Effects of storage on nutrient and proximate composition of fruits


Master's Thesis, 2018

56 Pages, Grade: 5.0


Free online reading

CHAPTER ONE

1.0 INTRODUCTION

1.1 BACKGROUND OF THE STUDY

Fruits are an excellent source of nutrition and should be consumed in moderation as part of a healthy diet (Stackelberg et al., 2013). Like vegetables fruits are a great source of vitamin, minerals, antioxidants, fiber and water. In the fruit group, several fruits are considered to be super foods (Oyebode et al., 2014). The daily consumption of fruits is positively related to health benefits and reduced incidence and mortality by degenerative disorders, such as cancer and cardiovascular diseases A considerable body of research has shown that fruits are a rich source of essential micronutrients (such as vitamin C and folic acid) and other bioactive compounds, including phenolic compounds (Beattie et al., 2005; Wang et al., 2014). These bioactives are “extra-nutritional” compounds commonly found in small amounts in plants and that have chemo-protective roles in human health, as demonstrated in epidemiological studies (Van Duyn and Pivonka, 2000).

There are some basic characteristics of fruits that make them appealing to most people. They are great sources of dietary fiber and most fruits are low in calories and fat; good sources of healthy fats. They can also be used as combination of sugars: Fructose, glucose, and sucrose. Fructose is the principal sugar of many fruits and is considered to be the sweetest. Sucrose is the main sugar in several other fruits such as orange, melons and peaches (De Ancos et al., 2012). Water makes up 80% to 95% of fruits. The water content in fruits keep their caloric content low and also provides fruit juice. Almost all fruits can be eaten raw juiced for a beverage, used in frozen desserts, preserved, or dried. Fresh whole fruits are considered to be the most nutrition (Ogunmoyela et al., 2013).

Storage is defined as holding goods until needed for further processing, marketing or consumption (Adepoju, 2009). The expression connotes the expectation that goods would not just be kept, but in the most appropriate conditions for maximum retention of both quality and quantity (Wajilda, 2008). The term preservation cover an enormous field of widely different treatments carried out to render food safe, edible and palatable (Bureau et al., 2009). The freezing method of preservation causes some changes in the nutritional value of fruits but the loss is not significant. Nutrients are those substances in fruits which when eaten provide nourishment to the body (Cayupan et al., 2011). The most sensitive nutrients to change in fruits are vitamins (Goulao and Oliveira, 2008). Other nutrients are much more stable and very little is lost in most processes. However, greater losses can occur due to improper storage of fruits under adverse environmental conditions (Giovannoni, 2001).

Micronutrient deficiency is still a public health problem in Nigeria despite the effort that has been made to eliminate it. World Health Organization (WHO) (2002) reported that about 30% of the population in developing countries suffer currently from one or more of the multiple forms of nutritional deficiencies, especially that of micronutrient. Adepoju (2009) stated that incidence of malnutrition is higher in the urban slums, particularly protein and micronutrient deficiencies.

Due to the freezing temperatures, crystallize water which accounts for approximately 80-95% of the fruit, thereby reducing water activity (aw), biochemical changes, and microbial growth (De Ancos et al., 2012). Although it has been suggested that low temperatures (around -18 °C) could accelerate some reactions and reduces the velocity at which most modifications occur (Cortellino, 2012).

One of the major problems is what happens to the nutritional quality parameters of the fresh produce during the period of storage. Quantifying these can actually help in determining how long the produce can be kept without losing substantial part of the nutrients.

1.2 STATEMENT OF THE PROBLEM

In recent times, there is too low in nutritional quantity of edible fruits in the developing countries like Nigeria (Odebode et al., 2008). In order to overcome this challenge, a lot of research is being carried out to discover and exploit new sources of preserving fruits and vegetables (Oboh, 2005). Malnutrition results directly from inadequate dietary intake and infectious diseases caused by food insecurity at the household, village, community and national levels. Food insecurity is linked to dietary intake, nutritional status, and ultimately to physical health outcomes like child growth morbidity and mortality. In Nigeria, food insecurity is mainly caused by problems related to food production, harvesting, preservation, processing, distribution, preparation and use.

Food losses in the developing world are thought to be 50% for fruits and vegetables and 25% for harvested food grains. Losses of fruits and vegetables can be caused by several factors, ranging from growing conditions to handling by retailers and consumers (Adeoye et al., 2009). The factors include poor storage facilities and poor transportation to move the fruits to the market before it spoils (Adeoye et al., 2009). Other factors are refrigerated storage, drying equipment or poor drying season and traditional processing and marketing systems can be responsible for high losses of nutrient content (Atanda et al., 2011). The effect of food processing on nutrient content will depend on the sensitivity of the nutrient to the various conditions prevailing during the process, such as heat, oxygen, pH, temperature and light. The nutrient retention may vary with a combination of conditions, such as the characteristics of the food being processed and concentration of the nutrient in the food. During processing and storage of the fruits and vegetables, beta-carotene is degraded through oxidation reactions (Nyambaka et al., 2012). Storage of the fruits and vegetables under normal atmospheric conditions results in nutritive degradation, especially of beta-carotene.

1.3 OBJECTIVES OF THE STUDY

The general objective of the study is to examine the effect of storage on nutrient and proximate composition of five selected fruits in five Local Government Areas in Lagos State. The specific objectives were to,

(i) determine the proximate, minerals and vitamins levels of the five selected fruits .
(ii) examine the varying effects of storage on the nutrient quality of the fruits.

1.4 JUSTIFICATION OF THE STUDY

Fruits is an important staple food crop in Africa. It contains Vitamins with sufficient quantities of a precursor beta-carotene (Odebode et al., 2008). The three most common strategies for addressing malnutrition in Nigeria are large scale vitamin supplementation programmes, food fortification with vitamins, and food-based approaches that encourage diet diversification and promote consumption of vitamin rich foods, including bio-fortified foods. Fruits are important sources of micronutrients (pro-vitamin A, vitamin C, vitamin E, zinc, iron) and dietary fibre (Nyambaka et al., 2012). Intervention measures used to alleviate vitamin A and iron deficiencies include supplementation and food fortification. However, the best long-term approach is through production and consumption of locally available Vitamins and iron rich foods. Fruits and vegetables have considerable potential to contribute to this food based approach to tackle the problem of vitamins and iron deficiency, major public health concerns of the poorer sections (Nyambaka et al., 2012; Hagenimana et al., 2000). The study will assist help in the estimation of dietary requirement of the fruits and vegetables. The accurate information on the nutrient composition of these fruits will also help to integrate them in the food based approach for fighting micronutrients deficiency.

