Effect Of Storage Time On The Functional Properties Of Bambara Groundnut And Wheat Blend For Cake

Effect Of Storage Time On The Functional Properties Of Bambara Groundnut And Wheat Blend For Cake

Effect Of Storage Time On The Functional Properties Of Bambara Groundnut And Wheat Blend For Cake



Wheat is perhaps the most popular cereal grain for the production of bread and especially for the production of cake and other pastries. Wheat produces a white flour. Its uniques properties alone produce bread dough of strength and elasticity required to produce a low density bread and pastries of desirable texture and flavour.

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In a general way, wheat are classified according to;-

a) The texture of the endosperm because, this characteristic of the grain is connected with the way the grain breaks down in milling.

b) The protein content, because the properties of the flour and its suitability for various purposes are related to this characteristics.

Vitreous and mealy wheat

The endosperm texture may be vitreous (steely flenty, glassy, horny) or mealy (starchy, chalky). Samples may be entirely vitreous or entirely mealy or may consist of a mixture of vitreous and mealy grains with one type predominating. Individual grains are generally completely vitreous or completely mealy but grains which are partly vitreous or mealy are frequently encountered. The specific gravity of vitreous grain is generally higher than that of mealy grain 1.422 and 1.405 respectively (Barley 1916).

Their character is hereditary, but is also affected by the environment. This T. Gegilopoided, T. Dicoccords, T. Monococcum and T. Durum are species with vitreous kernels, where as T. Tugidum and T. aestivum are mealy T. compactum and T. aestivum are mealy 9percival 1921). There character may be modified by the cultural conditions mealness is favoured by heavy rainfall, light sandy soils and crowded planting and is more dependent on these condition than on the type of grain grow. Virtuousness can be induced by nitrogenous manning or commercial fertilizing and is positively correlated with high grain yield’s capacity.

Vitreous kernels are translucent and appear brining against a strong light where as mealy kernel are opaques and appear dark under similar circumstances under similar circumstances.

The opacity of mealy kernel optical effect due to the presence of minute vacuous between and perhaps within the endosperm cells. The development of a mealiness seems to connected with maturation, since immature grains of all wheat types are vitreous, and vitreous grains are found on plants that grow and ripen quickly.

The protein content of wheat varies over a wide range 96-21%) and is influenced less by heredity than by edaphic factor – soil and climatic conditions – preailing at the place of growth and by fertilizer treatment. Range of protein content encountered among samples of various wheat types are shown in Table 2.

Protein content is not a factor determining milling quality, expect in so far as the protein content tends to be higher in vitreous than in mealy wheat, and virtuousness is often associate with hardness and good milling quality. Sample of the English soft wheat varies cappelle Desprez or Flanders may be high protein content and a large proportion of vitreous grains and yet mill as

soft wheat; on the other hands a low protein predominantly mealy-grained sample of the hard variety Maris Widegom will as a hard wheat. The protein content of the endosperm, its quality and chemical structure is however, a most important characteristics in determining baking quality.

Vitreous grain tend to be hard and strong, mealy grains to be soft and weak, but the association is not invariable.

Hard and soft wheat. Hardness’ and softness’ are milling characteristics relating to the way the endosperm break down. In hard wheat, fragmentation of the endosperm tends to occur along the lines of the cell boundaries where the endosperm of soft wheat fractures in a random way. This phenomenon suggests a pattern of areas of mechanical strength and weakness in hard wheat. One view is that ‘hardness’ is related to the degree of adhesion between starch and protein; another is that hardness depends upon the degree of continuity of the protein matrix (Stenvert and Kingwood 1977).

Hard wheat’s yield coarse, gritty flour, free following and easily sifted, consisting of regular-shaped particles, many of which are whole endosperm cells, soft-wheat’s give very fine flour consisting of irregular-shaped fragments of endosperm cells (including a proportion of quite small cellular fragments and free starch granules), with some flattened particles, which adhere together, sift with difficulty , and tend to cloy the apertures of sieves, the degree of mechanical damage to starch granules produced during milling is greater for hard wheat than for soft wheat.

