MICROBIOLOGICAL, CHEMICAL AND PROXIMATE CHANGES DURING THE FERMENTATION OF BREADFRUIT SEEDS

LIST OF FIGURES

4.1:      Changes in the total bacterial counts during fermentation of

boiled breadfruit seeds (BBS) and unboiled breadfruit seeds (UBS)                        51

4.2:      Changes in the lactic acid bacteria counts during fermentation

of boiled breadfruit seeds (BBS) and unboiled breadfruit seeds (UBS)       52

4.3:      Changes in the total fungal counts during fermentation of boiled

breadfruit seeds (BBS) and unboiled breadfruit seeds (UBS)                       53

CHAPTER 1

INTRODUCTION

A lot of food products owe their production and characteristics to the fermentative activities of microorganisms which helps to preserve and extend their shelf life. These fermented foods account for one-third of total food consumption by human beings (Oyeyipo, 2011) and have been with us since humans arrived on earth and they will remain far into the future. African breadfruit (Treculia africana), is a tropical leguminous crop of the family Moraceace and genus Treculia. It is generally cultivated in the tropics and its tree could grow up to be 40-50 ft high (Fasasi et al., 2007). The seeds from the fruit are edible and are of high nutritional properties (Keay, 1989). It has been estimated that the fruit may contain as much as 1,500 seeds (Ajayi, 2008) whose length is about 8.5mm (Nwokocha and Williams, 2011).

African breadfruit is popular in Nigeria; and humid rain forest of Southeast Cameroon (Omobuwajo et al., 1999). It grows as a large tree in the wet and forest areas of tropical Africa and other countries, such as Senegal, Sudan and Angola; the tree grows well in the riverine forest of tropical Africa, Madagascar, Uganda and Tanzania. It can also be found in some other countries like Guinea-Bissau, Sierra Leone, Liberia, Ghana (Burkill, 1997) and also Mozambique.  This tree with a good biomass yield is often produced in surplus between March and May.Its seeds are often called by various tribal names in Nigeria. Names such as “afon” by the Yorubas, “barafuta” by the Hausas, “Ize” in Bini “eyo” by the Igalas “edikang” in Efik land and “Ukwa”’ in Igbo land (Irvine, 1961; Onweluzo and Odume, 2008).

Treculia africana is commonlly called African breadfruit because it’s large compound fruit (Ejiofor, 1988). It is high yielding with an average sized tree canopy cover of 25 m² and produceing 400-600 fruits per year whereas Morton, (1987) reported yields between 16 and 32 ton/ha/year. They are found from sea level to about 1,550 m elevation. The latitudinal limits are approximately 17 ^oN and 17 ^oS, but maritime climates extend that range to the Tropics of Cancer and Capricorn (Ragone, 2007).  Yields are superior to other starchy staple foods due in part to their verticality production (NTBG, 2009). A single tree produces between 150 kg and 200 kg of fruits per season (Singh, 2009). They grow easily in a wide range of ecological conditions with little or no input of labour or materials and require little attention or care (NTBG, 2009). The seeds have an excellent polyvalent dietetic value whose biological value exceeds even that of soybeans (WAC, 2004). The fruit is hard and spongy in texture when ripe and contains numerous seeds like orange pips embedded at various depths in the fleshy pulp (Ejiofor, 1988; Enibe, 2001). A mature seed consists of an outer covering or seed coat and an inner edible endosperm. The husk is coated with a thin viscous highly hydrated layer or mesocarp which is similar to coffee bean mucilage.

