DEPARTMENT
OF FOOD SCIENCE AND TECHNOLOGY
FACULTY
OF AGRICULTURE AND NATURAL RESOURCES MANAGEMENT (FARM)
IN
PARTIAL FULFILLMENT FOR THE AWARD OF BACHELOR OF SCIENCE (B.Sc) DEGREE IN FOOD
SCIENCE
AND
TECHNOLOGY
TABLE OF CONTENT
Dedication ii
Acknowledgements iii
CHAPTER ONE
1.0 Introduction 1
1.1 Objectives of the Study 3
CHAPTER TWO
2.0 Literature Review 4
2.1. Yam 4
2.1.1. Origin / History of yams 4
2.1.2. Agronomic characteristics
of yam 4
2.1.3. Nutritional composition
of yam 5
2.1.4. Utilization and
processing of yam 7
2.1.5. Production process in instant
poundo yam flour 9
2.1.6 Utilization of instant poundo yam flour 16
2.1.7 Nutritional aspects of
yam processing 16
2.2 Millet 17
2.2.1 Origin/History of Millet 17
2.2.2 Description of Millet 18
2.2.3 Nutritional Composition of Millet 19
2.2.4 Utilization of Millet 20
2.2.5 Production
process of Millet Flour 22
2.2.6Storage of Millet Flour 23
2.3 Composite Flour 23
2.3.1 Importance of composite flour 24
CHAPTER THREE
3.0 Materials
and Methods 25
3. 1. Source of Raw Materials 25
3. 2.Equipments and
Instruments used 25
3.3.Methods for Flour Production 25
3.4. Dough
Making 29
3.5.
Proximate Analysis 29
3.6
Functional Properties Determination 33
3.7. Sensory
Evaluation 42
REFERENCES 43
CHAPTER ONE
INTRODUCTION
Yam (Dioscorea species) is
an important tropical root crop. It is also an important source of carbohydrate
for many people of the Sub-Sahara region, especially in the yam zone of West
Africa (Akissoeet al, 2003). Babaleye (2003) reported that yam
contributes more than 200 dietary calories per capita daily for more than 150
million people in West Africa and serves as an important source of income to
the people.
Yam constitutes a nutritious high
carbohydrate and fibre food source. Other nutrients present in yam are caloric
proteins, minerals and vitamins (Onwueme and Charles, 1994). The crop is
important in household food security, diet diversification, employment and
income generation as well as alleviation of poverty (Akinoso and Olatoye,
2013). Yams are ranked as the fourth major root crop in the world after
cassava, potatoes and sweet potatoes (Adeleke, 2010). Yams are characterized by
high moisture content, which renders the tubers more susceptible to microbial
attacks and brings about high perishability of the tubers with an animal
production of above 28 million metric tonnes (FOS, 2011); Nigeria is the
world's largest producer of edible yam with D. rotundataand D. alataas
the two most cultivated yam species in the country.
According to Egbeet al. (1984),
D. rotundata(white yam) is made up of 67% moisture. By dry weight, the
yam is composed of 80% starch, 7% protein, 7% minerals, 3% fiber and 1.7%
lipids. Industrial processing and utilization of yam includes starch, poultry
and livestock feed, production of yam flour and instant-pounded yam flour
production. Traditionally, the processing of pounded yam using pestle and
mortar is highly valued but is gradually being replaced in the market with the
instant -pounded yam flour. Instant- pounded yam flour requires short
processing time and less energy (Akinoso and Olatoye, 2013).
Poundo yam which is also referred
to as instant pounded yam flour (IPYP) is a processed white powdery form of yam
(dehydrated yam flour) which is produced in a desiccating machine (Ayodejiet
al., 2012). It is a fast means of making pounded yam which is done by
pouring a measured quality of the yam flour into boiling water, which is
stirred continuously until the required texture and taste is achieved (Ayodejiet
al., 2012). The basic technology of yam includes peeling, washing,
slicing/dicing, cooking, drying, milling and packaging.
Millets
are indigenous African cereals that, unlike wheat or rice are well adapted to
African semi-arid and sub-tropical agronomic conditions. They are basically use
as human foods and folder (Wikipedia, 2012). The most widely grown millet is
the Pearl millet, which is an important crop in India and parts of African
(FAO, 1996). Indeed, in many African countries, millet is often the main
component of many meals and is essentially consumed as steam –cookedproducts
(couscous), thick porridges (TO) and thin porridge (Ogi), which can be used as
complementary food for infants and young children and also used in brewing beer
(Fasasi, 2010). Pearl Millet is nutritional better than most other cereals; it
has high levels of calcium, iron, zinc, fiber, vitamin, lipids and proteins
(Wikipedia, 2012). However, millet also features high fiber content and poor
digestibility of nutrients, which severely limits their value in nutrition and
influence their consumer acceptability (FAO, 1996).
Although Millets are nutritionally
superior to other cereals, yet their utilization in the country is not
widespread (Vijayakumar and Mohankumar, 2009). They are mostly used in
preparation of traditional dishes. One possible way of extending their
utilization could be done by blending them with other flours like yam flour as
the suitable processing. On addition of millet flour to yam flour or other
flours, there would be changes in nutritional and functional characteristics of
the flour. This is because some of the chemical composition of the yam flour
will be increased. For example, the millet flour which is high in fiber content
will increase the low fiber content of the yam flour, since high fiber content
of the food product increases bulk in humans and helps to reduce constipation
among the consumers. Such information will be useful to food processors and
nutritionists to formulate commercial product based on yam and millet flour
blends.
OBJECTIVES OF THE STUDY
The objectives of this study are:
I.
To produce high fibre instant
poundo yam flour with millet flour blend.
II.
To determine the proximate and functional
properties of the high fibre instant poundo yam blended with millet flour.
III.
