ABSTRACT
This study evaluated the formulation and evaluation of breakfast cereals from blends of acha and fermented okara (soybean residue). Acha grains were cleaned, winnowed, washed, dried (at 50˚C for 4 hours) and milled into flour. Okara was processed from soybeans seed through the stepwise procedure of cleaning, soaking, washing, milling and sieving. The residue was divided into five portions, fermented differently for 0, 12, 24, 36, and 48 hours and then dried at 50˚C for 6 hours. Acha flour (UFAC) was milled and blended at 50, 60, 70, 80, 90, 100% ratio with milled okara flour. Functional properties (bulk density, water absorption capacity, swelling capacity, wettability, viscosity and particle size distribution), microbial load, and proximate composition were carried out on the individual flour samples. The blended flours were conditioned, partially heat treated (for 10 minutes), aged (4˚C for 6 hours), cut, toasted (120˚C for 1 hour), cooled and packaged. The different toasted breakfast cereals, TBFC, were subjected to sensory evaluation, proximate composition, micronutrient composition (vitamin A, B1, B2, B3, calcium, iron, phosphorus, and zinc) and microbial analyses (mould count and total viable count). The proximate composition of the unfermented okara (UFOK) and fermented okara (FEOK 1, 2, 3, and 4 fermented at 12, 24, 36, 48 hours respectively) flour samples showed that fermentation increased moisture from 4.71±0.06 to 6.11±0.05, crude fibre from 36.62±0.01 to 46.18±0.55, and carbohydrate from 2.50±0.18 to 2.71±0.34 contents. There was a decrease in the fat content from 13.27±0.22 to 16.29±0.04, ash from 1.41±0.17 to 6.36±0.17 and crude protein from 30.32±0.21 to 33.53±0.11 contents. From the sensory evaluation, the result showed that 70:30 acha- unfermented okara TBFC, FEOK 1D 60:40 acha-12hrs FEOK TBFC, 70:30 acha-24hrs FEOK TBFC, 50:50 acha-36hrs FEOK TBFC, and 70:30 acha-48hrs FEOK TBFC had the overall acceptability for the different fermentation times. The functional properties, proximate and sensory evaluation were the basis for selection of the best products which were UFAC (control), UFOK C (70:30 acha UFOK TBFC) and FEOK 4C (70:30 acha 48hrs FEOK TBFC) which were further subjected to proximate, micronutrient, and microbial analyses. There was an increase in the protein, fat, ash, crude fibre content whereas the moisture and carbohydrate contents decreased. A considerable decrease was found in vitamin A and B1 contents of the products, whereas vitamin B2 and B3 increased. Also the mineral contents of all the products were improved as indicated in the increase in ash content. Microbial count of the flour samples and the products were also carried out.
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF STUDY
Breakfast in simple term means “breaking the fast” of the night. It is the most important meal of the day because it is the meal which is used to break the fast of the long night usually 10-12 hours. Breakfast is regarded by many nutritionists as the most important meal of the day, because food consumed at breakfast seem to be more utilized than the same amount eaten at night. Most researchers who have studied the effect of eating breakfast have suggested that the benefits are due mainly to the protein that is eaten from the meal, because high protein breakfast were found to be better than low protein breakfast in helping to maintain a normal blood sugar level between mid-morning and lunch (Ensminger, 1994).
Breakfast is basically produced from cereals which are the dry seeds of those members of the grass family grown for their grains and are by far the most important plants eaten by man. Cereal is typically a low-fat, nutrient-dense food with many essential vitamins and minerals such as zinc, phosphorus, calcium among others. In addition to delivering important nutrients and essential vitamins such as iron, B vitamins and zinc, cereals also provide the important benefits of grains.
Breakfast cereal is defined as dry cereal eaten at breakfast (Thorndike and Bamhart, 1977) which has been processed into different forms by soaking, swelling, roasting, grinding, rolling or flaking, shredding or puffing of any cereal and is eaten as breakfast. Breakfast cereal consisting of vegetable protein foods (bread, cereals and soy bean milk) were reported to be as effective as those consisting chiefly of animal protein foods (eggs, meat and milk) in keeping the blood at a normal level (Chaudhri and Muller, 1970). The level of protein eaten as breakfast cereal may depend partly upon the amount supplied by a cereal.
Breakfast cereal products were originally sold as milled grains of wheat and oats that required further cooking in the home prior to consumption. In this century, due to efforts to reduce the amount of in-home preparation time, breakfast cereal technology has evolved from the simple procedure of milling grains for cereal products that require cooking to the manufacturing of highly sophisticated ready-to-eat products that are convenient and quickly prepared (Tribelhorn, 1991).
Cereals have been used over the years as industrial raw material because of the high carbohydrate, low fat and protein contents. Meanwhile, proximate composition of a food material would not give indication of limited use because sorghum, millet, fonio (acha) among others, are under-utilized. These under-utilized cereals lack some essential nutrients thereby reducing their uses. Also, their uses had been relegated to household preparation of local dishes. Their potentials could be brought to limelight when the under-utilized cereals are processed technologically into industrial or commercial products. Though, the cereal grains provide the bulk of the energy requirement in local meals because of their low cost, they are surplus in the essential sulphur-containing amino acid, methionine and cystine but poor in lysine (Siegel and Fawcett, 1976). This deficiency could be complemented by others constituents, structure and colour, qualities which are locally available, under-exploited legumes that incidentally are high in protein, mainly lysine but limited in cystine and methionine and probably tryptophan (Bressani,
1975). Cereals and legumes, therefore, complement each other in both traditional food preparation and for industrial uses (Oke, 1975; Nkama, 1990).
