ABSTRACT
Chemical composition of some local spices and their antimicrobial activities in yam pepper soup stored at refrigeration temperature for 48 hours were studied. Three spices, M. myristica seeds, O. gratissimum leaves and Z. officinale roots in their fresh and dried forms were used in the study. The proximate composition, mineral and vitamin contents as well as phytochemical screening and antioxidant activities of the spices were determined using standard analytical methods. Their antimicrobial activities in yam peppersoup stored in a refrigerator for 48 hours were also determined using standard microbiological techniques. For proximate composition such as ash, fat, fibre and mineral content such as k, Na, Ca,Mg,and P, the dried spices had the highest composition and were significantly (P<0.05) different from each other. The data obtained for vitamin C showed that fresh M. myristica (240.60 mg/100g) had the highest value and dried Z. officinale (1.33mg/100g) the least. For vitamin B1 and, B2, no value was detected for all the dried spices and fresh O. grastissimum. Qualitative phytochemical screening showed that alkaloid was present in moderate concentration in the fresh and dried spices. Quantitatively, the concentration of the phytochemicals varied significantly in the different spices in their fresh and dried forms. The fresh spices had higher flavonoid (0.13-1.31%) and saponin (0.15-0.74%). Antioxidant activity of the spices varied significantly with the fresh spices having better scavenging and chelating capacities than the dried spices. Z. officinale was observed to have a significantly higher (P<0.05) ferric-reducing antioxidant potential (FRAP) value (3.97mg/ml) in its dried state than in its fresh state (3.69mg/ml). There were significant variations in the microbial load of the spiced soup. The control soup (no spice) had the highest microbial load. No synergistic effect was recorded with the mixed spices. For sensory evaluation, on the overall acceptability level, the pepper soup prepared with O. gratissimum had the highest acceptability mean score of 8.05. The result of this study suggests that the spices can be exploited as natural antioxidants and antimicrobials in food- related systems.
TABLE OF CONTENTS
Title Page i
Declaration Page ii
Certification iii
Dedication iv
Acknowledgments v
Table of Content vi
List
of Tables vii
List of Figures xi
Abstract
CHAPTER
1: INTRODUCTION
1.1
Background of the Study 1
1.2
Statement of the Problem 2
1.3
Justification for the Study 3
1.4
Aims and Objectives 3
CHAPTER 2: LITERATURE REVIEW
2.1 Spices 4
2.2 Phytochemicals 5
2.3 Classes
of Major Phytochemicals, Food Sources and
Nutritional
Benefits 6
2.4 Anthocyanins 8
2.5 Polyphenols 8
2.6 Phytates 9
2.7 Flavonoids 9
2.8 Antioxidant Properties of Spices 10
2.9 Major Micro-organisms of Food Poisoning 11
2.10 Preservative Properties of Spices 12
2.11 Ecology, Botany and Distribution of African
Nutmeg
(Monodora myristica Gaertn) 12
2.12 Chemical Composition and Uses of African Nutmeg
(Monodora myristica Gaertn) 13
2.13 Ecology, Botany and Distribution of Ginger
(Zingiber officinale Roscoe) 13
2.14 Chemical Composition and Uses of Ginger
(Zingiber officinale Roscoe) 14
2.15 Ecology Botany and Distribution of Ocimum viride (Willd) 14
2.16 Chemical Composition and Uses of Ocimum viride (Willd) 15
CHAPTER
3: MATERIALS AND METHODS
3.1 Materials 16
3.2 Methods
16
3.2.1 Preparation of samples 16
3.2.2 Preparation of yam pepper soup 20
3.2.3 Proximate analysis 22
3.2.3.1 Moisture content 22
3.2.3.2 Crude protein content 22
3.2.3.3 Ether extract 23
3.2.3.4 Total ash content 23
