ABSTRACT
This
work was carried out to study the effect of varying the levels of sugar, fat,
tigernut and wheat flour in biscuit production. Emphasis was placed on the
effect of varying these ingredients on the acceptability of the product.
Fourteen biscuit samples were produced from blends of tigernut flour (TF) and
wheat flour (WF) at ratios of 25:75, 42.5:57.5 and 60:40TF:WF respectively, fat
content ranging from 10-40g and sugar content ranging from 15-25g. Biscuits
made with 25TF:40F:25s served as the control.
Proximate composition of the
flours and the most preferred biscuit, physical and sensory analysis were
carried out. The most preferred biscuit was produced with 42.5TF:10F:205. the
percentage fat of this preferred biscuit was 18.88% protein was 7.80%, ash
content was 1.80%, fibre was 1.24%, moisture was 7.77% while the carbohydrate
content was 62.51%. Biscuits made with 42.5TF:25F:25S had the highest spread
ratio of 7.06 while biscuit with 60TF:10F:25S had the least spread ratio of
4.77. biscuit made with 60TF:40F:15S had the lowest break strength of 623g.
Sensory evaluation results showed that all the biscuits had high sensory ratings
for all the selected attributes evaluated. Biscuit with 42.5TF:10F:205 (most
preferred) result in the highest score for taste, texture, appearance and
general acceptability.
A PROJECT WORK SUBMITTED TO THE
DEPARTMENT OF FOOD SCIENCE AND
TECHNOLOGY
FACULTY OF AGRICULTURE AND NATURAL
RESOURCE MANAGEMENT
IN PARTIAL FULFILLMENT OF THE
REQUIREMENT FOR THE AWARD OF THE DEGREE (B.Sc.) IN FOOD SCIENCE AND TECHNOLOGY
LIST OF TABLES
Table
2: Formulation of The Sa
mples
of Biscuit
Produced with Tigernut – Wheat Flour
Blends………………………………………………. 34
Table
3 : Proximate composition of wheat
and Tigernut
Fours………………………………………………… 41
Table
4: Physical properties of
Biscuits produced from
Tigernut and Wheat flour
Blends………………. 44
Table
5: Sensory Quality of Biscuits
Produced from
Tigernut and Wheat flour
Blends……………… 49
Table
6: Proximate composition of the
most Preferred
Biscuit………………………………………………. 54
CHAPTER ONE
INTRODUCTION
Biscuits are baked, edible and
commonly flour-based products. Biscuits may be regarded as a form of
confectionary dried to very low moisture content. The simplest form of biscuit
is a mixture of flour and water but may
contain fat, sugar and other ingredients mixed together into a dough which is
rested for a period, passed between rollers to make a sheet; the sheet is then
stamped out, baked, cooled and packaged (Okaka, 2009). Generally, biscuits have
high fat and sugar levels and at the same time, low water level. The components
that are involved in making a biscuit will have a significant effect on the
quality of the dough produced, how the biscuit will react when placed in heated
oven and the final level of quality of the product (Pareyt et al., 2008).
Fat is an indispensable ingredient
in baked foods and contributes to nearly all aspects of a biscuit (Pareyt et al., 2008). Most consumers enjoy the
taste, texture and aroma fat gives to food, it imparts richness, shortening and
tenderness and improves mouth feel, flavour and perception. Fat also
contributes to biscuit spread and to general product appearance; it enhances
aeration for leavening and volume and makes biscuits easily breakable (Zoulias
et al. 2002).
Rankin and Bingham (2002) reported
that biscuits generally contain a substantial amount of fat, but the dietary
recommendations should be put into consideration. The World Health Organization
(2004) listed increased intake or consumption of energy-dense food high in
saturated fat as one of the main causes of some health diseases. Consumption of
excess saturated fat is one of the major risk factors for this global epidemic.
Excess intake of fat may lead to obesity, building up of cholesterol in the arteries;
it increases the risk of heart diseases. It also increases the risk of certain
types of cancer.
Sugar is another indispensable ingredient
in biscuit production. It imparts sweetness and is responsible for the brown
colouration of biscuits (Pareyt et al.,
2008). Zoulias et al. (2002) reported
that sugar contributes to the crumb size of the final product and also aids in
the water binding capacity. Sugar has been linked to diseases like diabetes and
obesity (Neha, 2011). Neha (2011) also reported that other effects of excess
sugar intake include retina damage, thickening of arteries, increased cancer
risk, activates hunger by dropping the blood glucose level. Biscuits according
to Rankin and Bingham (2000) contains high amount of sugar that can lead to
these diseases. The idea of substituting these basic ingredients in biscuit
production is not new. Bokanga (1995) reported that efforts have been made to
partially substitute fat and sugar with other natural ingredients or replacing
them altogether. Nweke (2012) reported that biscuits of high acceptability can
be produced from blends of tigernut flour and wheat flour.
Tigernut flour has been demonstrated
to be a rich source of quality oil and contains moderate amount of protein and
fibre and also classified as cholesterol free (Ontario, 2009). It also contains
natural sugar which can be used in replacing sugars added to baked products
that can be easily digested by the body without side effects (Oladele and Aina,
2007).
With the high fat and sugar contents
in tigernut, this work aims at determining the effects of reduced fat and sugar
in the recipe on consumer acceptability. This is geared toward taking advantage
of the high fat and sugar content, naturally present in tigernut (with the aim
of reducing the levels of added fat and sugar in biscuit production). This
should ultimately result in better and improved health implications for
consumers.
OBJECTIVES OF STUDY
The
objectives of this work are to:
1. Produce
biscuits with varying proportions of tigernut flour, sugar and fat contents.
2. Determine
the effect of varying these ingredients on the physical and sensory quality.
CHAPTER TWO
2.0
LITERATURE REVIEW
2.1 BISCUIT
The word biscuit came form the
French word “biscuit” which means twice cooked. It was a term applied to
traveling rations, such as ship’s biscuit, which were twice cooked, dry all the
moisture and enhance their keeping qualities, such is unleavened bread and also
known as hard tack, the hard tack is hard dry biscuit-like bread of Swedish originally
made from rye flour and rye meal combined with sugar, salt and milk. In U.S.A Parkle,
they are called hard crackers or pilot crackers. In those days of
explorationship, biscuit was notorious for being so hard that it was
practically impossible to bite into them unless they were either honey combed
internally by weevils or softened in water.
According to Coyle (1982), biscuit
was developed by American colonist and consist basically of flour, sweeteners
and milk. The comparatively large amount of softening in the recipe produced
the flaky texture in biscuits.
In England, the term biscuit is a
general term that covers both the cookies in sweetened form and cookies in unsweetened
form. The flavouring agent added to the basic dough include caraway seed, sour
cream, cheese, honey, cinnamon, lemon, orange, raising, shrino and tomatoes,
generally, it is made from flour mostly enriched with fat and sugar hence, it
is of high energy value ranging from about 420-510kcal or 1.7-2.1 MJ / 100g
(Walters et al., 1983). They further described that biscuits can be stored for
a long period of time due to the high content of sugar and fat.
