COMPARATIVE DETERMINATION OF THE PROTEIN CONTENTS OF BREADFRUIT, BROWN BEANS AND SOYABEANS SEMINAR
1.1 Background of the Study
Proteins are essential nutrients for the human body (Hermann, 2002). They are one of the building block of the body tissue, and also serve as a fuel source. As a fuel, protein contain 4kcal (17kj) per gram, just like carbohydrates and unlike lipids, which contain 9kcal (37kj) per gram. The most important aspect and defining characteristics of protein from a nutritional stand point is its amino acid composition (Laurence, 2000).
Proteins are polymer chains made of amino acids linked together by peptide bonds. During human digestion, proteins are broken down in the stomach to smaller polypeptide chain via hydrochloric acid and protease actions. This is crucial for the synthesis of the essential amino acids that cannot be biosynthesized by the body (Genton, 2010). There are nine essential amino acids which humans must obtain from their diet in order to prevent protein-energy malnutrition. They are phenylalanine, valine, lysine, leucine, threonine, tryptophan, methionine, isoleucine and histidine (Laurence, 2000). There are five dispensable amino acids which humans are able to synthesize in the body. These five are alanine, aspartic acid, sernine, asparagines and glutamic acid. There are six conditionally essential amino acids whose synthesis can be limited under special pathophysiological conditions, such as prematurity in the infant or individuals in severe catabolic distress (Laurence, 2000). These six are argnine, cysteine, glycine, glutamine, proline and tryrosine (Laurence, 2000). Sources of protein include grains, legumes and nuts, as well as animal sources such as meats, dairy products, fish and eggs (Young, 1994).
African breadfruit (Treculia Africana Decne) belongs to the mulberry family. Moracceae, which is of African origin but now grown in the most tropical and sub-tropical countries (Agu and Nwabueze, 2007). African breadfruit or wild jack fruit in some areas, is a neglected and under exploited tropical tree (Osuji and Owei, 2010).
According to Okonkwo and Ubani (2012), it is a common forest tree called various names among different tribes in Nigeria, such as “Ukwa” (Igbo), “afon” (Yoruba), “eyo” (Igala), “barafuta” (Hausa), “Ize” (Benin) and “edikang” (Efik). The tree crop is widely grown in the southern state of Nigeria where it serves as low cost meat substituent for poor families in some communities (Badifu and Akuba, 2001; Ugwu, et al, 2001). the plant produced large, usually round, compound fruit covered with pointed outgrowths and the seeds are buried in the spongy pulp of the fruits (Nwokolo, 1996). the seeds are seldom eaten raw but can be baked, roasted or fried before consumption, or they can be ground into flour in bakery products (Agu et al, 2007; Ijeh et al, 2010). African breadfruit seeds are highly nutritious and constitute a cheap source of vitamins, minerals, proteins, carbohydrates and fats.
Brown beans (Phaseolus Vulgaris) is a herbaceous annual plant grown worldwide for its edible dry seeds (Known as just ‘Beans”) or unripe fruit (Green beans). It’s leaf is also occasionally used as a vegetable and the straw as fodder. It’s botanical classification, along with other phaseolus species, is as a member of the legume family fabaceae, most of whose members acquire the nitrogen they require through association with rhizoidal, a species of nitrogen-fixing bacteria (Edet, 1982). Beans are grown in every continent except Antarctica. Brazil and India are the largest producers of dry beans, while china produces by far, the largest quantity of brown beans. Worldwide, 23 million tones of dry common beans and 17.1 billion tones of green were grown in 2010 (Philips, 2010). Similar to other beans, the brown beans is high in starch, protein and dietary fiber, and is an excellent source of iron, selenium, potassium, molybdenum, thiamine, vitamin B6and folate (Paul, 1998) .
The soybean (Glycine max(L.) Merrill family Leguminosae, subfamily Papilionoidae) originated in Eastern Asia, probably in north and central china. It is believed that cultivated varieties were introduced into Korea and later Japan some 2000 years ago. Soybeans have been grown as food crop for thousands of years in China and other countries of East and South East Asia and constitute to this day, an important component of the traditional popular diet in these regions (William, 2003). Although the U.S.A and Brazil account today for the most of the soybean production of the world, the introduction of this crop to Western agriculture is quite recent. Soybeans are primarily, an industrial crop, cultivated for oil protein. Despite the relatively low oil content of the seed (about 20% on moisture-free basis), Soybeans are the largest single source of edible oil and account for roughly 50% of total oil seed production of the world (Singh, Nelson and Chung, 2008). With each ton of crude soybean oil, approximately 4.5 tons of soybean oil meal with a protein content of about 44% are produced. For each ton of soybeans processed, the commercial value of the meal obtained usually exceeds that of the oil. Thus, soybean oil meal cannot be considered by-product of the oil manufacture. The soybean is, in this respect, an exception among oil seed (Shurtleff; Steenhuis and Spiers, 2013). It can be calculated that the quality of protein in the yearly world production of soybeans, if it could be totally and directly utilized for human consumption would be sufficient for providing roughly one third of the global need for protein (William, 2003). This makes the soybeans one of the largest potential source of dietary protein. However, the bulk of soybean oil meal is used in animal feed for the production of meat and eggs. Despite considerable public and commercial interest in soybean products as food, the proportion of soybean protein consumed directly in human nutrition is still relatively small (Smith, 1972).