3.2.3.5 Crude fibre content 24
3.2.4 Determination of minerals 24
3.2.4.1 Determination of potassium, sodium, calcium and
Magnesium
by atomic absorption spectrophotometer 24
3.2.4.2 Determination of phosphorus 26
3.2.5 Determination of vitamins 28
3.2.5.1 Determination of ascorbic acid (vitamin C)
content 28
3.2.5.2 Determination of riboflavin content
29
3.2.5.3 Determination of thiamin content
30
3.2.6 Determination of phytochemical content 30
3.2.6.1 Qualitative determination of
phytochemicals 30
3.2.6.2 Quantitative determination of
phytochemicals
32
3.2.7 Determination of antioxidants
` 35
3.2.7.1 Determination of DPPH radical scavenging
activity 35
3.2.7.2 Determination of ferric- reducing activity 36
3.2.7.3 Determination of chelating activity
36
3.2.7.4 Determination of IC50
(antioxidant activity) 37
3.2.8 Determination of antimicrobial activity of
the spices 37
3.2.8.1 Determination of microbial load
38
3.2.8.2
Enumeration of staphylococcus, listeria and enterobacteria 39
3.2.9 Sensory evaluation 40
3.2.10 Statistical analysis
40
CHAPTER
4: RESULTS AND DISCUSSION
4.1 Proximate Composition of the Spices 41
4.2 Mineral Composition of the Spices 46
4.3 Vitamin Composition of the Spices 50
4.4 Phytochemical Content of the Spices 53
4.4.1 Qualitative phytochemical screening
53
4.4.2 Quantitative phytochemical screening 55
4.5 Antioxidant Properties of the Spices
57
4.6 Microbiological
Analysis of the Spices 60
4.6.1 Bacteria load of yam pepper soup prepared
using the spices 60
4.6.2 Fungi load of yam pepper soup prepared using
the spices 64
4.6.3 Staphylococcus
load of yam pepper soup prepared
using
the spices 66
4.6.4 Enterobacteria
load of yam pepper soup prepared
using
the spices 69
4.6.5 Listeria load of yam pepper soup prepared
using the spices 71
4.7 Sensory Evaluation 75
CHAPTER
5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion
78
5.2 Recommendations
79
References
80
Appendix
90
LIST OF TABLES
1.3
Phytochemical constituents of some plant
foods
and their function 7
4.1. Proximate composition of M.myristica
Z. officinale and O. gratissimum 42
4.2 Mineral
composition (mg/100g) of M. myristica,
Z.officinale
and O. gratissimum 47
4.3 Vitamin composition of spices
(mg/100g) 51
4.4 Qualitative phytochemical screening 54
4.5 Quantitative phytochemical screening of
the spices (%) 56
4.6 Antioxidant activity of spices (extract)
mg/ml 58
4.7 Bacteria load of yam pepper soup during
storage at
refrigerated
temperature (cfu/g) 61
4.8 Fungi load of yam pepper soup prepared
with the
spices (cfu/g) 65
4.9 Staphylococcus
load of yam pepper soup prepared
with
the spices (cfu/g) 67
4.10 Enterobacteria load of yam pepper soup
prepared
with
the spices (cfu/g) 70
4.11 Listeria
load in yam pepper soup prepared with the
spices (cfu/g) 71
4.12 Sensory evaluation mean scores 76
LIST OF FIGURES
1 Flow
chart for the processing of Zingiber
officinale roots
into powder 17
2 Flow chart for the processing of Monodora
myristica seeds into
powder 18
3
Flow chart for the processing of Ocimum gratissimum leaves into
powder 19
4
Flow chart for preparation of
yam pepper soup containing
the spices 21
5
Determination of microbial load 38
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Plants constitute important
source of active natural products, which differ widely in terms of structure
and biological properties. They have played a remarkable role in the traditional
medicine of various countries. In recent years, the prevention of cancer and
cardiovascular diseases has been associated with the ingestion of spices, fresh
fruits, vegetables, or teas rich in natural antioxidants (Uhegbu, et al., 2011).
