ABSTRACT
Cassava fufu flours were produced following 72 h fermentation, of two cassava varieties (TME 419 and Umucass 45) by lactic acid fermentation and natural fermentation (0-72 h). Two starter cultures (L. plantarum, L. fermentum and their combination) were used to initiate lactic acid fermentation. At 24 h intervals the pH, titratable acidity (TTA), microbial load (Starter culture count, total LAB count of natural fermenting mash, yeast/mould count, microbial quality) and molecular characterization of natural fermentation isolates were determined. The wet mash samples were dried and milled to flour and analyzed for chemical, functional and sensory properties of the flours. The results revealed that the percentage titratable acidity of the cassava varieties increased from 0.23 – 1.18% as fermentation progressed in relation to decrease in pH (5.22 -3.70). Samples (419 LP+LF and 45LP) gave the highest starter culture count of 5.62 log CFU/g at 48 h and showed a decrease at 72 h of fermentation. The sequencing of PCR of 16s rRNA gene, identified the bacterial isolates as Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus pentosus, Lactococcus lactis and Saccharomyces cerevisae. The cassava flour samples were safe for consumption since potential pathogens were not detected. The fresh cassava carotenoid content of Umucass 45 had the highest carotenoid value (11.7mg/g) which showed significant difference (p < 0.05) from other samples. The sugar and starch contents showed similar trends. Sugar content ranged from (4.93 – 2.20), with unfermented sample having the highest value. The proximate composition of the products ranged from; Moisture (8.58 – 11.14%), Ash (1.30 – 2.54%) crude protein (1.38 – 5.73%), crude fibre (0.70 – 1.76%), fat (0.52 – 0.93%) and carbohydrate (81.09 – 84.84%). Functional properties increased in bulk density (0.66 – 0.79 g/ml), oil absorption (1.25 – 1.36 g/ml), water absorption (2.98 – 3.52 g/ml), swell index (2.73 – 3.45 g/ml), while a decrease in gelatinization temperature (70.10 – 67.450c) was observed. Fermentation reduced significantly, the anti-nutritional factors: HCN (48.03 - 3.16mg/100g), phytate (5.12 – 0.23 mg/100g), tannin (2.22 – 0.20 mg/100g), alkaloid (3.84 – 0.06 mg/100g). Amino acid profile revealed that fermentation led to significant improvement of protein quality of the flour products. The highest essential amino acid leucine (6.36 g/100g) and non-essential amino acids glutamic acid (7.64 g/100g) were recorded for flour from yellow cassava. Minerals of samples ranged from 28.42 – 31.10 mg/100g for calcium; 15.30 – 21.67 mg/100g magnesium; 35.29 – 46.31 mg/100g potassium; 13.07 – 18.33 mg/100g phosphorus; 0.67 – 1.75 mg/100g zinc; and 1.25 – 3.52 mg/100g iron respectively. The Gas Chromatograph Mass Spectrometer (GCMS) profile of samples detected the presence of alcohol (penatdecanol) and acids (hexadecanoic acid) indicating the flour products contain different flavor compounds, due to different microorganisms present during processing. Sensory evaluation, showed that starter culture and natural fermented flours were not significantly different (p > 0.05) in odour mould-ability, hand feel and overall acceptability but showed significant difference (P < 0.05) in appearance and acceptable. The flours had good functional and sensory properties. Fermentation either natural or with starter cultures can enhance the nutritive value of cassava tubers for sustainable local technologies and utilization of the value-added product for human nutrition.