To determine the sensory
properties of the meal of the fibre instant pound yam flour blended with millet
flour
CHAPTER TWO
LITERATURE REVIEW
2.1. YAM
2.1.1. ORIGIN / HISTORY OF YAMS
Yam (Dioscorea species) is
an annual or perennial tuber-bearing and climbing plants belonging to the
family of Diocoreceae. Some species of yam originated from Africa before
spreading to other parts of the world while some originated from Asia and have
spread to Africa (Halmet al, 1987). Today, yams are grown widely
throughout the topics and they have a large biological diversity including more
than 600 species worldwide (Burkill, 1960; Coursey, 1967), but only six species
are widely cultivated in West and Central Africa. There cultivated species are D.
alata, D. bulbifera, D. dumetorun, D. esculenta, D. cayenensis and D.
rotundata. Wild types of yam also exist and may be used as food after
undergoing processing during the' hunger seasons (Tettch and Saakwa, 1994). A
few yam species are also grown and used as health food and for medicinal
purposes (Albrecht and McCarthy, 2006). In the West Africa, which is the
principal producer of yam on a global basis, D rotundata, D. cayenesisand
D. alataare commonly grown.
2.1.2. AGRONOMIC CHARACTERISTICS OF YAM
Yam is a plant of the tropical
climates and does not tolerate condition (Coursey, 1967). It is grown and
cultivated for its energy - rich tuber. It is adapted to fairly fertile soils
and is suitable for intercropping with grain legumes such as cowpeas, soybeans
and a variety of leafy vegetables. A well drained rich loamy soil however is
the most favourable for yam cultivation. Yam requires a warm humid climate;
however the crop possesses considerable drought resistance (IITA, 2009). Light
intensity is known to affect growth and tuber formation. Short days between 10
to 11 hours promote tuber formation while days longer than 12 hours promote
vine growth. This is usually the reason why yam vines are staked to ensure
maximum interception of light by the leaves to promote yield (Coursey, 1982,
Okezie, 1987).
Traditionally, yams are propagated
vegetatively from whole tubers (seed yams); large tuber pieces (sets) or from
mini sets. The growth of yam starts with a sprout from the post dormant
(Passam, 1977; Onwueme, 1978). Yams exhibit a sigmoidal growth pattern common
to most annual plants. A period of slow growth during establishment is followed
by a phase of rapid exponential growth as the canopy reaches a maximum area and
finally growth rates decline as the canopy senesces (Sobulo, 1972). Maturity
has not been defined in yam even though it is traditionally measured by the
dryness of vines (Okoli, 1980). Osagie and Oputa (1981) also reported that the
physiological status of yam tuber at harvest may be influence its storage
period and food quality characteristics.
2.1.3. NUTRITIONAL COMPOSITION OF YAM
Yam tuber is the most economically
utilized part of the yam plant. Its chemical composition varies with species.
It may vary due to the environmental condition of the places of cultivation
(Onwueme, 1978). Yam is essentially a starchy food. Its greatest single
component is water accounting for about 65 - 85% of the fresh weight.
Carbohydrate on the other hand is the major component of dry weight basis and
second on wet weight basis accounting for about 20 - 35% of the fresh weight
(Dutta, 2003).
Most of its species contain
carbohydrate which are mainly starch i.e. amylopectin branched chain starch
existing in the cells in form of starch granules (Uguru, 1993). Sugar and
protein are only in a quantity of about 2 -3% respectively, with protein being
mainly sulphur containing amino-acid most of which are caused if the tuber is
chilled (Purseglove, 1976). When cut the tuber exudes mucilage and these are
mostly glycoprotein containing the enzymes that help in the defence of the yam
tuber under the soil against external attack or when injured (Asiedu, 1992).
Yam also has small amount of fat,vitamins and minerals like iron, phosphate,
and zinc. Alkaloids and steroids, for examples dioscorine and diosgenien
respectively, are also found in yam and they create a bitter taste which
discourage pest from eating the tuber. This toxin could kill the consumer if
taken in a large quantity in its raw state. Basically yams contain low fibre
content.
Table 1: Chemical composition of yam (D. rotundatd) (White
yam)
|
Component
|
% Composition
|
|
Energy
|
112 KJ
|
|
Moisture
|
70.2
|
|
Protein
|
35
|
|
Fat
|
0.1
|
|
Fibre
|
0.5
|
|
Ash
|
1.0
|
|
Total Carbohydrate
|
25.2
|
Source:
Walsh, (2003)
Furthermore, most yams tend to be
rich in thiamin, riboilavin, niacin, etc (Edijala, 1980). Yam products
generally have a lower glycemic index than potato production which means that
they will provide a more sustained form of energy and give better protection
against obesity and diabetes (CCIAR, 2006).
2.1.4. UTILIZATION AND PROCESSING OF YAM
By far, the greater part of the
world's yam crop is consumed fresh. Tuber utilization is mostly as boiled or
pounded yam. For use in fresh form, tubers are stored between harvest periods.
The use in fresh form, tubers has been in home food with little including trial
involvement (Rasper and Coursey, 1967). Changes in whole wholesomeness during
storage include would repair diseases and pests of stored tubers. Hence, yam
tubers are lost after 4 -5 months of storage. Drying of (injured) tubers soon
after harvest and converting into slices or milling into flour for fufuensures
availability of yam in various forms. Traditionally processed yam products are
made in most yam-growing areas, usually as a way of utilizing tubers that are
not fit for storage. Usually, fresh is peeled, boiled and pounded until a
sticky elastic dough is product (Coursey, 1967; Osagie, 1992). Another important
product from yam processing is yam flour (instant poundo or pounded yam flour).
Traditionally yam is processed to
fufu by peeling, slicing/cubing, cooking, and pounding in mortar (wooden
mortar) and fufu is constituted though this process. Up till today, this
procedure is still practiced in remote parts of South East Nigeria and yam
pounding into fufu still accompany many ceremonial occasions in this part of
the country (Bonetalet al, 1994),
Industrial processing has brought
a more enhanced and efficient method of yam processing into instant fufu flour
or instant poundo yam flour (yam yam). It has made the fufu making process
easier and the availability of yam fufu increased, as the yam flour can be
stored for a very long period of time than the fresh yam which is used for the
traditional processing; as well as the stress in pounding the yam (cooked
cubes) are reduced as it only needs reconstitution of the flour into fufu with
hot boiled water and stirring it till the required texture is formed (Bonetaet
al, 1994).