African breadfruit seed husk is brown in colour but the colour changes to black due to oxidation after a fermentation period that varies between 6 to 12 days. The fermentation is done to degrade the fruit pulp and seed mucilage in order to facilitate the extraction of the seeds. The extracted seeds of Treculia africana are identified to become extremely healthy whenever it is correctly processed (Ejiofor et al., 1998; Okafor, 2008). The seeds are roasted and are used as thickeners in soups and are eaten as snacks. The seed is a rich protein source (25-35%) among the plants consumed in the world; it is one of the richest in terms of its benefits (Giami et al., 2004). The de-fated seed contains 20% protein, which is higher than that for cereals and comparable to most pulses. It is primarily high in aromatic amino acids, hence making it a feasible method to obtain good quality protein (Makinde et al., 1995). The raw seed contains 40 - 45% carbohydrates and also a good amount of vitamins and minerals (Oyetayo and Omenwa, 2006). It is also a good source of vegetable oil 15 – 20%. The oil yield of the seed compares well with that of cotton seeds, palm kernel and sunflower seeds. The fat and oil content of the seed makes it probable industrial raw material in the production of pharmaceutical drugs, vegetable-oils, soaps, and paints with perfumes (Nwabueze et al., 2008). It has been used severally in producing biscuits, breakfast meals and complementary foods (Ariahu et al., 1999; Nwabueze and Atuonwu, 2007).

Diverse foods could be produced from the seeds on the basis of custom, tradition and ethnic background.  The seed is variously cooked as porridge alone or mixed with other food stuff such as sorghum (Onweluzo and Nnamuchi, 2009), or roasted and sold with palm kernel (Elaeis guineensis) as roadside snack. Sunday et al (2000) reported that pastries, weaning foods, breakfast cereals and beverages could be developed from African breadfruit seeds.  Onyekwelu and Fayose (2007) reported that the seed kernel was used in preparing pudding, as a thickener in traditional soups and in the manufacture of food products such as flour for bread, beverages and weaning food for children. It can also be fried, baked, steamed, boiled and made into pudding. In West Africa, it is sometimes made into puree (Morton, 1987). In the animal industry, the under-ripe fruits can be cooked for feeding pigs and it is a potential feed material for poultry. Breadfruit leaves and barks are also eaten by domestic livestock. Its latex is used for making chewing gums. The wood is used for furniture and surf boards. The fiber in the bark is fashioned into clothing. In Trinidad and Bahamas a decoction of the breadfruit leaf is believed to lower blood pressure and relief asthma (Morton, 1987). Additionally, a powder of roasted leaves is employed as remedy for enlarged spleen and toasted flowers are rubbed on gums to soothe aching tooth (Logie, 2010).

 In the past consumption was limited to poor village dwellers for which it supplemented their diets during times of food scarcity and substituted rice which was more expensive during festivals and other ceremonies on the basis of tradition and cost (Nwabueze and Nwokenna, 2006). But today, African breadfruit (Treculia africana) has become a delicacy and a specialized meal not only for the rich and the urban dwellers in Nigeria but also has become a source of foreign exchange as the dehulled seeds are sundried and exported to cater for African consumer interests overseas.

1.1       STATEMENT OF PROBLEM

Onweluzo and Nnamuchi (2009) reveal that fermentation enhances the detoxification of breadfruit. But fermentation as a method of processing and preserving breadfruit is not quite popular in most areas (Adekanmi et al., (2012). The nutritional quality of the breadfruit seeds is lacking due to the effect of fermentation and this has made consumers unaware of its nutritional worth.

Despite the great nutritional and medicinal potential of the African breadfruit, there is little analytical information on the microbiological, biochemical changes and the proximate composition of fermented breadfruit seeds.

1.2       JUSTIFICATION FOR THE RESEARCH

Despite the social and economic importance and the great nutritional potential, researchers have not shown much interest in the microorganisms involved, nutritional qualities and sensory properties of African breadfruit seeds processed through fermentation. The unfamiliarity of the actual effect on the nutritional composition and sensory properties of this seed needs to be filled. Orwa et al., (2009) has reported breadfruit to be a good source of nutrients. In order to promote its use as food, knowledge of its nutritional composition, micobiological and biochemical changes as well as its proximate composition must be generated.

1.3       AIM OF THE STUDY

The aim of this study is to assess the changes in microbial population, proximate and biochemical composition of fermented breadfruit (Treculia africana).

1.4       SPECIFIC OBJECTIVES

To determine the microbial load and the microorganisms associated with the fermentation of breadfruit (Treculia africana).

To determine the effect of fermentation on proximate composition of breadfruit (Treculia africana) in order to assess its nutritional benefits.

To determine the effect of fermentation on the chemical composition of breadfruit (Treculia africana).

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