CHAPTER ONE

INTRODUCTION

The worsening food crisis and the consequent widespread prevalence of malnutrition in developing and under-developed countries have resulted in high mortality and morbidity rates, especially among infants and children in low-income groups (Enujiugba and Akanbi, 2005). Food has been defined as any substance containing primarily carbohydrates, fats, water, protein, vitamins and minerals that can be taken by an animal or human to meet its nutritional needs and sometimes for pleasure. Items considered as food may be sourced from plants, animals or fungus as well as fermented products like alcohol. Food is also anything solid or liquid that has a chemical composition which enables it provide the body with the material from which it can produce heat or any form of energy, provide material to allow for growth, maintenance, repair or reproduction to proceed and supply substances, which normally regulate the production of energy or the process of growth, repair or reproduction. Food is therefore, the most basic necessity of life (Turner, 2006).

Nutrition is the science that deals with all the various factors of which food is composed and the way in which proper nourishment is brought about. The average nutritional requirements of groups of people are fixed and depend on such measurable characteristics as age, sex, height, weight, degree of activity and rate of growth. Good nutrition requires a satisfactory diet which is capable of supporting the individual consuming it, in a state of good health by providing the desired nutrients in required amounts. It must provide the right amount of nutrients and fuel to execute normal physical activity. If the total amount of nutrients provided in the diet is insufficient, a state of under- nutrition develops.

Plants are primary sources of medicines, food, shelters and other items used by humans everyday. Their roots, stems, leaves, flowers, fruits and seeds provide for humans (Amaechi, 2009; Hemingsway, 2004). Fruits are sources of minerals, fibre and vitamins which also provide essential nutrients for the human health (Anaka et al., 2009). Some fruits are also known to have antinutritional factors such as phytate and tannins,that can diminish the nutrient bioavailability if they are present at high concentrations (Baum, 2007). It has been reported that these anti-nutritional factors could also help in the treatment and prevention of certain

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important diseases like the anti-carcinogenic activities reported for phytic acid which has been demonstrated both invivo and invitro (Anaka et al., 2009).

The reliance on starchy roots and tubers and certain cereals as main staples result in consumption of non-nutritious foods. The insufficient availability of nutrient rich diets and the high cost of available ones have prompted an intense research into harnessing the potentials of the lesser known and underutilized crops, which are potentially valuable for human and animal foods to maintain a balance between population and agricultural productivity, particularly in the tropical and sub-tropical areas of the world. The challenge of improper nutrition especially in developing countries which include Nigeria, is indeed alarming. The World Health Organization (WHO, 2007) reported that poor nutrition contributes to one out of two deaths associated with infectious diseases among children within five yearsand the aged. Poor diet can have an injurious impact on health, causing deficiency diseases such as scurvy, beriberi and kwashiokor, health-threatening conditions such as obesity, metabolic syndrome, and such common other diseases as cardiovascular diseases, diabetes and osteoporosis. Under-nutrition among pregnant women in developing countries leads to one out of six infants being born with low birth weight, which is a risk factor for neonatal deaths, learning disabilities, mental retardation, poor health and premature death. One out of three people in developing countries is affected by vitamin and mineral deficiencies making them prone to infectious diseases and impaired psycho intellectual development. Under and chronic nutrition problems and diet related chronic diseases account for more than half of the worldÕs diseases (WHO, 2007). In most of these side effects or diseases, the biochemical and haematological parameters are usually altered. For a food to be considered safe for human and animal consumption, its effect on these parameters need to be investigated to understand the nutritional potentials and safety of such foods with a view to determining their acceptability.

1.1 Sweeteners

Sweeteners are food additives that are used to improve the taste of everyday foods. Natural sweeteners are sweet-tasting compounds with some nutritional value; the major ingredient of natural sweeteners is either mono- or disaccharides. Artificial sweeteners, on the other hand, are compounds that have very little or no nutritional value. This is possible because artificial sweeteners are synthesized compounds that have high-intensities of sweetness, meaning less of

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the compound is necessary to achieve the same amount of sweetness. Artificial sweeteners are used in products intended to limit caloric intake or prevent dental cavities. Sugar alcohols are natural compounds with varying degrees of sweetness which are often added to boost or fine tune flavours of products while increasing their sweetness. They are often used in conjuncture with natural or artificial sweeteners in order to achieve a desired degree of sweetness, taste or texture. Sugar alcohols typically provide some amount of nutrition but have other benefits such as not affecting insulin response or promoting tooth decay which makes them a popular sweetening choice.