CHAPTER TWO

2.0 LITERATURE REVIEW

2.1 MICRONUTRIENTS

Calcium: Calcium is one of most minerals found in the human body. The teeth and bones contain most of calcium (about 99%). Nerve cells, body tissues, blood and other body fluids contain the remaining calcium (Hamrick and Count, 2008). Calcium helps in maintaining healthy bone and teeth. Proper levels of calcium over a lifetime can prevent osteoporosis. Calcium assists in blood clotting, nerve signaling, muscle contraction and relaxation, and the release of certain hormones. It is also needed for normal heart beat. Calcium is one of the minerals believed to be an important factor governing fruit storage quality (Adeoye et al., 2009). It has been reported to delay ripening senescence and reduce storage disorder in fruits (Barrett et al., 2010). Institute of Medicine (IOM) (2000) reported the following to be daily dietary intake of calcium, 210 mg-270 mg for infants, 500 mg-1,300 mg for children, 1,300 mg for male and female adolescents (14-18years), 1000 mg for adults' males and females 19 to 50 years.

Phosphorus: Phosphorus is a mineral that makes up 1% of a person's total body weight, (IOM, 2000). It is present in every cell of the body but most of the phosphorus in the body is found in bone and teeth. Phosphorus is needed in the formation of bone and teeth. It plays a vital role in the body in the utilization of carbohydrates and fats and in the synthesis of protein or the growth, maintenance and repair of tissue. It is crucial for the production of ATP, a mode to store energy in the body.

Phosphorus works with vitamin D, assists in the contraction of muscles, in the functioning of kidneys, in maintaining the regularity of the heat beat, and in nerve conduction (IOM, 2000).They reported the recommended dietary intakes of phosphorus to be 700 mg/day for adults, 1,250mg per day for pregnant and lactating women who are younger than 18 years, 500mg per day for children who are between four to five years, 275mg per day for children who are 7 to 12 months, 100mg per day for children birth to 6 months old.

Iron: Iron is an essential nutrient. Iron occurs in two forms in foods, heme („organic") and non-heme („inorganic").The body require iron for the oxygen synthesis, transport of proteins heamoglobin and myoglobin, and other iron containing enzymes which participate in electron transfer oxidation -reduction reactions (IOM, 2000).They recommended the following daily dietary intake of iron, 10mg for adults males, 18mg for adolescents 11years and above, 6­10mg for infants, 15mg for six months to three years old,

Zinc: Zinc is needed for the body's defensive system (immune) to work properly. It plays a role in cell division, cell growth, wound healing and break down of carbohydrates. Zinc is also needed for senses of smell and taste (IOM, 2000). The following recommended daily dietary intake were given by (IOM, 2000), 2mg for infants 0-6 months, 3mg for infants 7-12 months, 3mg for children 1-3 years, 5mg for children 4-8 years, 8mg for children 9- 13 years, 11mg for male adolescents and adults 14 years and over, 9mg for female adolescents and adults 14- 18 years, 8mg for female adolescents and adults 19 years and over.

Iodine: Iodine is a trace mineral and an essential nutrient found naturally in the body. Iodine is needed for normal metabolism of cells. Human needs iodine for production of thyroid hormones.

Vitamin A: Vitamin A occur in forms. The first is retinol, vitamin A from animal sources, another one is carotenes, a yellow pigment found in fruits and vegetables (Galindo, 2004). They stated that carotene is not absorbed or utilized as efficiently as retinol, but it is an important source. Vitamin A is essential for maintaining healthy eyes and preventing night blindness. Vitamin A is involved in bone and teeth development. Vitamin A keeps the tissue linings of the respiratory, digestive and urogenital tracts healthy. Vitamin A is also necessary for healthy skin.

2.2 IMPORTANCE OF FRUITS AND VEGETABLES IN DIET

Fruits and vegetables are highly beneficial in human diet. The main physiological action of fruits and vegetables are as follows:

(i) Hydrating effect

Fruits and fruit juice, vegetables and vegetable juice are the most pleasant way of hydrating the organism (Maestrelli, 2000). The water absorbed by sick person in this manner has added advantage of supplying sugar and minerals at the same time.

(ii) Diuretic effect

Clinical observations have showed that potassium, magnesium and sodium contents of fruits and vegetables act as diuretic. The diuretic frequency of the urination is considerably increased when fruits and vegetable juice are taken (MacGee and Harold, 2004). They lower the urine density and thereby accelerate the elimination of nitrogenous waste and chloride. The diuretic effect of vegetables like potatoes, beans, spinach, radish, turnip are especially important in cases of edema or swellings, kidney and heart conditions (Maestrelli, 2004).

(iii) Alkalinizing effect

The organic acids of the salts in fruits and vegetables provide alkaline carbonates when transformed within the organism, which alkalize the fluids. All the fruits and leafy vegetables promote intestinal elimination. This keep the body free from toxic wastes, which creep into blood system from an overloaded, sluggish intestinal tract. Fibre in vegetables act as mechanical intestinal expanders, draws more water and protein in them. Carbohydrates of vegetables are chiefly in the form of sugar, dextrin and acids, which are easily digestible and are completely absorbed. On account of this, they are very useful for sick and invalids for quick energy and heat. Fibres inform of cellulose help, elimination of cholesterol. Fibre lowers serum cholesterol by reducing the absorption of dietary cholesterol. Fibre complex with bile acids, which are compounds manufactured by the liver from cholesterol that are necessary for the proper digestion of fat. After complexing with bile acids, the components are removed from circulation and do not make it back to the liver as a result the liver must use additional cholesterol to make new bile. Bile acids are necessary for normal digestion of fat, American Dietetic Association (Maestrelli, 2004).

2.3 MINERALIZING EFFECT

Fruit furnish minerals to the body. Some are rich in calcium and iron. These minerals are essentials for strong bone and teeth, respectively (Pukszta and Palich, 2007). Two important minerals, calcium and iron, found in vegetables are useful, calcium is for strong bone and teeth, iron is needed for blood formation and an essential constituent of hemoglobin (Yamada et al., 2002).

2.4 LAXATIVE EFFECT

Cellulose, the fibrous matter in fruit and vegetables, aids in the smooth passage of food in the digestive tract and easy bowel action. The sugar and organic acids contained in fruits also increase their laxative effect. Hence, regular use of fruits and vegetables prevent and cure constipation (Fava et al., 2006). He stated that certain types of fibre are referred to as fermentable because they are fermented by the “friendly” bacteria that live in the large intestine. The fermented dietary fibre in the large intestine produces a short-chain fatty acid called butyric acid which serves as the primary fuel for the cells in the large intestine and help in maintaining the health and integrity of the colon. Fibre that are not fermentable in the large intestine help maintain bowel regularity by increasing the bulk of the faeces and decreasing the transit time of faecal matter through the intestine. Bowel regularity is associated with a decreased risk for colon cancer and hemorrhoids when the hemorrhoids are related to screening and constipation (Breton et al., 2000).