2.1.5. PRODUCTION PROCESS IN INSTANT POUNDO YAM FLOUR
The production process consisting of simple unit operation
which have been mechanized the Hour chart for the production of poundo yam
flour production is presented below:-
Yam Selection
and Weighing
Peeling
Washing and Slicing
Dicing and Sulphiting (0.1% Sodium metabisulphite)
Steam
Blanching
Drying
(hot air oven 50 – 700C)
Milling
Sieving
INSTANT
POUNDO YAMFLOUR
Packaging
Storage
|
The Basic unit operations in yam processing are:-
2.1.5.1.YAM SELECTION AND WEIGHING
Wholesome suitable yam tubers are selected for IPYF
(Instant Pound Yam Flour) production; the wholesome tubers are sorted during
sorting. During sorting, yam tubers that are disfigured during harvest are
rejected and it is very important to select carefully or internal deterioration
due to aging may have started. If the yam tuber have been stored for a long
period of time, the enzymes that are present may have brought about
deterioration due to temperature of the storage area (barn, store house,
underground etc). If the yam tubers have been exposed to some light, this type
of condition can also lead to spoilage which may not be visible at mere looking
at the yam tuber. A simple way of detecting spoilage is by scalping off the
back of the yam tuber and viewing it for seconds, if there is internal
spoilage, it will show brown to black discolouration in few seconds depending
on the level of spoilage. The enzymes that can cause discoloration of yam and
spoilage are polyphenoxidase (PPO), perioxide (POP), fenitic acid, flavanol,
climanic acid, hexokinase, phosphorylase, alcohol dehydrogenase (Ugochukwuet
al, 1984).
The second unit operation after
the sorting of the yam tubers is weighing and it involves using a measuring
balance, to know the weight of the yam tubers.
2.1.5.2. PEELING OF YAM
This is the removal of the outer corky periderm. The
method of peeling varies. The general methods apply include:-
(a) Steam Peeling: This
involves the exposure of the tubers to steam pressure for a period of time. The
process may be batch or continuous.
During this steam exposure, the
stream penetrates the cortex, often the peel and results in a slight expansion
of the space between the peel and the cortex. This makes it easy for the peels
to be removed when subject to minor abrasive or mechanical processing.
(b)Chemical Peeling: This
involves the immersion of the yam tuber in some non-toxic chemical such as
caustic soda solution of low concentration which helps to soften the peel.
Usually, when this method is used, they are couplet with the use of heat. The
process is controlled by varying the concentration of the lye and its
temperature for effective peeling process. One major setbacks of this method is
the need to use a large volume of water to remove the effect of the chemicals
during the post-peeling washing.
(c) Mechanical Peeling: The basic
mechanical methods includes the Abrasive peelers, rotary laid mounted rim
peelers and use if belt conveyor. In the abrasive peeler, the peeler consists
of a vertical cylinder with a rotating disc in the bottom and a hinge cover at
the top. Abrasive grits may be applied to the inner walls of the chambers or to
rotating disc or both. A measured load of the root or tuber is put into the
cylinder and when the disc is rotated, the tuber spins or thimble so that the
peels are rubbed off when the tubers shall against the abrasive surface.
2.1.5.3 SULPHITING
Sulphiting serves a
multifunctional role in foods. They posses antimicrobial activity and inhibit
both enzymatic non-enzymatic browning reactions which during. Bisulphate exerts
competitive inhibitory effect on polyhenoloxides, by binding a sulphydrl group
at the active site of the enzyme. On the other hand, bisulphate inhibition is due
to the reaction of sulphites with intermediate quinones, resulting in the
formation of sulphoquinones which irreversibly inhibits polyhenol oxidase
causing complex inactivation.
Although sulphites are very
effective in controlling browning, they are subject to regulatory restrictions
owing to their potentially adverse effect on health. Many reports have
described allergic reactions in humans, following the ingestion of
sulphite-treated foods by hyper sensitive asthmatics. The of sulphiting agents
in food processing is based on sulfurdioxide equivalences. The Joint Expert
Committee on Food Additives (JECFA) of the World Health Organization (WHO) and
the Food and Agriculture Organization (FAO) recommended an acceptable sulphite
intake of 0.07mg sulphur dioxide per kg of body weight. Food and Drug
Administration (FDA) has proposed maximum residual sulpher dioxide levels for
certain foods.
2.1.5.4 BLANCHING: Steam
blanching is the operation that takes care of phenoxidase and polyphenoxidase
compounds and other enzymes which act on the phenol compounds present in yam
tubers to bring about discolouration (Browning), when exposed to air for some
time after cutting. When the yamclips turn brown, the colour of the yam flour
after milling will also be brownish due to the fact that the colour of the
dried yam chips must affect the colour of the flour after milling.The purpose
of blanching operation is to reduce browning or discoloration of the yam clips
when milled to flour and will have a brighter colour and more acceptable look
or appearance to compare with unbalanced yam flour. The time of blanching also
determines the levels of enzyme reduction (Negron, 1995).
The blanching temperature is the
most important parameter in the unit operation, because if the temperature is
not up to achieved deactivation. The purpose of blanching is not achieved but
if the operation is carried out at required temperature which is not favourable
to the target enzymes 20 minutes can deactivate polyphenoxidase, or either use
of 100 °C in 2 minutes
can still do the same (Bonetaet al., 1984).Blanching
time can also affect the operation. If the time is not well kept, it can lead
to over blanching or under- blanching and some of the targeted enzymes will not
be favoured by this phenomenon.
Blanching time is directly
proportional to the temperature used for the operation and when blanching at
low temperature, longer time should be taken than when blanching at high
temperatures.
2.1.5.5 DRYING
Drying is defined as a process of
simultaneous heat and moisture transfer in which heat is required to evaporate
the moisture that flows from the product surface into an external drying medium
usually air. It could also be defined as the removal of biologically active
water. These stop the growth of microorganisms, reduce the rate of enzyme
activity and chemical reaction.
The main objective of drying is to preserve the product
during prolong storage. The drying process meets the objective by reduction the
moisture content of the product to levels which are adequate to limit microbial
growth or other reactions. Moisture content reduction results in preservation
of quality characteristics such as flavour, nutritive value and the significant
reduction in product volume. The removal of moisture to produce most dehydrated
foods is accomplished by thermal dehydration, a process that utilizes heat to
remove the moisture held in the product. First heat transfer is involved in
removing the heat from the heating medium to the point at which evaporation
occurs (Heldman, 1975).
Drying not only inhibits microbial growth in foodstuffs
but also preserves colour, texture, flavour and nutritive value; so the process
of drying should benecessarily controlled in order to prevent thermal
degradation of the products. The level of moisture required to prevent
microbial growth is usually less than 10% where as for prevention of
biochemical deterioration, is much lower than 5% (Peterson and
Johnson, 1974). The basic methods of drying include oven drying,
sun drying and micro wave or UV radiation drying.