1.1.1 Common Sweeteners and Their Production

A sugar substitute is a food additive that replicates the effect of sugar in taste, but usually has less food energy. Some sugar substitutes are natural while others are synthetic, those that are not natural are referred to as artificial sweeteners (Mattes and Popkin, 2009). An important class of sugar substitutes is known as high-intensity sweeteners. These are compounds with sweetness that is many times that of sucrose, a common table sugar. As a result, much less sweetener is required, and energy contribution often negligible. The sensation of sweetness caused by these compounds is sometimes notably different from sucrose, so they are often used in complex mixtures that achieve the most natural sweet sensation. This may be seen in soft drinks labelled as “diet” or “light”; they contain artificial sweeteners and often have notably different mouth feel. In the United States, six intensely-sweet sugar substitutes have been approved for use (Mattes and Popkin, 2009). They are saccharin, aspartame, sucralose, neotame, acesulfame potassium, and stevia. The US Food and Drug Administration regulates artificial sweeteners as food additives. The majority of sugar substitutes approved for food use are artificially-synthesized compounds. However, some bulk natural sugar substitutes are known, including sorbitol and xylitol, which are found in berries, fruit, vegetables and mushrooms (Mattes and Popkin, 2009). Some non-sugar sweeteners are polyols, also known as “sugar alcohols.” These are, in general, less sweet than sucrose, but have similar bulk properties and can be used in a wide range of food products. Sometimes the sweetness profile is ‘fine-tuned’ by mixing high-intensity sweeteners. As with all food products, the development of a formulation to replace sucrose is a complex proprietary process.

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1.1.1.2 Natural Sweeteners

Natural sweeteners are extracted from natural products without any chemical modifications during the production or extraction process. Some of these sweeteners have been in use for decades while other for centuries. Natural sweeteners are well known and their production processes have been perfected over time making their cost low and leaving their demand high.

1.1.1.2.1 Honey

Honey is a sweet food made by certain insects using nectar from flowers. The variety produced by honey bees is the one most commonly referred to and is the type of honey collected by beekeepers and consumed by humans. Honey produced by other bees and insects has distinctly different properties. Honey bees transform nectar into honey by a process of regurgitation and evaporation. They store it as a food source in wax honeycombs inside the beehive (National Honey Board, 2012). Beekeeping practices encourage overproduction of honey so that the excess can be taken without endangering the bee colony. Honey gets its sweetness from the monosaccharides fructose and glucose and has approximately the same relative sweetness as that of granulated sugar (74% of the sweetness of sucrose, a disaccharide) (NHB, 2012). It has attractive chemical properties for baking, and a distinctive flavour which leads some people to prefer it over sugar and other sweeteners. Most micro-organisms do not grow in honey because of its low water activity (Arcot and Brand-Miller, 2005). The main uses of honey are in cooking, baking, as a spread on breads, and as an addition to various beverages such as tea and as a sweetener in some commercial beverages. Honey is also used as an adjunct in beer. Its glycaemic index ranges from 31 to 78, depending on the variety (Arcot and Brand-Miller, 2005).

Honey is a mixture of sugars and other compounds. With respect to carbohydrates, honey is mainly fructose (about 38.2%) and glucose (about 31.0%).The remaining carbohydrates in honey include maltose, sucrose, and other complex carbohydrates (Martos et al., 2000). Honey contains trace amounts of several vitamins and minerals (Gheldof et al., 2002). As with all nutritive sweeteners, honey is mostly sugars and is not a significant source of vitamins or minerals. Honey also contains tiny amounts of several compounds thought to function as antioxidants, including chrysin, pinobanksin, vitamin C, catalase, and pinocembrin (Gheldof et

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al., 2002). The specific composition of any batch of honey depends on the flowers available to the bees that produce the honey. A typical honey analysis shows the following: fructose: 38.2%, glucose: 31.0%, sucrose: 1.5%, maltose: 7.2%, water: 17.1%, higher sugars: 1.5%, ash: 0.2%. Honey has a density of about 1.36 kg/L (36% denser than water) (NHB, 2012). The pH of honey is between 3.2 and 4.5. This relatively acidic pH level prevents the growth of many bacteria (Arcot and Brand-Miller, 2005).

