COMPARATIVE STUDY ON NUTRITIONAL COMPOSITION OF SOME BRANDS OF POPCORN COMMERCIALLY AVAILABLE IN ENUGU STATE NIGERIA

ABSTRACT

This study was therefore designed to determine and compare the nutritional contents of some commonly  consumed  brands  of popcorn  snacks  in unprocessed  (uncooked)  form  of  the cereal.  Processed  popcorn  samples  were  procured  from  vendors  at  a  movie  theatre,  an amusement park and markets in Enugu and Nsukka. The samples were grouped as follows: Sample A was sweetened popcorn obtained from an amusement park in Enugu. Sample B was salted popcorn obtained from a movie theatre in Enugu. Sample C was salted popcorn obtained from a vendor in Nsukka main market. Sample D was sweetened popcorn obtained from a vendor in Nsukka main market. Sample E was sweetened popcorn obtained from a vendor in Nsukka main market.  Sample F was unpopped  (unprocessed)  popcorn obtained from a vendor in Nsukka main market. All the samples were then pulverized using a grinder and  later  digested  with  aqua  regia  (Conc.  HNO3   and  HCl  at  ratio  of  1:3  v/v).  The concentrations  of  sodium,  chloride,  potassium  and  magnesium  ions,  calorie  and  fiber contents,  fructose, glucose and iodine contents were determined by classical methods. The

results  showed  that the mean sodium  ion (Na+) concentration  in salted  popcorn  samples (samples B and C) were significantly (p < 0.05) higher when compared to the unprocessed sample (sample F). However, the sweetened popcorn samples (A, D and E) showed a non- significantly (p > 0.05) lower sodium ion (Na+) content when compared to the unprocessed sample. There was a non-significantly (p > 0.05) higher chloride ion (Cl-) concentration in salted popcorn samples (B and C) as well as in sweetened popcorn samples when compared to the unprocessed sample. Similarly, the mean chloride ion (Cl-) content of sample E was non-significantly   (p   >   0.05)   lower   than   the   unprocessed   sample.   Also,   the   mean concentrations  of  potassium  ion  (K+)  contents  of  samples  A,  B,  D,  and  E  were  non- significantly  (p  >  0.05)  higher  when  compared  to  the  unprocessed  sample.  The  mean magnesium  ion (Mg2+) content  of sample D was significantly  (p < 0.05) higher  than  in samples C and E. However,  a non-significantly  (p > 0.05) lower magnesium  ion (Mg2+) contents were observed in samples A, B, C and E when compared to  sample F. The mean fibre content  in all the  processed  popcorn  samples  were  significantly  (p  <  0.05)  higher compared to that of unprocessed sample. The mean fructose and glucose concentrations were significantly  (p  <  0.05)  higher  in  all  the  processed  samples  when  compared  to  that  of unprocessed sample. Similarly, the mean calorific values of all processed popcorn samples were significantly (p < 0.05) higher than that of unprocessed sample. It is therefore advised that the use of additives in processing of popcorn and the quantity to be consumed per time should be considered with caution.

CHAPTER ONE

INTRODUCTION

Popcorn is a popular snack consumed in Nigeria and indeed all over the world. It is made from a variety of corn known as Zea mays everta. It is a special type of flint maize which explodes when  exposed  to  heat  treatment  and  produces  flakes  (Jele  et  al.,  2014).  Popping  is  a simultaneous starch gelatinization and expansion process during which grains are exposed to high temperatures for a short time (Mishra et al., 2014). During popping, super heated vapour produced inside the grains by heat, cooks the grain and expands the endosperm, breaking out the outer skin.

Puffing is similar to the above process but differ from popping due to the fact that controlled expansion of kernel is carried out during puffing, while the vapour pressure escapes through the micropores of the grain structure due to high pressure or thermal gradient (Maisont and Narkrugsa, 2010).   Popping and puffing imparts acceptable taste and desirable aroma to the snack (Whitney and Rolfes, 2013).  During popping and preparation of the snack, salt and/or sugar is added to produce salted or sweetened popcorn (Hoseney et al., 2013). Table salt (NaCl) is usually added and as such consumption of salted popcorn increases the average Na+  and Cl- intake, if not compensated. Sodium is a very important cation found in the extracellular fluid which plays a central role in the maintenance of the normal distribution of water and osmotic pressure in the various body fluids (Tiez, 1995). Low serum sodium level (hyponatraemia) is found in a variety of   medical conditions including polyuria, metabolic acidosis, Addison’s disease, diarrhea and renal tubular disease whereas increased serum sodium level is found in hyperadrenalism, severe dehydration and diabetic coma after insulin therapy (Henry, 1994). Low