2.1.1 NUTRITIONAL
VALUE OF BISCUITS
The nutritive value of biscuit
depends on the ingredients used in mixing the dough. Most biscuits contain a
lot of fat plus the basic ingredient, flour and also sugar. Consequently, they
are of high energy value, they are also rich in protein since they contain milk
and in some cases, egg. For example, finger biscuits contain a lot of eggs,
minerals and vitamins (Pearson, 1976).
Table 1: Chemical Composition of Various Biscuits
|
TYPE
|
Moisture
(%)
|
Fat
(%)
|
Protein
(%)
|
Sugar
(%)
|
Ash
(%)
|
Salt
(%)
|
Energy
(%)
|
|
Cream
|
4.3
|
16.3
|
9.6
|
Trace
|
_
|
1.5
|
1857
|
|
crackers
|
|
|
|
|
|
|
|
|
digestive
|
4.5
|
20.6
|
9.6
|
16.4
|
_
|
1.1
|
1981
|
|
Plain
|
5.2
|
13.2
|
7.4
|
15.8
|
_
|
_
|
1877
|
|
Sweet
|
0.7
|
30.7
|
5.5
|
25.0
|
_
|
_
|
2282
|
|
Short
cake
|
2.2
|
23.5
|
5.1
|
20.0
|
1.0
|
0.4
|
2124
|
|
Water
|
4.5
|
12.5
|
10.7
|
2.3
|
_
|
_
|
1888
|
|
Ginger
nut
|
3.4
|
15.2
|
5.6
|
35.8
|
_
|
0.8
|
1923
|
|
Short
bread
|
5.0
|
20.0
|
6.2
|
17.2
|
_
|
0.7
|
2115
|
|
Water
filled
|
2.3
|
29.9
|
4.7
|
44.7
|
_
|
0.2
|
2241
|
Source:
Pearson, 1976
2.2.0 WHEAT
Wheat (Triticum aestivum) is perhaps
the most popular cereal grain for the production of biscuits, bread and other
pastries (Ihekoronye and Ngoddy, 1985). Wheat is grown in almost all parts of
the world, from near the equator to the borders of the arctic and at altitudes
ranging from sea level to about 500 meters above sea level (Okaka, 2005). Okaka
(2005) reported that the crop is most successful between latitudes 30 and 600
North and a soil rich in nitrogenous manure. Okaka (2005), also mentioned that
wheat flourishes more in sub-tropical, warm and cool temperate climate where
annual rainfall ranges from 229-762mm and falls prior to peak sunshine period
identified as summer in temperate regions and as dry season in the tropics.
Wheat produces white flour in addition, the unique properties of wheat protein
alone can produce bread dough of the strength and elasticity required to
produce low density bread and pastries of desirable texture and flavour (Ihekoronye
and Ngoddy, 1985; Okaka 2005).
The times of sowing and harvesting
of the wheat crop in various growing countries are naturally dependent on
climatic conditions, harvesting would usually take place during periods of
longest and optimum sunshine preferably devoid of rainfall (Okaka, 2005).
2.2.1 STRUCTURE
OF A WHEAT GRAIN
The grain of wheat consist of an
outer fibrous covering, the pericarp and testa which is hard and indigestible,
and an inner lining aleurone layer which contains a higher proportion of protein
and carbohydrate, an embryo attached to small structure, the scutellum, at the
lower end of the grain and the endosperm comprising 85% of the whole grain from
which the flour is derived (Ihekoronye and Ngoddy, 1985).
2.2.2 PROXIMATE
COMPOSITION OF A WHEAT GRAIN
The composition of wheat varies with
the variety of the seed, the nature of the soil and the climate. Wheat grain
has a starch content of 65-75%, protein content of 8-10%, water content of
10-14%, fat content of 1-2%, fibre content of 1.5-2.5%, ash content of
0.4-1.0%, food energy of 334 calories (Ihekoroonye and Ngoddy, 1985).
2.2.3 CLASSES
OF WHEAT
Wheat is classified as either hard
wheat or soft wheat. The hardness and softness as applied to the wheat grain
are in their milling characteristics, relating to the way the wheat grain
endosperm breaks down during milling (Okaka, 2005). There seem to appear
specific areas of weakness and mechanical strength on the grain of hard wheat,
for soft wheat varieties, the grain exhibits a uniform distribution of areas of
mechanical weakness. Hence, hard wheat when milled cracks or shatters following
lines of weakness and so yield flours that are coarse, gritty, free flowing and
easy to sieve, soft wheat on the other hand, will grind more uniformly during
milling, yields flours that are fine, difficult to sieve and have irregularly
shaped endosperm cells. Bran separation is less completely achieved during
milling of soft wheat than hard wheat (Okaka, 2005).
Flour is a powder which is made by
grinding cereal grains, other seeds or roots (Okaka, 2009). Biscuits are made
using flour and wheat flour is the most suitable. It is however; relatively
expensive being made from imported wheat that is not cultivated in the tropics
due to climatic reasons (Olaoye et al.,
2006). Generally, wheat flour finds its use in several common products like
bread, biscuit, cakes, composite flour products e.t.c. (Okaka, 1998). Wheat
flour is also unique in yeasted products because it is the only crop possessing
gluten in appreciable quantity to permit substantial increase in volume, which
is both palatable and digestible (Okaka, 1998).
The term strong and weak used when
discussing about wheat as a crop are associated with the baking strength of the
flour obtained from the grains after milling. Strong flour is one which has the
ability to produce bread of large loaf volume good crumb texture and good
keeping properties. Strong flours generally have higher protein content than weak
flours. Weak flours yields smaller loaves with coarse open crumb texture and
generally are low in protein content. Wheat flours of weak type are ideal for
the manufacture of biscuits in generally, hard wheat tend to yield strong
flours while soft wheat tend to yield weak flours (Okaka, 2009).
Although wheat is a crop of the
temperate region, wheat product including biscuits is a very popular food item
in many developing, tropical and sub-tropical countries including those in West
Africa. To reduce the import expenditure on wheat, some tropical countries
including Nigeria are experimenting on its possible local production and
partial substitution in traditional baked foods (Okaka, 2009; Olaoye et al., 2006).
2.3 COMPOSITE
FLOUR
Composite flour is a mixture of
different flours from cereal, legume or root crops that is created to satisfy
functional characteristics and nutrients composition. Alternatively, it may be
defined as two or more materials brought together to make a new product better
than the individual components. Better may refer to improved properties or
performances, or in some cases improved economics (Dendy, 1992). The use of any
food raw material in processing depends on its availability. The main problem
facing the bakery industries in Nigeria is the total dependence on importation
of wheat to sustain it. Nigeria has unfavourable climatic condition for wheat
cultivation, but suitable for other cereals (Soghum, millet e.t.c), legumes
(soybean, groundnut, bambara nut, cowpea) and vegetable (Eneche, 1999),
therefore any efforts made to substitute part of the wheat flour by other kind
of available flour will contribute to the lowering of cost (Ayo et al., 2007). Legumes, cereals, roots
and tubers are not always consumed by themselves, they are sometimes processed
into various products after proper combinations have been made, legumes
combined with cereals increase protein content and complements the amino acid
profile of the product while in combination with roots and tubers also modifies
the product (Enwere, 1998).
