PHYTOCHEMICAL SCREENING AND MINERAL COMPOSITION OF PAWPAW.
Pawpaw is a common fruit consumed in the world. Pawpaw is a spermatophyte (seed plant). So there are hardly any true varieties, rather there are types which are classified based on fruit size, shape, flesh colour, flavor and similar characteristics.
Carica papaya is a single stem plant that grows from 5 – 10m and is about 1 foot in diameter. The stem or trunk is simple, erect, without branches and gradually tapers from the base to the to the summit where it terminates its entire length is thickly covered with scars of fallen leaves and fruits. The leaves are large 50 – 70cm diameter, alternate, close together, deeply palmately divided into 5 – 7 irregular.
Carica papaya is polygamous, with three primary sex types, bisexual, male and female. Bisexual plants produce more than one kind of flowers (male and female) at the same time. The male flowers are borne on long pedundedracemes while the females are solitary and auxillary on short stalks and consists of a small, 5 – parted Calyx, 5 – twisted pale yellow petals and a large ovary. Carica papaya is a non-seasonal plant bit thrives best during dry season.
Papaya is a fruit of the plant Carica papaya. The fruit is round, oblong or pear-shaped to about 45 cm and below. The fruit is irregularly ovoid, with 4 – 6 rib-like projections, pulpy and enclosing numerous blackish seeds. When unripe, the fruit appear green and on ripening yellow-orange. The fruit is ripe when it feels soft (like ripe avocado). The fruit taste is vaguely similar to pineapple and peach. The flesh is yellow, orange or red (Rahmat et al, 2009).
Papaya flesh has been recorded to contain high nutritive value, nutritional value per 100g recorded for papaya flesh shows that it contains 9.81g carbohydrates which comprise of 5.90g sugar and the dietary fibre. Fat is 0.14g while protein content is 0.01g IU/100g) 6%, vitamin E (276 IU/100g) 3%, Thiamine (0.04 riboflavin (0.05mg) 3%, niacin (0.338mg) 2% vitamin B6 8% vitamin C (61.8Ug) 103%.
Papaya also showed high mineral content. Potassium (275mg) 5% has the highest value while calcium is (24mg) 2% Magnesium (10mg) 3%, phosphorus (5mg) sodium (3mg) 0% and the heavy metal iron (0.10mg) 1%. This data gives a valuable reason why papaya is greatly consumed and the seeds discarded due to absence of reliable data of its nutritional composition.
Papaya seed is one of the seeds considered waste by individuals who consume the flesh. Papaya seed are small, blackish when matured and whitish when not matured. The seed is enclosed in a sac of liquid. Within the sac is a hard and rough epicarp which encloses the testa. The testa contains varying quantities of minerals and nutrients. This suggests that the seed has important nutrients. This suggests that the seed has important nutritional properties and can be useful in the treatment of diseases and ill health.
A study of the nutritional, mineral, phytochemical, fatty acid and amino acid compositions of this seed, behevably will open an avenue to a wider utilization of the seed. This project work was designed to undertake such study with hope that findings will reveal a lot of potentials for utilization of papaya seeds. Therefore, the aim of this study was to determine the phytochemicals and minerals that are present in papaya (Carica papaya L.) seeds. This will help in determining its medicinal and nutritional values which may be useful in pharmaceutical and food industries.
Statement of the Problem
*Fruits and vegetables are nutrient suppliers which have effects on several functions of man. Pawpaw (Carica papaya) belongs to the family caricaceae with over 22 species while only one member of the genus carica is cultivated as fruit tree. According to Food and Agriculture Organization (2008), it is an invaluable plant that is prevalent throughout tropical Africa and Nigeria is the third largest producer globally. It is eaten because of its nutritional value and its medicinal properties. This also makes it to be of economic value. The fruit is rich in provitamin A, carotenoids, lycopene, vitamins, dietary minerals and dietary fibre. The skin, pulp and seed contain varieties of phytochemicals including natural phenol and flavonoids which have antioxidant properties.
Objective Of The Study
*The main objective of this study is to investigate phytochemical and mineral composition of pawpaw (papaya) seed.