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgments v
Table of Contents vi
List of Tables xi
List of Figures xiii
List of Plates
xiv
Abstract xv
CHAPTER 1: INTRODUCTION 1
1.1 Statement
of Problem 6
1.2 Justification
7
1.3 Objectives
of The Study 8
CHAPTER 2: LITERATURE REVIEW 9
2.1 Fermentation
9
2.2 Fermented
Foods 11
2.3 Types
of Food Fermentation 11
2.3.1 Fermentation
with lactic and bacteria (LAB) 11
2.3.2 Acetic
acid fermentation 12
2.3.3 Alcoholic
fermentation 13
2.3.4 Traditional
fermentation 13
2.4 Lactic
Acid Bacteria (LAB) Metabolism of Carbohydrates 15
2.5 Important
Characteristics of Lactic Acid Bacteria 16
2.6 Importance
of Fermented Foods 17
2.6.1 Healthy and safe products 17
2.6.2 Probiotic and prebiotic potentials 17
2.6.3 Nutritional and health
benefits of LAB fermentation 18
2.7 Nigeria
Indigenous Fermented Foods (NIFF) 18
2.8 Advantages
of Fermented Foods 21
2.8.1 Role
and function of fermentation on cassava food 22
2.9 Anti-nutrient
Reduction in Cassava Fermented Food 23
CHAPTER 3: MATERIALS AND METHODS 25
3.1 Location 25
3.2 Materials
25
3.3 Organisms
and Culture Methods 25
3.4 Preparation
of Inoculum 26
3.5 Preparation
of Fermented Yellow Cassava Roots 26
3.6 Yellow
Cassava Fufu Flour Production 27
3.7 Determination of
Titratable Acidity (%) 33
3.8 pH
Measurement 33
3.9 Isolation
and Enumeration of Lactic Acid Bacteria (Lab) and Yeast
Population
During Natural Fermentation of the Cassava Varieties 34
3.9.1 Yeast
count and isolation 35
3.9.2 Microscopic
characterization 35
3.9.3 Gram
staining 35
3.9.4 Motility
test 36
3.10 Biochemical
Tests 36
3.10.1 Catalase test 36
3.10.2 Oxidase test 36
3.11 DNA
Extraction of Lactic Acid Bacteria (Lab) and Yeast Isolated
During
Natural Fermentation of Cassava Varieties. 37
3.11.1 DNA extraction 37
3.11.2 Polymerase chain reaction
(PCR) amplification of extracted DNA 38
3.11.3 The PCR purification 39
3.11.4 DNA sequencing and BLAST search 40
3.12 Total
Carotenoids Determination 40
3.13 Determination
of Starch and Sugar Contents 41
3.14 Determination
of Proximate Composition of Yellow Cassava Flours 42
3.14.1 Moisture determination 42
3.14.2 Carbohydrate content determination 43
3.14.3 Ash content determination 43
3.14.4 Fat determination 43
3.14.5 Determination of crude fibre 44
3.14.6 Determination of protein 45
3.15 Functional
Properties Determination 45
3.15.1 Bilk density 45
3.15.2 Gelatinization temperature (GT) 46
3.15.3 Water absorption capacity (WAC) 46
3.15.4 Oil absorption capacity (OAC) 46
3.15.5 Swelling index 47
3.16 Anti-nutrient
Composition 47
3.16.1 Determination
of alkaloid 47
3.16.2 Determination
of tannins 48
3.16.3 Determination
of phytates 48
3.16.4 Determination
of hydrogen cyanide 48
3.16.5 Determination
of amino acid profile 49
3.17 Defatting Sample 49
3.18 Nitrogen Determination 49
3.19 Hydrolysis of the
Sample 50
3.19.1 Loading
of the hydolysate into analyzer 51
3.19.2 Method
of calculating amino acid values 51
3.20 Determination
of Minerals 51
3.20.1 Determination of calcium and magnesium 51
3.20.2 Determination of potassium 52
3.20.3 Determination of phosphorus 52
