ABSTRACT
The proximate, mineral, vitamin and phytochemical contents of orange fleshed sweet potatoes (O), yellow fleshed sweet potato (Y), Beetroot (B), and carrot (C) were analysed. The samples analysed showed significant differences in their proximate composition, mineral, vitamin and phytochemical contents. The carbohydrate content decreased in the order O (32.37 %) > Y (29.71 %) > B (14.31 %) > C (9.26 %). The crude fibre decreased in the order Y (4.16 %) > B (3.82 %) > O (2.42 %) > C (1.61 %). The Fat content decreased in the order B (4.04 %) > C (2.97 %) > Y (1.54 %) > O (1.06 %). The protein content decreased in the order B (14.85 %) > C (10.51 %) > Y (4.82 %) > O (3.89 %). The ash content decreased in the order B (0.35 %) > C (0.26 %) > Y (0.05 %) > O (0.05 %). The moisture content decreased in the order C (3.54 %) > O (3.41 %) > B (3.21 %) > Y (2.88 %). The samples analyzed are rich sources of minerals (iron, zinc, copper, manganese, phosphorous, nitrogen, sodium, potassium, magnesium calcium and cobalt) that can be used to supplement daily requirements needed for physiological functioning necessary for life. The heavy metals such as nickel (0.01-0.02 ppm), lead (0.02-0.3 ppm) and cadmium (0.00-0.03 ppm) found in the samples were below the permissible limit. Thus, consumption of these samples as foods poses no immediate danger. The samples analyzed have shown to be rich sources of b-carotene (3.25-7.87 mg/100g), vitamin C (17.61-40.71 mg/100g), vitamin A (9.51-18.45 mg/100g), Riboflavin (0.08-0.38 mg/100g), niacin (0.77-2.24 mg/100g) and thiamine (0.11-0.15 mg/100g). Yellow fleshed sweet potato recorded the highest values for vitamin A, C and b-carotene. Carrot recorded the highest values for riboflavin and thiamine. The quantitative phytochemical screening of the samples revealed the presence of alkaloids, phenol, saponin, flavonoids, phytate, and tannin. Beetroot showed highest values for all the phytochemicals analysed. Except for phenol, orange and yellow fleshed potato recorded higher values for all the phytochemicals analysed than carrot. The result of this study showed that the samples analysed contained appreciable amount of essential nutrients and are safe for human consumption.
TABLE OF CONTENTS
Title page ii
Certification page iii
Dedication iii
Acknowledgements iv
Table of Contents v
List of Tables vii
List of Figures ix
List of Plates x
Abstract xi
CHAPTER
1: INTRODUCTION 1
1.1
Background of the Study
1.2
Statement of Problem 3
1.3
Aim and Objectives 4
1.4
Significance of Study 4
CHAPTER
2: REVIEW OF RELATED LITERATURE
2.1. Carrot 5
2.2. Chemical Composition of Carrots 6
2.3. Health Benefits of Carrots 9
2.3.1
Antioxidant,
anticarcinogen and immunoenhancer benefits 9
2.3.2
Anti-diabetic,
cholesterol and cardiovascular disease lowering
and
anti-hypertensive benefits 13
2.3.3
Hepatoprotective,
and renoprotective benefits 14
2.3.4
Wound
healing benefits 15
2.4. Sweet Potato 16
2.5. Importance of Sweet
Potato 18
2.6. Chemical Composition of Sweet Potato 19
2.7. Nutritional Benefit of Sweet Potato 20
2.8. Health Benefit of Sweet Potato 23
2.9. Beetroot 23
2.10. Importance of Beetroot 24
2.11. Chemical Composition of Beetroot 24
2.12. Health benefit of Beetroot 25
CHAPTER
3: MATERIALS AND METHODS
3.1. Sample
Collection and Processing 26
3.2. Proximate Composition 26
3.2.1. Determination of
moisture 26
3.2.2. Determination of Ash 27
3.2.3. Crude protein
determination 27
3.2.4. Determination of
crude fat 29
3.2.5. Determination of Crude
fiber 29
3.3. Phytochemical
determination 30
3.3.1
Preliminary qualitative analysis 30 3.3.2
Quantitative Analysis 31
3.4. Heavy Metal
Determination 33
3.5. Vitamin
Determination 35
3.5.1. Determination of ascorbic acid 35 3.5.2
Determination of riboflavin 38
3.5.3. Determination of thiamin 38
3.5.4. Determination of vitamin A and carotenoid. 38
3.6. Statistical
Analysis
40
CHAPTER
4: RESULTS AND DISCUSSION
4.1. Proximate
Composition 41
4.2. Mineral
Content 44
4.3. Vitamin
Content 50
4.4.
Phytochemical Content 54
CHAPTER 5: CONCLUSION AND RECOMENDATION
5.1. Conclusion 57
5.2.
Recommendation 57
References
Appendices
LIST
OF TABLES
2.1 Composition
of raw carrot (per 100g) 8
2.2.
Nutritive value of sweet potato per 100g to other food source 22
4.1 Proximate composition
of orange fleshed potato, yellow flesh sweet potato,
Beetroot and carrot 41
4.2: Mineral content of
orange fleshed potato, yellow flesh sweet potato, beetroot
and carrot 45
4.3: Vitamin content of orange
fleshed potato, yellow flesh sweet potato,
beetroot and carrot 50
4.4: Phytochemicals content of orange
fleshed potato, yellow flesh sweet potato,
beetroot and carrot
54
LIST
OF FIGURES
2.1 Alpha Carotene 9
2.2 Beta Carotene 9
LIST
OF PLATES
2.1 Carrot 6
2.2 Sweet Potatoes 18
CHAPTER 1
INTRODUCTION
1.1.