Significance Of The Study
*In this study, the researcher set out to investigate phytochemical and mineral composition of pawpaw (papaya) seed. Therefore, this study will be immense benefits to all laboratory scientists in Nigeria.
Laboratory scientists would also benefits from this study as the recommendations made in this study will be useful for them.
This study will also help to serve as literature (reference source) to students, individuals or corporate bodies into what to carry out on further research on the similar topic.
Scope Of The Study
*This study concerns about phytochemical and mineral composition of pawpaw (papaya) seed.
Limitation Of The Study:
* There is no study undertaken by a researcher that is perfect. The imperfection of any research is always due to some factors negatively affecting a researcher in the course of carrying out research. Therefore, time constraint has shown no mercy to the research. The limited time has to be shared among many alternative uses, which includes reading, attending lectures and writing of this research, also distance and its attendant costs of travelling to obtain information which may enhance the writing of this study was a major limitation.
*In recent years, the role and beneficial effects of many phytonutrients from plant sources such as fruits and vegetables had attracted much attention from food scientists as well as the public. These phytochemicals are natural antioxidant which frequently promoted due to the concerns regarding toxicity of the synthetic ones. Apart from free radical scavenging activity, antioxidants found from most of the plants possess antibacterial, antiviral, antimetastasis activity, antiulcer activity, antimutagenic, antiallergic and anticarcinogenicity (Moure et al., 2001).
Increasing numbers of studies on residual sources in replacing synthetic antioxidants with the natural ones are due to the augmented recycling interest of the agro-food industry. These are playing an important role in improving the complete utilization of the residual sources. The wastes or by-products from food processing such as seed and peel of some fruits contain higher source of potential antioxidant activities than the edible portion (Okonogi et al., 2007).
Carica papaya L. belongs to the family of Caricaceae. It is an herbaceous plant that grows in tropical and subtropical countries (Da Silva et al., 2007). According to Food and agriculture Organization (Food and Agricultural Organisation (FAO), 2008), it is an invaluable plant that is prevalent throughout tropical Africa and Nigeria is the third largest producer globally. It is eaten because of its nutritional value and its medicinal properties. This also makes it to be of economic value. Nutritionally, the major components of papaya fruit pulp dry matter are carbohydrates. At the early stage of fruit development, glucose is the main sugar but the sucrose content increases during ripening and can reach up to 80% of the total sugars. Ripe papaya is most commonly consumed as fresh fruit whereas green papaya as vegetable usually after cooking or boiling (Anuar et al., 2008).
Papaya, as a tropical fruit, was traditionally used as therapeutic remedy due to its medicinal properties. Papaya is also known to be a thirst quencher by people living in tropical countries. Besides its juicy pulp, the peel and seeds of papaya are valuable too. Papaya seeds were known to give several health benefits (Adebiyi et al., 2003; Thomás et al., 2009). In some of the poor countries in tropical region, papaya peel is used for cooking as one of the dishes. The increase in processing of papaya pulp necessitates the determination of the potential of papaya seed utilization in human and /or animal
*Origin of pawpaw
The pawpaw is believed to be native to southern Mexico and neighboring Central America. It is currently cultivated in Florida, Hawaii, Eastern British Africa, South Africa, Sri-Lanka, India, Canary Islands, Malaysia and Australia. It is now present in every tropical and subtropical country. Pawpaw was first described in 1526 by the Spanish chronicler Oviedo, who found it first on Panamanian and Colombian coasts. The fruit was rapidly propagated in the tropics, most likely due to the abundant and highly viable seeds. The crop has adapted quite well to tropical areas with fertile soils and abundant rainfall. The history of pawpaw spread was initiated approximately in 1500, when the Spanish conquerors carried seeds to Panama and Dominican Republic. During the following century Spanish and Portuguese sailors took the seeds to the Phillipines, Malaysia and India. For 1600 the fruit had been produced in warm regions of South and Central America, Southern Mexico, the Antilles, Bahamas, Bermuda y Florida. In the same century pawpaw seeds were taken from India to Naples in Italy. The crop reached Hawaii between 1800 and 1820. Until 1900, pawpaw seeds were taken to Florida, probably from Bahamas' plantations. The Solo variety has been cultivated in Hawaii since 1911, probably brought from Barbados and Jamaica. The first seeds of the Maradol variety were introduced into Mexico in 1978, through CONAFRUT, in Xalapa, Veracruz (CRFG, 1998)
*Taxonomy
Family: Caricacea.