3.20.4 Determination of iron and zinc 53
3.21 Identification and Qualification of Flavor
Profile Fermented Flours 54
3.22 Sensory
Evaluation of Fufu Flour 54
3.23 Statistical
Analysis 55
CHAPTER 4: RESULTS AND DISCUSSION 56
4.1 pH and Titratable Acidity of Fermented
Cassava Varieties 56
4.2 Total Lactic Acid Bacteria Count 59
4.3 Lactic Acid Bacteria Profile During the Natural
Fermentation of
Cassava Varieties 62
4.4 Molecular Identification of Isolates
During Natural Fermentation 64
4.5 Yeast Count (Log cfu/g) During the
Natural Fermentation of the
Cassava Varieties. 78
4.6 Microbial Count (cfu/g) of the Fermented
Cassava Flour Samples 81
4.7 Carotenoid Content of the Cassava Flours 83
4.8 Changes in Starch and Sugar Content of
the Cassava Flours 86
4.9 Proximate Composition of Raw and Fermented Cassava Flours 88
4.10 Functional
Properties of Fermented Cassava Flours 94
4.11 Amino Acid Profile of Fermented Cassava
Flours. 98
4.12 Anti-Nutrient Content of Fermented Cassava
Flours 99
4.13 Mineral
Content of the Fermented Cassava Flours. 102
4.14-21 Flavor
Profile of Fermented Cassava Flour. 106
4.15 Sensory Properties of Fermented Cassava Fufu Flour 117
CHAPTER 5: CONCLUSION
AND RECOMMENDATIONS 119
5.1 Conclusion 119
5.2 Recommendations 121
References 122
Appendix 140
LIST
OF TABLES
3.1 PCR
Conditions for 16s rRNA of bacteria 38
3.2 PCR
conditions for its fungi 38
3.3 PCR
cocktail mix 39
4.1: The
pH and Titratable Acidity of starter fermented cassava
varieties
at different fermentation periods 58
4.2. Lactic acid bacteria (LAB)
count (1ogCFU/g) during
fermentation periods
with starter cultures of
L. plantarum, L. fermentum and both 61
4.3:
Lactic acid bacteria
(LAB) profile during natural
fermentation of cassava
varieties (log CFU/g)
63
4.5: Yeast/mould
count (log CFU/g) during natural fermentation of
cassava
varieties 80
4.6:
Microbial count (CFU/g)
of fermented cassava flours. 82
4.7 Effect
of starter cultures on the carotenoid retention of
cassava
flours 85
4.8: Effect
of starter culture fermentation on starch and sugar
content
of flour samples 87
4.9: Effect
of starter culture fermentation on the proximate
composition
(dry weight basis) of cassava flour samples 93
4.10: Effect
of starter culture fermentation on the functional
properties
of cassava flour samples 97
4.11: The
amino acid profile (g/100g protein) of fermented cassava
fufu flours
of TME 419 and Umucass 45 cassava varieties 99
4.12: Effect
of starter fermentation on anti-nutrient produced
fufu flours 102
4.13: Effect of starter culture
fermentation on the mineral content
(mg/100g) of the
fermented flours 106
4.14:
GCMS retention time and
area percentage (concentration)
. of
flavor compounds in natural fermented cassava flour (NF 419) 110
4.15: GCMS retention time and Area %
(concentration) of flavor
compounds in
starter culture fermented cassava flour (LP 419) 111
4.16: GCMS retention time and area %
(concentration) of flavor
compounds in starter
culture fermented cassava flour (LF 419) 112
4.17:
GCMS retention time and
area % (concentration) of flavor
compounds
in starter culture fermented cassava flour (Both 419) 113
.