serum chloride values are found with extensive burns, excessive vomiting, intestinal obstruction, nephritis, and metabolic acidosis. Chloride ion (Cl-) is important in the maintenance of cation/anion balance between intra- and extra-cellular fluids. Elevated levels may be seen in dehydration,  hyperventilation, prostatic  or  other  types of urinary obstruction.    Table  sugar (sucrose) is commonly used in the sweetening of popcorn (Aletor and Ojelabi, 2007). Sucrose is a  disaccharide of glucose and fructose (Nelson and Cox, 2005) and as such is metabolized to yield fructose and glucose. Other sweeteners such as sugar alcohols may also be added during this cereal-processing, to improve taste and marketability. This work is designed to determine

and compare the nutritional composition of some commonly consumed brands of popcorn snacks relative to the unprocessed form of the cereal.

1.1 Popcorn Plant Profile

Popcorn, like all types of corn, is a cereal grain and originates from a wild grass (Iken, 1991). Its scientific name is Zea mays everta (Fig. 1), and it is so named because this type of corn actually

pops.

Fig. 1: The popcorn plant

Like other cereals, popcorn kernels consist of three main parts (Fig. 2): the pericarp (the hull or outer covering), the germ (the part that sprouts), and the endosperm; the starch that expands (Ertas et al., 2009).   Popcorn acts the way it does because of the special construction of the pericarp and the microscopic structure of the endosperm.

Fig. 2: The popcorn kernel

i.   The Pericarp

This is the outer covering that protects the kernel.  It resists entry of water and water vapour, and is undesirable to  insects and  microorganisms (Karababa, 2006). Popcorn has a  very strong pericarp.

ii.  The Germ

This is the part that sprouts during germination of the kernel. It is the only living part of the kernel and contains essential genetic information, enzymes, vitamins and minerals, necessary for the kernel to grow into a corn plant (Ziegler, 2001). About 25%of the germ is corn oil (Singh et al., 1997). Corn oil is a very valuable part of the corn kernel. It is high in linoleic acid (a polyunsaturated fatty acid) and has a mild taste (Allred-Coyle et al., 2000).

iii. Tip Cap

The tip carp is the only area of the kernel not covered by the pericarp. It is the attachment point of the kernel to the cob. The pericarp and the tip cap make up the bran (Ertas et al., 2009).

iv. Endosperm

The endosperm constitutes about 82% of the kernels dry weight and is the source of energy (starch) and protein for the germinating seed (Viana, 2009). There are two types of endosperm: soft and hard. In the hard endosperm, starch is packed tightly together but loosely packed in the soft endosperm (Fig 3). When yellow dent corn dries in the field before harvesting, the moisture loss causes the soft endosperm to collapse and form a dent in the top of the kernel; thus the term dent corn (Ertas et al., 2009). Starch is the most widely used part of the kernel and is found in different products either as starch granule or metabolized to form other chemicals, sweeteners and fuel (Gokmen, 2004). The figure below shows the structural composition of popcorn kernel.

Fig. 3: The internal structures of popcorn kernel

Source: Ziegler, 2001

1.2 Popping Mechanism

Popcorn, a cereal grain like wheat or oats, is about three-fourths carbohydrate in the form of starch, with smaller amounts of protein, fat, minerals, and water. The water plays a critical role in the popping process. When heated, the moisture inside the kernel turns into steam. As the pressure increases, the starch expands and the kernel explodes. Consumers prefer popped corn that is large and tender. This requires just the right amount of water in each kernel (Mishra et al.,

2014). To ensure maximum popping expansion, the corn is then carefully cured or dried until the moisture content reaches just the right amount for popping. Popcorn acts the way it does because of the special construction of the pericarp and the microscopic structure of the endosperm (Iken,

1991). Popcorn has a very tough pericarp. This tough, protective layer acts like a seal, holding in

the steam until the pressure builds up high enough and the kernel explodes. If the pericarp has been cut or cracked during processing, the steam will be vented and the kernel will not pop properly. Corn has two kinds of endosperm, translucent and opaque, which are named according to their appearance. The expansion, or popping, takes place in the tightly packed translucent endosperm. Popcorn contains mostly translucent endosperm, which is better at popping (Li et al., 2007).

Before cooking popcorn, the pressure inside and outside the kernel is the same. As the kernel heats,  the  moisture turns to  steam,  and  the  internal pressure of the  kernel rise.  When the temperature inside the kernel rises above 100 ºC, one might expect that all the water would turn to steam. In fact, only a small amount vaporizes because the tough pericarp acts like a pressure cooker. The high-pressure steam penetrates the starch granules and transforms them into hot, gelatinized globules, the more the corn is tends to pop. At about 175 ºC, when the pressure inside the kernel is about 9 Atm, the pericarp ruptures (Farahnaky et al., 2013).