2.3.1 UTILIZATION
OF COMPOSITE FLOUR
Composite flour containing wheat and
legume have proven practical uses and are being utilized in many parts of the
world to improve the nutritional and functional properties of flour. Composite
flours could be utilized in the production of baked foods like cookies,
biscuits, bread, cakes, pies e.t.c, in the processing of pastas, breakfast
foods, in glucose syrup production, in the production of weaning foods and can
act as substrate in alcohol production. Composite flours find other uses or
roles in providing variety to the diet e.g. corn bread, potato bread and also
nutritional enhancement which leads to its increased use in the baking industry
(Iwe, 2003). The application of composite flours has also led to the reduction
of cost and increased saving, improved protein quality and increased
utilization of some local crops. A combination of these major classes of food
crops has been utilized in the production of baby foods (Enwere, 1998).
2.3.2 BENEFITS
OF PRODUCTS PRODUCED WITH COMPOSITE FLOUR
The benefits derived from these
products lies mainly in the fact that the protein of cereals which are usually
low in lysine and rich in sulphur containing amino acids in methioine and
cystine are complemented when in combination with legumes that are rich in
their deficiencies, thus ideal proteins for humans are produced from plant
sources in this manner. This quality protein helps to improve the nutrition of
people, especially those in developing countries where the protein gap is
evident (Enwere, 1998). Enrichment of cereal- based foods with other protein
sources such as oil seeds and legumes have received considerable attention
(Okaka and Isieh, 1980; Dhingra and Jood, 2005; Alobo, 2001, Elkahifa and
El-tinary, 2003; Ayo and Gafa, 2002; Ayo and Olawale, 2003; Grewal, 1992), this
is because oil seeds and legumes protein are high in lysine, and essential
limiting amino acid in most cereals (FAO, 1970). Biscuits are improved in
protein content and nutritional quality when high levels of fortification with
protein-rich flour are used (Okafor, 2002).
2.3.3 NUTRITIONAL
VALUES OF COMPOSITE FLOUR
The nutritional values of composite
flours depend on the food group which makes up the composite flour, whether
cereal, legume or root crop and on the quantity or percentage fraction of the
group in the composite flour. Supplementation of cereal flour with inexpensive
staples such as legumes/pulses helps in improving the nutritional qualities of
cereal products (Sharma et al.,
1999). For example, since cereals contain pre-dominantly carbohydrates, the
addition of cereals will bring about increase in the carbohydrate fraction of
the composite flour. Further more, increase in addition of legume will bring
about increase in the protein content of the flour since legumes are pre-dominantly
proteins while the increase in the addition of roots and tuber crop will bring
about more increase in the calorific value of the flour.
2.4
TIGERNUT
Tiger nut (Cyperus esculentus) is
sedge of the family Cyperaceae which produces rhizomes from the base and tubers
which are some what spherical with sitting diameters of 5-17mm (Lowe and
Stanfield, 1974).
2.4.1 ORIGIN
AND CULTIVATION OF TIGERNUT
Tigernut is an underutilized crop
which belongs to the division Magnoliophyta, classliliopsida, Order-Cyperales
family and was found to be a cosmopolitan perennial crop of the same genus as
the papyrus plant. Other names of the plant are earth almond as well as yellow
nut grass (Odoemelan, 2003; Belewu and Belewu, 2007). Tigernut also known as chufa
is thought to have originated in the Mediterranean area and Western Asia but
has spread mainly as weed to many parts of the world. It will grow in a very
wide range of climatic conditions and occur in the tropics, sub-tropics and
warm temperate regions and is cultivated in several countries (Kay, 1987). The
plant is not really a nut but a “Tuber” first discovered some 400years ago
(Lowe and white well, 2000). Tigernut is known in Nigeria as Aya in Hausa, Ofio
in Yoruba and Aki Hausa in Igbo. It grows mainly in the middle belt and
Northern regions of Nigeria.
2.4.2 UTILIZATION OF TIGERNUT
Tigernut has been cultivated since
early times for its small tuberous rhizomes which are eaten raw, baked or
roasted, grated to make refreshing beverages and ice-creams, or dried (Kay,
1987; Belewu and Belewu, 2007; Oladele and Aina, 2007). They can be dehydrated
by soaking before consumption and even softened further by boiling (manson,
2008). According to Kay (1987), tigernuts are used as subsidiary in animal feeding,
confectionery, coffee and cocoa adulterant while the secondary and waste
products are oil, starch, flour, alcohol, leaves.
2.4.3 VARIETIES OF TIGERNUT
Three varieties which include
yellow, brown and black are cultivated in Nigeria but only two (yellow and
brown) are readily available in the market (Oladele and Aina, 2007). The yellow
variety is preferred to all other varieties because of its inherent properties
like its bigger size, attractive colour and fresher body (Belewe and Belewu, 2007;
Belewu and Abodurin, 2008; Umerie et al.,
1997). The yellow variety also yields more milk upon extraction, contains lower
fat and more protein and possesses less anti-nutritional factors especially
polyphenols (Okafor et al., 2003).
2.4.4 CHEMICAL
COMPOSITION OF TIGER NUT
Although tigernut is under utilized,
the high crude lipid and carbohydrate content and its fairly good essential
amino acid composition make it a valuable source of food for man (Temple et
al., 1990). Tigernut is rich in energy content such as starch, fat, sugar and
protein, and also a rich source of minerals like calcium, sodium, magnesium,
phosphorus, potassium, zinc and traces of copper and contains Vitamins E and C
as well (Belewu, 2007; Belewu and Abodurin, 2008). Kordylas (1990) reported
that tigernut contains from 3.2-4.6% protein, 13.3- 21.5% fat, and are high in
carbohydrate (14.4-62.3%), fibre content 3.9-7.5% and ash content of 2-3% for
raw and dried tigernuts respectively (values per 100g edible portions). The
moisture content ranges from 9.6-40.8% with energy measured in calories from
444 and 247 for dried and raw tigernuts respectively (Eyeson and Ankra, 1975; purseglove,
1974). The nuts which are valued for their high starch content (26.54%) and
dietary fibre (24.13%) have been reported to be rich in sucrose (17.40-20.0%)
by Umerie and Enebeli (1997).
In addition, tigernut has been
reported to contain higher essential amino acids than those proposed in the
protein standard for satisfying adult needs (Adejuyitan et al., 2009). According
to Belewu and Abodurin (2008) and Adejuyitan et al. (2009), tigernut produces
high quality oil, about 25.5% of its content and protein of about 8% of the
nut. The nut is high in oil content and the oil was implicated as lauric acid
grade oil, non acidic stable and very low unsaturation (Belewu and Abodurin,
2008; Adejuyitan, 2009). The nut was found to be rich in myristic acid, oleic
and linoleic acid (Eteshola and Oraedu, 1996) and chufa oil is resistant to
oxidative changes and it has been suggested that it could be added to oil like
coconut oil to retard rancidity as reported by Kay (1987).