1.1.1.2.2 Maple Syrup

Maple syrup is a sweetener made from the sap of some maple trees. In cold climate areas, these trees store sugar in their roots before the winter and the sap which rises in the spring can be tapped and concentrated (Ball, 2007). The sap has only 3 to 5% total solids, consisting mainly of sucrose. Other components of the maple syrup include organic acids (primarily malic acid) and minerals (potassium and calcium), amino compounds (trace) and vitamins (trace). Maple Syrup has about the same 50 cal/tbsp as white cane sugar. However, it also contains significant amounts of potassium (35 mg/tbsp), calcium (21 mg/tbsp), small amounts of iron and phosphorus, and trace amounts of ?- complex vitamins. Its sodium content is as low as 2 mg/tbsp. The sugar content of sap averages 2.5% and the sugar content of syrup averages 66.5% (Ball, 2007).

1.1.1.2.3 Molasses

Molasses is a viscous byproduct of sugar cane or sugar beets processing into sugar. The quality of molasses depends on the maturity of the sugar cane or sugar beet, the amount of sugar extracted, and the method of extraction exployed (Taubes, 2011). Molasses has the molecular formula C6H12NNaO3S, molecular weight of 201.22 g/mol, and a density of 1.41 g/cm3 (Taubes, 2011). A typical composition of molasses shows the following substances: sucrose 35.9 %, fructose 5.6 %, nitrogen 1.01 %, reducing substances 11.5 %, glucose 2.6 %, and sulfur 0.78 % (Taubes, 2011).

1.1.1.2.4 Stevia

Stevia is one of the newest sweeteners available in the market. It has been known since 1899 for its sweet taste and has been cultivated in Japan since 1970. It was not until recently that

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a safe and successful extraction of glycosides (the chemical in the Stevia plant which gives it a sweet taste) allowed for the Food and Drug Administration (FDA) to approve Stevia as a general sweetener (Raji and Mohamed, 2012). Stevia is also known under different trade names as

TruViaand PureVia patents by Coca Cola and Pepsi(Raji and Mohamed, 2012). Many different forms of Stevia as sweeteners exist such as: Reb A, B, C, D, Rebiana, Stevioside,

SunCrystalsand Enliten. Each has a small variation in the manufacturing process or how it is used.

Stevia is an all natural sweetener because it is extracted from the Stevia plant and undergoes no chemical changes in the manufacturing process. This makes it very desirable to many consumers looking for healthy alternatives to sucrose sugar. Stevia is a general term referring to a plant, Steviarebaudiana (Bertoni), native to Paraguay. The plant contains a number of diterpene glycosides that taste sweet; the main ones are stevioside and rebaudioside A. These glycosides are 200 and 300 times sweeter than sucrose respectively (Mattes and Popkin, 2009).

1.1.1.2.5 Sucrose

Sucrose is a disaccharide, formed from the monosaccharides glucose and fructose. It is the organic compound commonly known as table sugar and sometimes called saccharose.It has the molecular formula C12H22O11 and a molecular weight of 342.30 g/mol. In sucrose, the component sugars glucose and fructose are linked via an ? (alpha) 1 on the glucose, to a ? (beta) 2 on the fructose glycosidic linkage.

Sucrose forms a major element in confectionery and desserts. Cooks use it for sweetening, its fructose component which has almost double the sweetness of glucose makes sucrose distinctively sweet in comparison to other carbohydrate foods (Taubes, 2011). It can also act as a food preservative when used in sufficient concentrations. It is a common ingredient in many processed and junk foods.

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Fig 1: Structure of sucrose (Stryer, 1995)

1.1.1.3 Artificial Sweeteners

Table 1: Uses for common artificial sweeteners
Chemical Trade Names Sweetness Uses
Name
Acesulfame Sweet One¨ 200 times Found in more than 4,000 productsincluding
Sunett¨ sweeter than candies, tabletop sweeteners, chewing gums,
sugar beverages, dessert and dairyproduct mixes,
baked goods,alcoholic beverages, syrups,
refrigerated and frozen desserts,and sweet
sauces and toppings.

Aspartame Equal¨ 180 times Found in more than 6,000 productsincluding
NutraSweet¨ sweeter than carbonated powderedsoft drinks, chewing gum,
NatraTaste¨ sugar confections, gelatins, dessertmixes, puddings
and fillings, frozendesserts, yoghurt, tabletop
sweeteners, and somepharmaceuticals.