2.1.5.6
MILLING
Milling is aimed at grounding the food materials to the
required particle size of the fine flour which required. Good milling
quality gives good reliable flour. There are many types of machines used
in the milling of food products. The recommended milling machine like hammer
mill is good for the instant poundo yam flour processing operations as it
is efficient in obtaining the particle size, as well sieves of required aperture size can be
used to sieve the flour after milling to
get the required size of flour particle.
2.1.5.7 PACKAGING
AND STORAGE CONDITIONS OF YAM FLOUR
After the production of yam flour, it is still prone to
spoilage if not well packaged. The flour can re-absorb moisture from the
atmosphere and microbial activity can be enhanced from this point. The
packaging material should be such that there will be no interaction with the
packaged product (yam flour) and the external environment which means that the natural should be
permeable to moisture and gases that can
cause spoilage. When yam flour is stored in a good packaging material like
polyethylene bags, the shelf life is not altered (OtusanyaandJegar,
1996).
Yam after packaging can be effectively stored for a long
period of time of about 12 months or more. It is stored in environments where
rodents and insects are absent, because rodents and insects cause a great
deal of damage to stored yam flour. Storage of yam flour should be
done in correctly constructed storage silo, built very well so that rodent
and insect infestation will be impossible aswell insecticide should be applied on the
surrounding of the storage silo, but care
should be taken so that the insecticide being toxic do not get close of diffuse into the stored yam flour. Example of
insect that attack the yam flour is fasciculate D.G. (Krokida, 1998).
2.1.6
UTILIZATION OF INSTANTPOUNDO YAM FLOUR (IPYF)
IPYF is generally stirred vigorously in boiled hot water to yield fufu
of good texture and consistency which can be eaten with vegetable soups or meats
and fish stews. IPYF can also be combined with other flours like wheat,
cocoyam, potato, cassava, maize, millet flours to form better
flour for the production of confectionary foods, For example, IPYF and wheat
flour can be combined in making of biscuits (Bonetaet al, 1984).
As well, IPYF can serve as stabilizers in soup making. For
example, Nsala soup, this is an Ibo soup from the south eastern
part of Nigeria. It is normally consumed by women that newly gave
birth to babies; it can serve as household soup as well, but in cultural
aspect it is regarded especially as soup for women that just
put bed (Okaka and Okaka, 2001).
2.1.7 NUTRITIONAL
ASPECTS OF YAM PROCESSING
On the basis of reduction in nutrients the preparation of
yam flour appears to be most detrimental process dealing to heavy nutrient
losses, particularly minerals and vitamins.
Fufu preparation and boiling of peeled yam (blanching)
also causeexcessive losses due to the fact that yam contain water
soluble vitamins and minerals which are lost during this process.
Although blanching unpeeled yam tuber is a relatively lengthy process, but it has little effect on
the nutritional values (Bonetaet al, 1994).
The processes that appear most advantageous are charcoal
grilling and frying in palm oil. Nutrient loses thus appear to depend
primarily on the amount of edible surface exposed during processing.
Peeling after blanching reduces loses in the edible portion source less is
removed during this operation.
Blanched yam flour when compared to un-blanched yam flour
will have lower nutritional quality due to vitamins and minerals
loss during the blanching operation, to reduce the rate of nutrients
loss. Time of blanching should not be so long or lengthy as well as
blanching of unpeeled yam can go a long way in retention of nutrients in yam
(Krokida, 1998).
2.2 MILLET
2.2.1 ORIGIN/HISTORY OF MILLET
Millets are a group of highly variable small-seeded
grasses, widely grown around the world as cereal crops, or grains for both human food
and folder. Millets are indigenous African
cereals that unlike wheat or rice are well adapted to African semi- arid and sub-tropical agronomic
conditions (Wikipedia, 2012). The crop is favoured due to its productivity and
short growing season under dry, high
temperature conditions (McDonough etal, 2000).
The most widely grown millet is Pearl millet, which is an
important crop in
India and parts of Africa (especially in Nigeria and Niger). Finger millet, Proso millet and Foxtail millet are also important
crop species. In the developed world,
millets are less important. For example, in the United States the only significant crop is Proso millet, which is mostly
grown for bird seeds (McDonough et
al, 2000).
While
millets are indigenous to many parts of the world, millets most likely had an evoluntary origin in tropical
Western African, as that is where the greatest
number of both wild and cultivated forms exist (FAO, 1995). Millets have been an important food staples in human
history, particularly in Asia and Africa, and they have been in cultivation in
East Africa for the last 10,000 years (Luetal, 2009).
2.2.2 DESCRIPTION OF MILLET
The height of the Pearl millet plant may range from 0.5
to 4 meters. The Pearl
millet grain has great variation, and can be nearly white, pale yellow, brown, grey, slate blue or purple. The kernel
shape has different classification; obovate,
hexagonal, lancerlate globular and elliptical (McDonough et al, 2000).
Grains of Pearl millet are about 3 to 4mm long, much larger than those of other
millets. The seeds usually weigh between 2.5 and 14 grams, with a typical mean of
8 grams. The size of the pearl millet kernel is about one-third of sorghum. The relative proportion of germ to endosperm is
higher in pearl millet than in sorghum.
2.2.3 NUTRITIONAL COMPOSITION OF MILLET
Millets, like sorghum are predominantly starchy. The protein content is
comparable to that of wheat and maize. Pearl and little millets are higher in
fat, while finger millet contains the lowest fat. They are also rich in
carbohydrate content and energy valve. Millets are also relatively
rich in iron and phosphorous. The bran layers of millets are good sources
of B-compare vitamins. However millets also feature high fiber content
and poor digestibility of nutrients, which severely limit their valve in
nutrition and influence their consumer acceptability (FAO, 1995).
The protein content in millet is very close to that of
wheat; both provide about 11% protein by weight, on a dry water basis. Millets
are rich in B vitamins (especially niacin, B6 and folic
acid), calcium, iron, potassium, magnesium and zinc. Millets contain no
gluten, so they are not suitable to raise bread. When combine
with wheat, they can be used to raise bread. Alone, they are
suited for flat bread (FAO, 1999).