The steam and superheated water, now surrounded by normal-pressure air, become the driving force that expands the kernel. The gelatinized starch granules do not explode, but expand into thin, jellylike bubbles. Neighboring bubbles fuse together and solidify, forming a three- dimensional network much like a sink full of soapsuds. This is the white fluffy solid we eat. The moisture content of the kernel is now about 1-2% by mass, and the popcorn is transformed into a tender, fluffy morsel (Mishra et al., 2014).

1.3 Nutritional Composition of Popcorn

Popcorn provides a full complement of nutrition benefits, including dietary fibre, protein and B vitamins  (Donkeun  et  al.,  2000).  The  nutritional  composition  of  popcorn  showed  that  it contained 3.8–4.6% crude fat, 8.1–10.5% crude protein, 0.07–0.23% reducing sugars and 61.0–

67.9% starch, in which 27.0–28.5% of the starch was amylase. Popcorn hybrids contain on an average approximately 12.6% palmitic, 2.0% stearic, 25.5% oleic, 58.4% linoleic and 1.5% linolenic acids, respectively. The major fatty acids in the popcorn hybrids were linoleic and oleic acids. The energy value (380 kcal/100g) and other essential nutrients of the kernel were high when compared with other cereals like sweet corn and sorghum (Donkeun et al., 2000).

1.3.1   Dietary Fiber

Dietary fiber is that part of plant material in the diet which is resistant to enzymatic digestion. It includes  cellulose,  non-cellulosic  polysaccharides  such  as  hemicellulose,  pectic  substances, gums, mucilages and a non-carbohydrate component, lignin (Dhingra et al., 2012).  It consists of remnants of plant cells resistant to hydrolysis (digestion) by the alimentary enzymes of humans. The diets rich in fiber such as cereals, nuts, fruits and vegetables have a positive effect on health since their consumption has been related to decreased incidence of several diseases. Dietary fiber can be used in various functional foods like bakery, drinks, beverages and meat products (Otles and Ozgoz, 2014).

1.3.1.1 Classification of Dietary Fiber

Tungland and Meyer (2002) suggested several different classification systems to classify the components of dietary fiber. These systems include:

i.     Based on their role in the plant

ii.   Based on the type of polysaccharide

iii.  Based on their simulated gastrointestinal solubility iv.   Based on site of digestion and

v.   Based on products of digestion and physiological classification.

However, none is entirely satisfactory, as the limits cannot be absolutely defined. The most widely accepted classification for dietary fiber has been to differentiate dietary components on their solubility in a buffer at a defined pH, and/or their fermentability in an in-vitro system using an aqueous enzyme solution representative of human alimentary enzymes. Thus most appropriately, dietary fiber is classified into two categories such as water- insoluble/less fermented fibers: cellulose,  hemicellulose,  lignin, and water soluble/ well fermented fibers: pectin, gums and mucilages (Anita and Abraham, 1997). The classification of dietary fibre components on the basis of water solubility and fermentability is presented below:

a. Water Insoluble/less Fermented i. Cellulose

Cellulose is present in plants such as vegetables, sugar beet and various brans. It is the main structural component of plant cell wall and is insoluble in concentrated alkali but soluble in concentrated acid. Cellulose is a linear polysaccharide polymer with many glucose monosaccharide units. The acetal linkage is beta which makes it different from starch. This peculiar difference in acetal linkages results in a major difference in digestibility in humans. Humans are unable to digest cellulose because the appropriate enzymes to breakdown the beta acetal linkages are lacking. Undigestible cellulose is the fiber which aids in the smooth working of the intestinal tract (Wong and Jenkins, 2007). Cellulose is an organic compound with the formula (C6H10O5)n, a polysaccharide consisting of a linear chain of several hundred to many thousands of     β(1→4) linked D-glucose units. This linkage contrasts with that for α (1→4)- glycosidic bonds present in starch, glycogen, and other carbohydrates. Cellulose is a straight chain polymer: unlike amylopectin component of starch; no coiling or branching occurs, and the molecule adopts an extended and rather stiff rod-like conformation, aided by the equatorial conformation of the glucose residues (Crawford, 1981). The multiple hydroxyl groups on the glucose from one chain form hydrogen bonds with oxygen atoms on the same or on a neighbor chain, holding the chains firmly together side-by-side and forming microfibrils with high tensile strength. This confers tensile strength in cell walls, where cellulose microfibrils are meshed into

a polysaccharide matrix. The chemical structure of cellulose is shown in the Figure 4 below:

Fig. 4: The structure of cellulose

ii. Hemicellulose

The main source of this fiber component is cereal grains. It is the cell wall polysaccharides, which  contain  backbone  of  β-1,4  glucosidic  linkages.  It  is  soluble  in  dilute  alkali.  A hemicellulose   (also   known   as   polyose)   is   any   of   several   heteropolymers   (matrix

polysaccharides), such as arabinoxylans, present along with cellulose in almost all plant cell walls (Scheller and Ulvskov, 2010).   While cellulose is crystalline, strong, and resistant to hydrolysis, hemicellulose has a random, amorphous structure with little strength. It is easily hydrolyzed by dilute acid or base as well as myriad hemicellulase enzymes (Lattimer and Haub,

2010). Hemicelluloses include xylan, glucuronoxylan, arabinoxylan, glucomannan, and xyloglucan (Gibson, 2013). These polysaccharides contain many different sugar monomers. In contrast, cellulose contains only anhydrous glucose. For instance, besides glucose, sugar monomers   in   hemicellulose   can   include   xylose,   mannose,   galactose   and   arabinose. Hemicelluloses contain most of the D-pentose sugars, and occasionally small amounts of L- sugars as well.  Not only regular sugars can be found in hemicellulose, but also their acidified form, for instance glucuronic acid and galacturonic acid can be present (Gibson, 2013). The

biochemical structure of hemicellulose is shown in Figure 5.

Fig. 5: The structure of hemicelluloses

iii. Lignin

Lignin is a class of complex organic polymers. Lignins are one of the main classes of structural materials in the support tissues of vascular plants and some algae. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Chemically lignins are cross-linked phenol polymers. They are complex

cross-linked phenyl propane polymers which are non-carbohydrate cell wall components. Lignin

resists bacterial degradation. The biochemical composition of lignin is illustrated in Figure 6.

Fig. 6: The structure of lignin

Source: Gibson, 2013

ii. Water Soluble/Well Fermented a. Pectin

Pectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. Pectins, also known as pectic polysaccharides, are rich in galacturonic acid. Several distinct polysaccharides have been identified and characterised within the pectic group. Homogalacturonans are linear chains of α-(1–4)-linked D-galacturonic acid. Substituted galacturonans are  characterized  by the  presence  of saccharide  residues (such as  D-xylose) branching from a backbone of D-galacturonic acid residues. Pectin can be sourced from fruits, vegetables, legumes, sugar beet and potato (Buchanan et al., 2000).

b. Gums

Gums are secreted at site of plant injury by specialized secretary   cells. They are sourced from leguminous  seed  plants  (guar,  locust  bean),  seaweed  extracts  (carragenan,  alginates)  and microbial gums (xanthan and gellan) (Nunes and Malmlof, 1992).

c. Mucilage

This is usually synthesized by plants to  protect  from desiccation of their seed endosperm. Mucilage can be utilized in food industries as a stabilizer. It is sourced from plant (gum acacia, gum karaya, gum tragacanth) (Buchanan et al., 2000).

1.3.2   Protein

Popcorn contains protein (Ijarotimi et al., 2012). Protein provides the body with amino acids, which are used for endogenous protein biosynthesis (Koolman and Roehm, 2005). Excess amino acids are broken down to provide energy. Most amino acids are glucogenic. i.e., they can be converted into glucose. Proteins are essential components of the diet, as they provide essential amino acids that the human body is not capable of producing on its own. Some amino acids, including cysteine and histidine, are not absolutely essential, but promote growth in children. Some amino acids are able to substitute for each other in the diet. For example, humans can form tyrosine, which is actually essential, by hydroxylation from phenylalanine, and cysteine from methionine (Nelson and Cox, 2005). Individual protein sources are considered “complete” if they supply all the essential amino acids in adequate amounts and “incomplete” if they do not. Meat, fish, poultry, eggs, milk, cheese, and soy provide complete proteins. Incomplete proteins, which come from plant sources such as nuts and legumes, are good sources of most essential amino acids (Nelson and Cox, 2005).

1.3.3   Vitamins

Vitamins are essential organic compounds that most organisms are not capable of producing, although they are required in small amounts for metabolism. Most vitamins are precursors of coenzymes; in some cases, they are also precursors of hormones or act as antioxidants. Vitamin requirements vary from species to species and are influenced by age, sex, and physiological conditions such as pregnancy, breast-feeding, physical exercise, and nutrition. Meanwhile, popcorn has been shown to possess antioxidant properties (American Chemical Society, 2009).

