ABSTRACT
The effect of duration of fermentation on microbial population, proximate and chemical composition of two samples (boiled and unboiled) of breadfruit (Treculia africana) was investigated. Breadfruit samples purchased from Afor ogbe market, Ahiazu, Mbaise, Imo State were subjected to spontaneous fermentation for a period of 0 to 72 hours and assessed at every 24 hours interval. The microorganisms isolated during fermentation include Lactobacillus plantarum, Lactobacillus casei, Lactobacillus paracasei, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Micrococcus lutens and Saccharomyces cerevisiae. The total viable count for the boiled and unboiled breadfruit samples increased from 4.40 x 105 to 8.73 x 105 cfu/ml and 4.73 x 105 to 9.66 x 105 cfu/ml respectively; Lactic Acid Bacteria count at different fermentation periods increased with increase in the fermentation time from 4.13 x 105 to 8.76 x 105cfu/ml for the boiled breadfruit sample and from 5.20 x 105 to 9.53 x 105 cfu/ml for the unboiled breadfruit sample with a significant difference. The total yeast count for the boiled and unboiled breadfruit samples increased from 5.33 x 105 to 8.80 x 105 cfu/ml and 6.30 x 105cfu/ml to 1.18 x 105 cfu/ml respectively. The pH decreased from 6.52 to 4.68 for boiled breadfruit sample and 6.32 to 4.46 fpr unboiled breadfruit sample while the total titratable acidity increased from 0.49 % to 0.63 % for boiled breadfruit seeds sample and 0.41 % to 0.48 % for the unboiled breadfruit seeds sample during the fermentation. The proximate compositions of the boiled and unboiled breadfruit were assessed. The crude protein and moisture content of the boiled and unboiled breadfruit samples increased from 11.38 % to 12.69 % with a reduction at 48 hours and 5.25 % to 9.19 % from 0 to 48 hours with a decrease at 72 hours to 4.35 % respectively; 57.20 % to 66.07 % and 43.04 % to 59.76 % respectively, the cabohydrate content also decreased from 11.87 % to 0 % for boiled breadfruit seeds sample and 40.29 % to 0 % for unboiled breadfruit seeds sample whereas the ash, crude fibre and crude fat contents varied among all the samples. The proximate analysis reveals that the breadfruit has rich food value and hence may be used with other food supplements in the production of human food and also recommended for diabetic patients due to the reduction in carbohydrate content.
TABLE
OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of Contents vi
List of Tables ix
List of Figures x
Abstract xi
CHAPTER
1: INTRODUCTION 1
1.1 Statement
of Problem 4
1.2 Justification
for the Research 4
1.3 Aim
of the Study 4
1.4 Specific
Objectives 5
CHAPTER
2: LITERATURE REVIEW 6
2.1 Indigenous
Fermented Foods 6
2.1.1 Purpose
and benefits of food fermentation 7
2.2
Nigerian Fermented Foods 12
2.3 Some Fermented Products from Related
Seeds 13
2.4 Microorganisms
Involved in Fermentation of Food Products 14
2.5 Description of Treculia africana 14
2.6 Varieties of Treculia africana 16
2.7 Nutritional Composition 16
2.8 Uses of Treculia africana 17
CHAPTER
3: MATERIALS AND METHODS 19
3.1 Materials 19
3.2 Sample
Collection 19
3.3 Sample
Preparation 19
3.3.1 Boiled
sample 19
3.3.2 Unboiled
sample 20
3.4 Microbiological
Analysis 20
3.4.1 Preparation of culture media 20
3.4.2 Total viable count 20
3.4.3 Isolation,
characterization and identification of microorganisms 21
3.4.3.1 Gram staining 22
3.4.3.2 Motility test 22
3.4.4 Biochemical
identification 23
3.4.4.1 Catalase test 23
3.4.4.2 Coagulase test 23
3.4.4.3 Methyl red test 23
3.4.4.4 Sugar fermentation test 23
3.4.5 Bacterial
DNA isolation 24
3.5 Proximate
Analysis of Samples 26
3.5.1 Moisture
content 26
3.5.2 Ash 26
3.5.3 Crude
protein 27
3.5.4 Crude
fat 27
3.5.5 Crude
fibre 27
3.5.6 Carbohydrate
content 28
3.6 Chemical
Analysis 28
3.6.1 pH 28
3.6.2 Titratable
acidity 29
3.7 Statistical
Analysis 29
CHAPTER
4: RESULTS AND DISCUSSION 30
4.1 Results 30
4.2 Discussion 56
CHAPTER
5: CONCLUSION AND RECOMMENDATION 60
References 61
Appendices 68
LIST
OF TABLES
4.1: Cultural
and biochemical identification of microbial isolated 33
4.2: Cultural
and biochemical identification of of isolated yeast. 34
4.3: Molecular
identification of isolates 35
4.4: Proximate
composition at different fermentation period 54
4.5: Physicochemical
parameters at different fermentation period 55
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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