Tonic action: Fruit and vegetables are dependable sources of vitamins, exert a tonic effect in the body (Chassagne-Berces et al., 2010).Guava, apples and citrus fruits, like lemons and oranges, are particularly valuable sources of vitamin C. These fruits are usually eaten raw and fresh, thus making the vitamins fully available to the body. Several fruits contain good amounts of carotene which gets converted to vitamin A in the body. He further stated that a medium-sized mango can provide as much as 15,000 international units of vitamin A which is sufficient for full one week and this vitamin can be stored in the body, Common papaya is an excellent source of vitamin A and carotene (Liang et al., 2015).

Fruit cure: Fruits are highly beneficial in maintaining acid-alkaline balance in the body. They neutralize the toxic condition of the body resulting from excessive intake of acid-forming foods and restore its alkalinity (Chassagne-Berces et al., 2010). They clear the system of morbid waste and cater to the body's requirement of natural sugar, vitamins and minerals.

Vitamins, minerals, enzymes and trace elements contained in fresh fruits juices are extremely beneficial in normalizing all the body processes. They supply needed elements for the body's own healing activity and cell regeneration and speed up the recovery (Liang et al., 2015).

2.5 FRUITS

The term fruits have different meaning. Botanically, a fruit is the ripened ovary together with seeds of a flowering plant. In many species, the fruit incorporates the ripened ovary and surrounding tissues. Fruit are the means by which flowering plant disseminate seeds (Lewis, 2002), in cuisine fruits that are sweet and fleshy, examples of which include apple and orange (MacGee, and Harold, 2004). However a great many common fruits as well as nuts and grins are the fruit of the plant species they come from (MacGee and Harold, 2004). Majority of the fruit are fleshly or juicy (Delgado and Rubiolo, 2005).

2.6 NUTRIENT COMPOSITION OF FRUITS

Fruits are found to be rich in vitamins, especially vitamin C, minerals, sugar (Chassagne- Berces et al., 2009). However, higher values for carbohydrate have been reported in various fruits (Delgado and Rubiolo, 2005). The main sugar in fruits are glucose and fructose and sucrose. Some fruit are low in carbohydrate and consequently low in calorie.

2.6.1 Protein: The protein constituents of fruits are low. They serve as components of nuclear and cytoplasmic structures that take part in determining and maintaining cellular organization, including the full components of enzymes involved in the metabolism during growth and maturation of the fruit (Delgado and Rubiolo, 2005).

2.6.2 Moisture: The moisture content of fresh fruits at maturity is generally high (Delgado and Rubiolo, 2005). Moisture content of fruits determines how fresh the fruits were at harvest, or for how long they have been stored before analysis (Pukszta and Palich, 2007).

2.6.3 Fats: Fruits are not good sources of fat and are usually recommended as part of weight reduction diet (Delgado and Rubiolo, 2005), reported on the nutritional value and chemical composition of fruits such as lesser-known fruit and seeds. Their reports showed that oil fruit and seeds contain oils and fats.

2.6.4 Fiber: Fruits and vegetables as sources of dietary fibre normalizes blood glucose levels. Fibre slows the rate at which food leaves the stomach and by delaying the absorption of glucose following a meal. Fibres also increase insulin sensitivity. As a result, high intake of fiber plays a role in the prevention and treatment of type 2 diabetes. In addition, by slowing the rate at which food leaves the stomach, fibres promotes a sense of satiety, or fullness, after a meal, which prevents overeating and weight gain (Lom, 2001).

2.6.5 Minerals: Fruits contain mineral elements in low quantities. Girault et al. (2009) reported that plants tend to concentrate calcium in their leaves and phosphors in the seeds. Fruits, like dried fruits are rich in calcium and iron (Mauseth and James, 2003).

2.7 VITAMINS IN FRUITS

Delgado and Rubiolo (2005) stated that the main contribution of fruits and their products to nutrition is their supply of vitamins most, especially the antiascorbic vitamins (Lisiewska and Kmiecik, 2000). Fruits and vegetables are the main sources from which primates derive their vitamins. Ascorbic acid alongside with other vitamins performs useful functions in the body. Drugs such as asprin and the contraceptive pills affect the plasma levels of ascorbic acid (Mauseth and James, 2003).

Ascorbic acid in the body aids in iron absorption from the intestines. It is required for connective tissue metabolism especially the scar tissue, bones and teeth. It is also necessary as an anti-stress and protector against cold, chills and damp. It prevents muscle fatigue and scurvy. It is thought to be necessary for metabolism of cholesterol, reduces the degree of formation of carcinogenic nitrosamsin from their precursors and is required in the hydrocylation of proline to hydroxyperoline of the collagen in the body (Mauseth and James, 2003).

2.8 COMMONLY USED FRUITS

2.8.1 Guava: Guava is a rich source of vitamin c. It contains a far higher amount of vitamin C than most of the imported and local fruits. It contains three to six time more than vitamin C than in orange, 10-30 times more than bananas and about 10 times more than papaya (USDA, 2001). Most of the vitamins C is concentrated in skin and outer mesocarp, reaching a maximum green fully mature fruit and declining as the fruit ripens. Guava is very good source of vitamins, fibres as well as minerals.

2.8.2 Pineapple: Pineapples nutrients include calcium, potassium, fibre, and vitamin. It is low in fat and cholesterol. It is also a good source of vitamins B1, B6, and fiber. Pineapple is a digestive and a natural anti-inflammatory fruits. A group of sulfur containing protolytic enzyme in pineapple aid digestion. Fresh pineapples are rich in bromelain. Bromelain has demonstrated significant anti-inflammatory conditions such as acute smusitis, sorethroat arthritis and gut and speeding recovery from injuries and surgery. Pineapple should be eaten alone between meals (USDA, 2001).

2.8.3 Mangoes: Mangoes contain several important phytochemicals including cryptoxanthin, lutein, garlic acid and anacardic acid. Mangoes are an incredibly healthy snack. The entire fruit can be eaten for just over hundred calories. High in fibre, virtually fat free and mangoes contain numerous vitamins. Mangoes contain, B - carotene which may slow the aging process, reduce the risk of certain forms of cancers, improve lung function, and reduce complications associated with diabetes. Mangoes are rich in antioxidants such as beta carotene (44.5g/100g fruit) and minerals (USDA, 2001).

