ABSTRACT
Three garden egg varieties (Solanum marcrocarpon, S. aethiopicum and S. gilo) were process into powder by steam blanching a portion for 30 sec and dried at 60oC in an oven until constant weight was obtained while the remaining portion was dried without any pretreatment to serve as control. Evaluation of the functional, nutritional, phytochemical, anti-nutritional and sensory characteristics of powder samples were carried out with standard analytical methods. The results showed the proximate composition of both the steam blanched and controlled powder samples were as follows; moisture content ranged from 5.40% to 6.15%. Crude protein of 11.35% to13.05%, crude fat of 1.45% to 1.85%, crude fibre of 11.93% to 12.75%, crude ash of 7.50% to 8.00% and carbohydrate of 59.55% to 61.23%. Functional properties ranged from 6.90 mL/g to 11.50 mL/g water absorption capacity, 11.20 to 11.70 mL/g oil absorption capacity, 0.48 to 0.53 g/mL bulk density, 25.02 to 35.40 emulsion capacity and 6.52 to 11.33 mL/100g foam capacity, 1.47 to 3.92 ml swelling index and 11.00secs to 15.50 secs wettability. Mineral contents ranged from 718.75 to 811.18 potassium, 30.30 to 40.60 magnesium, 21.46 to 33.46 calcium, 328.13 to 431.14 sodium, 94.40 to 129.74 phosphorus and 12.65 to 27.18 Iron. The powder samples recorded higher concentrations (mg/100g) of retinol ranging from 17.89 to 56.11, but lower range of concentration of thiamine 0.03 to 0.22, riboflavin 0.02 to 0.17, niacin 0.51 to 1.21, ascorbic acid 1.05 to 6.00 and tocopherol of 0.03 to 0.46. The phytochemical analysis revealed that the garden egg powder sample contained 0.14 to 0.75 flavonoid, 0.02 to 0.23 mg/100g alkaloids, 0.22 to 1.52 mg/110g phenols, 0.78 to 1.92 mg/100g steroids and 0.07 to 0.34 mg/100g. Anti-nutritional content ranged from 0.41 to 1.40 saponin, 0.03 to 0.18 tannin, 0.07 to 0.14 oxalate, 0.08 to 0.26 phytate and 5.23 to 22.10 cyanogenic glycosides. Sensory scores of the sample showed that steam blanching the samples reduced the scores of colour, taste, flavour and general acceptability. Sensory scores of the samples showed the score range of 4.60 to 7.48 colour, 5.12 to 6.80 taste, 5.12 to 7.28 flavour, 4.60 to 5.88 Texture and 5.68 to 7.28 general acceptability. From the result, maximum nutritional content was observed in steam blanched Solanum aethiopicum followed by S. macrocarpon then S. gilo. Minerals and vitamins content were highest in S. gilo while S. macrocarpon had the highest phytochemical and anti-nutritional properties compared to the other two eggplant varieties used in this study as such is suggested as the optimum eggplant with good nutritional and phytochemical properties retention as well as appreciable levels of minerals and vitamins content. S. macrocarpon therefore is a potential ingredient for food enrichment and preparation of food with functional properties since it is rich in pharmacologically important phytochemicals.
TABLE OF CONTENT
Title page i
Declaration ii
Dedication iii
Certification iv
Acknowledgement v
Table of content vi
List of tables vii
List of figures viii
List of plates ix
Abstract x
CHAPTER
1: INTRODUCTION
1.1 Background
of the Study 1
1.2 Problem
Statement 3
1.3 Significance
of the Studies 3
1.4 Objective of the Studies 3
CHAPTER 2: REVIEW OF RELATED LITERATURE
2.1 History
of Garden Egg 5
2.1.1 Varieties of Garden Eggs used 6
2.2 Garden egg as a Nutraceutical. 8
2.3 Health benefits of Garden Egg 9
2.3.1 Heart health 9
2.3.2 Blood cholesterol 10
2.3.3 Prevention of cancer 10
2.3.4 Cognitive function 11
2.3.5 Weight management and satiety 11
2.3.6 Anti-ulcer agent 11
2.3.7
Prevention of diabetes. 11
2.3.8 Aids digestion 12
2.4 Uses
of Garden Egg 13
2.4.1 How to incorporate
more garden egg into your diet 14
2.5 Potential
Health Risks of consuming Eggplant 15
2.6 Techniques
for Processing Garden Eggs 15
CHAPTER 3: MATERIALS AND METHODS
3.1 Source of Raw Material 16
3.2 Sample Preparation 16
3.3 Methods of Analysis 20
3.3.1. Proximate analysis. 20
3.3.2 Functional properties
analysis 22
3.3.3 Mineral analysis 24
3.3.4 Vitamin analysis 25
3.3.5 Phytochemical analysis 25
3.3.6 Anti nutritional factors 27
3.3.7 Sensory analysis 29
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Proximate
Composition of Eggplants 31
4.2 Functional
Properties of Eggplants 35
4.3 Mineral
Content of Eggplants 40
4.4 Vitamin Content of Eggplants 45
4.5 Phytochemical Composition of Eggplants 48
4.6 Anti-nutritional
Composition of Eggplants 52
4.7 Sensory Scores of Eggplants 56
CHAPTER 5: CONCLUSION
AND RECOMMENDATION 60
5.1 Conclusion 60
5.2 Recommendation 60
REFERENCES
APPENDICES
LIST OF TABLES
4.1: Functional
properties of Eggplants Powder
4.2: Proximate composition of Eggplants
Powder
4.3: Mineral content of
Eggplants Powder
4.4: the vitamin content of
Eggplants Powder
4.5: Phytochemical composition of Eggplants Powder
4.6: Antinutritional composition of Eggplants Powder
4.7: Sensory Scores of
Eggplants Powder
LIST OF FIGURES
3.1. Flow chart for Production of garden egg powder
LIST OF PLATES
1: Solanum macrocarpon
2: Solanum aethiopicum
3: Solanum gilo
4: Dried Solanum macrocarpon powder
5:
Dried Solanum aethiopicum powder
6:
Dried Solanum gilo powder
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF THE
STUDY
Solanum
spp (garden egg) exists as a member of the plant family Solanaceae and
the genus Solanum with over 1,000 species worldwide. In Nigeria, it is denoted
by about 25 species including the domesticated once whose fruits, leaves or
both are eaten as vegetables or used in native medicine (Bonsu et al., 2002).
