Proximate, Phytochemical and Sensory Properties of Maize Diet (Elekute) Supplemented With Soybean Flour
Objective of the Study
The objective of this project study is to determine the proximate, phytochemical, and sensory properties of maize flour supplemented with soybean flour.
Production and Distribution of Maize (Zea may L)
Maize (Zea mays L.) is one of the most important cereal crops used in the human diet in large parts of the world and it is an important feed component for livestock. In terms of total world production, maize on average over the last five years out ranked paddy rice (Oryza sativa) and wheat (Triticum aestivum).
Global production exceeds 600 metric tons (McDonald and Nicol, 2005), with about 60% produced in the developed countries, particularly by the United States of America, China produces 27% of the world’s maize and the rest is grown in countries of Africa, Latin America, and southern Asia with a large proportion being produced in the tropics and subtropics. World total maize consumption and production of 2016-17 are shown in graphically below. Total world maize production is 40,861 million bushels. As this graph showed that after U.S, China is largest maize production with 8,643 million bushels while production of maize from Brazil, Eu-27, Argentina, India is 3405, 1437 and 965 respectively.
Total world maize consumption is 40,429 million bushels, U.S is largest maize consumption with 12,360 while China is second largest maize consumption 8937 million bushels. By the early 20th century, maize had become one of China’s major crops. The maize area expanded to 10 million ha, approximately 12% of total cultivated area, between 1900 and 1930. The area sown to maize continued to increase rapidly during subsequent periods; in 22 provinces (not including northeastern China and Inner Mongolia) it increased by 20% between the periods 1937-1945 and 1946-1949 (Wei et al., 2014).
Next to rice, wheat, and millet, maize was the fourth most cultivated cereal crop in China in 1949, when the People’s Republic of China was established. By 1951, maize had exceeded millet in terms of sown area, and maize took its place as the third most cultivated cereal crop in China. Maize area continued to increase substantially during the 1950s, as yields increased. In recent years, however, trends in maize area and production have exhibited higher levels of variability.
Taxonomy of maize
Species: Zea mays
The genus Zea consists of four species of which Zea mays L. is economically important. The other Zea species, referred to as teosintes, are largely wild grasses native to Mexico and Central America. The number of chromosomes in Zea mays is 2n = 20. The tribe Andropogoneae comprises seven genera, namely old and new world groups. Old world comprises Coix (2n = 10/20), Chionachne (2n = 20), Sclerachne (2n = 20), Trilobachne (2n = 20), and Polytoca (2n = 20), and new world group has Zea and Tripsacum (Biology of maize, 2011).
Nutritive value of maize
Maize provides approximately 1400 Kcal/100 g (on a dry basis) of energy that is sufficient to maintain the equilibrium. This energy is also used to perform different types of physiological task. Maize or corn can be consumed as a source of energy in the form of breakfast cereals as cornflakes, chapattis, tortillas, etc. Maize also contains an appreciable amount of fat content that helps in the carrier of fat-soluble vitamins A, D, E and K. The presence of fat in maize or corn is responsible for much of the texture and flavour of food. Thus it helps in increasing the palatability (Longvah et al., 2017).
The fat content beneath the skin known as the subcutaneous fat also serves as an insulating material for the body and is effective in preventing heat loss. Moreover, fat content also acts as a body reservoir for energy conservation purpose (Higgins, 2004).
Another important component in maize after fat is dietary fibre and is defined as the portion of food derived from plant cell, which is resistant to hydrolysis or digestion by the elementary enzyme system in human beings. However, some of the bacteria in the large intestine can degrade some components of fibre releasing products that can be absorbed into the body and also used as a source of energy. Crude fibre is the residue remaining after the treatment with hot sulphuric acid, alkali and alcohol. The major component of crude fibre is a polysaccharide called cellulose and a part of dietary fibre. Insoluble fibres are indigestible and insoluble in water, while soluble fibres are indigestible but soluble in water. Total fibre is the sum of insoluble and soluble fibres. Dietary fibre is isolated and extracted from a synthetic fibre that has proven health benefits. Resistant starch also functions as dietary fibre (Higgins, 2004; Willis et al., 2009; Longvah et al., 2017).