2.4.5 HEALTH
AND NUTRITIONAL PROPERTIES OF
TIGERNUT
According to Mason (2008) tigernuts
have long been recognized for its health benefits as they are high in fibre,
protein and natural sugars. Its tubers are said to be aphrodisiac, carminative,
diuretic, stimulants, emmanogogue and
tonic (Chopra et al., 1986; Chevallier, 1996). Tigernut has also been reported
to be used in the treatment of flatulence, indigestion, diarrhoes, dysentery
and excessive thirst (Chevallier, 1996). In addition tigernut has been
demonstrated to contain higher essential amino acids than those proposed in the
protein standard by the FAO/WHO (1985) for satisfying adult needs (Bosch et
al., 2005). Tigernuts have excellent nutritional properties, with a fat
composition similar to olives and also rich mineral contents especially
phosphorus and potassium. The oil of the tuber was found to contain 18%
saturated (Palmitic acid and stearic acid) and 82% unsaturated (oleic acid and
linoleic acid) fatty acids (Bamishaiye and Bamishaiye, 2011). It can be useful
in replacing milk in the diets of people intolerant to lactose to a certain
extent, its flour has been demonstrated to be a rich source of quality oil and
contains moderate amount of protein, it is also an excellent source of some
useful minerals such as iron and calcium which are essential for body growth
and development (Oladele and Aina, 2007). The extract from tigernut is a product
of plant origin with high nutritional and health benefits which can be used as
milk substitute (Nwokolo, 1985). The nuts were found to be ideal for children,
the elderly and also for sports men and women (Martinez, 2003). Beniwal (2004)
reported that the very high fibre content combined with its delicious taste
makes tigernut ideal for healthy eating. Tigenruts was also reported to be high
in dietary fibre content, which would be effective in the treatment and
prevention of many disease like colon cancer, coronary disease, obesity,
diabetes and gastro intestinal disorders (Anderson et al., 1994). Tigernut was
reported as healthy and helps in preventing heart attacks, thrombosis and
activates blood circulation. It helps in preventing cancer, due to its high
content of soluble glucose (Adejuyitan et
al., 2009). Tigernut can be taken by diabetic patients for its content of
sucrose and starch and its high content of arginine which stimulate the
production of insulin (Adejuyitan et al.,
2009).
2.4.6
ANTI - NUTRITIONAL AND TOXIC COMPOSITION
OF TIGERNUT
Food contain various composition of
nutrients and anti-nutrients and could have important and deleterious effects
in the body when consumed. The composition of the anti-nutrients and nutrients
lead to side effects found in the plants, which may lead to toxicity, hyperlipidaemia,
excessive weight gain, hyperglycaemia, constipation, carotenemia, kidney stone,
body odour, bad breath, allergies, diarrhea, frequent urination and acne
(Anonymous, 2009). Different plant extracts have been known to possess
different level of anti-nutrient inherent in the plants (Sofowora, 1993).
Anti-nutrient properties of any food substance can be said to be a compound
that acts to reduce nutrient utilization and/or food intake (Osagie and Eka,
1998).
Some of the anti-nutrient factors contained
in the tigernut are tannins and trypsin inhibitors (Addy and Eteshola, 1984).
But unlike several other underutilized crops, it does not produce any
undesirable effect even when eaten raw (Ekeanyanwu et al., 2010). Ekeanyanwu et
al. (2010) reported that preliminary investigations on the acute toxicity
of the tuber extract of tigernut in mice showed that the aqeous extract of
tigernut tuber was not toxic to mice at the administered concentration. The
tuber is used in making a refreshing beverage mostly in Northern region of
Nigeria but there have not been any reported cases of toxicity in humans
(Belewu and Abodurin, 2008).
2.5 FAT
Fats are the best known members of a
chemical group called lipids. Like carbohydrates, lipids contain carbon,
hydrogen and oxygen and some also have phosphorus and nitrogen. Lipids are
found widely spread in nature and are insoluble in water but will dissolve in
either chloroform, benzene or other fat solvents (Babaya, 1977). Every fat
molecule has essentially four parts. The core of the molecules is glycerol, a
three carbon compound that is related to alcohols (Orji, 1992). Orji (1992)
also reported that the nature of fat depends on what kind of fatty acids are
linked to the glycerol core, the number of carbon atoms of the faty acids and
the degree of saturation or unsaturation of the fatty acid. Wilson (1979)
reported that fat and oils are source of energy in diets, they are the most
concentrated form of energy in foods, yielding more than twice as much energy
per gram as either carbohydrate or protein in the body. Fats are not just a
calorie powerhouse, they are an important component in most emulsions.
2.5.1 FUNCTIONS
OF FAT IN BISCUITS
Consumer acceptance of any food product
depends upon taste, which is the most important sensory attribute (Akoh, 1998).
As a food component, fat contributes key sensory and physiological benefits in
biscuits. Fats contribute to flavour or the combined perception of mouth feel,
taste and aroma/odour (Ney, 1988). Fat also contributes to texture, creaminess,
appearance, palatability and lubricity of biscuits (Leland, 1997). They also
provide one of the most efficient modes of heat transfer during baking which also
facilitates crust formation. Fats play important roles in making biscuits satisfying.
Fats also make biscuits tender by impeeding the formation of gluten strands,
keeping the final product tender and flakey. Most consumers enjoy the texture,
taste and aroma fat gives to food, it imparts richness, shortening and
tenderness and improves mouthfeel, flavour and perception. Fats also
contributes to biscuit spread and to general product appearance; it enhances
aeration for leavening and volume and makes biscuit easily breakable (Zoulias et al., 2002).
2.5.2 USES
OF FAT REPLACER IN BISCUITS
Awareness of adverse effects of
excessive dietary fat intake is universally known. Consequently health
conscious individuals are modifying their dietary habits and eating less fat
(Miller and Groziak, 1996). Although consumers want foods with minimal to
non-fat or calories, they also want the foods to taste good. Consumers’ survey
indicates that 56% of adult Americans try to reduce fat intake and many show
interest in trying foods containing fat replacers (Brulin et al., 1992). Food formulated with fat replacers are an enjoyable
alternative to familiar high–fat foods and by choosing these alternative foods,
health conscious consumers are able to maintain basic food selection patterns
and more easily adhere to a low-fat diet (CCC, 1996).
Many types of fat replacers like
polydextrose (Armbrister and Setser 1994; Campbell et al., 1994), avocado frit puree and oatrim (Benhilda and
Khursheed, 2007), pureed white beans (Rankin and Bingham, 2000), Pawpaw puree
(Wiese and Duffrin, 2003) have all been used as fat replacers with their
different successes and short comings. Substituting fat in biscuit with tigernut
is expected to reduce the calories it provides and at the same time, produces a
final product that has the properties of a fat-based biscuits.