2.8.4 Pawpaw: Pawpaw is very nutritious fruits. They are high in vitamin C, magnesium, iron, copper and manganese. They are good sources of potassium and several essential amino acids .They also contain significant amount of riboflavin, niacin, calcium, phosphorus, and zinc. Pawpaw contain these nutrients in amounts that are generally about the source or greater than those found in bananas, apples, or oranges (USDA, 2001).

2.8.5 Orange: Orange like other citrus fruits is known for vitamin C content. Due to this high amount of vitamin C, orange helps in absorbing calcium into the body and maintaining the health of teeth and bones. It also contains vitamin A and vitamin B. 100g of orange contains about 60 calories. This energy is available in form of sugar which can be absorbed by the body easily. Hence orange juice is often fed to people who have become weak due to some illness. Orange juice is also a good refresher after a long exhaustive day (USDA, 2001).

2.8.7 Apple: The health benefits of apple are enormous. These makes it one of the most valuable and savored fruits throughout the world. Apple contains minerals such as magnesium, copper, manganese, calcium, iron, potassium and phosphorus in small quantities. Apple also contains dietary fibre, which helps in reducing the bad cholesterol level (Girault et al., 2009).

2.8.8 Banana: Banana is rich in potassium, it also contains other minerals such as calcium, iron, magnesium and phosphorus in large quantities. It is rich in fibre making it useful laxative and good for easing constipation. Bananas contains about 90 to 93 calorie per 100g. This energy is easily absorbed by the body. Consumption 3-4 bananas daily, especially with milk, is often recommended to gain weight, banana is useful for 100mg, weight because it has only 90 calories per 100g (USDA, 2001).

2.9 CHANGES IN NUTRIENTS DURING STORAGE

2.9.1 Changes in Vitamins and Minerals during storage

There is every reason to believe that only insignificant level of vitamin B is lost during storage of frozen meats provided the temperature is low enough and does not fluctuate. The most susceptible vitamins are B and B Milk may lose substantial amounts of vitamins B and C within few hours if stored in a clear bottle in sunlight whereas vitamins A and D are not affected (Follows, 2000).

2.9.2 Changes in Proteins during storage

The biological value of proteins is usually little affected by proper storage of food products. High storage temperature will cause certain amino acids (e.g. lysine) to chemically bind with simple sugars to form brown pigments through mallard reaction. The reaction affects the nutritional value of the food because it causes the essential amino acid to become physiologically unavailable (for example improperly stored dried milk and egg white powder are particularly susceptible to this browning reaction) the reaction will also occur if poor packaging of dried foods allow as increase in moisture level (Behsnilan et al., 2003).

2.9.3 Changes in Proteins during Processing

A number of changes may occur during processing, some of which are desirable while others are undesirable. Some chemical changes may lead to compounds which are non-hydrolysable by the intestinal enzymes; or to improvement of nutritional value by deactivating certain anti- nutritional factors such as trypsin inhibitors (Nielsen, 2004).

2.9.4 Changes in Lipids during Storage

The nutritional value of fat lies in the energy it supplied to the body during digestion. Fats are fairly stable to processing (except frying) but may undergo quality deterioration during prolonged storage. Oxidation and hydrolytic rancidity occurs in stored foods leading to off flavor development. These reactions can be caused by enzymes or by moisture and air. They occur more rapidly under adverse conditions but can also develop in properly stored fatty acids. Lipids oxidation produces off flavor components called hydro peroxides and peroxides which react chemically with fat soluble vitamins rendering them nutritionally useless. Loss of these nutrients can be minimized by wrapping foods in moisture proof and oxygen impermeable packaging materials (Odeyemi and Daramola, 2000).

2.9.5 Changes in Carbohydrates during Storage

Carbohydrates can be said to be relatively stable to processing and storage compared to sensitive nutrients such as vitamins. There is no significant loss in the nutritional value of carbohydrates in frozen, canned or dried foods In fact, some carbohydrates are made more digestible through processing and thus nutritionally available and complex carbohydrates are converted to simple sugars. Adverse brown pigments occur in frozen and dried foods when carbohydrates react with proteins (Okaka and Okaka, 2001).

2.9.6 Changes in Moisture during Processing

Changes in moisture content of dried and frozen food can affect the nutritional quality of food. Increase in the moisture level of dried food promotes microbial deterioration and accelerate rancidity. Improperly wrapped foods suffer from freezer burn which is a form of dehydration from the food surface. This loss of moisture causes oxidation of fats and browning leading to off flavor development and at the same time lowering the nutritional value of the food (Wajilda, 2008).

CHAPTER THREE

MATERIALS AND METHODS

3.1 Sample Collection

Five (5) fresh fruit varieties namely Pineapple (Ananus comosus), Watermelon (Citrullus lanatus), Sweet orange (Citrus sinensis), Banana (Musa paradisiaca) and Cucumber (Cucumis sativus) were collected from massively patronised sale points of fruits in five Local Government areas (LGAs) in Lagos state, Nigeria (see figure 1). The fruits were considered representative of the commonly consumed fruits in Lagos. The sampling locations for these LGAs include Eti-Osa (Ajah), Lagos mainland (Oyingbo), Amuwo Odofin, Surulere and Ifako-Ijaiye (Ifako-Ijaiye). Lagos is situated at 6°45' North latitude, 3°4'East longitude and 35 meters elevation above the sea level. Lagos is mega city in Nigeria, having about 9,000,000 inhabitants (Omoyajowo et al., 2017). A total of 50 fruits were sampled in 5 sampling points in the 5 LGAs which imply that 2 pineapples, 2 water-melons, 2 bananas , 2 sweet oranges and 2 cucumbers were sampled per location. Samples were put in polythene bags, labelled properly and taken to the laboratory for appropriate analysis. Fruit samples were thoroughly shredded and homogenized.

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Figure 1: Map of Lagos showing the geographical locations of the study area. (Source: Omoyajowo et al., 2017)

3.2 Sample Preparation

The fruits were washed up with tap water thoroughly to remove the attached dust particles, soil, unicellular algae, etc. Then they were washed with distilled water and finally with deionized water. The washed fruits were dried at room temperature to remove surface water. The fruits were immediately kept in refrigerator for 72 hours. Then the unripe fruits were crushed in a mortal and kept in air tight polythene packet at room temperature before being taken to the laboratory for nutritional composition and proximate analysis.