BACKGROUND OF THE STUDY
Over the last decade an abundance of
research has shown that common foods and vegetables constitute important
functional food components by contributing vitamins, minerals and biologically
active compounds which are associated with dietary activities (Kimura and
Rodriguez-Amaya, 2003). These foods and vegetables also contain several types
of photosynthetic pigments that are chlorophylls and carotenoids (Kimura and
Rodriguez-Amaya, 2002). The composition of these pigments produces specific colouration
of the food, which is one of the assessed visual quality attributes (Xue and
Yang, 2009). In addition, chlorophyll and carotenoid concentration correlate to
the photosynthetic potential of plants giving some indication of the
physiological status of the plant (Gamon and Surfus, 1999). However, the
content of pigments in plants is important, not only due to the colouration and
physiological function, but also due to their acknowledged roles in health (Liu
et al., 2007).
The
name carotenoids is derived from the fact that they constitute the major
pigment in the carrot root, (Daucus carota). Carotenoids are undoubtedly
among the most widespread and important pigments in living organisms.
Carotenoids are the pigments that are responsible for the colours of many
plants, fruits and flowers. Carotenoids are fat soluble nutrients and
categorized as either xanthophylls or carotenes according to their chemical
composition. Carotenoids are found in common foods and vegetables. Most
xanthophylls are found in green leafy vegetables and nearly all carotenes are
found in yellow vegetables. The most important carotenoids are alpha-carotene,
beta-carotene, and beta-cryptoxanthin, lutein, violaxanthin, neoxanthin, and lycopene. Beta-carotene, alpha-carotene, beta-cryptoxanthin
are carotenes that are converted into vitamin A or retinol in the body. They
are found in many yellow fruits and vegetables. Beta-carotene is the most
widely studied carotenoid. Lutein and zeaxanthin are both stored in the retina
of the eye. Neither converts to vitamin A. Both are powerful antioxidants and
may be very important for healthy eyes (Wisniewska and Subczynski, 2006). Lycopene is responsible for the red colour in
fruits and vegetables, including tomatoes, red grapes, watermelon, and pink grapefruit.
It is also found in papayas and apricots. It does not convert to vitamin A but
may have important cancer fighting properties and other health benefits (Sangeetha and Baskaran, 2010).
Currently,
interest is being focused on the nutritional and medicinal aspects of different
individual carotenoid. Since they are growing in importance and value, their sources
are very important. For
example, carotenes are the sources of vitamin A (Olson, 1994). Lutein and
zeaxanthin are important factors for human vision (Wisniewska and Subczynski,
2006). Carotenoids have an important role in the prevention of various diseases
associated with oxidative stress, such as cancer, cardiovascular diseases and
other chronic diseases (Sangeetha and Baskaran, 2010). Humans cannot synthesize
the pigments but are able to deposit dietary pigments as absorbed or with
slight modification of their structure (Larsen and Christensen, 2005).
1.2.
STATEMENT
OF THE PROBLEM
Among succulent vegetable
crops, the carrot ranks third in world production (Yamaguchi, 1983). In
Nigeria, it is a recent addition to our diet before the mid-50s. But, currently
the crop has become a common commodity in the Northern part of the Country,
particularly at the end of the dry season - March to May, when large quantities
are produced and marketed further south, where little of the crop is grown
(Green, 1973, Sarkindiya and Yakubu, 2006).
Nigeria is said to be the third
largest producer of sweet potatoes in the world when it comes to quantity,
after China and Uganda. In 2010, about 2.5 % of the world’s production of sweet
potatoes was produced in Nigeria (Ahmad et
al., 2014). However, sweet potatoes are still not considered a major crop
in the country. In the year 2010, sweet potatoes was the tenth highest produced
single food crop in Nigeria (after cassava, yam, oil palm fruit, maize,
sorghum, millet, paddy rice, and plantains)(Ahmad et al., 2014). In 2010, the total income from agricultural
production value for sweet potatoes was $954 million USD and accounted for 1.73
% of total agricultural production value for all crops (Ahmad et al., 2004). Despite this, sweet potato and carrot have
received limited research attention especially as sources of carotenoids and other
micronuitrents. The carotenoid profiles of some tropical root and tuber crops
have been reported in literature: yams and cocoyam (Champagne et al., 2010),
cassava (Ceballos et al., 2012), sweet potato (Ukom et al.,
2011).
Appropriately
processed root and tuber staples needs to be potential food-based intervention
in order to combat micronutrient deficiency since they are fair sources of
iron, zinc and vitamin A.
1.3.
AIM
AND OBJECTIVES
This study was designed to evaluate the
chemical compositions of sweet potato, carrot and beetroot.
The specific objectives are
I.
To determine the proximate composition, phytochemical, mineral
and vitamin contents of carrot and sweet potato and beetroots
II. To compare the chemical composition of
sweet potato, beetroot and carrot.
1.4.
SIGNIFICANCE OF THE STUDY
The results of this study can be used as
fundamental data for dietary recommendation to help the consumers to select
appropriately to meet their nutrient and health needs.
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