ABSTRACT
The effect of processing methods on the chemical composition, proximate, mineral, vitamin and microbiological quality of vegetable drink extract of Irvingia gabonensis was studied. The processing methods included drying (shade and solar drying), blanching (at 0, 2, 4 and 6 minutes) as well as blanching and drying of the leaves. Aqueous extracts were obtained from the leaves and the analysis carried out using standard methods. The result showed that whereas some parameters analyzed varied with processing, others remained unaffected. The moisture, protein and fat content did not vary significantly (p<0 .05="" ash="" content="" drying="" increased="" shade="" significantly.="" span="" treatments="" while="" with=""> drying also increased the phytochemicals from 17.50 to 72.50 % for total phenol; 4.53 to 6.72 % for flavonoids and 2.98 to 3.86 % for alkaloid. It also reduced steroids and saponin significantly (p<0 .05="" span="">
Phytate content was non-significantly (p<0 .05="" and="" by="" drying="" other="" reduced="" shade="" solar="" span="" the="" whereas=""> processing methods increased it to the range of 5.38 to 14.33 mg/100g. Six minutes blanching reduced oxalate from 8.15 to 7.25 mg/100g and tannin content from 0.023 to 0.019 mg/100g. Cyanide content of 0.03 mg/100g was increased by all the processing methods though minimally by blanching and solar drying. Carotenoid content of 164.56 IU was reduced significantly (p<0 .05="" 92.83="" of="" ranges="" span="" the="" to=""> 151.90 IU for blanched and 16.88 to 59.07 IU for dried vegetable drink extracts. Vitamin A content of 987.34 IU was significantly (p<0 .05="" 101.27="" all="" by="" methods="" of="" processing="" range="" reduced="" span="" the="" to=""> 632.91 IU. Vitamin C, on the other hand, was increased significantly (p<0 .05="" 10="" all="" also="" and="" blanched="" by="" count="" drink="" drying="" extracts="" gave="" highest="" in="" inconsistent="" methods.="" minerals="" negligible="" of="" plate="" processing="" rest="" shade="" sup="" the="" total="" vitamins="" was="" were="" while="" with="" x="">3
cfu/g). Total coliforms were reduced in all the drinks from the processed leaves. The mould count in the blanched drink extract remained relatively low, but increased mould counts occurred in drink extract from shade dried leaves.
TABLE OF CONTENTS
Title Page
Abstract
Table of Contents
List of tables
List of figures
CHAPTER ONE
1.0 Introduction
1.1 Statement of problem
1.2 Justification of study
1.3 Aims and objectives
1.4 Significance of the study
CHAPTER TWO
2.0 Literature Review
2.1 Leafy vegetables
2.2 Chemical compounds found in leafy vegetables
2.2.1 Phytochemicals
2.2.1.1 Carotenoids
2.2.1.2 Plants phenols
2.2.1.3 Flavonoids
2.2.1.4 Phenolic acids
2.2.1.5 Terpenes
2.2.1.6 Tannins
2.2.1.7 Sterols
2.2.1.8 Saponins
2.2.1.9 Pectin
2.2.2 Antinutritive phytochemicals
2.2.3 Vitamins and minerals in leafy vegetables
2.3 Micro-orgranisms encountered in fresh leaves
2.4 Processing of leafy vegetables
2.4.1 Blanching
2.4.2 Drying
2.4.2.1 Sun drying
2.4.2.2 Solar drying
2.4.3 Pasteurization
2.5 African bush mango (Irvingia gabonensis)
2.5.1 Description of African bush mango
2.5.2 Uses of African bush mango
2.5.3 Chemical compounds found in African bush mango
2.5.4 Medicinal uses of African bush mango
CHAPTER THREE
3.0 Materials and methods
3.1 Materials
3.2 Methods
3.2.1 Sample preparation and extraction of vegetable from the leaves of Irvingia gabonensis
3.2.2 Analysis of the vegetable drink extract
3.2.2.1 Proximate analysis
3.2.2.1.1 Determination of moisture content
3.2.2.1.2 Determination of protein content
3.2.2.1.3 Determination of fat content
3.2.2.1.4 Determination of ash content
3.2.2.1.5 Determination of fibre content
3.2.2.1.6 Determination of carbohydrate content
3.2.2.2 Quantitative evaluation of phytochemicals