3.3 Determination of nutritional composition of fruits by proximate analysis

3.3.1 Moisture content (%) determination

Moisture content of fruit samples was determined according to the method of AOAC (2005). An empty clean crucible was weighed; 5 g of the fresh fruit samples was weighed into a crucible and dried in an oven at 105°C to constant weight. The moisture content was then calculated using this equation:

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3.3.2 Ash content (%) determination

Ash content of fruit samples was determined according to the method of AOAC (2005). An empty clean crucible was weighed; 5 g of sample was weighed into the crucible and ashed in a furnace at 550°C to a constant weight. Total ash was calculated as follow:

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3.3.3 Crude fat (%) determination

Crude fat was obtained by exhaustively determined method of AOAC (2005); 5g of sample was massed into a polypropylene centrifuge bottle. Sodium acetate, aliquots of methanol, chloroform and water were added into the bottle and shaken for 30 minutes. The content of the bottle were centrifugated at 2500 rpm for 10 min, then it was set in 25°C water bath for 15 minutes. The samples were evaporated to dryness under nitrogen blanket, heated in a drying oven for 30 minutes, and cooled in a desiccator for at least 30 minutes. Fat content was then determined using:

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Where, W2 was the weight of glass tube and dried extract (g), W1 was the weight of empty dried glass tube (g), VC was the total volume of chloroform (ml), VA was the volume of extract dried (ml), and SW was the weight of the sample in grams.

3.3.4 Crude protein (%) determination

Crude protein content of fruit was determined according to the method of AOAC (2000). Briefly, 1.0g of sample was weighed into digestion tubes. Two Kjeltabs Cu 3.5 (catalyst salts) were added into each tube; then 20 ml of concentrated sulphuric acid (H2SO4) was carefully added into the tube and shaken gently in order to digest samples. Digested samples were cooled for 10 to 20 min. Distillation procedure was then performed using distillation unit and the distillate was titrated with 0.025N sulphuric acid (H2SO4) until the end point changes from green to pink. Volume of acid required in the titration was recorded. Blank was prepared with the exclusion of sample.

1000 mL 1N H2SO4 = 1000 mL 1 N NH3 = 17 g NH3 = 14 g N

1 mL 1N H2SO4 = 1 mL 1 N NH3 = 0.014 g N

The percentage of protein content was calculated according to Jolaoso et al. (2016):

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% Protein = %N x F

Where, VD is the Volume of digest; N is the normality of acid; TV is the titre value; AD is the aliquot of digest and F is the conversion factor for nitrogen to protein (6.25).

3.3.5 Crude fibre (%) determination

Fibre content was determined according to the method of AOAC (2005). 5g of each fruit sample was weighed into a 1 litre conical flask. Then 200ml of boiling sulphuric acid was added and boiled for 30 minutes over a burner. Swirling is done occasionally to remove solids from adhering to the sides of the flask. The hot solution was decanted through Buchner funnel fitted with Whatman 52 filter paper. All residues were rinsed with boiling water until no colour change in litmus paper to be sure acid has been removed. Then the residue was transferred into a 200 ml of 1.25% Sodium hydroxide (NaOH) solution into a 1 litre flask and brought to boil, maintaining a gentle ebullition for 30 minutes, then it was filtered through rapid hardened filter paper. 1% HCl and distilled water, 15 ml of ethyl alcohol and 10ml of diethyl ether were also added. The sample was dried in an oven at 100OC for 1 hour, cooled in a desiccator and weighed (W1). Sample was put in a crucible in a furnace at 55OC for 3-4 hours; it was cooled in a desiccator and weighed again (W2). Fibre was calculated thus:

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3.3.6 Carbohydrate content (%) determination

Carbohydrate content was calculated based on difference calculation (AOAC, 2005):

Carbohydrate = 100% - (% moisture % ash+ % crude protein + % fat)

3.4 Procedure for heavy metal determination

The standard procedure described by Association of Official Analytical Chemists (2000) was followed for the samples preparation for the analysis of heavy metals. Samples were digested by measuring exactly (1.0 g) of the milled sample into a digesting glass tube. 12 ml of HNO3 was added to the food samples and mixture was kept for overnight at room temperature. Then 4.0 ml perchloric acid (HClO4) was added to this mixture and was kept in the fumes block for digestion. The temperature was increased gradually, starting from 50oC and increasing up to 250-300oC. The digestion was completed in about 70- 85 min as indicated by the appearance of white fumes. The mixture was left to cool down and the contents of the tubes were transferred to 100 ml volumetric flasks and the volumes of the contents were made to 100 ml with distilled water. The wet digested solution was transferred to plastic bottles labelled accurately. The digest was used for metal determination by Atomic Absorption Spectrophotometer (AAS-700, Perkin-Elmer, USA) using acetylene/air as gas mixture.

Stock standard was prepared by dividing the molar mass of the compound of the element by the molar mass of the element. The standard solution prepared was used to calibrate Atomic Absorption Spectrophotometer (AAS). The prepared sample was aspirated into the AAS; the air, the fuel of the instrument (acetylene) and the sample, formed aerosol inside the AAS. About 10% of the aerosol goes into the flame and 90% passed out as waste. The flame vaporized, dissociated, and atomized the sample from ground state to excited state. The readings were taken from the equipment in mg/g and the results were converted to mg/kg which is the actual concentration of the metal in the sample using the equation (Aderinola et al., 2009):

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3.5 Statistical analysis

Two ways analysis of variance (ANOVA) was done for proximate composition and minerals content in fruits using Graph pad prism 7. Results were expressed as Mean of triplicate determination.

CHAPTER FOUR

4.0 RESULTS

4.1 Proximate composition of Selected fruits in Amuwo-Odofin

Proximate analysis results (Table 1) indicated that there was no significant difference in moisture content between stored fruits and ripe fruits at (p<0.05). Stored banana had 88.2% moisture, 5.30% carbohydrate, 6.52% protein, 2.25% fat, 12.52% ash and 13.58% fibre. Watermelon contained 63.39% moisture, 19.45% carbohydrate, 6.5% protein, 0.46% fat, 6.56% ash and 3.49% fibre. Pineapple contained 61.15% moisture, 15.64% carbohydrate, 3.09% protein, 0.46% fat, 10.84% ash and 8.91% fibre, Cucumber species contained 60.46% moisture, 14.41% carbohydrate, 2.08% protein, 2.52% fat, 11.05% ash, and 9.48% fibre Orange contained 75.40% moisture, 20.04% carbohydrate, 2.60% protein, traces of fat, 0.66% ash and 1.38% fibre.

Table 1: Proximate composition of selected fresh fruits (%) from Amuwo Odofin

Abbildung in dieser Leseprobe nicht enthalten

Values are % mean of triplicate determinations; ND= Not Detected.