1.3.4 Minerals

Popcorn also naturally contains minerals. However, during popping and preparation of the snack,  salt  and/or  sugar  is  added  to  produce  salted  or  sweetened popcorn respectively (Hoseney et al., 2013). Minerals can be classified into two:

1.3.4.1 Major Minerals

Major minerals, also called macro minerals, are present in relatively large amounts in the body and are required in fairly large amounts in the diet- more than 250 milligrams daily. Calcium, phosphorus, and  magnesium fall  into  this category as well as the electrolytes sodium, chloride, sulfur, and potassium (Lattimer and Haub, 2010). The electrolytes are grouped together because their work is so interrelated. They help regulate cellular fluid and transmit nerve impulses (Lattimer and Haub, 2010). Some of these macrominerals and their impacts on health are highlighted below:

1.3.4.1.1 Magnesium

It is one of the most abundant cations in the body and is essential for many physiochemical processes.  Approximately one-half of the  body  magnesium is  present  in  the  bone,  the remainder is found in soft tissues and blood cells with a small amount present in the blood. Magnesium is an activator of various enzymes and is also essential for preservation of the macromolecular structure of DNA, RNA and ribosomes (Henry, 1984). Decreased levels of this cation have been observed in cases of diabetes, alcoholism, diuretics, hyperthyroidism, malabsorption,  hyperalimentation,  myocardial  infarction,  congestive  heart  failure  and cirrhosis (Long and Romani, 2014). Increased serum magnesium levels have been found in renal failure, diabetic acidosis, Addison’s disease and  vitamin D intoxication (Faulkner,

1982). Diets with higher amounts of magnesium are associated with a significantly lower risk of diabetes, possibly because of the important role of magnesium in glucose metabolism (Larsson and Wolk, 2007).

Magnesium is widely distributed in plant and animal foods and in beverages. Green leafy vegetables, such as spinach, legumes, nuts, seeds, and whole grains, are good sources (Ross

et al., 2012). In general, foods containing dietary fiber provide magnesium. Magnesium is also  added  to  some  breakfast  cereals  and  other  fortified  foods.  Some  types  of  food processing, such as refining grains in ways that remove the nutrient-rich germ and bran, lower magnesium content substantially (Gibson, 2005).

Magnesium has many novel uses for common health conditions. As an antacid, magnesium salts react with gastric acid to form magnesium chloride, thereby neutralizing hydrochloric acid (Long and Romani, 2014). As a laxative, magnesium acts osmotically in the intestine and colon as well as triggering the release of gastrin and cholecystokinin, stimulating gastric motility. The inhibitory effect of magnesium on pre-term labor contractions (tocolysis) is attributed to antagonism of calcium-mediated uterine contractions (Faryadi, 2012). Its deficiency has been found to allow for increased intracellular concentrations of sodium and potassium, which results in increased peripheral resistance and vasospasm (Hu et al., 2001).

1.3.4.1.2 Sodium

Recent studies have sought to find links between high sodium and reduced vascular function. Endogenous ouabain (EO) has emerged as a key player in the pathogenesis of sodium- induced hypertension. EO is a recently discovered hormone secreted by the adrenal glands and the hypothalamus (Linde et al., 2012). EO controls the expression of numerous factors which influence vasoconstriction and vascular resistance. Consumption of excess sodium will increase the sodium concentration in the cerebrospinal fluid, which activates the sympathetic nervous system (Harsha et al., 2004). The elevated sympathetic nerve activity will invoke secretion of EO from the adrenal cortex and hypothalamus. The pressor effects of EO include the stimulation of vasoconstriction via increased cytosolic calcium concentration and impairment of vasodilation via inhibition of nitric oxide production. EO has been shown

to block the activity of the Na+/Ca2+  pump, which is responsible for sodium intake and

calcium extrusion in arterial smooth muscle cells and endothelial cells. Blocking the pump will result in elevated Ca2+  concentration within the cytosol of pulmonary smooth muscle cells. High Ca2+ levels are strongly associated with vasoconstriction and increased myogenic tone, a hallmark of hypertension (Dickinson et al., 2006).

1.3.4.1.3 Potassium

Potassium is a principal cation of the intracellular fluid being also an important constituent of the extracellular fluid and functions in maintaining acid-base balance and osmotic pressure. Elevated   potassium  levels   (hyperkalaemia)  are   often  associated   with   renal   failure, dehydration  or  adrenal  insufficiency.  Decreased  potassium  levels  (hypokalaemia)  are associated with malnutrition, negative nitrogen balance, gastro-intestinal fluid losses and hyperactivity of the adrenal cortex (Pohl et al., 2013).