Order: Parietals.
Genus: Carica
Species: Papaya.
SCIENTIFIC NAME: Carica papaya L.
*Botanical Description
Plant: It is a fast growing arborescent herb, with short life, it has single straight or sometimes branched stem reaching 2-10 m height (Fig. 4 Pawpaw tree), the stem is cylindrical spongy-fibrous, loose, hollow, gray or gray-brown colour, 10-30 cm diameter and toughened by large and protuberant scars caused by fallen leaves and flowers.
: Pawpaw tree
The pawpaw is a polygamous species. The plants may be classified into three primary sex types:
i) male (staminate)
ii) hermaphroditic (bisexual)
iii) female (pistillate).
In addition, some plants can produce, at the same time, more than one kind of flower. Also, some produce flowers that are not of these basic forms, but exhibit different degrees of maleness and femaleness. This tendency to change in sexual expression seems to be triggered by climatic factors, such as drought and variable temperatures. The tendency to produce male flowers seems to increase at high temperatures. Since male trees are unfruitful and fruit from bisexual plants is preferred in some markets, it is very important to select seed which will give a maximum number of fruitful trees of the desired type. This can't be do by simply saving seed from productive open-pollinated plants, but one can predict fairly accurately the progeny by knowing the source of pollen and the kind of flower the fruit came from. Accordingly, the grower must hand pollinate to obtain the desired combination of flower types. This is done covering an unopened flower, either bisexual or pistillate, with a paper bag until it opens and then transferring the desired pollen onto the receptive pistil. Pollination studies have shown that: a) pistillate flowers pollinated by staminate flowers give equal numbers of male and female progeny; b) pistillate flowers pollinated by pollen from bisexual flowers give an equal number of female and bisexual progeny, c) bisexual flowers either self or crossed-pollinated with other bisexuals give a ratio of one female to 2 bisexual, d) bisexual flowers pollinated by staminate ones produce equal numbers of female, male and bisexual progeny. It is evident that the second and third combinations will produce the maximum number of fruit-bearing plants (Malo, 2001).
2. Leaves: Alternate, bundled at the apex between stem and branches, long petioles; widely evident, 25-75 cm diameter, smooth, moderately palm shape with thick middle irradiant veins, the base is deeply string shape with overimposed lobes; from 7-11 large lobed, each with a wide base or slightly constrained and sharp-pointed, and sharp apex. The bundle of leaves is dark green to yellow-green, bright, visibly marked by the off-white nerves embedded and reticulated veins; the underneath surface is pale green-yellow and opaque with visibly prominent vascular structures; the petioles are round and yellow-green, with sporadic purple or violet stains, fistulous form, fragile, 25-100 cm length and 0.5-1.5 cm thick. (Fig. 2.2 Pawpaw leaves).
: Pawpaw leaves
:Pawpaw Seeds
3. Distribution Cultivars: There are many distinct, true-breeding varieties in the world today. Many were developed from systematic breeding programmes and while others were from selections made by growers. Recently, transgenic varieties were developed through biotechnology processes. Papaya varieties can be self or cross-pollinated. In general, gynodioecious varieties (having hermaphrodite and female trees) are self or cross-pollinated, while the dioecious varieties (having male and female trees) are enforced cross-pollinators.