Native and urban families consume garden egg species
almost on daily basis. The garden egg makes up part of the traditional African culture,
the fruits, is believed to represent blessings and are offered during marriages,
visits and other social events as a demonstration of goodwill. (Eze and Kanu
2015). According to McGuire, (2013) eggplants come in diverse
colours, it could be violet, cream, orange, pink, red, plum, burgundy,
yellow, white, green, lime, lavender, purple or dusky black among Africa’s overall
garden egg varieties and many are multi-coloured and striped. All species of
garden eggs tend to shimmer in the sunlight. Apart from the egg-shaped, some
are ribbed, round, flat, and pumpkin-like. Some impose as beefy tomatoes; in
general, garden eggs, closely emulate duck or chicken eggs in size. Most garden
eggs are eaten at maturity before ripening into their final colour.
Eggplant is composed of 92% moisture, 1% protein, 6%
carbohydrates and negligible fat with low amounts of essential nutrients. Slight
changes in nutrient composition may occur with genotype, season and environment
of cultivation. (San-jose, 2014). Garden
eggs are either cooked as in preparation of garden egg stews, soups and
sauces (eaten with yam or plantain), or eaten raw as dessert (Agoreyo et
al., 2012).
According to Faostat, 2013, global production of
eggplants in 2013 alone was 49.4 million tonnes and more than 1,600,000
hectares (4,000,000 acres) of land are dedicated to the cultivation of
eggplants in the world. Other Asian countries combine with major producers like
Egypt, Iran, and Turkey to constitute 94% of world production while 57% of
output comes from China alone India (27% of world total) (Faostat, 2016).
Fruits from these species could be easily damaged if kept in temperature below
10oC but can be stored for up to 10 days in cool moist condition, (Mayhew
and Penny, 1988). The fruits of these garden egg species are usually eaten
fresh while some other species are cooked with meats, onions and tomatoes and
can also be grilled or fried to give a good flavour (MAFF, 1997). Garden Egg is
used in the cuisines of many countries and it is sometimes used as a meat
substitute in vegan and vegetarian cuisines due to its texture and bulk.
Garden-egg possess numerous nutritional and medicinal
uses that present them as appreciable addition to diets basically because they
have considerable reserve of nutrients and lots of phytochemical compounds
(Ossamulu et al, 2014), Due to its phenolic constituent, garden-egg is graded
as one of the top ten vegetables in terms of oxygen radical scavenging capacity
(Cao et al., 1996). Garden egg may be used as a medicinal plant to sustain
and promote healthy life, cure ailments and prevent disease (Lakshman, 2012).
Many studies have recommended that increasing
consumption of eggplant declines the risk of general mortality, diabetes, obesity,
heart disease, escalates energy, and lower weight (Ware, 2016). According to
Paul et al. (2002), consuming foods
containing flavonoids is associated with a lower risk of mortality from heart
disease. Consumption of even small quantities of flavonoid-rich foods is
beneficial to human health.
Anthocyanin, an important food
pigment of red and/or purple coloured fruits, are the main phenolic compounds
in eggplant peel (Mazza et al., 2004). According to research the polyphenols
inherent in eggplants add to their bitter flavour that is to say that, the most
bitter and unpleasant to consume eggplants have the highest levels of
antioxidants.
However, scientists are exploring
to be able to genetically advance garden egg so that they contain high levels
of valuable nutrients and stay appealing (Ware, 2016). Cooking probably affect
the presence of phytochemicals in garden eggs. Recent research has established
that cooking at times increases the total polyphenol content in garden egg
(Uchida et al, 2016)
1.2 PROBLEM STATEMENT
Many research studies have been
conducted on the nutritional content, polyphenol content and antioxidant
capacity of raw garden eggs but no research work has been conducted on ways of maximizing
the usage of garden egg for food enrichment. Also the Processing, preservation and storage of
garden eggs during peak season can prevent the massive post-harvest losses in garden
eggs and make them obtainable in the off season at relatively lower cost.
1.3 SIGNIFICANCE OF THE STUDIES
This research work is to create
alternative ways for the use of garden-eggs as functional ingredient and to
minimize the unnecessary wastage due to lack of specific processing and
preservation methods.
1.4 OBJECTIVES OF THE STUDIES
The main objective of this study is
to evaluate the quality effects of steam blanching on the quality of three
varieties of eggplants powder.
The specific objectives of this
study are;
i.
To produce eggplant powder that can be used as a functional
ingredient in the preparation of other healthy foods from three varieties of garden-eggs.
- To evaluate
the functional properties, phytochemical, antinutritional, vitamin
and mineral content of untreated and steam blanched garden-eggs powder
iii.
To assess the sensory attributes of
untreated and steam blanched garden-eggs powder
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