According to Berg (1947), hardness is a milling characteristic that is transmitted by breeding and is inherited in Mendelian fashion. The endosperm of hard wheats may be flinty in appearance, but its breakdown is always typical of hard wheat.

Hardness affects the ease of detachment of the endosperm from the bran. In hard wheat, the endosperm cells come away more cleanly and tend to remain intact, whereas in soft wheats, the sub-aleurone endosperm cell tend to fragment part coming away while part is left attached to the bran.

The granularity of flour gives a measure of the relative hardness of the wheat, the proportion of the. Flour passing through a fine flour silk decreasing with increasing hardness, Greer (1949).


Wheat yielding flour which has the ability to produce bread of large loaf volume, good crumb texture and good keeping properties and generally have a high protein content and are called ‘strong’ whereas those yielding flour from which only a small loaf with coarse open crumb texture can be made, and which are characterized by low protein content are called ‘weak’. The flour from weak wheat is ideal for biscuit (cookies) and cakes, although unsuitable for bread making unless blended with stronger flour.

Flour from strong wheat is able to carry a proportion of weak flour i.e the loaf maintains its large volume and good crumb structure even when a proportion of weak flour is blended with it. It is also able to absorb and retain a large quantity of water.


Nearly all the hard red spring wheat is grown in the North West State of Minnesota, North and South Dakota, Montana, Idoho and Washington. In the drain area of the Western Dakotas, Idaho and Washington, it is common to summer fallow to conserve moisture. In this more humid area, spring wheat is part of regular crop rotation practices.

It is a general custom to seed spring wheat with a drill as soon as the soil is sufficiently dry to work. Early seeding provides a better opportunity to escape the effects of charge from hot whether as well as assuring high yield spring wheat predominates where winter wheat are killed by severe winters.


Amber and red durums are grown in a relatively small area in North and South Dakota and Minesota. The small quantity of red durum grown usually sells at a discount. Seeding and harvesting practices from durum wheat are the same as for seed requirements and generally weak straws that may lodge. In addition, the yield per acre of durum wheat winter recently has average less than spring and winter wheat. During the past 10 wheats yield per seeded acre for durum averaged 22.3 by compared with 20.1 bu paracre for hand spring wheat and 23.5 bu for hard red winter.


White wheat may be either springs or winter in habit. Principal area of production are the Western State of California, Idoho, Oregon, Washington and in Michyigari in the Midwest, new yolk in the East. In the U.S. most white wheat are soft and have in as soft red winter wheat.


According to (Inglett 1974), Kent (1975) and (Shellenberger 1969), wheat kernel composition varies to a large extent, more widely than any other cereal grain. Variation may be due to varietals differences, cultural practices and climatic conditions. The composition of different, parts of the wheat is in Table 3. the chemical composition of different products from wheat varies depending on the processing technique employed, extraction rate and other ingredients added.

The wheat kernel contains 10 – 16% protein, 62 – 70% carbohydrates, 1 – 3.9% fat, 1.8 – 20% ash and some vitamins and pigments. Proteins of wheat occur in all the tissue of the grain. There is variation in the protein content of the whole gain (12%) endosperm and aleurone layer (24%) and embryo (26%). Wheat protein is divided into four types which include albumin, globulim, glindin and glutenin. Elaidin and glutenin are collectively called gllutein. The wheat gluten is responsible for the difference between the baking quality of wheat flour and other cereal flour to form elastic dough during bread and other baking operations is conferred on it by the gluten (Kent 1975).

The gluten structure is necessary for retaining carbon dioxide gas generates during the fermentation of the dough or the chemical leavening of other baked products. Thuds the gluten content and quality are the prime factions used for the evaluation of the quality of wheat flour.