2.5.3
EFFECTS OF EXCESSIVE FAT INTAKE ON
CONSUMERS
According to the World Health
Organization (2004) and the American Health Association Nutrition Committee,
excessive intake or consumption of fat (saturated), is one of the major risk
factors for heart diseases. A diet high in saturated fat causes a soft, waxy
substance called “Cholesterol” to build up in the arteries. Too much fat also
increases the risk of being obese because of its high calories content. A large
intake of polyunsaturated fat may increase the risk of some types of cancer in
the body.
2.6 SUGAR
Sugar is a pure carbohydrate whose
physical and chemical properties make it an essential ingredient in a wide
variety of manufactured food products (Stewat, 1961). Sugar is made up of
carbon, hydrogen and oxygen. Naturally occurring sugars are mostly hexoses and
sugar is the simplest form of carbohydrate (Ihekoroonye and Ngoddy, 1985).
Glucose is the sugar normally found in
the blood, it therefore has an important medical application as a substance
that can be administered intravenously as source of carbohydrates for patients
unable to take nourishment by mouth (Ihekereonye and Ngoddy, 1985). Heid and Josyln
(1967) defined sugar as a sweet crystallizable substance colourless or white
when pure, occurring in many fruit plant juice, forming an important article of
food.
2.6.1 FUNCTION
OF SUGAR IN BISCUITS
Sugars are important for the taste
and structure of most biscuits (Manley, 2008). Sugar imparts sweetness and
flavour. It forms structure and hardness, particularly in short dough and as a
bulking agent. Sugar also functions as a flavour enhancers and to make flavours
seem correct. Sugars as well functions as a fermentation food in doughs which
are fermented such as cream cracker, encouraging the yeast to grow more
vigorously and hence speed the fermentation process. Sugar also aid surface
colouration during baking and is also used as a decoration on the surface of
biscuits, adding to the attractive appearance of the biscuits (Manley,
2008).
2.6.2 USE
OF SUGAR REPLACERS IN BISCUITS
A sugar substitute is a food
additive that duplicates the effect of sugar in taste, usually with less food
energy some sugar substitutes are naturally and some are synthetic. Those that
are not natural are generally called “artificial sweeteners”. Sugars in
biscuits are to be replaced for a number of reasons which include assisting in
weight loss, dental care because sugars are tooth-friendly, reactive
hypoglycemia amongst others. Natural sugar in tiger nut which is easily broken
down in the body may be used to substitute or reduce the amount of sugar being
added in biscuits.
2.6.3 EFFECT
OF EXCESSIVE SUGAR INTAKE ON
CONSUMERS
Consumption of excess sugar
according to various health authorities can cause series of diseases in the
body.
(1) It
feeds cancer cells and has been connected with the development of cancer of the
breast, ovaries, prostate, rectum, pancrease, lung, gall bladder and stomach.
(2) It can
cause autoimmune diseases like asthma, arthritis, multiple sclerosis.
(3) It
greatly assists the uncontrolled growth of Candida yeast infection.
(4) It can
increase the size of the liver by making the liver cells divide and it can
increase the amount of liver fat.
(5) It
increases kidney size and produce pathological changes in the kidney such as
the formation of kidney stones.
(6) It can
cause hormonal imbalances such as increasing estrogen in men, exacerbating PMS,
and decreasing growth hormones.
(7) It
upsets the mineral relationships in the body causing chromium and copper
deficiencies and interferes with absorption of calcium and magnesium.
(8) Excessive
intake of sugar ages the skin and causes wrinkles and skin sagging.
(9) Excessive intake of sugar depresses the
immune system
(10) It causes Obesity and Overweight
(11) Excess
sugar intake results to disease like diabetes amongst others.
CHAPTER THREE
3.0 MATERIALS AND METHODS
3.1 MATERIALS
3.1.1 SOURCE
OF MATERIALS
Fresh tigernut seeds (yellow
variety) used for this work was
Purchased form Abakaliki meat market in Ebonyi State. What flour and other ingredients for barking
like sugar, fat salt e.t.c, will as well be purchased form Abakaliki mear
market in Ebonyi State.
3.2
METHODS
PREPARATION OF SAMPLE
The tigernut flour was prepared
using the method described by Adeyemic (1988).
The nuts were sorted in order to remove unwanted materials like pebbles,
stones and the foreign seeds before being washed with tap water. The cleaned nuts were dried, milled and
sieved through 100mm aperture size sieve.
The resultant flour was packaged in cellophane until analyzed. Wheat was
purchased as already milled flour.
3.2.1
FLOUR BLENDING
Tigernut flour and wheat flour were mixed at
ration of 25:75, 42.5:57.5 and 60:40 respectively.
The blends were thoroughly mixed and kept
in plastic containers until needed.
3.2.2
BISCUIT PREPARATION
The
method of Okpala and Chinyelu (2011) was used.
The ingredients that were used for making the biscuits included 100g
flour (blended), 10-40g fat, 15 -25g sugar, 1g of salt, ½ teaspoon liquid
vanilla flavoring and 1g of baking powder.
All the ingredients except for the flour were mixed thoroughly in a
dough mixer while little amount of water was continuously added. The blended flours and baking power were
added with continuous mixing until smooth dough is obtained. A piece of this dough was cut and placed on a
clean plate form of board with a rolling pin to roll out the dough until a
uniform thickness of 0.25cm was obtained with a diameter of 4.6cm. The biscuits were baked a 1850c
for 15-20mins in an oven, cooled and was packaged in polythene bags and stored
until the biscuits were evaluated.
FORMULATION OF BISCUIT SAMPLES
Table 2: Formulation of
the samples of biscuit produced with Tigernut-Wheat flour blends
|
Tigernut flour
(TF) (g)
|
Wheat flour
(WF) (g)
|
Fat(F)
(g)
|
Sugar (S)
(g)
|
|
25
|
75
|
10
|
15
|
|
25
|
75
|
10
|
25
|
|
25
|
75
|
40
|
15
|
|
42.5
|
57.5
|
10
|
20
|
|
42.5
|
57.5
|
25
|
15
|
|
42.5
|
57.5
|
25
|
20
|
|
42.5
|
57.5
|
25
|
25
|
|
42.5
|
57.5
|
40
|
20
|
|
60
|
40
|
10
|
15
|
|
60
|
40
|
10
|
25
|
|
60
|
40
|
25
|
20
|
|
60
|
40
|
40
|
15
|
|
60
|
40
|
40
|
25
|
|
25
(Control)
|
75
|
40
|
25
|
TF
= Tigernut Flour, WF = Wheat Flour,
F = Fat, S =
Sugar
Nweke (2011) produced biscuits from tigernut and
wheat flour blends and reported that blends from 25 TF:40F:25S had better
sensory ratings than biscuits form wheat flour. In this study, 25TF:40F:25S
served as control.
3.3 PROXIMATE COMPOSITION ANALYSIS
The following analysis were carried out to
determine the proximate composition of 100% tigernut flour, 100% wheat flour
and the most preferred biscuit.