3.2.2.2.1 Determination of total phenol content
3.2.2.2.2 Determination of flavonoid
3.2.2.2.3 Determination of alkaloid content
3.2.2.2.4 Determination of tannins
3.2.2.2.5 Determination of saponin content
3.2.2.2.6 Determination of steroid content
3.2.2.2.7 Determination of phytate content
3.2.2.2.8 Determination of oxalate content
3.2.2.2.9 Determination of cyanide content
3.2.2.3 Estimation of mineral elements
3.2.2.3.1 Estimation of sodium contents
3.2.2.3.2 Estimation of potassium contents
3.2.2.3.3 Estimation of iron contents
3.2.2.3.4 Estimation of zinc contents
3.2.2.3.5 Estimation of magnesium contents
3.2.2.3.6 Estimation of calcium contents
3.2.2.4 Determination of vitamins
3.2.2.4.1 Determination of vitamin A
3.2.2.4.2 Analysis of vitamin C
3.2.2.4.3 Determination of riboflavin
3.2.2.4.4 Determination of thiamin
3.2.2.4.5 Determination of carotenoid
3.2.2.5 Determination of pH
3.2.2.6 Microbiological analysis
3.2.2.6.1 Determination of total plate count
3.2.2.6.2 Determination of total coliforms
3.2.2.6.3 Determination of mould count
3.2.2.7 Data analysis/experimental design
CHAPTER FOUR
4.0 Results and Discussion
4.1 Effect of treatment methods on the proximate composition of vegetable
drink extract from Irvingia gabonensis (African bush mango) leaves
4.2 Effect of treatment methods on the phytochemical composition of vegetable
drink extract from Irvingia gabonensis (African bush mango) leaves
4.3 Effect of treatment methods on anti-nutrients in vegetable drink extract from
(African bush mango) Irvingia gabonensis leaves
4.4 Effect of treatment methods on vitamins content of vegetable drink extract
from Irvingia gabonensis (African bush mango) leaves
4.5 Effect of treatment methods on the mineral content of vegetable drink extract
from Irvingia gabonensis (African bush mango) leaves
4.6 Effect of treatment methods on the microbiological quality of vegetable
drink extract from Irvingia gabonensis (African bush mango) leaves
Chapter five
5.0 Conclusion and Recommendation
5.1 Conclusion
5.2 Recommendations
5.3 Contributions of the study
5.3.1 The food industries
5.3.2 The academic community
5.3.3 The policy makers
5.3.4 The government
REFERENCES
CHAPTER ONE
1.0 INTRODCTION
There is a growing awareness that plant based foods make for healthy living. Much of the evidence so far has come from observations of cultures in which the diet comes mainly from plant sources, and which seem to have lower rates of certain types of cancer and heart disease. For instance, the relatively low rates of breast and endometrial cancers in some Asian cultures are credited, at least in part, to dietary habits. These cancers are much more common in the United States, possibly because the typical American diet is higher in fat and lower in fruits, vegetables, legumes, and grains (American Cancer Society, 2013).
Green vegetables are an imperative component of a nutritious diet. The varieties of leafy vegetables are diverse, ranging from leaves of annuals and shrubs to tree leaves (Sood,et al., 2012). They play a significant role in human nutrition, especially as sources of vitamins, minerals and dietary fiber; they offer a high concentration of micronutrients for low contents of calories and fat (Lintas, 1992). The benefits of a diet rich in fruits and vegetables are also provided by the complex mixture of chemicals present in whole foods. In the science of food, no change has been bigger than the discovery of phytonutrients and their unique place in our health. Phytonutrients include all of the unique substances that give foods their brilliant colors, their delicious flavors, and their unique aromas. They are also the nutrients most closely linked to prevention of certain diseases (Lintas, 1992), many chronic diseases associated with cancer, inflammation, atherosclerosis, and aging caused by free radicals (Liu, 2003, 2004).
