSTIFICATION
Composite flour technology has been used as a means
for augmenting supply of wheat used in the production of biscuit (cookies) and
other baked goods. The attempt to incorporate cocoyam flour into wheat flour as
composite would result in net savings of income and reduced cost of bakery
goods. A study has been carried out on the comparative characteristics of
cocoyam varieties to determine their utilization potentials in food processing (Amanze,
2009).
Cocoyam like other root crops deteriorate few weeks
after harvest due to inadequate postharvest technologies and this makes the
crop scarce and expensive outside the harvesting period. Processing of cocoyam
into flour will extend the shelf-life of the commodity thereby making it
available for use all year round. The use of cocoyam flour in cookies production
will enhance the utilization of an important local crop and improve the
nutritional value of cookies since cocoyam is very nutritious. The conversion
of cocoyam into a stable form such as cocoyam flour and its usage in composite
flour technology will demonstrate the nutritional and economic benefits of
cocoyam. Study by Huang (2005) has shown that cocoyam has fine granular starch
which has been reported to improve binding and reduce breakage of snacks (cookies)
produced from it. According to McWatters et
al. (2003), cookies are easier to
make from composite flour than bread. They are produced in ready to eat (RTE) form,
have wide consumption and relatively long shelf life with good eating quality.
1.4 OBJECTIVES
The general objective of this study was to produce composite
flours from cocoyam (Colocasia esculenta)
and wheat and evaluate their potentials in the production of cookies.
The specific objectives were to:
- Determine
the functional and pasting properties of the wheat:cocoyam composite flours;
- Evaluate
the physical properties, proximate composition, minerals and antinutritional
factors in cookies produced from the flours; and
- Determine
the sensory attributes of the cookies.
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