The carbohydrate of wheat kernel (62 – 70%) consists mainly of starch which is the most abundant substance found in the endosperm. Other carbohydrates in wheat grain include reducing sugars, pentosana, and cellulose. The gellation of the starch and the penetration of the protein of wheat flour are responsible for the formation of the rigid but spongy structure formed after baking. Caramelization axtrinization and mailard reaction are responsible for the brown colour of the crust and some vitamin content is different parts of the wheat grain and also varies. The wheat aleurone layer contains larger quantities of niacin, pyridoxine and pantonthenic acid than other parts.

However, most of them are lost during the milling of wheat into refined flour following the removal of the bran. Thus whole wheat flour has much higher levels of B – Vitamins than refined wheat flour.

The vitamins of what are affected by various processing techniques. Naici is not affected by heat but Riboflavin is little affected during bread baking.


The ash content of wheat kernel is about 1.8%. The minerals in the wheat kernel are distributed differentially in the various. Components pericarp contains 5.0% the deurone layer 11.0%, the tests and hyaline embryo and scuttelum 4.5%. the mineral content of wheat flour varies depending on the extraction rate. The mineral content of wheat products depends on the other ingredients added during processing.


The pigments found in wheat grain include carotene (precausor of vitamin A). Xanthophylls, flavones and degradation product of chlorophyll. These contributed to the colour of the wheat grain.


According to Inglett (1974), Kent (1975) and Davidon et al (1975). The nutrient content of wheat is derived from its protein, carbohydrate lipids, minerals and vitamins. Carbohydrates, which are the most abundant nutrient in the wheat grain, contribute energy and dietary fibre to the diet. Protein provide both essential amino acid. The first limiting amino acid in wheat protein is lysine. Others are tryptophan and methionine. Wheat protein has high levels of amino acid glutamine and praline proteins also provide alternative energy in the diet.

The lipids in wheat provide calories in the diet in addition to the essential and non essential fatty acids. However, due to the low level of lipids in wheat kernels, its contributions to energy and essential fatty acid is also low.

Wheat grain contributes many vitamins to the diet, especially the B – vitamins. It has a high level of thiamine and niacin which are concentrated in the embryo scutellum, and highest in the aaleurone layer. Therefore, during the milling of wheat to produce white extraction flours, in which the aleurone layer, embryo and suctdellum are removed as bran, the greater percentage of these vitamins is lost. Thus the white flour from wheat has low levels of these vitamins. This is also applicable to minerals which are lost in the bran to a very large extent during white flour production. Unless the flour is enriches wheat flour is produced or whole wheat grain to minerals and vitamins in wheat grain to minerals and vitamins in the diet of man is on the low side.


Wheat is almost entirely used in the food industry as flour. Thus wheat milling is a very different process to rice milling.

Two aims in wheat milling are:

1. To separate the endosperm from bran and germ.

2. To crush the endosperm to flour.

Wheat grains


Condition to about 17% moisture by soaking in water

Pass through rollers (to break open the bran and free the germ from the endosperm

Pass through roller (to pulverize the brittle endosperm and flatten the germs

Sieve 9to remove bran flakes and germ

Pass through roller (to further pulverize the endosperm and sieves and obtain various endosperm fraction

Flow diam for production of wheat flour

Fig 2.1 (Ikekoronye and Ngoddy 1985) source

(1) Wheat cleaning: This process freed the grain from dirt, non-wheat seeds, sticks, straw, stones, insect, other impurities, damages, shrunken, broken kernels, and metal fragments. The techniques used to achieve this include wet and dry abrasion, magnetic cleaning, use of air current and sieves.

(2) Wheat conditioning: Conditioning of wheat is done primarily to improve the physical state of the grain for milling and some times to improve the baking quality of the flour. Conditioning involves the adjustment of the average moisture content and the distribution throughout the wheat grain so as to toughen the bran, and facilitate its separation from the endosperm. The endosperm it also made more friable and easier to grind by conditioning. The optimum moisture level in the grain to give maximum flour yield. This level is approximately 17% but varies depending on wheat variety, individual flour mills and the desired properties of the flour. The endosperm is made more friable and easier to grind by conditioning. Conditioning is brought about by a combination of moisture additions. Healing and drying.