3.3.1
PROTEIN DETERMINATION
Crude protein content was determined by
micro kjeldahl method (AOAC, 1990).
Sample (0.5g) was weighed into a 5ooml kjildahl flask. Ten gremmies (10g) of sodium sulphate (Na2 S04) and 1g of copper
sulphate (Cu2SO4), followed by 20ml of hydrogen sulphate
(H2 S04). The
mixture was digested under a fume cupboard until a clear solution was
obtained. The digest was cooled and
200ml of distilled water was added followed by 60ml of 40% sodixm hydroxide
solution. The distillate that was collected
is titrated with 0.1NHCL. The nitrogen
content was multiplied by 6.25 to obtain the protein contents of flour and
biscuit respectively and expressed as percentage of flour and biscuit weight on
the dry basis.
% protein = TV x N x 6.25 x 100
0.5
1
Where
TV =
Titre value
N = The Normality of Hcl used
6.25 =
Conversion factor of protein
0.5 =
Weight of sample used.
3.3.2
FAT DETERMINATION
Fat content of the sample was also
determined using soxhlet apparatus (AOAC, 1990). Five grammes (5g) of sample was wrapped with
a filter paper and poured into a porous thimble attached to the reflux
condenser of the apparatus. N- Hexane was
poured in a weighed flat bottom flask (half full), then heat was applied with
water bath so as keep the hexane gently boiling. The solvent vaporized to the reflux condenser
where it condenses and dropped on the solid substance (sample) contained in the
thimble and extracts soluble compounds.
The solvent automatically siphoned back into the flask where the liquid
level fills the body of extractor. This
process was continued as the solvent in the flask was vapourized and condensed,
allowed to flush back like 6-7times.
When the fat extractor was completed, the extracted solvent containing
the solute was isolated by either evaporation to dryness or using a
distillation apparatus (to recover the solvent). The oil in the flask was dried in an even to
expel the N-Hexane completely, allowed to cool down and the flask re-weighed.
%
Fat = Weight of fat extract x 100
Weight of sample 1
= W2- W1
x 100
W 1
Where
W =
Weight of sample
W1 = Weight
of flask
W2 = Weight of flask and oil extract
3.3.3
ASH CONTENT DETERMINATION
The ash content of biscuit was
determined using AOAC (1990). A quantity
of dry sample (2.5g) was measured into a tared silica dish and the sample was
heated inside a fume cupboard to drive off most of the smoke. The sample was transferred into a muffle
furnace at the temperature of 5500c for 2 hours until white or light
gray ash resulted. When the residual is
black in colour, it was moistened with a small amount of water to dissolve
salts. It was cooled in a dessicator and
re-weighed.
% Ash = Weight of ash x
100
Weight of original food 1
i.e: W3
–W2 x 100
W2
-W1 1
Where W1=
Weight of crucible
W2
=Weight of crucible + sample before ashing
W3 = Weight of crucible + sample
after ashing
3.3.4
CARBOHYDRATE DETERMINATION
Carbohydrate content was
determined by difference.
% moisture = total carbohydrate
Carbohydrate
= 100 – (% M + % P + % F + % A)
Where M = % moisture
P = %
protein
F = % Fat
A = % ash
3.3.5
PHYSICAL
ANALYSIS
The weight and diameter of the baked
biscuits was determined by weight on a weight balance and measuring with a
calibrated ruler respectively. The
spread ration was determined using the method of Gomez et al., (1997). Three rows
of five stacked biscuits were made and the height of the five stacked biscuits was
measured. The horizontal measurement of
the biscuit was measured as the diameter.
The spread ration was calculated as diameter/ height.
The break strength of the biscuit was
determined according to Okaka and Isieh (1990).
The biscuit of known thickness was placed between two parallel wooden
bars. Weight was placed on the biscuit
until the breaking of the biscuit. This weight was regarded as the break
strength of the biscuit.
3.3.6
SENSORY EVALUATION
Sensory evaluation was carried out 24
hours after baking by 20 semi-trained panelists that will comprise of staff and
students randomly selected from the department of Food Science and Technology,
Ebonyi State University, Abakaliki.
Properties of the biscuit that were evaluated are taste, appearance,
texture, crispness and general acceptability of the biscuit. A 9- point hedonic scale was used with 9 =
like extremely, 8 = like very much, 7 =
like moderately, 6 = like slightly, 5 = neither like nor dislike 4 = dislike
slightly, 3 = dislike moderately, 2 = dislike very much, 1 = dislike
extremely. Samples was cooled and
presented in a random sequence to the panelists.
3. 3. 7 STATISTICAL ANALYSIS
Data was analyzed using analysis of variance
(ANOVA). Mean separation was done using Duncan
Multiple Range Test using SPSS v:16.
CHAPTER FOUR
4.0 RESULTS AND DISCUSSION
4.1 PROXIMATE
COMPOSITION OF WHEAT AND
TIGERNUT
FLOURS
Presented
in table 3 below is the proximate composition of wheat and tigernut flours.
Table 3: Proximate composition of wheat and tigernut flours
|
Flour
|
Fat(%)
|
Protein(%)
|
Ash(%)
|
Fibre(%)
|
Moisture(%)
|
Carbohydrate(%)
|
|
TF
|
23.30
|
3.16
|
1.50
|
1.18
|
10.26
|
58.60
|
|
WF
|
1.60
|
6.23
|
1.73
|
1.14
|
10.56
|
64.73
|
Values
are means of Triplicate Determinations
TF
= Tigernut flour, WF = wheat flour
From table 3 above, the fat content obtained from
tigernut flour was 25.30% however, Oladele and Aina (2007) reported that
tigernut flour had a fat content of 32.13%. The difference in values obtained
could be due to varietal or environmental differences. Fat content for wheat
flour (1.60) was close to the value 2.00% reported by Aroyeun (2009). The
higher value in the tigernut flour when compared to wheat flour could be due to
the fact that tigernut is a plant rich in oil content while wheat is a plant
low in oil.
Protein content obtained in this
work for tigernut flour (3.16%) was lower than the value of 7.15% reported by
Oladade and Aina (2007). Similarly, the protein content of wheat flour in this
work was 6.23% which was lower that 12.10% reported by Aroyeun (2009). Values
obtained in this work suggest that wheat has higher protein content than tigernut
flour.
The ash content of the tigernut
flour in this work (1.50) was lower compared to 3.97% reported by Oladele
and Aina (2007) while the ash content of
the wheat flour (1.73) was close to 1.80% reported by Aroyeun (2009).
The fibre content for tigernut flour
(1.18) was much lower than 6.26% reported by Oladele and Aina (2007), while
that of wheat flour (1.14) was close to 1.90% reported by Aroyesin (200).
The moisture content of tigernet
flour (10.26) was greater than 3.50% reported by Oladele and flour (19.56) was
lower than 13.40% reported Aroyeun (2009).
The carbohydrate content in this
work for tigernut flour was 58.60 which was higher than carbohydrate content of
wheat flour was 58.60 which was higher
than 46.99% reported by Oladel and Aina (2007) while carbohydrate content of
wheat flour wad 64.73%, which was close to 69.80% reported by Aroyaun (2009).