Table 2.1: Common Varieties of Pawpaw
Country
Variety
Sex Type
Flesh Color
Australia
Improved Petersen
dioecious
Yellow
Guinea Gold
hermaphrodite
Yellow
Sunnybank/S7
dioecious
Yellow
Richter/Arline
dioecious
Yellow
America – Mexico
Verde
–
–
Gialla
–
–
Cera
–
–
Chincona
–
–
USA – Florida
Cariflora
dioecious
Yellow
Betty
dioecious
Yellow
Homestead
dioecious
Yellow
USA – Hawaii
Kapoho Solo
hermaphrodite
Yellow
Sunrise
hermaphrodite
Red
Waimanalo
hermaphrodite
Yellow
Rainbow
hermaphrodite
Yellow
Venezuela
Paraguanera
–
–
Roja
–
Red
Caribbean – Barbados
Wakefield
–
–
Graeme 5, and 7
–
–
Cuba
Maradol
hermaphrodite
Red
Trinidad
Santa Cruz Giant
–
–
Cedro
–
–
Dominican Republic
Cartagena
hermaphrodite
Yellow
Asia – India
Coorg Honey Dew
hermaphrodite
Yellow
Coimbitor 2
dioecious
Yellow
Indonesia
Semangka
hermaphrodite
Red
Dampit
hermaphrodite
Red
Malaysia
Eksotika
hermaphrodite
Red
Sekaki
hermaphrodite
Red
Philippines
Cavite / Sinta
hermaphrodite
Red
Taiwan
Tainung No. 5
hermaphrodite
Red
Thailand
Sai-nampueng
hermaphrodite
Red
Khaek Dam
hermaphrodite
Red
South Africa
Hortus Gold
dioecious
Yellow
Kaapmuiden
–
Yellow
Honey Gold
dioecious
Yellow
Minerals and Phytochemical Composition of Pawpaw
Minerals are substances that are naturally present in the earth’s crust and are not formed by animals and plants. Minerals occur in food both in organic and inorganic compounds. The major organic compounds includes carbohydrates, phosphates, chlorides and sulphates of sodium, calcium, potassium and magnesium (Onwuka, 2005). Minerals make up fourteen out of the total nutrients needed for human nutrition. These minerals includes calcium, chlorine, cobalt, copper, fluorine, iodine, iron, magnesium, sodium, phosphorus and sulphur (James, 1996).
Phytochemicals are chemical substances that occur naturally in food. Most phytochemicals are beneficial to health while some others are not and are considered food toxicants. Phytochemicals like alkaloids, tannins, saponins and flavonoids are of medical importance and are commonly used in herbal medicine. Okwu, (2005) reported that isolated plant alkaloids and their synthetic derivatives are known for their analgesic, antispasmodic and antibacteriacidal effects.
Some other phytochemicals like cyanogenic glycoside (HCN), Phytate and trysin inhibitor are considered food toxicant. Some of these compounds occur naturally in foods, others probably remain undiscovered but generally, the cause signs or symptoms of toxicity in animals (Onwuka, 2005).
The percentage composition of typical pawpaw is: seed (8.5 %), skin (12 %) and pulp (79.5 %). As a dual- or multi-purpose, early-bearing, space-conserving, herbaceous crop, it is widely acclaimed, despite its susceptibility to natural enemies.
Typical pawpaw maradol variety
Table 2.2: Pawpaw Maradol variety % composition
Component
Percentage Composition(%)
Skin
25.3
Pulp
69.3
Seeds
5.4
The edible portion of the ripe papaya fruit contains both macro and micro minerals and these are Na, K, Ca, Mg, P, Fe, Cu, Zn and Mn. Carica papaya is a source of carotenoids, vitamin C, thiamine, riboflavin, niacin, vitamin B6 and vitamin K (Bari et al., 2006).
The fruit is also rich in provitamin A, carotenoids, lycopene, vitamins, dietary minerals and dietary fibre (Bari, et al., (2006); Adetuyi, et al., 2008). The skin, pulp and seed contain varieties of phytochemicals including natural phenol and flavonoids which have antioxidant properties (Zhou, et al., 2011). The fruit is rich in phytochemicals, especially carotenoids and polyphenols (Sancho et al., 2011).
It was also reported that they may contain immunomodulary compounds that can cause growth and contains compounds that kill parasites (Wabo, et al., 2011). Okeniyi et al., (Okeniyi, et al., 2007), noticed that they are antihelminthic and antiamoebic in activities as well as anticancer and antidiabetic properties.