1.3.4.2 Altered Sodium and Potassium Homeostasis and its Health Implication

Reabsorption of filtered sodium by the renal tubules is increased in primary hypertension because of stimulation of several sodium transporters located at the luminal membrane, as well as the sodium pump, which is localized to the basolateral membrane and provides the energy for such transport (WHO, 2012b). Primary hypertension, also known as essential or idiopathic hypertension, accounts for as many as 95% of all cases of hypertension and results from the  interplay of internal derangements (primarily in  the  kidney)  and  the  external environment (Kaplan, 2006). A pivotal luminal transporter is sodium–hydrogen exchanger type 3, which resides in the proximal tubule and the thick ascending limb of the loop of Henle, where the bulk of filtered sodium is reabsorbed.   Moreover, potassium depletion enhances sodium–hydrogen exchanger type  3  by  inducing  intracellular  acidosis and  by stimulating the sympathetic nervous system and the renin–angiotensin system (Soleimani et al., 1991). Dietary potassium supplementation has opposite effects. The sodium–chloride co- transporter in the distal tubule, the epithelial sodium channel in the collecting duct, and the sodium pump are  activated  by the  aldosterone excess  in primary hypertension, thereby promoting sodium retention and potassium loss (Meneton et al., 2005). A high-sodium diet increases potassium excretion by increasing distal sodium delivery (Geleijnse et al., 2003).

1.3.4.3 Trace Minerals

Trace minerals, also known as trace elements, are needed in much smaller quantities, less than 20 milligrams daily. Most trace minerals do not occur in the body in their free form, but

are  bound  to  organic  compounds  on  which  they  depend  for  transport,  storage,  and functioning. Some trace minerals have been identified, including tin, arsenic, silicon, vanadium, nickel, and boron (Zimmermann, 2009). Therefore, a balanced diet that includes a variety of foods in a moderate amount is the best way to consume a safe and adequate amount. Iodine is an important trace element as explained below:

1.3.4.3.1 Iodine

Iodine is a trace element  that  is  naturally present  in some foods, added to others, and available as a dietary supplement. Iodine is an essential component of the thyroid hormones- thyroxine (T4) and triiodothyronine (T3). Thyroid hormones regulate many important biochemical reactions, including protein synthesis and enzymatic activity, and are critical determinants of metabolic activity (Patrick, 2008). They are also required for proper skeletal and central nervous system development in foetuses and infants. Iodine in food and iodized salt is present in several chemical forms including sodium and potassium salts, inorganic iodine (I2), iodate, and iodide, the reduced form of iodine (Zimmermann, 2009).

1.3.5    Sugars and Sweeteners

Research on taste indicates that “sweet” is an innately preferred sensation (Malik and Schulze,

2006). This recognition of the importance of sweetness confirms why sweet foods are by far the most popular treats. Sugars and other sweeteners are often used in the preparation of popcorn snack. Sugars are forms of monosaccharide. Examples of monosaccharides are glucose (also called dextrose), fructose, and galactose. When two monosaccharides combine, a disaccharide is formed. For example, when glucose and fructose join together, the disaccharide sucrose, also called table sugar, results. Maltose is composed of two glucose molecules, while lactose (milk sugar)  is  formed  by  one  molecule  of glucose  and  one  molecule  of galactose.  Fructose  is commonly referred to as “fruit sugar” because of its presence in fruits. Fructose as a product is available in crystalline form (from cornstarch), as liquid honey, or as liquid high-fructose corn syrup (HFCS) when combined with glucose. HFCS is used in the preparation of many beverages and sugars are carbohydrates and contain four calories per gram (Malik and Schulze, 2006).

1.3.5.1 Reduced-Calorie and Low-Calorie Sweeteners

1.3.5.1.1 Polyols

Polyols, also called “sugar alcohols” or sugar replacers, may be classified as monosaccharide- derived (sorbitol, erythritol, xylitol, mannitol), disaccharide-derived (maltitol, isomalt, lactitol), and polysaccharide-derived (hydrogenated starch hydrolysates). They are carbohyrates imparting a sweet sensation but are neither sugars nor alcohols (Dills, 1989). Polyols are mostly reduced- calorie sweeteners and may be used in the same amount as table sugar but are frequently used in conjunction with other sweeteners to achieve the desired sweetness level and taste. With fewer calories than sucrose, they provide sweetness to sugar free cookies, candies, chewing gum, baked goods, ice cream, toothpastes, mouthwashes, breath mints, and pharmaceuticals. The U.S. Food and Drug Administration allow the use of the following caloric values for polyol sugar replacers (see Table 1 below). Polyols also add bulk and texture to foods, provide a cooling effect or “cool” taste, help retain moisture in foods, do not lose sweetness, and do not cause browning when heated. Because molds do not grow well on polyols, they may contribute to longer shelf life of foods. They are naturally occurring in many fruits and beverages, but for commercial uses they are  made from other carbohydrates, such as starch, sucrose, and glucose. The USDA considers the sugar alcohols listed above as either generally recognized as safe (GRAS) or approved food additives (USDA, 2000).