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Figure 2: Effect of storage on fresh fruits at 22o for 78 hours in Amuwo odofin

4.2 Proximate composition of selected fruits in Eti - Osa

The proximate comparison of selected fruits in Eti-Osa are shown in (Table 2). There was an overall increase in the moisture content of watermelon (97.8%), Cucumber (96.9%), orange (94.1%), pineapple (92.7%) and banana (86.7%) stored in ordinary refrigerator and deep freezer storage in contrast to a lower content found in an open air. There was decrease in Ash content, protein contents and crude fibre in all selected fruits. However, there was no significant difference at (p>0.05).

Table 2: Proximate composition of selected fresh fruits (%) from Eti-Osa

Values are % mean of triplicate determinations; ND= Not Detected.

Abbildung in dieser Leseprobe nicht enthalten

Figure 3: Effect of storage on fresh fruits at 22o for 78 hours in Eti-Osa

4.3 Proximate composition of selected fruits in Lagos mainland

The proximate composition of selected fruits are presented in table 3. The protein content ranged from 11.6 % for ripe fruits to 0.28 % for stored fruits, while moisture contents for stored fruits had the highest 97.4 %, the ash content of the stored fruits ranged from 2.18 - 0.45 % shows significance difference at (P<0.05). Pineapple had the highest carbohydrate content (1.46%). Crude fibre for stored cucumber had the highest (2.69%), However, there was no significant difference at (P>0.05).

Table 3: Proximate composition of selected fresh fruits (%) from Eti-Osa

Abbildung in dieser Leseprobe nicht enthalten

Values are % mean of triplicate determinations; ND= Not Detected.

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Figure 4: Effect of storage on fresh fruits at 22o for 78 hours in Lagos mainland

4.4 Proximate composition of selected fruits in Surulere

Proximate composition of each fruit is shown in Table-4. The moisture content in all fruits was very high ranging 97.28% watermelon and 94% both ripe and stored in cucumber. After moisture the second major chemical constituent found was protein with a maximum content (11.45%) in banana and minimum content (0.98%) in watermelon. Crude fibre content was estimated 1.98% in ripe Orange and 0% in banana and cucumber, while Ash content showed high concentration 1.23% in ripe banana. Crude fat content observed was 3.40% in banana and 0.07% in watermelon. Carbohydrate content with maximum concentration 1.27% was determined in pineapple while minimum amount 0.38% was found in watermelon. There was no statistical difference at (P<0.05).

Table 4: Proximate composition of selected fresh fruits (%) from Surulere

Abbildung in dieser Leseprobe nicht enthalten

Values are % mean of triplicate determinations; ND= Not Dectected

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Figure 5: Effect of storage on fresh fruits at 22o for 78 hours in Surulere

4.5 Proximate composition of selected fruits in Victoria Island

Proximate composition of each fruit is shown in Table-5. The moisture content in all fruits was very high ranging 97.88% in stored watermelon and 94.11% in stored orange. After moisture the second major chemical constituent found was carbohydrate with a maximum content (1.45%) in stored pineapple and minimum content (0.42%) in watermelon. Crude protein content was estimated 0.21% in cucumber and 11.58% in banana, while pineapple showed second high concentration 4.23%. Crude fat content observed was 0.09% in cucumber and 3.92% in banana, there is significant difference at (P<0.05). The crude fiber content with maximum concentration 2.54% was determined in stored pineapple, while minimum amount 0.42% was found in stored orange. Ash contents were 1.99% in cucumber and 0.32% in stored watermelon. There was no significant difference at (P>0.05).

Table 5: Proximate composition of selected fresh fruits (%) from Victoria Island

Abbildung in dieser Leseprobe nicht enthalten

Values are % mean of triplicate determinations; ND= NOT Detected.

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Figure 6: Effect of storage on fresh fruits at 22o for 78 hours in Victoria Island

4.6 Nutritional compositions (%) of fruit species in Amuwo Odofin

The results obtained from the fruits samples collected selected Local government areas in Lagos State for Zinc (Zn), Iron (Fe), Calcium (Ca), Magnesium (Mg), Potassium (K) and Manganese (Mn) are shown in Table 6. The recommended limits for various heavy metals vary depending on the food being considered and the country. The recommended maximum limit of cadmium, chromium, lead and copper for vegetables by FAO/WHO (2001) was set as 11 mg/kg, 15 mg/kg, 1000 mg/kg, 350 mg/kg, 400 mg/kg and 500 mg/kg respectively. All the mineral levels were below permissible limits. The highest mean content of Zn (0.77 mg/kg) was estimated in banana and lowest was recorded in cucumber (0.21mg/kg). The highest concentration of Fe (4.52 mg/kg) was found in stored pineapple, while in cucumber it was lowest in concentration (0.26 mg/kg). Ca level was observed within each fruit specie sampled shows no significant difference at (p>0.05). The mean Ca levels in the fruit species varied between 27.93 and 6.23 mg/kg with the highest observed in orange and the lowest observed in watermelon. There was no significant difference (P>0.05) observed for Mg, K and Mn in each fruit specie sampled. However, the level of Mg ranged from 37.88 mg/kg, being the highest in banana to 11.78 mg/kg being the lowest in cucumber. Most importantly, K and Mn levels observed for all the fruit species were found within the WHO/FAO permissible limit of 400 mg/kg and 500 mg/kg.

Table 6: Nutritional compositions (mg/kg) of fruit species in Amuwo Odofin .

Abbildung in dieser Leseprobe nicht enthalten

Values are mg/kg mean of triplicate determinations; ND = Not Detected; * values greater than FAO/WHO permissible limit (mg/kg), Safe limit (WHO/FAO, 2001).

Abbildung in dieser Leseprobe nicht enthalten

Figure 7: Effect of storage on nutritional value of selected fruits

4.7 Nutritional compositions (%) of fruit species in Eti-Osa

The results obtained from the fruits samples collected selected Local government areas in Lagos State for Zinc (Zn), Iron (Fe), Calcium (Ca), Magnesium (Mg), Potassium (K) and Manganese (Mn) are shown in Table 7. The recommended limits for various heavy metals vary depending on the food being considered and the country. The recommended maximum limit of cadmium, chromium, lead and copper for vegetables by FAO/WHO (2001) was set as 11 mg/kg, 15 mg/kg, 1000 mg/kg, 350 mg/kg, 400 mg/kg and 500 mg/kg respectively. All the mineral levels were below permissible limits. The highest mean content of Zn (0.77 mg/kg) was estimated in banana and lowest was recorded in pineapple (0.18mg/kg). The highest concentration of Fe (4.52 mg/kg) was found in stored pineapple, while in cucumber it was lowest in concentration (0.29 mg/kg). Ca level was observed within each fruit specie sampled shows no significant difference at (p>0.05). The mean Ca levels in the fruit species varied between 27.95 and 6.25 mg/kg with the highest observed in orange and the lowest observed in watermelon. There was no significant difference (P>0.05) observed for Mg, K and Mn in each fruit specie sampled. However, the level of Mg ranged from 37.78 mg/kg, being the highest in banana to 11.77 mg/kg being the lowest in cucumber. Most importantly, K and Mn levels observed for all the fruit species were found within the WHO/FAO permissible limit of 400 mg/kg and 500 mg/kg.