(3) Milling Process: The milling system for making white flour may be described as a series of interlinked grinding and sieving operations aimed at extracting the maximum amount of white flour that is free from contamination with bran specks. The system aims to open out the grain, often along the crease, then to detect the endosperm from the bran and gradually to reduced the particle size of the endosperm achieving as complete as possible the removal of bran and germ. The interposition of siftings between successive millingoperations facilitate this removal, since the endosperm fragments move easily than the bran and germ. During these process, there is some loss of moisture and dust, and mechanical damage is sustained by the starch granutea of the endosperm. The milling operation is done sequentially through.

(a) Break System: he modern roller milling system attempts to overcome the problem presented by the crease by using rollers with corrugated surfaces in the first stage of milling. A pain of corrugated or fluted rollers at the first break open out the grain usually along the crease, thereby exposing the endosperm still attached to the intact bran.

Subsequently, the second, third and fourth breaks progressively scrape endosperm from the bran.

The roller surfaces are covered with the flutes which spiral round the roller. There is a difference in the tare of rotation between the two rollers of the pair (2 ½ :1 speed ratio for break rollers) such that the flutes of the slower roller.

The first break is fed with the while grains. The second deals with attached endosperm. The brain coasts material derived from the previous break which becomes progressively more thinly covered with endosperm towards the last break. The bran coast from the last breaks pad to a bran finisher, then diverted to by products.

After passing through a pain of break rollers, the crushed material passes to a multiple sifter which segregates the material by size into four or more fractions. Sifting after the first break segregated the grind into large bran coats with attached endosperm and pieces of pure or relatively bran-free endosperm of various sizes, the smallest of which is flour and is therefore removed from the system. The bran coats passes to its associated sifter. This sequence is repeated on the later breaks; at each break stage some flour of decreasing purity is obtained from the sifter and is diverted away from system.


The reduction rollers have smooth or slightly frosted or roughened surfaces and operation with only small speed differential (1 ¼ :1) between the two roller of a pain. The number of reduction roller stages varies from 8 to 16.

At each stage in the reduction system, the average particle size is reduced a little further, and the ground material is fed to the associated sifter for particle size segregation. Hence, according to particle size and degree of purity, fractions rare fed back to appropriate stages in the reduction system for further grinding while the smallest particles are removed from the system as flour.

By carefully adjusting roller pressures in the reduction system, the endosperm, particles can be further fragment while the tougher bran and the more oiling embryo tend only top be flattened. It is then possible to separate most of the bran and embryo particles from the fragmented endosperm by sifting and to feed the bran plus embryo fraction to particular roller grinding stages further down the system to recover any useful endosperm, and then remove the bran plus embryo residue from the system as a further component of the milling by products.

The numbers of rollers pairs, sifters purities and product flow lines linking all these together make a flow lines linking all mill highly complicate and difficult to follow. Materials are removed within the mill mechanically downward by gravity horizontally be worm conveyors, upwards in bucket elevators or pneumatically entrained in moving air currents from which the stocks are separated in cyclomes.


It has been recommended that, for long period of conservation, flour should be stored in a closed atmosphere (Bellenger and Godon 1972). In these conditions, flour acidity increases owing to accumulation of linoleic and linolenic acids which are slowly oxidized, reduction of disulphide group ( – 5: 5 – ) is slow and is little increase in sulphydrl groups (-8H); solubility of gluten protein decreases, as a result, changes in baking strength are ownly minor.

The optimum moisture content for the storage of flour must be interpreted in relation to the length of storage envisaged and to the prevailing ambient temperature and relative humidity. Flour will gain or lose moisture to the surrounding atmosphere unless packed in hermetically sealed containers. Flour can be packed at 14% moisture content but moisture contents higher than 13% mustiness, due to mould growth. Amy develop at moisture content lower than 12% the risk of oxidation and development of rancidity increases.

Experience has shown that freshly milled flour will not yield satisfactory products, either bread or cake for some purposes, the flour may also be deficient in some enzymes notably analyse. While the baking quality of a flour improve with time. It is not economically practical to store flour for the time necessary to age it properly.