Spices are condiments of plant origin
consisting of parts of trees, seeds, shrubs and grass which abound in the
tropical rain forest and savannah grass land zones (Ogunka-Nnoka and Jaja,
2012). Some examples are rosemary, chili, nutmeg, thyme etc. In Africa,
especially in the rain forest zone of Nigeria, Ghana and Cameroon, some indigenous
spices and herbs have found much use in food preparations. They include Xylopia aethiopica (African pepper), Monodora myristica (Africa nutmeg/calabash
nutmeg), Piper guineense (West African
pepper), Tetrapleura tetrapetra
(Aidan fruit), Ocimum gratissimum,
(scent leaf), etc. These spices are used to prepare sauce, soup and porridge
during the cold season due to their hot and peppery taste. Hot aqueous extracts
of Tetrapleura tetrapetra, Xylopia aethiopica and Piper guineense are prepared as
restorative soup and sometimes with yam (Dioscorea
rotundata) for post – partum women to aid contraction of the uterus
(Ojimelukwe and Ukom, 2017). It is believed by the people of South Eastern
states of Nigeria that these spice extracts or their restorative soup serve
some important roles for lactation, after birth cleansing of the woman’s womb
and restoration of the women’s tummy to normal shape after childbirth within a
period of three months (Ojimelukwe and Ukom, 2017).
A number of exotic spices of international
recognition with known phytochemical constituents have been proven to be good
natural antioxidants, antimicrobial and health promoting agents (Ugwuona,
2014). One of the benefits of spices is primarily due to their antioxidant
properties. Free radicals cause damage in living system resulting in oxidative
stress (Alobi et al., 2012). Free
radical scavengers (antioxidants) which are in spices have potentials to
prevent, delay or ameliorate many of human chronic and ageing diseases such as
cancer, diabetes, heart disease, stroke, malaria and rheumatoid arthritis (Agbaire,
2011).
These local spices such as Ehuru (Monodora Myristica), Nchuanwu
(Ocimum gratissimum) and Ginger (Zingiber officinale) are usually consumed
because of their flavour and taste and people do not concern themselves with
their nutritional composition.
The study is therefore designed to
evaluate the chemical composition and antimicrobial properties of these spices.
1.2
STATEMENT OF THE PROBLEM
Various medicinal plant spices are consumed
as food along with their medicinal benefits. Evaluating their nutritional
significance can help to understand the worth of these plant species. There are
also various claims about the usefulness of these spices, especially their use
in fattening homes and remarkable growth of new born babies whose mothers use
these spices. It is therefore necessary to evaluate the chemical composition
and antimicrobial qualities of some popular Nigerian spices, namely “Ehuru” (Monodora, Myristica), “Nchuanwu” (Ocimum
gratissimum) and Ginger (Zingiber
officinale) to diversify their use as natural preservatives and as culinary
spices that contain active ingredients that promote health and reduce the risk
of diseases.
1.3
JUSTIFICATION FOR THE STUDY
The paucity of knowledge of the chemical
and antimicrobial properties of these indigenous spices has resulted in their
neglect and under utilization. Research findings from this work will not only
help to sensitize the ignorant masses on the importance and benefits of incorporating
these spices in their diet but also assessing their nutritional content.
1.4
AIMS
AND OBJECTIVES
The main objective of this study was to
evaluate the chemical and antimicrobial activities of three indigenous Nigerian
spices namely: Monodora myristica, Ocimum
gratissimum and Zingiber officinale
The specific objectives of the study were :
1.
To determine the
proximate composition, mineral and vitamin content of fresh and dried Monodora myristica, Ocimum gratissimum
and Zingiber officinale.
2.
To determine the
phytochemicals and antioxidants of fresh and dried Monodora myristica, Ocimum gratissimum
and Zingiber officinale.
3.
To evaluate the microbial
loads of the yam pepper soup prepared using the three spices during storage.
4. To evaluate the sensory properties of
the spices in cooked yam pepper soup.
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