Neotame None yet 8,000-13,000 Approved for use in beveragesdairy products,
times sweeter frozen desserts,baked goods, and gums.
than sugar

Saccharin Sweet N Low¨ 300-700times Fountain Diet Coke¨ and pepsi¨,Tab¨, and
sweeter than often mixed withaspartame.
sugar

Sucralose Splenda¨ 600 times Found in everything from frozendesserts,
sweeter than cookies, gum, sodas,candies. Can also be used
sugar forbaking.

Source:(http://www.jigsawhealth.com/resources/artificial-sweetner).Retrieved 5/14/2013 5:03pm

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Artificial sweeteners are derived from chemical synthesis of organic compounds which may or may not be found in nature. They are relatively new and their uses are being researched and extended every day. Much controversy surrounds artificial sweeteners and their health effects as they may break down into harmful chemical sub-compounds. New artificial sweeteners are always being researched and due to their low cost and ease of production, they will likely become the primary sweetening compounds in the future (Mattes and Popkin, 2009).

1.2 Synsepalum dulcificum

Synsepalum dulcificumis a shrub that grows up to 6.1m high in its native habitat but does

not usually grow higher than 10ft (3.048m) in cultivation (Wiersema and Leon, 1999).Its leaves are 5-10cm long, 2-3.7cm wide and glabrous below. They are clustered at the end of the branchlets. It is an evergreen plant that produces small orange fruits (Duke and Ducellier, 1993). The seeds are about the same size as coffee beans (fig. 2). The plant is also known as

Richardelladulcificum (old name), miracle fruit, magic fruit, miraculous or flavor fruit (Duke and Ducellier,1993). The miracle fruit plant (Synsepalum dulcificum) produces fruits or berries that, when eaten, causes sour foods (including lime and lemon) consumed later to taste sweet (fig. 3) (Joseph et al., 2009). The fruit was first documented by explorer Chevalier des Marchais who searched for many different foods during a 1725 excursion to its native West Africa (Roecklin and Leung, 1987). Marchais noticed that local tribes picked the fruit from shrubs and chewed it before meals.

The berry contains an active glycoprotein molecule, with some trailing carbohydrate chain called miraculin (Forester and Waterhouse, 2009). When the fleshy part of the fruit is eaten, the molecule binds to the tongueÕs taste buds, causing sour foods to taste sweet. While the exact cause of this change is unknown, one theory is that the glycoprotein, miraculin works by distorting the shape of sweetness receptors so that they become responsive to acids, instead of sugar and other sweet things (Duke and Ducellier,1993).This effect can last for 10min-2hr (Joseph et al.,2009).

In Africa, S. dulcificum leaves are attacked by lepidopterous larvae and fruits are infested with larvae of fruit flies. A fungus which has been found on this plant is microporous (Duke and Ducellier, 1993). In tropical West Africa where this specie originates, the fruit pulp is used to sweeten palmwine (Joseph et al., 2009). Attempts have been made to make a commercial

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sweetener from this fruit with an idea of developing this for patients with diabetes (Joseph et al., 2009). Fruit cultivators also report a small demand from cancer patients, because the fruit allegedly counteracts a metallic taste in the mouth that may be one of the many side effects of chemotherapy. This claim has not been researched scientifically. In Japan, miracle fruit is popular among patients with diabetes and dieters (Duke and Ducellier, 1993).

The detailed scientific classification of the plant is as follows:

Kingdom: Plantae

Superdivision: Angiosperms

Division: Eudicots

Class: Asterids

Order: Ericales

Family: Sapotaceae

Genus: Synsepalum

Species: S.dulcificum

Binomial name: Synsepalumdulcificum

(Source: Wiersema and Leon, 1999)

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Fig. 2: Synsepalum dulcificum fruit (taken at source)

Fig. 3: Synsepalum dulcificum tree (taken at source)

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1.3 Nutrients

A nutrient is any substance that is assimilated by an organism to promote growth (Harper,

1999). Nutrients consist of various chemical substances in the foods that make up each diet. Many nutrients are essential for life and an adequate amount of the nutrients in the diet is necessary for providing energy, building and maintaining of the body organs and for various metabolic processes (Morrison and Mark, 1999). There are six major classes of nutrients found in the food: carbohydrate, protein, fats, vitamins (both fat soluble and water soluble), mineral and water.