Flour naturally aged frequently not uniform and is more susceptible to insect attach during the long storage period. Modern milling practices speed up the aging process by the addition of certain oxidizing agent, and to add certain enzymes in the form of malted barley or malted wheat flour if needed.

Freshly milled flour, as mentioned before, will bake properly, it also has a creamy colour which is not suitable for producing the white bread crumb, both these condition is remedied at the mill by the addition of maturing and bleaching agents such as gaseous chlorine dioxide used at a rate of about 0.2gm/cwt for patent bread flour. Chlorine dioxide also have some bleaching properties but it is insufficient, however, to bleach the flour properly, Benzoyl peroxide which is solely a bleaching agent is used at a rate of about 65ppm in conjunction with maturing agents.

Soft wheat flours, by themselves or in blends with hard wheat flour are used in great variety of product like cake, cookies and pastries. Chlorine treated soft wheat flours produce batters that are more tolerant and cakes that are higher in volume and have improved grain and more tender texture; chlorine treatment also increase the ability of a lour to ‘carry’ more shortening and sugar in a formula, thereby permitting the production of cakes with enhanced eating qualities. The expected shelf life of plain (i.e. non-self raising) white flour packed in paper bags and stored in cool, dry conditions and protected from infestation is 2 – 3years.

(Kebt 1975). The rate of increase in acidity increases with temperature rise and with fall in flour grade (i.e as the ash residue. Hence, the shelf life of brown and whole meal flour is shorten than that of white flour.


The chemical composition of Bambara groundnut is given in table 4, like other legumes, it is high in calories, carbohydrates and protein but low in fat. Its chemical composition has not been extensively studied with regard to its amino acid profile.

Fatty acid composition of the fat, vitamins and minerals.


Bambara groundnut are processed mainly into paste and flour. The seeds are soaked in water to soften the coat, before they are delulled oven dried and milled into flour in a hammer or ay other types of mill followed by sieving using sieves with fire pores.


Cakes are one of the most adaptable of desserts. They are appropriate to serve as a simple refreshment on occasions. They may be classified according to two general. Shortened or butter cake and foam or sponge cakes which contain little or no shortening. In butter type, the shortening may be butter or other kind of fat and the leavening is chemical, plus aim that may be incorporated in whites. Chiffon cakes contain oil which are leavened with chemical leaven and air beaten into egg whites.

Cakes of desired quality have satisfactory volumes and contour and a fine – grained appearance. They are light and have a soft, most texture, the flavours most preferred are those resulting from an appealing blend of good materials and delicate flavouring.


FLOUR: Generally, cake flour are normally milled from soft winter wheat which is characterized by its relatively low protein content only the best grade of flour, averaging usually between 7 and 8.5% protein are used for cake a cake flour is subjected has some tenderizing effect on the gluten. Flour is the chief ingredient in cake making and it must have some gluten forming properties to give the cake its characteristic structure. A given volume of cake flour is lighter than the same volume of all purpose flour.

LIQUID: The liquid used in cake is mainly whole milk, but evaporated milk, skim milk or non fat dry milk solids with water may also be used. On occasion, sourced milk butter milk fruit juice or fruit pulp 9such a bananas and apple sauce) may serve as the liquid ingredient. When this are used, some adjustment in the leaving agent is necessary. This use of butter milk, some milk or molasses as liquid calls for neutralizing the acid with the right amount of soda for proper leavening and palatable flavour. Good volume and liquid. It is important for the amount to be in balance sufficient liquid, not only to dissolve the sugar but to supply liquid to develop the gluten in the flour and to gelatinize the starch.

SUGAR: The amount of sugar in the formular has an influence on the moistness, sweet flavour and tenderness of the cake. The influence on tenderness is believed to be largely due to sugar’s interference both with the gluten formation in the flour and with the coagulation of the egg protein.

The finer the granulation of the sugar, the better the volume of cake. When sugar is increased, more fat is needed for proper formation of aim cells and to improve volume.