4.18:
GCMS retention time and
area % (concentration) of flavor
compounds
in natural fermented cassava flour (NF 45) 114
4.19:
GCMS retention time and
area % (concentration) of flavor
compounds
in starter culture fermented cassava flour (LP 45) 115
4.20:
GCMS retention time and
area % (concentration) of flavor
compounds
in starter culture fermented cassava flour (LF 45) 116
4.21:
GCMS retention time and
area % (concentration) of flavor
compounds
in starter culture fermented cassava flour (both 45) 117
4.22: Effect
of starter culture fermentation on the sensory properties
of
instant cooked fufu flour 119
LIST OF FIGURES
3.1: Traditional method of
production of cassava flour 28
3.2: Traditional
method of production of cassava flour with
inoculation
of Lactobacillus plantarum 29
3.3: Traditional
method of production of cassava flour with
inoculation
of L. fermentum 30
3.4: Traditional
method of production of cassava flour with
inoculation
of L. plantarum and L. fermentum 31
3.5:
Traditional method of
production of unfermented cassava flour 32
4.1: L. Plantarum (NF 45 MRS) 70
4.2: L. Fermentum (NF45 MRS) 71
4.3: L.Pentosus (NF45 MRS) 72
4.4: S. Cerevisiae (NF45 PDA) 73
4.5: L. Fermentum (NF 419 MRS) 74
4.6: L. plantarum (NF419 MRS) 75
4.7: L. Lactis (NF419 MRS) 76
4.8: S. cerevisiae (NF419 PDA) 77
4.9: S. cerevisiae (NF36 PDA)
77
LIST
OF PLATES
1: Shows the total genomic DNA of L. Plantarum,
L. fermentum and
L. pentosus as shown in agarose gel
electrophoresis for 45 NF MRS. 65
2: Total genomic DNA of L. plantarum, L. fermentum and L. lactic as
revealed in agarose gel
electrophoresis for NF 419 MRS 65
3: Shows the total genomic
DNA of S. cerevisiae as revealed in
agarose gel electrophoresis for NF 45 PDA. 66
4: Total genomic DNA of S.cerevisiae
as shown in agarose gel
electrophoresis for NF 419 potato dextrose agar (PDA) 66
5: Shows
the PCR products of L. plantarum, L.
fermentum, L. pentosus
for NF 45 68
6: Shows
the PCR products of L. plantarum, L.
fermentum, L. pentosus
for NF 45 68
7: Shows
the PCR product of S. cerevisiae for NF 45 PDA (PCR
reaction gel picture
of fungi from NF45) 69
8: Shows
the PCR product of S.cerevisiae for NF 419 PDA 69
CHAPTER 1
INTRODUCTION
Cassava (Manihot esculenta Crantz) is an important crop widely cultivated in
Sub-Saharan African. Although cassava is grown virtually in all parts of the
sub-continent, its production is specific in the humid tropics (Okereke, 2001).
Cassava is one of the major essential food crops in the tropic (Burrel, 2003)
and used as a food preservation and income generation crop for many millions of
people in the unindustrialized world (Scott et
al., 2002).
Cassava is grown widely in Nigeria and in
many regions of the tropics, where it serves as one of the basic food sources
for about 200-300 million people (FAO, 1991). Cassava is a major starch staple
in Africa and it is particularly important in Nigeria. Nigeria accounts for
about 40% of cassava production in Africa. According to Oyewole and Odunfa (1992)
in African, cassava provides over 50% of the average daily caloric intake in
some countries. A diversity of national efforts to propagate optimized cassava
cultivars have recently been launched (Guira et al., 2016) to increase yield and opposition to infections and
through Harvest Plus Germplasm Development - African component develop cassava
cultivars with increases levels of β-carotene in the root tubers. Cassava
cultivars rich in pro-vitamin A (PVA) have been released in cassava-growing
countries in Africa as a consequence of effective biofortification attempts
across the world (Omodamiro et al.,
2012; Birol et al., 2015). The new
varieties besides adding to the energy intake of consumers also acts as vehicle
of conveying Pro-vitamin A (PVA) to vitamin A deficient (VAD) populations
(Tanumihardjo et al., 2008). Yellow
cassava is another name for these new bio-fortified cassava roots. The yellow
fleshed cassava according to (Egesi et
al., 2011) is a newly released bio-fortified crop which is similar to the
white varieties in terms of utilization for man and animal, though the pulp
colour differs. The yellow-fleshed cassava varieties are grown in Nigeria for
their high accumulation of β-carotene, a precursor of vitamin A. Yellow-fleshed
cassava shows great potential to alleviate vitamin A deficiency in Africa since
cassava is a staple food. Vitamin A is also a vital part of human nutrition as
it helps with sight, cell division, glycoprotein formation, fertility, and
total development and growth (Woolfe, 1992). African countries are not only
faced with problem of food preservation but that of nutritional insecurity
leading to different forms of micronutrients deficiencies in the diet.