Table 2: Chemical composition of Pearl millet (per l00g portion, raw grain)
Component Amount
Water (%) 9.2
Energy (KJ) 1582
Protein (%) 13.3
Fat (%) 6.3
Carbohydrate (%) 75
Fiber (%) 8.5
Ash(%) 1.7
Calcium (mg/kg) 55
Phosphorous (mg/kg) 358
Source: FAO, 1995
2.2.4 UTILIZATION
OF MILLET
Of the 30 million tonnes of millet produced in the world,
about 90 percent in utilized in developing countries and only a tiny
volume is used in the developed counties outside the former Soviet
Union. Exact statistics that are unavailable for most countries, but it is
estimated that a total of 20 million tonnes are consumed as food, the rest
being equally divided between feed and other uses such as
seed, the preparation of alcoholic beverages and waste. Six countries
(China, Ethiopia, India, the Niger, Nigerian and the former Soviet Union) are
estimated to account for about 80% of global millet utilization (FAO,
1996).
2.2.4.1 AsHuman
Food
Consumption of millet varies greatly among countries, though it is the
highest in Africa. In the Sahel, millet is estimated to account for about
one-third of the total cereal food consumption in Burkina Faso, Chad and the
Gambia, roughly 40 percent in Mali and Senegal and over two thirds in the
Niger. Other countries in Africa where millet is significant food item includes
Ethiopia, Nigeria and Uganda.
In Western India, sorghum has
been commonly used with millet flour, to make local staple, hand rolled flat
bread. Millet porridge is a traditional food in Russian, German and Chinese Cuisines. People with coeliac disease can
replace gluten-containing cereals in their diets with
millet (FAO, 1995).
2.2.4.2As Animal Feed
Utilization of millet as
animal feed is negligible in absolute terms and compared with other uses and other cereals. It has be estimated that only
about 10 percent of the millet used globally is fed to animals and birds
(Wikipedia, 2012).
2.2.4.3 As Alcoholic Beverages
Millets are traditional important grains used
in brewing millet bear in some countries,
for instance by the Tao people of Orchid island and in Taiwan. Various people
in East Africa brew a drink from millet known as "ajono", a traditional brew of the Teso. The fermented millet
is prepared in a large pot with hot water and people
share the drink by sipping it through long straws (Wikipedia, 2012)
2.2.5 PRODUCTION PROCESS OF MILLET FLOUR
Millet grains
Cleaning
Washing
Steeping (24 hours)
Steaming (20 minutes)
Drying (over at 70oC for 10hrs)
Milling
Sieving
Packaging
Cleaning
Washing
Steeping (24 hours)
Steaming (20 minutes)
Drying (over at 70oC for 10hrs)
Milling
Sieving
Packaging
Figure 2: Flow Diagram for the production of millet flour Storage
The millet grains are cleaned, winnowed and soaked in
water for 24 hours. The soaked grains are steamed for 20 minutes,
and sun-dried to moisture content of 10-12% and milled into flour.
2.2.6
STORAGE OF MILLET FLOUR
Flour is usually produced as it is needed and is not often stored for a
long period of time because it tends to turn rancid. This is particularly
evident with Pearl millet flour, because of its very high fat content.
Millets especially Pearl millets are therefore best stored as whole grain.
2.3
COMPOSITE FLOUR
Composite
flour is a mixture of different flours from cereal, legumes and roots and
tubers that air created to specific function characteristics and nutrition (Akobundu, 2009). Composite flour that contains
cereals and legumes has proven practical uses and are being utilized in many
parts of the world to improve the nutritional and functional properties
of the flour.
Basically, composite technology refers to be as the
process of mixing cereal flour with legumes, root and tubers to make use of
local raw to produce high quality food products in an economical way. In many cases, it
implies the practical substitution of wheat
flour in a staple diet with other cereals, or flour derived from legumes, root and tubers as a means of
divesting and upgrading the local agricultural find products (UNECA,
1985).
For economic and pulses as social reason, the India
sub-content heavily depends on pulses as sources of protein, minerals and
vitamins in the daily diet of people (Singh, 1997). In selecting the components
to be used in composite flour blends, the materials should be preferably be readily
available, culturally acceptable and provide
increase nutritional potential (Akobunduet al, 1998).
2.3.1
IMPORTANCE OF COMPOSITE FLOUR (A case study of the instant poundo yam flour and the millet
flour blend).
1. Nutritional Enhancement and their Proportion: Flours
produced from either cereals, legumes or tubers will have a
nutritional valve inferior to those produce from the combination of
cereals, legumes or tuber. For instance, yam flour is readily low in fiber
content; but blending the flour with millet flour whose fiber content
is richly high will make the flour blend to be richly high in fibre
content.
2. The use of composite flour of water yam and millet for
meal production would enhance the utilization of local crops as rawmaterials,
improve the nutritive quality of meals and improve the local economy
(Okpalaetal., 2010).
3. The use of composite flours finds their greater use in
providing variety to diet (Iwe, 2003). Since the importance of
fiber foods (instant poundo yam and millet flour blends) will help
nutritionally in high blood sugar and cholesterol reduction in the
body.
CHAPTER THREE
MATERIALS AND METHODS
3.1.
SOURCE OF RAW MATERIALS
The yarn
tubers (Diosocrearotundata] locally called white yam and the millet
seeds will be purchased from Abakaliki Main Market, Abakaliki, Ebonyi State, Nigeria.
3.2. EQUIPMENTS AND INSTRUMENTS
USED
a. Oven,
b. Weighing balance, c. Hammer Mill, d. Warring Blender
3.3. METHODS FOR FLOUR PRODUCTION
3.2.1. Preparation of Instant Poundo Yam Flour
3.2.1. Preparation of Instant Poundo Yam Flour
Instant Poundo Yam Flour (IPYF) will be produced from the method as described
by FIIRO (2005). The yam tubers will be selected, weighed and washed to remove
sand, dirt and other adhering materials. The yam tubers will be
peeled and sliced to 0.02mm thickness, after slicing the yam slices will be
dipped in water containing 0,1% Sodium metabisulphate so as to arrest the
browning reaction and placed in a sieve to remove excess water after which they
will be blanched for 10 minutes at 100°C. The blanched yam slices will be
dried in an oven at 70°C for 10 hours which will be milled and sieved,
packaged in polyethene bag and stored prior to analysis.