EGGS: It contribute to cake quality through enriching flavour and nutritive quality, and by giving structure to the cake. They have a toughening effect unless properly balanced in quality with the sugar and shortening.

Egg contain a considerable amount of protein that is extensible and congealable by heat, they form a portion of the network of the cake structure. And when egg white or whole egg foam is added, it will impart some leaving action to the batter.

SHORTENING: The amount and type of shortening used, also affects the quality of cakes in terms of volume, tenderness and flavour. Better is a flavones for its rich flavour. Fat entraps air during the creaming process, thereby contributing to the leaving of the butter and increasing the volume of the baked cake. As a shortening. It yields a cake that is tender and flavourful but on that has less volume might be obtained through using a hydrogenate fat. Emulsifiers in the hydrogenated shortening aid in the distribution of fat and fat soluble materials throughout the batter.

LEAVENING AGENTS: The major portion of the leavening in a cake batter is supplied through the evolution of carbon dioxide from the reaction of baking powder or baking soda and an acid. Some air is incorporated into the flour mixture through the creaming of fat and sugar, the blending of ingredient and the folding of beaten egg whites into the batter.


1. Butter or shortened cake: they are made with fat.

2. Sponge cake: They are cakes made without fat cakes made with fat include plain yellow, white chocolate spice and pound cake.

Sponge cakes include angle cakes, yellow sponge cakes and “mock” sponge cakes. Clifton cake contain oil but resemble sponge cakes.


Wheat flour 400g

Bambara groundnut flour 100g

Fat 250g

Sugar 200g

Egg 5pce

Brandy 8ml

Baking power 2 tea spoon










(a) Conventional cake method: The first step involves the creaming of the fat and the addition and the rough blending with sugar. Egg yolks or whole eggs may be incorporated with these. If the eggs are separate, only the yolks are blended in at his point, the whites are beaten and folded into the batter at the end, after the other ingredients have been added. The leavening agents, spices and other dry ingredients are sifted together and added to the fat and sugar mixture alternately with the liquid. This method is more time and effort consuming than other methods.

(b) Muffin method: This is quick and easy to perform. The dry ingredients are sifted and mixed together the wet ingredients, including the method fat are blended separately and stirred into the dry ingredients. Cake batter may be more thoroughly stirred than a muffin batter. The higher ration of sugar and fat to flour in the cake batter usually, is sufficient to prevent the formation of gluten strands and toughness as a result of stirring. The texture of this cake ends to be coarse and the cake state quickly. They are best when served warm. The muffin method, with some modification, is used for Clifton cakes.

(c) Simplified method: It is referred to as the high ratio method because of the increased proportion of sugar and fat used. The dry ingredient shortening (super glycerinated plastic fat at room temperature) and part of the milk are combined and beaten at medium speed. For two minutes. The reminder of the milk and egg is blended into this mixture for an additional two minutes. Cake made from this type has been scored highest in preferential test when the proportion of sugar to flour was between 125 and 140% rather than 100%.

(d) Pastry-blend method: In this, the fat and flour are blended before adding the other ingredients. The remaining ingredients are added in two steps. In the first step, half of the milk, sugar and baking powder are combined and blended into the fat and flour. The remaining milk and eggs are added next.


The baking temperature for shortened cakes vary with the ingredients in the batter. Generally, aluminum baking pans are used in laboratory work mainly because, they provide excellent heat distribution and also they are comparatively easy to clear and store. The baking temperature for cake is between 200 – 2200C.


It is concluded that long storage of flour blends decreases their functional properties, and I am recommending that flour should not be used after three months of storage for baking to ensure that desired end product is obtained.

Furthermore, sensory evaluation of the cake made from the stored flour blends should be determined to know the effect of long storage of the flour blends on the organoleptic qualities of the cake.

Effect Of Storage Time On The Functional Properties Of Bambara Groundnut And Wheat Blend For Cake

To place an order for the Complete Project Material, pay N5,000 to

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