Table 1: The U.S. Food and Drug Administration allowed caloric values for polyol sugar re-

  placers.                                                                                                                                                      

Calorie values

Polyol	Calorie/g	Sweetness relative to sucrose (%)
Hydrogenated starch hydrolysates	3.0	25–50
Sorbitol	2.6	50–70
Xylitol	2.4	100
Erythritol	0.2	60–80
Isomalt	2.0	45–65
Lactitol	2.0	30–40
Mannitol	1.6	50–70

Source: Sicard and Leroy, 1983

Polyols are incompletely absorbed from the small intestine into the bloodstream, producing a lower glycemic response (i.e., a lesser effect on blood glucose) than sucrose or glucose. Unabsorbed polyols  enter  the  large  intestine,  where they are  fermented by  bacteria.  Some individuals who consume excessive amounts of polyols may experience gastrointestinal symptoms, such as gas and laxative effects, similar to reactions to high-fiber foods and beans. The American Dietetic Association advises that consuming more than 50 grams per day of sorbitol or  20  grams per  day of mannitol may  cause diarrhea. In  such cases,  the  amount consumed on a single occasion should be reduced. Consequently, labels of polyol-containing products must bear the statement, “Excess consumption may have a laxative effect” (Sicard and Leroy, 1983).

Polyols are also non-cariogenic, they do not promote tooth decay because bacteria in the mouth do not metabolize and convert the sweetener into plaque or harmful acids that cause tooth decay. The U.S. Food and Drug Administration (USFDA) authorize the use of this claim on labels of products containing sugar alcohols. Xylitol is found even to inhibit oral bacteria. This is the reason for the use of polyols in many sugarless mints and chewing gums (USFDA, 2010).

1.3.5.1.2 Tagatose

Tagatose is a low-carbohydrate sweetener contributing 1.5 calories per gram, and it is especially suitable as a flavor enhancer at  low doses. Technically known as D-tagatose, it  is a white, crystalline powder that is prepared from lactose. Tagatose is ideal for use in diet soft drinks because of its synergistic flavor-enhancing effect when used in combination with other high- intensity sweeteners such as acesulfame-K, sucralose, and aspartame. Sweetness onset occurs rapidly, and bitterness is reduced. Tagatose is found to enhance mint and lemon flavors in chew- ing gums and mints, toffee flavor, and creaminess in some dairy product applications. It is pH- stable in acidic products, such as carbonated beverages and yogurts. Tagatose behaves like fructose in the body, but only 15–20 percent of tagatose is absorbed in the small intestine. Due to this incomplete absorption, tagatose has minimal effect on blood glucose and insulin levels. The rest of the ingested tagatose proceeds to the large intestine where it acts as a prebiotic, promoting the production of butyrate and  lactic acid  bacteria (considered “good” bacteria), which are

essential in maintaining a healthy digestive system. Like other low-digestibility carbohydrates and dietary fibers, tagatose is fermented in the colon to short-chain fatty acids that decrease acidity and may contribute to a healthy epithelium in the large intestine. These short-chain fatty acids are then almost completely absorbed and metabolized. This fermentation, however, may result in mild gastrointestinal discomfort (e.g., flatulence and laxation) in some sensitive individuals, just as high-fiber carbohydrates do (USFDA, 2010).

1.3.5.1.3 Trehalose

Trehalose is a disaccharide consisting of two glucose molecules. It is found in common foods such as honey, mushrooms, and shrimp and is naturally produced by the body. It is half as sweet as sucrose, provides sustained energy, and elicits a very low insulin response. Trehalose may be used in foods and beverages such as fruit juices, white chocolate chips, nutrition bars, and dehydrated fruits and vegetables. It  is heat stable, and in addition to being a sugar, it also stabilizes proteins, or prevents protein aggregation, making it useful as a biological preservative. Trehalose protects and preserves cell structure in foods and may be useful in freezing and thawing processes by maintaining a desired texture (USFDA, 2010).