The major plant-derived chemical groups now recognized as having potential health-promoting effects are the flavonoids, alkaloids, carotenoids, pre- and pro-biotics, phytosterols,
The key fruits and vegetables in human nutrition both in the developed and developing countries of the world are the yellow corn, spinach, green leafy vegetables, fruits, tomato, watermelon, pink-fleshed guava, red-fleshed papaya, red pepper, mango, orange, carrot, melon, yellow and orange-fleshed sweet potato, nuts, tea, wine, flaxseed, sesame seed, grapes, peanuts, cereals and pulses. Evidences of the benefits to human-health associated with their consumption have caused an increase in the demand for fresh-like fruits and vegetables (Oms-Oliu et al., 2012). Hence, the need for the identification and exploitation of other novel plants to fulfill the growing need of plant based chemicals. The emphasis therefore shifted to the underutilized plant foods which as a result of lack of attention from research and development has meant that their potential value to human well-being and income is underexploited (IPGRI, 2002). While such crops continue to be maintained by sociocultural preferences and the ways they are used, they remain inadequately documented and neglected by formal research and conservation (IPGRI, 2002). Irvingia gabonensis (Family: Irvingiaceae) commonly known as the African bush mango, Dika nut, bush mango or wild mango, and manguier sauvage in French is one of such crops, with the leaves only known to be used as food for livestock by farmers (Ayuk et al., 1999).
African bush mango (Irvingia gabonensis) belongs to the Irvingiaceae plant family (Lamorde et al., 2010). It is a wild forest tree 15 - 40 m with a bole slightly buttressed, possessing dark green foliage and yellow flowers (Kuete et al., 2007). The ripe fruit is green while the edible mesocarp is soft, juicy, and bright orange. The fruits are sometimes referred to as 'Mangoes' (hence the synonym of African Bush Mango) although they are unrelated, since the true Mango fruits are borne from the plant Mangifera indica of the plant family Anacardiacea (Bally, 2006). The pulp of this fruit is eaten fresh and can also be used for the preparation of juice, jelly and jam as well for a good quality wine (Akubor, 1996). The mango-like fruits of bush mango are especially valued for their dietary-fiber, fat- and protein-rich seeds (Jianghao and Pei, 2012). The bark of the Irvingia gabonensis tree (rather than the seeds, which are commonly used as fibrous supplements) appears to be traditionally used by the Mende tribe of Africa for pain relief (Okolo et al., 1995). Studies have shown that the seeds of Irvingia gabonensis could be effectively used as an ingredient in health and functional food to ameliorate certain disease states such as diabetes (Dzeufiet, 2009). And the leaves of plants have been shown to be richer in chemical compostion than the fruit pulps and seeds (Nwofia et al., 2012). Bush mango leaf/root extracts have documentary inhibitory activity against several bacteria and fungi. Aqueous leaf extract significantly protected mice against diarrhoea induced experimentally by castor oil in terms of severity and onset and the population of animals with diarrhoea (Abdulrahman et al., 2004). As reported by Kuete et al. (2007), the aqueous maceration of the leaves is used as anti-poison. And when taken in combination with palm oil, the leaves are also used to stop hemorrhages for pregnant women in Cameroon.
However, due to the varied growing and harvesting seasons of different vegetables at different locations, the availability of fresh vegetables differs greatly in different parts of the world. Thus necessitating processing, which can transform vegetables from perishable produce into stable foods with long shelf lives and thereby aid in the global transportation and distribution of many varieties of vegetables. Processing of leafy vegetables can have a major.....
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