Yam Selection and Weighing
Peeling
Washing and Slicing
Steam Blanching
Drying
Milling
Sieving
INSTANT POUNDO YAMFLOUR
Packaging
Storage
Peeling
Washing and Slicing
Steam Blanching
Drying
Milling
Sieving
INSTANT POUNDO YAMFLOUR
Packaging
Storage
Figure 3: Flow sheet for the production of IYPF
3.2.2. Millet Flour Production
Millet flour will be prepared by the method described by AOAC (1990). Millet
grains will be sorted to remove particles, defective seeds and stones
before cleaning thoroughly washed in clean tap water. The seeds will be
soaked in water (steeping) for 24 hours. The seeds will be boiled in water
for 20 minutes at 100°C and drained so as to deactivate the trypsin
inhibitors. The seeds will be oven dried at 70°C for 10 hours. After
drying, the millet seeds will be milled to fine powder and sieved through a
standard sieve of 400um particle size. The flour will be packed in a
polyethene bag and stored prior to analysis.
Millet grains
Cleaning
Washing
Steeping (24 hours)
Steaming (20 minutes)
Drying (over at 70oC for 10hrs)
Milling
Sieving
MILLET FLOUR
Packaging
Figure 4: Flow chart for millet flour production.
Storage
Cleaning
Washing
Steeping (24 hours)
Steaming (20 minutes)
Drying (over at 70oC for 10hrs)
Milling
Sieving
MILLET FLOUR
Packaging
Figure 4: Flow chart for millet flour production.
Storage
2.2.3 Blend formation
The instant poundo yam flour (!PYE) and millet flour (MF) will be
blended together using a warring blender at different ratio of 90:10, 80:20,
60:40 and 70:30% of IPYE and MF, respectively. The flour blends will be labelled
as follows: -
YF: (100% IPYE),
YFMF1: (90% IPYE: 10% Millet Flour), YFMF2: (80% IPYF: 20% millet flour),
YEMF3: (70% IPYE: 30% millet flour) and YFMF4: (60% IPYF: 40 millet flour).
Figure 5:
Flow diagram of blend formation.
IYPF = Instant
poundo yam flour
MF = Millet flour
YSMF 1 = 90%
IPYF + 10% millet flour
YSMF 2 = 80%
IPYF + 20% millet flour
YSMF 3 = 70%
IPYF + 30% millet flour
YSMF 4 = 60%
IPYF + 40% millet flour
3.3.4. Storage
of Samples
All flour samples will be stored in
polyethene bags prior to analysis.
3.4. DOUGH MAKING
The high fiber instant
poundo yam flour and millet flour will be prepared in the laboratory
using the manual method of processing.
3.4.1. Dough preparation
The hot water will be boiled on a pot on a gas cooker. A
quality of the flour blend i.e. 90:10%, 80:20%, 60:40% and 70:30% will
be poured in the boiling water and stirred continuously till it
gelatinizes into a thick dough. A little quality of water will
be added to allow the flour cook properly; the paste will be stirred till
semi-dough will be obtained.
Mixed flour Blends (Yam
and Millet Flours)
Boiling
water (1000ml)
Stirring
the dough
Addition of water
(500ml)
Cooking
(10mins)
Stirring
the dough unitl it gelatinizes
Packaging
Figure 6:
Flow diagram for high fiber Instant Poundo Yam and Dough Processing
3.5.
PROXIMATE ANALYSIS
Each
flour sample will be analyzed for moisture content, crude protein, crude fat, Ash,
crude fiber and the carbohydrate content will be calculated by difference
method.
3.5.1 DETERMINATION
OF MOISTURE CONTENT
The moisture content will be
determined using the procedure described by
AOAC (1990). The moisture content of each sample will be determined by weighing 5g of the sample into an
aluminum moisture canor a crucible.
The sample will be dried in the oven to a constant weight at 105±2°C .
% Moisture Content =
(weight
of can + sample) - (weight of empty can) x100
Weight of
sample 1
3. 5.2
DETERMINATION OF CRUDE PROTEIN
The protein content will be determined using a Foss Tescator Protein digester
and KJECTEC 2200 distillation apparatus (Kjeldhal method) according
to the procedure of AOAC, (1990). Concentrated H2SO4 (12ml) and
2 tablets of catalyst will be put into a kjedhal digestion flask containing
Ig of the sample. The flask will be placed in the digestor in a fume
cupboard and switched on and the digestion will be done for 45 minutes
to obtain a clear colourless solution. The digest will be distilled with 4%
boric acid, 20% sodium hydroxide solution will be automatically metered
into it in the KJECTEC 22000 distillation apparatus or equipment until
distillation will be completed. The distillate will then be titrated with 0.1
HCI until a purple colour
formation indicating the end point. A blank will be run under the same
condition as with the sample. Total nitrogen content will be calculated
according to the formula below:
Crude Protein = (Titre valve (of sample) -
blank) xO.Olx 14.007 x 6.25 x 100
Weight
of sample 1
3.5.3 DETERMINATION OF
CRUDE FAT CONTENT
Crude fat will be extracted in a soxhlet extractor with hexane and quantified
gravimetrically as described by AOAC (1990). Ig of sample will be
weighed into an extraction thimble and will be topped with grease-free
cotton. Before extraction will commenced, the round bottom flasks
will be washed, dried, cooled and weighed. The thimble will beplaced in the
extraction chamber and 80ml hexane will be added to extract the fat. The extraction will be carried out at
135°C and will last for 1 hour 40 minutes
after which the fat will be collected in the bottom flasks will be cooled in a dessicator.
% Crude Fat =weight of fat + 100
Weight of Sample 1
3.5.5. DETERMINATION
OF CRUDE FIBER
Crude fiber will be determined using the method described by AOAC (1990). 2g
of the sample will be transferred into 1 liter conical flask. 100ml of
Sulphuric acid (12.5M) will be heated to boiling and then introduced
into the conical flask containing the sample. The contents will be then
boiled for 30 minutes and ensuring that the level of the acid will be
maintained by addition of distilled water. After 30 minutes, the contents
will be filtered using a muslin cloth held in funnel. The residue will be
rinsed thoroughly until its washing will no longer acidic to litmus. The
residue will be transferred into a conical flask containing the sample. 100ml of
sodium hydroxide (12.5M) will be brought to boil and will be introduced
into the conical flask containing the sample. The contents will be boiled
for 30 minutes and ensuring that the level of the base was minted by
the addition of distilled water. After 30 minutes, the content will then
filter thoroughly until its washing will no longer be alkali. The residue will
be introduced into an already dried crucible and will be ashedat 600°C ±
200°C
% Crude
Fiber = Final weight of crucible - initial weight of cruciblex 100
Weight of sample 1
3.5.6 DETERMINATION OF CARBOHYDRATE CONTENT
The difference method described by
AOAC (1990) will be used to calculate the % carbohydrate content.