Bio-fortification of cassava is therefore highly appropriate as this will
contribute to the alleviation of diseases associated with vitamin A deficit
(VAD) which is a common dietary health problem, especially in countries where
cassava is a major staple food.
Therefore, its development and
dissemination by National Root Crops Research Institute Umudike (NRCRI) and
International Institute of Tropical Agriculture (IITA) Ibadan in collaboration
will compliment current effort to address vitamin A deficiency by delivering
vitamin A through a staple food consumers eat every day (www.harvestplus.org).
Nigeria is the major producer of cassava in the world (FAO, 2008) with about 45
million metric tonnes and cassava transformation is the most advanced in Africa
(Egesi et al., 2006).
Cassava is cultivated in the tropical
regions and may be the main valuable root crop in terms of overall output and
cultivated area (Ano, 2003). According to Ogbe et al. (2007), it is a main food crop in Nigeria. It is
strategically important for its position in food protection, alleviating
poverty, and input materials supplies for agro-allied sectors in Nigeria as
well as its export market potential (Egesi et
al., 2007). In municipal regions, cassava consumption of poor households is
double that of non-poor households. In rural area, poor households intake of
cassava is triple that of non-poor households. When dry, cassava is storable
and moveable across greater routes. The evidence from the Collaborative Study
of Cassava in Africa shows that cassava can be converted into a broad variety
of goods (COSCA). After boiling or roasting, the new sliced tubers are consumed
as a vegetable. Since the tubers degenerate quickly, they are cooked and beaten
into paste, and are frequently used in soups and stews (“fufu” in Nigeria). Once they are harvested (postharvest
physiological deterioration, PPD) occur. They are preserved as chip using solar
energy and eaten after cooking or being ground into flour. Apart from
processing cassava into foods, the crop can also be made into chips for animal
feed and into starch for many food and non-food uses. Cassava flour is utilized
in the production of glues, and pizza, biscuits, confectionery, pasta, and
couscous-like goods. Cassava starch is used in the dairy, clothing, and paper
manufacturing and in the making of plywood and veneer glues, and glucose and
dextrin syrups. Through fermentation, cassava can be used for alcohol
production and as a waste material can be processed to biogas (Kenyon et al., 2006). Several procedures
comprising fermentation are useful for cassava postharvest preservation. Today,
refining has been the most rampant technique of valuing cassava by-products. It
enhances food security nutritious value, hygienic and sterile properties,
energy density and organoleptic characteristics of diets (Guira et al., 2016) and facilitates transport
and most importantly, detoxifies cassava roots by removing cyanogens (Nyirenda et al., 2011).
Cassava is traditionally processed into a
great diversity of fermented products such as gari, lafun, attieke and
chips which is suitable for transportation, trade and rapid preparation of
meals (Koume, 2012). Fermented foods have become a significant aspect of the
global diet as demand for their cultivation and use has risen dramatically over
time (Ngobisa et al., 2015; Elyas et al., 2015). The fermentation method
has been shown to be a suitable method to improve the safety, organoleptic and
nutritional quality of many cassava derived foods (Oyewole, 1997). Increase
variety in the diet improves active features and reduce anti-nutritional
compounds (Ayoade and Sanni, 1992).
Although fermentation constitutes a
significant process during the production, this still remain spontaneous and
there is a dearth of evidence about the actual microorganisms that can be
utilized as starter cultures. Optimization of fermentation process during the
manufacture of indigenous food has been established and such practice will
enhance the industrial take up of the native fermented foods with a view to
support the nutritional intake of the people (Sanni, 1993; Holzapfel, 2002).