Results revealed that wheat flour
had higher amounts of protein and carbohydrate than the tigernut flour while
the tigernut flour had higher amount of fat than the wheat flour.
4.2 PHYSICAL PROPERTIES OF BISCUITS PRODUCED
FROM TIGERNUT AND WHEAT FLOUR BLENDS.
The physical properties of biscuits
produced from tigernut and wheat flour. Blends are shown in table 4.
Table 4: Physical properties of biscuits produced from tiger
and wheat flour blends.
|
Samples
TF : F : S (g)
|
Break Strength
(g)
|
Weight
(g)
|
Spread ratio
(g)
|
|
25:10:15
|
2700b
|
10.81abcde
|
6.02bc
|
|
25:10:25
|
3165a
|
11.44abc
|
5.76cd
|
|
25:40:15
|
995ef
|
11.76a
|
4.97de
|
|
42.5:10:20
|
1490c
|
8.76f
|
6.88ab
|
|
42.5:25:15
|
1135da
|
10.00bcdef
|
6.21abc
|
|
42.5:25:20
|
1535c
|
11.35abc
|
6.49abc
|
|
42.5:25:25
|
1496c
|
9.23ef
|
7.06a
|
|
42.5:40:20
|
905ef
|
11.16abcd
|
4.89e
|
|
60:10:15
|
1490c
|
11.02abcd
|
5.75cd
|
|
60:10:25
|
2789b
|
11.63ab
|
4.77e
|
|
60:25:20
|
1320cd
|
9.89cdef
|
6.18abc
|
|
60:40:15
|
623g
|
11.15abcd
|
6.45abc
|
|
60:40:25
|
1117def
|
11.83a
|
4.77e
|
|
25:40:25
(Control)
|
860f
|
9.66def
|
5.98e
|
Values
are the mean of then replicate determinations. Means with the same superscript
in the same coloumn are not significantly different (p<0.05).
TF = Tigernut
flour, F = Fat, S = sugar
4.2.1 BREAKSTRENGTH
Break strength of biscuits in the minimum weight or
force that can break or snap the biscuit (Mc Watters et al. 2003). The break strength of some of the biscuits were
significantly different (p<0.05) from each other; the break strength of the
biscuits ranged from 623-31.65g. Although the biscuits were significantly
different, there were some samples that were not significantly different
(p>0.05) from others. Biscuits made from 25TF:10F:15S had the higher break
strength values of 3165g while biscuits made from 60TF:40F:15S had the lowest
value of 623g. In this study, it was observed that increased amount of added
fat resulted in reduced break strength of the biscuits. All the samples containing
40g of fat which was has maximum amount of fat, had low breakstrength values.
The control had a low breakstrength of 860g and it wasn’t significantly
different (p>0.05) from other samples with 40g of fat, except from biscuit
made with 60TF:40F:15S which was significantly lower than it. The breakstrength
of the samples increased as the added fat reduced. Zoulias et al., (2002) reported that fat enhances aeration for leavening
and volume and makes biscuit more easily breakable. Biscuit sample of
60TF:10F:25S and 25TF:10F:25S which had low levels of added fat had high
breakstrengths of 2789 and 2700 respectively. This suggests that fat is a
principal factor that contributes to the easy snapping of biscuits. Zoulias et al. (2002) also reported that fat imparts
tenderness to biscuits and results from this work agree with this report.
4.4.2
WEIGHT
From Table 4, the average biscuit weight ranged from
8.76-11.83g. Biscuit sample with 60TF:40F:25S appeared to have the highest
weight value of 11.83g while sample with 42.5TF:10F:20S had the lowest value of
8.76g. Watters et al. (2003) produced cookies from wheat, fonio and cowpea
flours and reported that the weights of cookies produced ranged between
9.9-11.18g which happens to be close to values obtained in this work. The
weights were also comparable to weights reported by Ago et al (2007) on Acha
wheat biscuits supplemented with soybean flour; Iwe (2001) on soy-sweet potato
four cookies and Agiriga et al. (2008)
on cookies produced from cassava, groundnut-corn starch blends.
4.2.3
SPREAD RATIO
This
is one of the physical properties used to determine the spread ability of the
dough by measuring the diameter divided by the thickness. Though all the
biscuit samples had uniforms initial diameters prior to baking, the spread
ratio of the samples were significantly different (p<0.05), low spread
ratios were noted in some of the samples after baking. The spread ratio ranged
from 4.77-7.06, sample with 42.5TF: 25f:25S had the highest value of 7.06 while
samples with 60TF: 10f:25S and 60TF:40F:25S both had the least values of 4.77. The
spread ratio of the biscuits will go a long way in giving the processor an
insight on the type of packaging material to use. Matz (1992) reported that
controlling cookies spread is one of the most serious problems encountered in
cookie reduction; a cookie which spread so much that too cannot be filled in a package, or one that spreads
too little causing slack filled or excess eight for the package can create
havoc on the packing line.
4.3
SENSORY QUALITY OF BISCUITS PRODUCED FORM
TIGERNUT-WHEAT FLOW BLENDS
Table
5 below shows the sensory quality of biscuits made from tigernut and wheat
flour blends.
Table 5: Sensory quality of biscuits
produced from tigernut and wheat flour blends.
|
SAMPLE
TF:F:S(G)
|
TASTE
|
TEXTURE
|
CRISPNESS
|
Appearance
|
General
Acceptability
|
|
25:10:15
|
6.50cde
|
6.50bcd
|
6.75bcdef
|
7.00abc
|
6.80bcde
|
|
25:10:25
|
6.35de
|
6.45bcd
|
6.50cdefg
|
6.80bcd
|
6.95bcde
|
|
25:40:15
|
5.45f
|
5.70c
|
5.85fg
|
5.85e
|
6.20ef
|
|
42.5:10:20
|
8.10a
|
7.85a
|
7.60ab
|
7.80a
|
8.10a
|
|
42.5:25:15
|
6.35de
|
6.25cd
|
6.30defg
|
6.50cde
|
6.60def
|
|
42.5:25:20
|
6.15ef
|
6.25cd
|
6.25defg
|
7.00abc
|
6.75cde
|
|
42.5:25:25
|
6.80cde
|
6.80bc
|
6.95abcd
|
6.05de
|
6.85bcde
|
|
42.5:40:20
|
6.70cde
|
7.15abc
|
6.85abcde
|
6.50cde
|
6.95bcde
|
|
60:10:15
|
6.70cde
|
6.30cd
|
5.95efg
|
6.35cde
|
6.45def
|
|
60:10:25
|
7.75ab
|
7.10abc
|
7.30abc
|
7.55ab
|
7.60ab
|
|
60:25:20
|
7.15bed
|
6.75bc
|
6.60cdefg
|
6.80bcd
|
7.15bcd
|
|
60:40:15
|
6.00ef
|
5.65c
|
5.70g
|
5.70e
|
5.85f
|
|
60:40:25
|
7.30abc
|
7.30ab
|
7.60ab
|
7.00abc
|
7.50abc
|
|
25:40:25
(Control)
|
7.40abc
|
7.85a
|
7.75a
|
7.45ab
|
7.60ab
|
Means
with different superscripts in the same column are significantly different
(p< 0.0 5).