% Carbohydrate Content = 100% - %
(Protein + Moisture + Fat + Fiber
+ Ash
Contents).
3.6
FUNCTIONAL PROPERTIES DETERMINATION
3.6.1 DETERMINATION OF BULK DENSITY
The
method as described by Onwuka (2005) will be used to determine the bulk density
of the samples. Ten milliliters capacity graduated measuring cylinder will be
weighed and recorded. The cylinder will be filled with the sample and tapped
gently from the bottom for 30 times until there will be no further dimunsion of
the sample level after to the 10ml mark. The bulk density will be calculated as
follows.
Bulk Density (g/ml) = weight of sample (g)
Volume
of sample (ml)
3.6.2 DETERMINATION OF DISPENSABILITY
Dispensability will be determined using the method described by Kulkarniet
al. (1991). 10 grams of the flour sample will be weighed into 100ml
measuring cylinder, water will be added to each volume of 100ml. The set up
will be stirred vigorously and allow to stand for 3 hours. The volume of
the settled particles will be recorded and subtracted from 100. The
difference will be reproved as the percentage dispensability.
%
Dispensability = 100 - Volume of settled particles.
3.6.3DETERMINATION OF WATER
ABSORPTION CAPACITY
The water absorption capacity shall
be determined according to the method described by AOAC (1990). 1g of the
sample shall be weighed into a labeled test tube; 10ml of distilled water shall
be added. The tube shall be allowed to stand for 30 minutes at room
temperature, they shall be centrifuged at 5000rpm for 10 minutes and the
supernatant water shall be poured into graduated measuring cylinder. The volume
of water decanted shall be measure and recorded as the excess water remaining
after absorption. The water absorption capacity shall be calculated as:
Water Absorption Capacity = V1 – V2
x SG
W
Where:
V1 =
Initial volume of water
V2 =
Volume of water left after absorption
W = weight
of sample used
SG =
Specific gravity of water (1.0)
3.6.4 SWELLING
CAPACITY DETERMINATION
The swelling capacity of the sample shall be
determined by the method described by Lin (1973). 1g of the sample shall be
weighed into a centrifuge tube and the weight of the tube plus the sample shall
be taken. 10ml of distilled water shall be added and thoroughly stirred with a
glass rod for about a minute. The suspension shall be left to stand for 30
minutes at room temperature. The free water shall be decanted, after which the
new weight of the sample shall be recorded. The swelling capacity shall be
calculate as:
Swelling Capacity (%) = W2 – W1 x 100
W1 1
Where:
W1 =
Weight of sample after decanting water
W2 =
Weight of sample before water was added.
3.6.5.DETERMINATION OF GELATINIZATION
TEMPERATURE
The method as described by Onwuka
(2005) shall be used 10g of the sample will be weighted into a test tube. The
aqueous suspension shall be heated in a boiling water bath with continuous
stirring. Gelatinization temperature shall be determined and recorded 30
seconds after gelatinization shall be visually noticed.
3.6.6DETERMINATION OFOIL ABSORPTION CAPACITY
The
method of Onwuka (2005) will be used to determine oil absorption capacity. One
(1) gram of the sample will be weighted into a graduated centrifuge tube and
mixed thoroughly with 10ml of oil using a warring whirl mixer, for 30 seconds.
The sample will be allowed to stand for 30 minutes at room temperature and then
centrifuged at 1600 rpm for 30 minutes. The volume of free oil (the
supernatant) will be read directly from the graduated centrifuge tube.
Oil Absorption Capacity
= Total volume of oil – free oil x density
of oil
Weight of sample
3.6.7 DETERMINATION
OF EMULSION CAPACITY
The
emulsion capacity will be determined according to the method by Naczket al. (1985) with slight modifications.
A flour sample (3.5g), distilled water (25ml) and vegetable oil (25ml) will be
blended for 30 seconds in a moulinex blender at high speed. After complete
dispersion, vege table oil (25ml) will be blended for 30 seconds. After complete dispersion, the sample will be
transferred into graduated centrifuge and centrifuged at 1600 rpm for 10minutes
or until there is separation into two layers. The triplicate mean values of the
emulsified layer will be recorded. The emulsion capacity will be evaluated as.
Emulsion Capacity = X x 100
Y 1
Where:
x =
height of emulsified layer
y =
height of whole solution in centrifuge tube
3.6.8 DETERMINATION
OF FOAMING CAPACITY
The
foaming capacity will be determined by the modified method of Lin et al. (1974). Fifty milliliter of 3%
(w/v) dispersion of flour sample in water will be transferred into a 100ml
graduated cylinder and the foam volume in the cylinder will be recorded. The
volume will be recorded before and after whipping and measured as % of volume
increase due to whipping. The foaming capacity will be evaluated as:
Foaming Capacity
= Volume after mixing –
volume before mixing x 100
Weight of sample 1
Means of triplicate determinations will be reported.
3.7.SENSORY EVALUATION
Sensory
evaluation will be carried out 24 hours after the dough production
by 20 panelists that will comprise of staff and student that will be
randomly selected from the department of Food Science and Technology,
Ebonyi State University, Abakaliki. Sensory parameters of the dough
meal that will be evaluated are taste, appearance, mouth feel, flour and
general acceptability. A 9- point hedonic scale will be used with 9 = like extremely, 8 = like
very much, 7 = like moderately, 6 = like slightly,
5 = neither like nor dislike, 4 = dislike slightly, 3 mdislike
moderately, 2 = dislike slightly and
1 = dislike extremely.
3.8StatisticalAnalysis
All data will be collected in triplicate. One way
Analysis of Variance (ANOVA) will be conducted on each of the
parameters using SPSS version 15 .0 Statistical Package Significant
means will be separated by Duncan's Multiple Tests (DMRT) at a
significance level of P < 0.05 (Steel and Torrie, 1980).