Table 7: Nutritional compositions (mg/kg) of fruit species in Eti-Osa .

Abbildung in dieser Leseprobe nicht enthalten

Values are mg/kg mean of triplicate determinations; ND = Not Detected; * values greater than FAO/WHO permissible limit (mg/kg), Safe limit (WHO/FAO, 2001).

Abbildung in dieser Leseprobe nicht enthalten

Figure 8: Effect of storage on nutritional value of selected fruits.

4.8 Nutritional compositions (%) of fruit species in Lagos mainland

The results obtained from the fruits samples collected selected Local government areas in Lagos State for Zinc (Zn), Iron (Fe), Calcium (Ca), Magnesium (Mg), Potassium (K) and Manganese (Mn) are shown in Table 8. The recommended limits for various heavy metals vary depending on the food being considered and the country. The recommended maximum limit of cadmium, chromium, lead and copper for vegetables by FAO/WHO (2001) was set as 11 mg/kg, 15 mg/kg, 1000 mg/kg, 350 mg/kg, 400 mg/kg and 500 mg/kg respectively. All the mineral levels were below permissible limits. The highest mean content of Zn (0.76 mg/kg) was estimated in banana and lowest was recorded in cucumber (0.18mg/kg). The highest concentration of Fe (4.52 mg/kg) was found in stored pineapple, while in cucumber it was lowest in concentration (0.26 mg/kg). Ca level was observed within each fruit specie sampled shows no significant difference at (p>0.05). The mean Ca levels in the fruit species varied between 27.93 and 6.15 mg/kg with the highest observed in orange and the lowest observed in watermelon. There was no significant difference (P>0.05) observed for Mg, K and Mn in each fruit specie sampled. However, the level of Mg ranged from 37.77 mg/kg, being the highest in banana to 11.78 mg/kg being the lowest in cucumber. Most importantly, K and Mn levels observed for all the fruit species were found within the WHO/FAO permissible limit of 400 mg/kg and 500 mg/kg.

Table 8: Nutritional compositions (mg/kg) of fruit species in Lagos mainland .

Abbildung in dieser Leseprobe nicht enthalten

Values are mg/kg mean of triplicate determinations; ND = Not Detected; * values greater than FAO/WHO permissible limit (mg/kg), Safe limit (WHO/FAO, 2001).

Abbildung in dieser Leseprobe nicht enthalten

Figure 8: Effect of storage on nutritional value of selected fruits.

4.9 Nutritional compositions (%) of fruit species in Surulere

The results obtained from the fruits samples collected selected Local government areas in Lagos State for Zinc (Zn), Iron (Fe), Calcium (Ca), Magnesium (Mg), Potassium (K) and Manganese (Mn) are shown in Table 9. The recommended limits for various heavy metals vary depending on the food being considered and the country. The recommended maximum limit of cadmium, chromium, lead and copper for vegetables by FAO/WHO (2001) was set as 11 mg/kg, 15 mg/kg, 1000 mg/kg, 350 mg/kg, 400 mg/kg and 500 mg/kg respectively. All the mineral levels were below permissible limits. The highest mean content of Zn (0.77 mg/kg) was estimated in banana and lowest was recorded in cucumber (0.21mg/kg). The highest concentration of Fe (4.52 mg/kg) was found in stored pineapple, while in cucumber it was lowest in concentration (0.26 mg/kg). Ca level was observed within each fruit specie sampled shows no significant difference at (p>0.05). The mean Ca levels in the fruit species varied between 27.95 and 6.33 mg/kg with the highest observed in orange and the lowest observed in water melon. There was no significant difference (P>0.05) observed for Mg, K and Mn in each fruit specie sampled. However, the level of Mg ranged from 37.80 mg/kg, being the highest in banana to 11.77 mg/kg being the lowest in cucumber. Most importantly, K and Mn levels observed for all the fruit species were found within the WHO/FAO permissible limit of 400 mg/kg and 500 mg/kg.

Table 9: Nutritional compositions (mg/kg) of fruit species in Surulere.

Abbildung in dieser Leseprobe nicht enthalten

Values are mg/kg mean of triplicate determinations; ND = Not Detected; * values greater than FAO/WHO permissible limit (mg/kg), Safe limit (WHO/FAO, 2001).

Abbildung in dieser Leseprobe nicht enthalten

Figure 9: Effect of storage on nutritional value of selected fruits.

CHAPTER FIVE

5.0 DISCUSSION AND CONCLUSION

5.1 Proximate composition of fresh fruits

The high moisture content for Citrullus lanatus (cucumber) 97% above in all sampled locations, was not a surprise. Fruits are known to contain higher moisture relative to different samples (Chassagne-Berces et al., 2010). Location, maturity and seasonal variation affect moisture content of plants and their products (Bortey-Sam et al., 2015). The low moisture for fresh fruits might be attributed to seasonality. This is because Ananus cosmosus (pineapple) that had high moisture thrives during rainy season and other fruits thrive during dry season.

The carbohydrate levels of the fruits ranged from 1.20 - 1.47% in Ananus cosmosus to 0.38­0.67% in Citrullus lanatus in all the sampling locations. The carbohydrate level is low compared to carbohydrate level of 11.20% in pineapple (Pumploma-Roger, 2006). This indicates that the fruits can act as deficient food supplement in providing carbohydrate than commonly consumed fruits.

The relatively high protein content of Musa paradisiaca (16.22%) might be attributed to their high moisture content. It is known that the high the moisture content of a given food the lower is the protein. Deshpande et al. (2013) reported that moisture affects nutrient content of fruits. Citrullus lanatus is a rainy season fruit that contains high moisture and low protein (90>% and 0.88%) respectively.

Generally, all the fruits are low in protein, because they contain much more moisture and less protein when they are stored in deep freezer.

The low fat for Water melon (0.07%), Cucumber (0.20%), Orange (0.24%) and pineapple (0.14%) is expected. Fruits contain less than 0.50% fat. The low fat content of the fruits studied in the present work is comparable to the observations of many researchers (Doherty et al., 2012), who reported that fruits are not good sources of fat.