USES OF PAWPAW
a. Food for humans
Excellent quality fruit, high in vitamin A. Ripe fruit is consumed fresh as a breakfast or dessert fruit and with honey. Green fruits are grated in salads or boiled like squash.
b) Food for livestock
Foliage is sometimes used as a feed source in fish ponds (herbivorous Tilapia, etc.).
c) Used as meat tenderizer
The green fruit is the source of the enzyme papain, which is used in commercial meat tenderizers. In the Philippines, meat is wrapped in young leaves to tenderize it (Smith, et al., 1992).
Various parts of the pawpaw plant are used for medicinal purposes in various parts of the world. For example, as a treatment for intestinal parasites (Smith, et al., 1992, University of Cornell, 2000).
d) Medicinal uses
In tropical folk medicine, the fresh latex is smeared on boils, warts and freckles and given as a vermifuge. In India, it is applied on the uterus as an irritant to cause abortion. The unripe fruit is sometimes hazardously ingested to achieve abortion. Seeds, too, may bring on abortion. They are often taken as an emmenagogue (agent that promote the menstrual flow) and given as a vermifuge. The root is ground to a paste with salt, diluted with water and given as an enema to induce abortion. A root decoction is claimed to expel roundworms. Roots are also used to make salt.
Crushed leaves wrapped around tough meat will tenderize it overnight. The leaf also functions as a vermifuge and as a primitive soap substitute in laundering. Dried leaves have been smoked to relieve asthma or as a tobacco substitute. Packages of dried, pulverized leaves are sold by "health food" stores for making tea, despite the fact that the leaf decoction is administered as a purgative for horses in Ghana and in the Ivory Coast it is a treatment for genito-urinary illness. The dried leaf infusion is taken for stomach troubles in Ghana and they say it is purgative and may cause abortion (Morton, 1987).
e) Folklore, medicinal and non-food uses
A. Milky latex may cause dermatitis.
B. Hypoglycemic activity has been shown experimentally.
C. Toothache relief - the inner bark is used for this in Samoa.
D. Amebicide - latex and seeds used in Central America to kill Entamoeba histolytica which causes dysentery and liver abceses.
E. Cosmetics - pawpaw fruit pulp is the basic component of many facial creams, salves, and shampoos.
F. Papain - is one of two proteolytic enzymes (the other is chymopapain) found in pawpaw latex. Papain is extremely useful since it retains proteolytic activity over a wide pH range, unlike other proteases. Papain is used during surgical procedures to dissolve ruptured spinal discs; it is referred to as "nature's scalpel" because it preferentially degrades dead tissue. Latex is extracted on a commercial scale in East Africa and Sri Lanka. The green fruit are "tapped" by making incisions on the fruit surface in the morning, and catching the latex in a container hanging beneath. The latex is dried, ground into powder, and packed in tin containers. One thousand average-sized fruits will yield one pound of papain. Columbus, on one of his voyages to the Caribbean, noted that natives could consume a large amount of fish and meat without getting indigestion if unripe pawpaw was eaten after the meal. Green pawpaw can be rubbed onto a piece of meat, cooked with it, crushed leaves can be wrapped around meat, or a commercial tenderizer preparation sprinkled on the surface. Beef cattle are sometimes injected with papain 1/2-h before slaughter to tenderize them. Meat treated with papain should not be cooked "rare", as the enzyme will not have been inactivated. Additional uses include: beer clarification, wool and silk treatment before dyeing, de-hair hide before tanning, tuna liver oil extraction, treatment of ulcers, diphtheria, swelling, and fever, relief of gas and sour stomach.
G. Folk medicine - Fresh latex can be smeared on boils, warts or freckles to remove. Latex is smeared on the uterus to cause abortion in India, or sometimes the unripe fruit and/or seeds are eaten to induce abortion (The University of Georgia, 2002).
Uses of Pawpaw (Papaya) Seeds
Although, papaya seeds are considered as waste, they are useful in most aspects.
Papaya seeds could be used as an effective antibacterial agent for Escherichia coli, Staphylococcus aureus, Salmonella typhi, although further research is needed before advocating large scale therapy (Rahmat et al., 2009).
Papaya seed extracts may be nephron protective (protects the kidney) in toxicity induced kidney failure
Papaya seed extracts a real dissolving or digestive action on nitrogenous substances. This action is obtained in aqueous solution. Note that alcohol renders that extract inert.