REFERENCES
Adeleke, R.O and
Odedeji, J.O. (2010).Functional Properties of Wheat and Sweet Potato Flour Blends.Pakistan Journal of Nutrition 9:1775-1991
Akissoe,
N. Mestres C, Hounhouigan, J; Nago M. (2003). Biochemical origin of browning
during the processing of fresh yam (Dioscorea spp.) into dried Product. Journal of Agric. FoodChem.53(7):2552-2557.
Akobundu E.N.T, Ubbaonu C.N, Ndupuh C.E. (1998). Studies
on the baking Potential of non-wheat composite flours.Journal of Food
Science and Technology (2S)\2\ 1-214.
Albert, M.A and McCarthy (2006). Seed germination and
dormancy with medicinal woodland herbs Dioscoreavillosa
L,.(Disocoreasceae) and Cpllinsonia Canadensis L. (Laminaceae).Flora
201: 24-31.
AOAC, (1990).Official Methods of Analysis.Association of
Official Analytical Chemists International Washington, DC, USA.
Asiedu,
R; Ng, S.Y.C., Vuylsteke, D; Terauchi, R. and Hahn, S.K. (1992).Analysis of the need for biotechnology research
on Cassava, Yam and Plantain. In: Biotechnology,
enhancing Research on Tropical Crops in Africa. OTA/IITA, Ibadan, Nigeria, Thottappilly, G., Monti, L.M., Mohan Raj.D.R. and Moore A.W (Eds.).Pp.70-74.
Babaleye, T. (2003).Raising the status of the yam, a
Major food crop in West Africa.ANODBIA SUPPLEMENT ISSUE/EDITION. No
463. Pp. 1-3
Burkill, I.H. (1960). The Organographies and Evolution
of Dioscoreacea, the Family of Yams. Journal ofLinnaean Society
of London, Botany, 56:319-412.
Coursey D.G. (1967).Yams Dioscorea spp.In:
Simmonds N.W. cd Evolution of crop plants pp. 70-74.
Coursey, D.G. (1982).Magnitude and Origin of storage
losses in Nigeria yams.Journal of Food and Agric. Org. Vol. 12:
574
Dutta, B (2003).
Economic botany London print PP. 238
Egbe, T., Agbor T. and Treche, S. (1984). Variability in
the chemical composition
of yams grown in Cameroon. In Tropical Root Crops: Production and uses in Africa, 3rd ed., E.R. Terry, E.V.
Doku, O.B.
FAO (1996). Food and Agricultural Organization of United
Nations Production 1995 (Vol 43) Rome Italy
FIIRO, (2005).Federal Institute of Industrial Research,
Oshodi, Nigeria.Instant Pounded Yam Flour Production Technology.Available at
firro-ng.org/instant.pounded-yam-htmlaccessed. 6 May, 2004.
Halm, S.K., Osiru, D.S. O., Akoroda, M.O. and Otoo.J.A.
(1987) .Yam Production and Future Prospect. Outlook in Agriculture,
16 (3):105-110.
IITA, (2009).Yam Production in Africa. International
Institute of Tropical Agricultural Nigeria www.iita.org/cons/details/yamprojectdetailsaspx
Iwe, M.O (2003). The Science and Technology
of Soybean. Pp 221-226.
Okaka J.C and Okaka N.C (2006). Food Composition
Spoilage, Shelf-Life Extension. Serves No 1 Ocjanco Academics
publishers Enugu. Pp. 252-253.
Okezie, C.E.A. (1987). Involvement of day length in the
Tuberization of Dioscorearotundataministered under
Nsukka Conditions. In Tropical Root Crops: Root Crops and the African food
Crisis. Terry. E. E, Akoroda, M.O., Akene, O.B. (Eds);
International Development Research Center, Ottawa, Canada.
Okoli, O.O. (1980). Dry Matter Accumulation and Tuber
Sprouting in Yams (Dioscoreaspp).ExperimentalAgric.
16:161-167.
Okpala L.C, Okoli E, and Udensi
E. A. (2010). Physiochemical and Sensory Properties of
Cookies made from blends of germinated pigeon pea, fermented sorghum and
Cocoyam flours. Food Science and Nutrition.D01:
10/1002/FSN3:2
Onwueme, I.C. (1978). The
Tropical Tuber Crops Yams, Cassava, Sweet Potato and Cocoyam.John Willey and Sons.
Onwueme, I.C.
and Charles, W.B. (1994).
Cultivation of Cocoyam. In:
Tropical Root and Tuber Crop.Production,
Perspectives and FutureProspects. FAO
Plant Production and Perfection Paper 126, Rome, pp.139-161.
Onwuene I.C. (1978).
The tropical tuber
Crops. John Witey
and Sons.
Chichester. Pp. 234-240.
Passam, H.C, and Nooh, R.A.,
(1977). Biodeterioration of Yam and Cassavaduring Storage.Journals of Applied Biology 85:436-440.
Paterson, M.S. and Johnson A.H.
(1974).Encyclopedia of Food TechnologyProcessing of breakfast cereals.All
Publishing Company Inc. West Port.pp.124-127,
283-285.
Purseglove, J.W. (1976).
Tropical Crops.Monocotyledons.Longman Group LtdLondon. Pp 97-117.
Rasper, V and Coursey, D.G.
(1967).Properties of Starches of some WestAfrican Yams.Journal of Science Food Agric. 8: 99-106.
Sobulo R.A (1972). Studies on
White Yam (Dioscorearotundata).Growth
Analysis Experiment. Agric. 8:99-106.
Solsuki, F.N.
(1962). The Centrifugal
Method for Determining FlourAbsorptive in hard red spring wheat. Cereal Chemistry, 39: 344-346.
Tetteh, J.P. and
Saakwa, C. (1994). Prospects and
Constraints ofYamProduction in Ghana.Tropical Root Crops in a developing economy.Ofori, F. and Hahn S.K (Eds).
Proceeding of the 9th Syrup of the International Society of Tropical Root Crops. Oct., Accra, Ghana 20-26.
Uguru, M (1993). Roots and Tubers
Crop of the Tropical Region. Vol.23, Pp.102-108.
Afro- Orbis Publication Ltd.
Wikipedia, (2013).Sorghum and
Millet in Human Nutrition.Food and Agriculture Organization of the
United Nations, Food and Nutrition Services
No 27, Rome.