Total fibre = dietary fibre + functional fibre
The effect of fibre on the gastrointestinal tract is influenced by the characteristics of the fibre itself, the particle size, the interaction between fibre and other dietary components and the bacteria flora. Maize also contains a significant quantity of insoluble fibre found in the cell wall of the constituent (Raninen et al., 2011). The insoluble fibre present in maize or corn has a physiological effect in preventing constipation, diverticulitis and even cancer of the large intestine. Maize is also considered as a booster of nutrient like carbohydrates, fats, proteins and insoluble fibres that helps in providing sufficient energy to meet the human daily dietary requirements (David-Jenkins, 2002).
Maize contains 8–11% of protein that is made from different components like albumin, globulin, non-nitrogen substance, prolamin, etc. The quality of maize protein depends upon its agronomic practices and genotype as well. The quality of maize protein is not of good quality as compared to other cereal grains like rice, wheat, barley, etc. Recent researches have shown that with genetic modification, the quality of maize protein can be improved. The maize protein is known as zein that is lack of essential amino acids tryptophan and lysine. The opaque-2 gene is also helpful in reducing the concentration of zein up to 30% and improves the quality protein maize (QPM). The protein content present in maize helps in the growth and maintenance of tissues, formation of essential body compounds, transport of nutrients, regulation of water balance, maintenance of appropriate pH, defense and detoxification as well (David-Jenkins, 2002).
Essential amino acids
These amino acids cannot be synthesized by the body at a sufficient rate to meet the body requirement for optimum growth and development. The human body has certain limited powers of converting one amino acid into another. This is achieved in the liver by the process of transamination, whereby an amino group is shifted from one molecule to another under the influence of amino transferases, the coenzyme of which is pyridoxal phosphate. The inability to synthesize the carbon skeleton of these amino acids is the probable reason why they are dietary essentials. There are nine essential amino acids that are required for a human body to perform various functions (Kataria, 2014).
MATERIALS AND METHODS
The dried maize kernels (Zea may) and soybean (Glycine max) were purchased from the main market of Owo, Ondo State. The maize and soybean was processed into flour in the processing laboratory of Food Science Technology, Rufus Giwa Polytechnic, Owo, Ondo State.
Production of Maize Diet Flour
The maize were sorted to remove the debris, broken and spoilt grains, then 500 g was roasted on a cooker with constant stirring until it changes to brown colour (about 15 minutes). The roasted maize was then milled using a mechanical grinder. The milled maize was then packaged in polythene for further analysis (Figure 3.1).
RESULTS AND DISCUSSION
Table 4.1: Proximate composition of maize-soybean flour blends
CONCLUSION AND RECOMMENDATIONS
Proximate, phytochemical and sensory properties of maize flour were highly improved due to the addition of soybean flour up to 30%. The moisture content of sample MS C was observed lowest indicating higher shelf life compared to other samples, the protein and fat content was improved due to the protein and fat composition of soybean. All the samples content some reasonable amount of essential minerals due to their high content of ash, the control sample had the highest content of fibre this is because of the higher fibre in cereals compared to legumes. The carbohydrates content was observed higher in control sample this is because of the high content of maize flour compared to other samples. The phytochemical properties of the samples increased in terms of phytate, oxalate, tannin and flavonoid with addition of soybean, however it reduced in alkaloids and saponin with an increase in soybean flour.
The panel of judges preferred sample MS D in all parameters (appearance, texture, taste and overall acceptability) while sample MS C was poorly favoured in all parameters. In conclusion, soybean contribute tremendously to nutritional, medicinal and sensory attributes of the samples, hence it will be reasonable to adopt the blends of the flour for the production of snacks and complementary foods such as biscuits, pie, bread, pap, corn flakes etc.
Based on the findings of this study, it is therefore recommended that more research should be carried out to understand the functional properties of maize-soybean flour and to know if it will retain its physical properties if soybean is blended with maize up to 60%. Also the flour blends produced should be considered in developing countries like Nigeria in order to produced maize-based snacks due to its nutritional qualities, this will help reduce protein malnutrition while still retain its organoleptic attributes.
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