Lactic acid microbes (LAB) are generally regarded as safe (GRAS), (Giraffa et al., 2010; Elyas et al., 2015). They play an important function in the majority of
food fermentations and preservations and an extensive diversity of strains are
routinely used as starter cultures in the manufacture of bakery products,
dairy, meat and vegetable (Elyas et al.,
2015; Gemechu, 2015). And further used as starters in fermented dough, alcohol
beverages, probiotic animal feeds lactic acid fermentation of sorghum and
maize-based cereals used as infant weaning foods (Wakil and Onilude, 2009).
They assist in the improvement of cultured foods' descriptive and defensive
attributes (Holzapfel and Wood, 2014). Lactobacillus
plantarum has been used in food storage to extend stock life, add flavor,
and achieve the perfect fragrance (Daeshel, 2004). During fermentation, L. plantarum has been linked to a
reduction in anti-nutrients and waste substance in food (Smid et al., 2005). They have antimicrobial
properties as a result of synthesis of compounds such as organic acids, carbon
dioxide, hydrogen peroxide, diacetyl, and bacteriocins, which may prevent
diseases and decomposition microbes, increasing the shelf life and improving
the protection of fermented foods (Piard and Desmaxeand, 1992). The
lactobacilli represent one of the major microbial groups included in the
desirable fermentation.
The lactobacillus
plantarum is regularly noted among the LAB during cassava dough
fermentative germ (Edward et al.,
2012) and lactobacillus platarum and lactobacillus fermetum have been recognized in the solid state fermentation of
cassava through traditional gari
production (Oguntoyinbo, 2007). Buyers are becoming more mindful of the
practical and nutritious aspects of organic items, which has resulted in a rise
in the commonness of healthy eating and the production of beneficial foods that
fulfill basic nutritional needs (Nivien et
al., 2016).
Consequently, there is a greater need to
extract new LAB strains that can manufacture beneficial cannabinoid substances
and have other distinct probiotic features. The 16s ribosomal RNA (rRNA) gene
is one of the most common and faster approaches for verifying microbial (LAB)
recognition in food. The prominence of the strategies for confirming the
existence of LAB are focused on molecular biology. This method is focused on
the sum of sequence similarities between various organisms, which shows how
their genomes vary. Currently, more than 40% of cassava is refined into
conventional food items.
There are opportunities to extend the
traditional uses of cassava and introduce it into a widespread assortment of
new food products, specifically in the urbanizing societies of the developing
countries. Processing will also enable us to promote the use of composite
flours from local crops in many food applications especially in manufacture of
convenient foods to promote utilization of the white and yellow cassava
varieties. Cassava flour can be supplement for production of baby food, glucose
syrup and pastas as stated by (Nwabueze and Anoruoh, 2011).
Studies have also shown that cassava
composite flour is a better supplement to wheat flour when paralleled to other
root and tuber crops as reported by Olaoye et
al. (2011). Hence, it is used in confectionaries making in the food
industries. The use of cassava flour in food rations has clear advantages.
Incorporating cassava into synthetic flour for fast food processing will lower
costs and improve the quality of pasta, breakfast cereals, and pastries, among
other products (Falade and Akingbala, 2009). Individuals, in addition to
industries, bakers, and caterers, cultivate and buy cassava flour for use at
home in the cooking of chin-chin, pie (meat and fish), buns, and cake, among
other dishes.
1.1 STATEMENT
OF PROBLEM
Cassava (Manihot esculeuta) is highly perishable after harvest and
post-harvest losses are often substantial due to high moisture content. The
bulkiness and high perishability of the harvested stored white and yellow
cassava roots is major barrier to the wider utilization of the crop. Toxicity
due to Cyanogenic glucosides is also a problem (Amoa-awua et al.,1996). Cassava contains toxic and anti-nutritional
substances that interfere with digestion and up take of nutrients (Wobeto et al., 2007). Cassava is high in
cyanogenic glucosides, which are harmful to humans and can lead to severe
health problems.