1.3.5.1.4 Aspartame

Aspartame is a nutritive sweetener containing 4 calories per gram. Because it  is 200 times sweeter than sucrose, however, very little aspartame is needed to impart the same sweetness as sugar, resulting in minimal calories added to foods. Aspartame completely breaks down upon digestion into small amounts of methanol and the amino acids aspartic acid and phenylalanine. These components are then absorbed into the blood and used by the body in exactly the same ways as when they come from other foods and beverages. No accumulation of aspartame or its components occurs in the body over time. Aspartame has a clean, sugar-like taste, enhances fruit and citrus flavors, can be safely used under heat with some loss of sweetness at higher temperatures, and is non-cariogenic. It is primarily responsible for the growth of the low-calorie and reduced-calorie product market in the past two decades and is today an important component of thousands of foods and beverages. Because aspartame helps impart a good, sweet-tasting flavor to low-calorie and reduced-calorie foods and beverages, it is helpful to diabetics and

beneficial in weight control by managing caloric intake while still maintaining a healthful diet (USFDA, 2010).

1.3.5.1.5 Saccharin

Saccharin has been in use for over a century to sweeten foods and beverages without adding calories or carbohydrates. It was especially useful in Europe during the two world wars, when sugar was in short supply. It has been an integral component of the lifestyle of many people for weight  control and  caloric  or  carbohydrate  intake  restriction.  Like  most  other  low-caloric sweeteners, saccharin helps prevent the formation of dental cavities, compared to sugar. In 1977, FDA proposed a ban on saccharin based on studies that linked its use to bladder cancer. Research methodologies involved the use of a sensitive strain of laboratory rats fed with extremely high doses of saccharin. Although, the United States Congress overrode the ban because of the need at that time for a low-calorie alternative to sucrose, a warning label was required on products containing saccharin. In May 2000, due to a preponderance of scientific results obtained from nearly 20 years of studies, the government removed saccharin from its list of substances reasonably anticipated to be human carcinogens. Saccharin is not metabolized by the body and does not react with DNA, lacking two of the major characteristics of a classical carcinogen. Saccharin  continues  to  be  used  in  a  wide  range  of  low-calorie  and  sugar-free  foods  and beverages. It is found in soft drinks, baked goods, chewing gum, canned fruit, salad dressings, and also in cosmetic products and pharmaceuticals (USFDA, 2000).

1.3.5.1.6 Sucralose

The only non-caloric sweetener prepared from sucrose, sucralose is manufactured through a patented multi-step process that replaces three hydroxyl groups of the sucrose molecule with three chloride groups. These tightly bound chloride groups make sucralose exceptionally stable and indigestible, which makes sucralose free of dietary calories. Sucralose is a sweetener that is

600 times sweeter than sugar with a  clean,  sugar-like taste and  no  lingering objectionable aftertaste. It can be used anywhere sugar is used without losing its sugar-taste properties even when heated and stored for a long time. Thus it is now used as a spoonful-for-spoonful Replacement for sugar in eating, baking, cooking, and other sugar applications (USFDA, 2010).

Like the other low-calorie sweeteners, sucralose passes quickly through the body relatively unchanged and is not converted to energy. It is not recognized by the body as either a sugar or a carbohydrate. Sucralose is also non-cariogenic because it is an inert ingredient that cannot be acted upon by bacteria in the mouth. It is also stable over a wide range of temperatures over time, and it is used in many applications such as canned fruit, low-calorie beverages, apple sauce, baked goods, nutritional supplements, and medical foods. The following sweeteners do  not increase blood glucose levels: Brown sugar, icing sugar, invert sugar, white sugar, dextrose, maltodextrins, Agave syrup, brown rice syrup and corn syrup (USFDA, 2010).

1.4   Aim and Objectives of the Study

1.4.1   Aim of the Study

The aim of this work is to determine the nutritional compositions of some brands of popcorn relative to the unprocessed form of the cereal with a view of evaluating any possible health implications of consuming the cereal snack in view of the additional intake of sodium, chloride and sugars often utilized during processing.

1.4.2   Specific Objectives of the Study

The following objectives are kept in perspective:

        To determine the calorie content of both processed and unprocessed popcorn.

        To determine the mineral contents of both processed and unprocessed popcorn.

             To determine the sugar (glucose and fructose) content of both processed and unprocessed popcorn.

        To determine the iodine content of both processed and unprocessed popcorn.

        To determine the fibre content of the both processed and unprocessed popcorn.

₦5,000.00 – DOWNLOAD FULL PROJECT DOWNLOAD FULL PROJECT Added to cart

---

---

---

---

Related Project Topics :