Glycemic load

The glycemic index (GI) measures the speed at which a food increases blood sugar levels, and a low GI indicates higher-quality carbohydrates. Opting for foods with lower GI values can lead to a more gradual rise in blood sugar levels.

While the GI of a specific food is useful for comparing different foods, it doesn't fully capture the actual blood sugar impact of a regular serving. To address this, the concept of glycemic load (GL) was introduced.

Glycemic load (GL) takes into consideration both the quality and quantity of carbohydrates in a food. It is crucial to consume moderate amounts of high-quality foods to effectively manage blood sugar, insulin levels, and weight.

GL serves as an additional tool for a more precise assessment of the impact of carbohydrates on blood sugar. Unlike GI, which only reveals how quickly a particular carbohydrate converts to sugar, GL indicates the actual amount of carbohydrate in a serving.

Serving sizes can vary based on cultural and dietary practices, and GL helps individuals account for both the quantity and quality of carbohydrates they consume.

To calculate GL, multiply the grams of available carbohydrates in the food by the food's GI and divide the result by 100. Foods with higher GL values, especially those rich in carbohydrates, tend to have a more significant impact on glycemic response. GL values are categorized as low (≤ 10), medium (11 to 19), or high (≥ 20) for standardized portions of carbohydrate-rich foods or products.

Examples of foods with a low glycemic load (GL of 10 or less) include:
~¼ cup peanuts (GL of 1)
~8 oz skim milk (GL of 4)
~2 cups watermelon (GL of 4.3)
Glycemic load

Starches: Major polysaccharide in plants

Chemically is composed of two glucan polymers, amylose, and amylopectin. These polymers are deposited in granules of different sizes, large A-, medium B- and small C-type, and shapes, as disk-like and spherical.

It provides humans with energy (4 cal per gram) and is hydrolyzed to glucose, supplying the glucose that is necessary for brain and central nervous system functioning.

Nutritionists agree that carbohydrates should be an important part of human diet. The European Food Safety Authority (EFSA) recommends that the intake of total carbohydrates, including carbohydrates from starchy foods (generally in the form of tubers or root vegetables) should range from 45-60% of the total energy intake for both adults and children.

Amylose influences the packing of amylopectin into crystallites and the organization of the crystalline lamella within starch granules. This is important for properties related to water uptake as swelling and gelatinization.

Starch is used in the food industry either as food products or additives for thickening, preservation and quality enhancer in baked foods, confectioneries, pastas, soups and sauces, and mayonnaises.

Starch can be used as a food additive to control the uniformity, stability and texture of soups and sauces, to resist the gel breakdown during processing and to raise the shelf life of products.

Starch sources are numerous, with common ones derived from cereal grains such as wheat, corn, or rice. Wheat yields a cloudy, thick mixture, while cornstarch produces more clear mixtures such as gravies or sauces. Vegetables, roots and tubers, including the root of cassava, and potatoes.
Starches: Major polysaccharide in plants

Optical activity of carbohydrates

In 1811, Arago discovered that the “plane of polarization” of linearly polarized light was rotate when a beam of light propagated through quartz in a direction parallel to its optic axis. This property of quartz is called optical activity.

One of very important characteristic of sugars is their ability to rotate rays of polarized light. Carbohydrates contain several similarly substitute asymmetric carbon atoms and are therefore all optically active. This property is referred to as optical rotation and such compounds are said to be optically active.

A compound is optically active if its mirror image is not superimposable upon the original. In the application of this test, it must be realized that the atoms in a molecule are in constant motion with respect to each other.

The optical activity can be determined by optical rotation (OR), optical rotary dispersion (ORD) and circular dichroism (CD).
Optical activity of carbohydrates

Glucose, the simple carbohydrate

A 6-carbon sugar, glucose is one of the simplest carbohydrates found in foods. It is one of the most important carbohydrates in plant and animal metabolism.

The compounds D-glucose or dextrose is 2,3,4,5,6-pnetahydroxyhexaldehayde, or conventionally expressed as C6H12O6 with a molecular weight of 180,6 kDa. Glucose is readily soluble in water in a powder form.

Glucose is also the primary repeating sugar unit of most complex carbohydrates or starch.

While many foods contain traces of glucose, it is found in significant amounts only in fruits, such as grapes.

Photosynthesis converts carbon dioxide and water to glucose, which is stored in leaves, stems, fruits, roots, pods and seeds, as glucose, as other sugars or as starch.

The small, amount of glucose in the blood and cells provides the energy need for human body’s daily activities. Any galactose or fructose that is absorbed into the blood is converted to glucose by enzymes present in the liver.  It is an essential energy source for the adult human brain.