The high ash for Banana (3.09%) is an indicative of high minerals. This observation appeared to suggest that fresh banana is a better source of mineral than cucumber, water melon and orange (0%, 0.40%, and 0.66%) respectively. It is a known fact that foods that have high ash invariably would have higher mineral composition.

The high fibre for pineapple (15%) above in all locations was not a surprise. Fruits contain high fibre whether fresh or juicy. The highest moisture for water melon (90%) above precipitated its least fibre value (0.9%) above in all the locations. The high fibre for the fruits observed in this present work related to those of commonly consumed fruits, example, guava demonstrated their superiority as source of fibre (Pumploma-Roger, 2006). The differences in fibre content among the stored fruits might be associated with differences in moisture and varietal differences. On the other hand, the low fibre for all the stored fruits was not a surprised. It has been reported that freezing of fruits for longer period is associated with the low fibre degradation in fruits, whereas freezing led to loss of fibre due to freeze cracking (Chassagne-Berces et al., 2010)

5.2 Minerals concentration in fruits

Different fruits may accumulate different minerals, and the absorption ability varies in different biological species due to their diverse physiological character (Adedokun et al., 2016). The concentrations of Zn in the fruits from the selected local government areas, ranged between 0.77 mg/kg in Banana from Amuwo Odofin and Eti-Osa, Zn had 0.77 mg/kg in also banana from Lagos mainland Zn had 0.76 mg/kg in Banana . Differing values have been previously reported in fruits which include 0.916 mg/kg for cucumber by Sobukola et al. (2010) and 0.049 mg/kg by Muhammad et al. (2008) for lettuce. The concentration of Zn in this study is below the permissible levels by FAO/WHO (2001) in fruits (1.5 mg/kg). Reduction in zinc content in storage fruits is as a result of increased in their susceptibility to oxidative damage and impairs function. This is similar to levels reported by Akubugwo et al. (2007) in Amaranthus hybridus. Adedokun et al. (2016) also made similar observation in a study of fruit and vegetables obtained in some selected markets in Lagos, Nigeria.

In this study, the concentrations of Fe are generally within the permissible levels by FAO/WHO in fruits of 1.5 mg/kg in all sampled locations. The low levels of Iron in some fruits may probably be attributed to temperature at which the fruits are stored (FDA, 2001). Iron has the longest and best described history among all the micronutrients. It is a key element in the metabolism of almost all living organisms. In humans, iron is an essential component of hundreds of proteins and enzymes (Garcia-Rico et al., 2007)

Calcuim (Ca) is an essential mineral that plays catalytic, structural and regulatory roles as an integral part of many enzymes in human body. It is essential for normal growth, strong bone, mental ability, immune system, reproduction and healthy function of the heart (Deshpande et al., 2013). The level of Ca in the fruits from sampled areas ranged between 27 mg/kg and 6 mg/kg with the highest recorded in orange and the least in water melon in all selected LGAs. The concentration of Ca in this study is below the permissible levels by FAO/WHO (2001) in fruits (1000 mg/kg). A low level of calcium may contributes to poor mineralization of bones, soft bones and in children, rickets and impaired growth (Kumar et al., 2007).

Manganese (Mn) plays an important role in a number of physiological processes as a constituent of some enzymes and an activator of other enzymes (Khan et al., 2009). Mn plays an important role in the structure of proteins and catalytic activity for the antioxidant enzyme like superoxide dismutase (SOD). Loss of zinc from biological membranes of edible fruits increases their susceptibility to oxidative damage and impairs function (Khan et al., 2008). According to Linus Pauling Institute, the adequate daily intake for manganese is 2.3mg per day in adult. However, Mn deficiency may lead to skeletal defects such as enlarged joints, curved spin and shorter and thicker limbs (Jolly et al., 2013). Mn can also have a neurotoxic effect when consumed in large amounts.

Magnesium plays important role in the structure and the function of the human body. The adult human body contains about 25 grams of magnesium. Over 60% of all the magnesium in the body is found in the skeleton, about 27% is found in muscle, while 6 to 7% is found in other cells, and less than 1% is found outside of cells (Mensah et al., 2008). Maximum concentration of micro minerals Fe, Mg, Zn, Ca, K and Mn (1.5, 37, 0.77, 336, and 46) mg/kg was observed in orange, and banana respectively. While minimum concentration of Fe, Mg, Zn, Ca, K and Mn (0.2, 11, 19, 6.0, 119 and 8.9) mg/kg was observed in Cucumber, pineapple, Orange and water melon, respectively.

Potassium (K) content was high as compare to other minerals. Banana showed maximum concentration of 300 mg/ kg above in all sampled locations, while its minimum concentration 119 mg/ mg/kg was found in orange. Mn was the Second abundant mineral found in most fruits. Its maximum concentration 46 mg/kg was observed in banana. The concentration of K in this study is below the permissible levels by FAO/WHO (2001) in fruits (400 mg/kg).

Magnesium was also found in appreciable amount, maximum amount was found in banana and orange 37 mg/kg while minimum amount was found in the cucumber 11 mg/kg. Because of the reciprocal effects of Mg and K authorities have argued that a diet high in potassium and low in Mg (low urinary Mg and K ratio) favours lower blood pressure. Increase in dietary potassium as the chloride salt has shown to decrease blood pressure in some hypertensive individuals (Kim et al., 2004).

It is also possible that a low Mg and high K diet would decrease the development of cardio vascular disease (Mensah et al., 2008). The Mg requirement from fruits source is not much important because of its availability as NaCl salt. Deficiency of calcium, potassium and magnesium leads to the classic bone symptoms associated with rickets, such as bowlegs, knock knees, curvature of the spine and pelvic and thoracic deformities (Kim et al., 2004).

5.3 Conclusion

Inthis present study, five fruit species contained considerable nutritional value that may meet body needs. Additionally, there was no significant difference in minerals content of the fruits in all the sampled sites (locations) of the study. The study posits that all the fruit species had the minerals within world health organization (WHO) permissible limit. Thus it can be concluded that nutrients found in all the selected fruits are in variable concentrations. Therefore their consumption in different combinations is recommended for normal body function and healthy life.

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Details

Title
Effects of storage on nutrient and proximate composition of fruits
Course
Cell Biology and Genetics
Grade
5.0
Author
Year
2018
Pages
56
Catalog Number
V508369
ISBN (Book)
9783346109798
Language
English
Tags
effects
Quote paper
Kehinde Sowunmi (Author), 2018, Effects of storage on nutrient and proximate composition of fruits, Munich, GRIN Verlag, https://www.grin.com/document/508369

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