To boost interest and raise revenue, it's
essential to diversify the roots. Cassava roots are high in starch but low in
protein and a number of important micronutrients. In Nigeria, the recently introduced
yellow root cassava or β-carotene cassava cultivars are suitable for addressing
vitamin A deficiency. More efforts are required to enhance the crop's use,
particularly in the preparation of stiff dough (instant fufu) and snacks.
Lactic acid bacteria, yeast, and other
bacteria lead significantly to starch oxidation, acidification, detoxification,
and flavor production during cassava root fermentation (Oyewole, 1991). Lactic
acid bacteria are useful in inhibiting spoilage of food and growth of pathogens,
enhance the sensory value of fermented foods (Holzapfel and Wood, 2014),
preventing diseases and promoting health. This study will reveal the role of
the lactic acid bacteria in the modification of the white and yellow cassava
flours.
1.2 JUSTIFICATION
Cassava (Manihot esculenta Crantz) is propagated in the tropical regions for
its starchy roots. The roots are used for human intake, animal feed and as raw
material in many industries. Processing of the roots helps to reduce
post-harvest shortage and stabilizes seasonal fluctuations in the supply of the
crop. Technologies of processing should be developed to enable the production
of shelf-stable products which also will reduce post-harvest shortages and
reduces the bulk to be transported and marketed, thereby, reducing
transportation cost, and adding value at the rural areas. Nevertheless, it is
important to establish strong relationship between small-scale cassava
producers and new cassava products which is vital in creating awareness in
cassava utilization (Dufour et al., 2002).
Fermentation is an essential processing
method for the crop. Moreover, the fermentation method has been revealed to be
a suitable method to improve the safety, organoleptic and nutritional quality
of many cassava- based products. There is need to enhance the nutritional value
of the white and β-carotene cassava (yellow cassava) fufu flour. The existence of pro-vitamin A (β-carotene) in the new
cassava would improve the nutritional status of the consumers. Lactic acid
bacteria have a standing history of application because of their beneficial
effects on nutritional, shelf-life and organoleptic features of food.
There is need to evaluate the significance
of the lactic acid bacteria in the modification of the white and yellow cassava
flour. Constituents of cassava flour is essential in food industry as a result
of its special characteristic which include clarity of appearance and low
flavor. There seem to be limited literature on the fermentation of yellow
cassava and white variety included in this research by diverse types of lactic
acid bacteria (starter cultures) and their effects on nutritional, functional
and sensory characteristics of the white cassava and newly bred yellow cassava flour,
to obtain consistent product quality. Various food forms from these newly bred
crops for value addition will enhance a wide range utilization of the crop and
increase sales.
1.3 OBJECTIVES
OF THE STUDY
The general objective of the study is to
examine the influence of fermentation using diverse types of lactic acid
bacteria on nutritional, functional and sensory characteristics of the white
and yellow cassava fufu flour and to
identify proposed starters from the natural fermentation, using 16s DNA
sequencing.
1.3.1 Specific objectives
The specific objectives of the study include
to:
i.
Subject two varieties of
cassava to natural and starter culture fermentation for 72 h.
ii.
Determine the
physico-chemical properties of the fermenting mash at different fermentation periods (0h, 24h, 48h and 72h).
iii.
Isolate and identify
lactic acid bacteria (LAB) involved during spontaneous (traditional/ natural)
fermentation of the cassava varieties using 16s DNA sequencing
iv.
Produce cassava flours
from the fermented cassava varieties
v.
determine microbiological
analysis of the fermented cassava flours
vi.
determine the chemical
composition and flavor profile of the fermented and non-fermented flours
vii.
evaluate the sensory
properties of the reconstituted cassava (fufu)
flours.
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