However, the practice of producing breakfast cereal from blends of acha, and fermented okara is a way of improving the nutritional composition of breakfast cereal. Acha (Digitaria exilis), is one of the oldest and richest cereals of West Africa, which is unknown to many people and neglected by research and extension services. Adapted to poor soils and limited water supply, acha is an excellent dry crop which grows and produces where other crops fail. It is a cereal with very tiny seeds which poses difficulty in processing but is absolutely rich in amino acids (Vodouhè et al.,
2012) and needs to be supplemented with a legume for higher nutrient-dense product. Okara is a residue obtained from soybean (Glycine max) which is milled after removing the water- extractable fraction used to produce tofu or soymilk. About 1.2 kg of fresh okara is produced from 1 kg of soybean processed for manufacturing tofu (Li et al., 2008). It contains most of the carbohydrates, some of the protein and a small portion of the oil from soybeans.
Since acha is reported to be rich in amino acids, particularly methionine and cystine (Belton and Nuttall, 2002) which supply sulphur and other compounds required for normal metabolism and growth, it is important to blend acha, a cereal and fermented okara, a legume as a way of improving the carbohydrate, proteins, vitamins and beta-carotene contents of the breakfast cereals. The flour produced from a combination of acha and okara is regarded as composite flour. A composite flour is a mixture of flours from tubers rich in starch (e.g. cassava, yam, sweet potato) and/or protein-rich flours (e.g. soy flour) and/or cereals (e.g. maize, rice, millet buck, wheat), with or without wheat flour (Anon, 2000). For developing and under-developed countries, the use of composite flours has the following advantages;
• A better supply of protein for human nutrition.
• A saving of hard currency.
• Promotion of high yielding, native plant species.
• Better overall use of domestic agriculture production (Bugusu et al., 2001).
1.2 STATEMENT OF PROBLEM
The amount (yield) of cereals grown in Nigeria is high compared to its utilization. This is due to postharvest losses incurred from cereals, thus there is need to diversify the use of cereals into producing packaged foods such as breakfast cereals which can be made available all year round.
Intake of unhealthy or very low quality breakfast cereal can result in the following, inability to focus on tasks, less memory capacity, decreased alertness throughout the day among others. Also health related effects include high risk of developing diabetes, increased cholesterol, high blood pressure among others. Therefore, it is necessary to eat a balanced breakfast cereals that can help ameliorate these health problems and this can be provided from breakfast cereals formulated from acha and fermented okara.
Protein deficiency has become a dietary problem facing the world especially the underdeveloped and developing countries (Enweremadu et al., 2008). Animal protein is expensive in developing countries like Nigeria; therefore it becomes necessary to find an alternative means of compensating for low protein availability and also to fortify the staple foods with vitamins and minerals.
Huge quantities of okara are produced worldwide. In Japan about 800,000 tons, in Korea approximately 310,000 tons, and in China about 2,800,000 tons of okara are produced from the tofu industry every year (Ohno et al., 1993, Ahn et al., 2010). These huge quantities of
okara produced annually pose a significant disposal problem. Okara is sometimes used as animal feed but most is dumped and burned as waste. However, its nutritive composition makes it suitable for producing different fermentable edible products, like single cell protein for human food and feed. The high moisture content of okara makes it unfavorable to be utilized alone and so is incorporated into other food raw materials to produce a more shelf stable foods products.
1.3 AIM AND OBJECTIVES Broad objective
• The major aim of the study is to develop and evaluate breakfast cereal produced by blending acha and fermented okara.
Specific objectives
The specific objectives of this research include the following:
• To formulate composite flour from acha and fermented okara.
• To determine the appropriate blending ratio for the development of breakfast cereal from blends of acha and fermented okara.
• To produce nutrient-dense breakfast cereals from blends of acha and fermented okara.
• To evaluate the nutritional composition and sensory qualities of breakfast cereals made by blending acha and fermented okara.
1.4 JUSTIFICATION OF THE STUDY
Breakfast cereal is a widely consumed meal for breakfast. Thus, the study is based on improving the proteins, vitamins (vitamin A), and minerals (calcium, iron, and beta-carotene among others) from the blends of acha, and fermented okara. At the end of the research, the breakfast cereals produced would provide the body with high content of protein, vitamins and minerals and therefore prevent protein deficiency (malnutrition), night blindness, cognitive development, low resistance to infections associated with their deficiencies, damage of the white blood cell (which fights against infections) in the body. The research work is also a basis for producing quality breakfast cereals which would be readily made available and affordable to all (including the less privileged that do not have access to vitamin-rich foods) since breakfast cereal is a widely consumed meal for breakfast. Most of the breakfast cereals produced today is deficient in some basic nutrient probably because they are formulated with only cereals. Although, the cereal grains provide the bulk of the energy requirement in local meals because of their low cost, they are surplus in the essential sulphur-containing amino acid, methionine and cystine but poor in lysine. This deficiency could be complemented by others constituents, structure and colour, qualities which are locally available, under-exploited legumes which incidentally are high in protein, mainly lysine but limited in cystine and methionine and probably tryptophan. Therefore, the focus of this study is to produce breakfast cereals not just with cereals or grains but by blending with legumes as to have a well balanced breakfast cereal and also have diversified product.
This material content is developed to serve as a GUIDE for students to conduct academic research
PRODUCTION AND EVALUATION OF BREAKFAST CEREALS FROM BLENDS OF ACHA AND FERMENTED SOYBEAN PASTE (OKARA)
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