Glucose is stored as glycogen, an α-link polymer, predominantly in the liver and muscles.  On average m a 70 kg man may store 500g of glycogen.
Glucose, the simple carbohydrate

What are monosaccharide sugars?

The term ‘monosaccharide’ refers to simple sugars containing up to ten carbon atoms per molecule. Monosaccharides are the simplest carbohydrates of one unit, so they cannot be further decomposed to a simpler sugar.

They are simply known as sugars. Same sugars occur in nature and others are synthetic.

Monosaccharides are single-sugar molecules that are made up of carbon, hydrogen and oxygen atoms in the ration 1:2:1.

A hydrolysis reaction separates disaccharides into monosaccharides. During hydrolysis, the addition of molecule water splits the bond between the two sugar molecules, providing the H and OH groups necessary for the sugars to exist as monosaccharaides.

Monosaccharides are the simplest form of carbohydrates. They are sweet, require no digestion, and can be absorbed directly into the bloodstream from the small intestine. They include glucose, fructose, and galactose. Although the structures of these sugars differ, they all have one thing in common: each contains six carbons atoms.

Glucose, also called dextrose, is the form of carbohydrate to which all other forms are converted for eventual metabolism. Glucose is one of the most abundant organic compounds on earth. Glucose exists in some fruits such as grapes, figs, and dates.

Fructose also called levulose or fruit sugar is found with glucose in many fruits and in honey. Industrially, it can be produced from sucrose or inulin.

Galactose is a product of the digestion of milk. It is one of two single sugars that are bound together to make up the sugar of milk.
What are monosaccharide sugars?

Carbohydrate source of energy

In an energy-sufficient diet, carbohydrate can replace fat as a source of energy. In some populations, fat intakes are very low and body weight and health are maintained by high intakes of carbohydrate.

Beyond its continuing maintenance needs for energy, the body periodically needs relatively larger amounts of energy to do work or to engage in other vigorous physical activities.

Carbohydrates are the preferred energy source for athletes as they are the most efficient in producing the necessary fuel for energy requirements.

Human derive their energy mainly from carbohydrate (55 – 65%), although they can also utilize fats and proteins for this purpose.

Two main macronutrients provide energy for replenishing adenosine triphosphate (ATP) during exercise:
*Muscle and liver glycogen
*Triglycerides within adipose tissue and exercise muscle

During prolonged exercise, carbohydrates such as muscle glycogen and blood glucose derived for liver glycogenolysis are the primary energy substrate. One gram of carbohydrate supplies 4 kcal of energy.

The carbohydrates that are important in nutrition include the sugars, the starches, the dextrin, and glycogen. Cellulose, pectin, and other carbohydrate are not important nutritionally.

In adults, it is important that the amount of energy ingested be matched to the amount of energy expended. Maintenance of energy balance is important in order to avoid obesity and its associated co-morbidities such as diabetes and cardiovascular disease.

Carbohydrates constitute the main source of energy supplied by foods and may account for up to 100% of the total dietary caloric intake. In an average Westerns diet carbohydrates contribute around 50% of the ingested calories.
Carbohydrate source of energy 

Classification of lipids: Glycolipids

Glycolipids can be considered part of a larger family known as glycolconjugates. These are molecules in the cell surface that chains of carbohydrates bind to. It was established as the major brain tissue as early as 1874.

There are over 100 different types of glycolipid structure, reflecting variations in the fatty acyl chains of the hydrophobic ceramide portion (N-acylsphingosine) and the different combinations and types of sugar residue in the hydrophilic carbohydrate portion.

As the name suggest, the basic structure of a glycolipid consists of carbohydrate attached to a lipid.

The simplest glycolipid is called cerebrosides and contains galactose, i.e., O-galactosyl ceramide.

A more highly complex glycolipid containing ceramide polyhexosides and one or more sialic acid groups are called gangliosides.

As integral membrane components, glycolipids regulate cell membrane structural integrity, cell adhesion and signal transduction.

In neural tissue, glycolipids bind to adhesion molecule glycoproteins in myelin compaction.

In the area of consumer products, glycolipids are used as a main ingredient in detergents for the kitchens and emulsifiers of foods and cosmetic’s.

In biochemical research, glycolipids are key compounds for dissolving and crystallizing membrane proteins.
Classification of lipids: Glycolipids

The importance of carbohydrate in human body

Carbohydrates are polyhydroxy aldehydes, ketones, alcohols, acids, their simple derivatives and their polymers having linkages of the acetal type. Carbohydrates are synthesized by plants during photosynthesis. This is the process of trapping energy from sunlight with the aid of chlorophyll.