TF
= Tigernut flour, F = Fat, S = sugar.
The
results of the sensory evaluation (Table 5) shows that most of the samples were
highly rated for all the attributes with the least rated 5 which means the
panelists neither liked nor disliked the biscuits.
4.3.1 TASTE
Taste is one of the complex sensations
that we derive from foods (Ihekoronye and Ngoddy, 1985).
Table 5 showed some significant differences among the
samples for taste. Biscuits made with 42.5TF:10F:20S appeared to have the highest
rating but they were not significantly different (p>0.05) from the control
(25TF:40F:25S), biscuits made with 60TF:10F:25S and 60TF:40F:25S. The least
rated biscuit was 25TF:40F:15S which had the rating of 5.45. It is interesting
to note that the most preferred biscuit (42.5TF:10F:20S) had lower fat content
and lower sugar content than the control. The aim of this study was to cut down
on added fat and sugar contents and maintain good sensory quality as this will
help in reducing health challenges posed by consumption of these ingredients. This
suggests that consumption of this biscuit sample will help in reducing fat and
sugar related diseases.
4.3.2 TEXTURE
Texture of biscuit may be described
as that group of physical characteristics that arises from the structural
element of food which are sensed
primarily by feeling of touch and are related to the deformation,
disintegration and the flow of the food under a force (Bourne, 1965). The texture
of the biscuits were significantly different (p<0.05), sample 42.5TF:10F:20S
and the control had the best ratings of 7.85 while 60TF:40F:15S had the least
rating of 5.65.
4.3.3 CRISPNESS
This is one of the sensory
attributes used in examining the mouth fed of biscuits and the crispness of the
samples were significantly different (p<0.05) from biscuits with
42:5TF:10F:20S and 60TF:40F:25S while biscuits with 60TF: 40F:25S while
biscuits with 60TF:40F:15S had the least rating of 5.70. Manley (2008) reported
that sugar forms structure and hardness, particularly in short dough. In this
study, it appeared that the higher the added sugar the more crisp the biscuits
were, coupled with the natural sugar present in the tigernut flour in the
samples.
4.3.4 APPEARANCE
This is the way a product attracts a
prospective customer or consumer; this
is said to be the external look of a biscuit top which is the smoothness or
roughness of the crust (Ayo et al., 2007).
From table 5, the biscuit samples were significantly different (p<0.05) from
one another in terms of appearance. Sample 42:5TF:10F:20S again had the highest
rating of them all with a mean score of 7.80 while sample w 60TF:40F:15S had
the least mean score of 5.70. The level of added sugar appeared to play a role
in the ratings given for appearance. In some cases, as added sugar increased,
the scores for the appearance increased. For example, while the rating for
42.5TF:25F:20S was 7.00, the rating for 42:5TF:25F:15S was 6.50. Also biscuit
with 25TF:40F:15S had a mean score of 5.85 while 25TF:40F:25S had a score of
7.45. Manley (2008) reported that sugar aids surface colouration during baking
adding to the attractive appearance of the biscuits. Results from this work
agree with this report.
4.3.5 GENERAL ACCEPTABILITY
From Table 5, the biscuit showed
significant differences (p<0.05) among them in terms of their general
acceptability. The biscuit mean score ranged between 5.85 and 8.10 in which
biscuits with 42.5TF:10F:20S appeared to have the highest score of 8.10 while
biscuit with 60TF:40F:15S had the lowest score of 5.85.
4.4 PROXIMATE COMPOSITION OF THE MOST
PREFERRED BISCUIT PRODUCED WITH TIGERNUT AND WHEAT FLOUR BLENDS.
Biscuits made with 42.5TF:10F:20S appeared to the most
preferred with respect to all the sensory attributes evaluated. Based on this,
the proximate composition of the most preferred biscuit (42.5TF:10F:20S) is
shown in table 6 below.
Table 6: proximate composition of the most preferred biscuit,
|
TF:F:S
|
Fat(%)
|
Protein(%)
|
Ash(%)
|
Fibre(%)
|
Moisture(%)
|
Carbohydrate(%)
|
|
42:5:10:20
|
18.88
|
7.80
|
1.80
|
1.24
|
7.77
|
62.51
|
TF
= Tigernut flour, F = Fat, S = Sugar
From Table 6, it was observed that
the fat content of the most preferred biscuit was 19.88% which is comparable to
values of 17.1-18.1% reported by Eneche (1999) on biscuits made with
millet-pigeon pea flour blends and lower when compared to values of
16.21-29.62% reported by Aroyeun (2009) on biscuits produced from cashew kernel
meals. The protein content of the most preferred biscuit was higher when
compared to results reported by Balject et
al., (2010) on biscuits made from the incorporation of buckwheat flour. The
ash content (1.80) was higher than result gotten by Aliyu and Sani (2009) and
Bajeet et al. (2010) indicating that
the most preferred biscuit is less than result reported by Okpala et al, (2012) on cookies made from
germinated pigeon pea, fermented sorghum and cocoyam flours, indicating that
the biscuit can be eaten by adults and children and is with in the recommended
range of not more than 5g dietary fibre per 100g dry matter (FAO/WHO, 1994).
The moisture 100% wheat flour control reported by Okpala and Chinyelu (2011) on
cookies made from pigeon pea and cocoyam flour blends. With its value less than
10%, it suggest other the product can store for a long period of time without
mould infestation and effect on the quality attributes of the biscuit. The
carbohydrate content of the biscuit (62.51) was comparable to results reported
by Baljeet et al. (2010); Aliyu and
Sani (2009); Eneche (1999) and slightly higher than result reported by Aroyeun
(2009)
CHAPTER FIVE
5.0 CONCLUSION AND RECOMMENDATION
5.1 CONCLUSION
This study has established that
acceptable biscuits can be produced from blending tigernut flour and wheat flour
at ratios of 42.5:57.5 respectively, with reduced levels of fat and sugar. The
use of the tigernut flour and subsequent reduction in fat and sugar contents in
the production of biscuits yielded a product that was nutritionally and
organoleptically acceptable. Biscuits made with reduced fat and sugar help to
reduce the risk of contacting health related diseases posed by these
ingredients. The use of tigernut, a local grown crop will not only enhance the
nutritional qualities of the biscuit but also help in the reduction in
dependency on wheat flour, thereby reducing foreign exchange used in importing
wheat into the country.
5.2 RECOMMENDATION
Considering the nutritive and health
benefits of tigernut, there is need for increased utilization and awareness of
its health benefits. I therefore recommend, that more studies should be
conducted to investigate the possibility of using tigernut flour in other baked
products in order to increase applications of such value-added food
ingredients. I also recommend that a thorough nutritional evaluation of the
tigernut biscuit produced in this work be carried out to fully appreciate its
potentials.