The name carbohydrate was first used in 1844 by Schmidt, but the sweet nature of sugar had already recognized for many centuries. It was said that sugar was extracted as early as 3000 BC in India. 

Carbohydrate in the form of glucose serves as the most basic energy source for all cells in the body. Foods high in carbohydrates include breads, pastas, potatoes, rice and fruits. Legumes also a good source of carbohydrates.

Foods with a predominantly carbohydrate content are important because they form the basis of most diets, especially for poorer people in the developing world.

Carbohydrates are one of the four major classes of biomolecules and play several important roles in all life forms, including:

*The principle function of carbohydrates in human nutrition is the maintenance of the blood glucose and then absorbed into the blood stream.

*Sources of metabolic fuels and energy stores

*Parts of RNA and DNA in which ribose and deoxyribose, respectively are linked by N-glycosidic bonds to purine and pyrimidine bases

*Integral features of many proteins and lipids (glycoproteins and glycolipids), especially in cell membranes 

*It is the components o major dietary fibers.
The importance of carbohydrate in human body

Starch

Starch is by far the most important source of carbohydrates in the human diet amounting to approximately 50% of total carbohydrate in the United States, but often as much as 75% total carbohydrates in some of the developing countries.

Starch is a polysaccharide made up of many glucose units bonded together – 3000 or so in each molecule of starch. Shorter carbohydrate chains composed of 3 to 1o glucose molecules are called oligosaccharides.

Starch is partly digested in the mouth and changed in the small intestine to glucose.

All the major economic sources of starch are plants. Starch and starch like molecules can also be found in other kingdoms, of life, including bacteria, algae and animals.

Starchy foods such as potatoes, bread and pasta provide other nutrients as well as starch. For example, bread is a good source of protein, B-group vitamins and minerals such as calcium and iron.

Other major sources of starch include cereal grains, such as wheat, rice, rye, millet, sorghum and corn. These grains contain 76 percent starch. Tubers, such as potatoes and cassavas and root vegetables such as parsnips, also supply starch.

Starch

Carbohydrate in Human Nutrition

In order to carry out its day to day physiological functions and maintain a constant body temperature (due to invariably in an environment of changing temperatures), the body requires a constant source of energy.

Carbohydrates are an important energy source in the human diet. They generally supply about 45% of the energy requirement in developed countries and up to 85% in developing countries.

Carbohydrate are the cheapest, most efficient and most readily available source of food energy in the world, since they are the main constituents of the foods that are the easiest to produce and that can be obtained throughout the world, namely, grains, legumes and potatoes.

Carbohydrate are the most widely distributed, naturally occurring organic compounds on earth.

Carbohydrates have been considered a fundamental source of nourishment and inexpensive and versatile staple of the diet.

The carbohydrates that are important in nutrition include the sugars, the starches, the dextrin and glycogen.

The functional properties of carbohydrates in food include:
*Nutrition
*flavour and color production
*Sweetening
*Texturing
*Plasticizing action and humectancy

Dietary guidance for consumption of carbohydrates has resemble laboratory analysis of carbohydrates: take way fat and protein and the remainder must to be carbohydrate.

Nutritionist generally accept the fact that humans don’t need more than 10-12% kilocalories from protein, and less than 30% of kilocalories from fat.

Subsequently, intake of carbohydrate should be 55% of kilocalories or more.

Human diets historically have contained 40-80% of their energy as carbohydrate although as income increase, so does the fat content of the diet while carbohydrate content of the diet, especially the starch, decreases.

Starch is the major plant polysaccharide that is readily digested in the intestine and thus serves as a source of carbohydrates.

In human body, carbohydrates support the immune system and assist processes such as growth and blood clotting. Their primary role, however, is to supply energy to every cell of the body.

The major portion of energy requirements of human is met by starch of cereal grains and tubers such as potatoes.

For certain body systems such as the brain and the nervous system, , carbohydrates are the preferred energy source. The brain an nervous system are sensitive to the concentration of glucose in the blood. Normal blood glucose levels are important for a feeling of well being.

What exactly is a carbohydrate? A carbohydrate molecule is made of carbon, hydrogen and water and these building blocks can be joined in countless ways to form different carbohydrates. As the names implies, an empirical formula of CH2O (or CH2O) was often encountered, with molecular formulae of C5H10O5 and C6H12O6 being most common.

It was founded in the nineteenth century that carbohydrates in general have a formula Cn(H2O)n. They were therefore thought to be hydrates of carbon and hence were called ‘carbohydrates’.

The water solubility of these molecules was commensurate with presence of hydroxyl groups and there was always evidence for the carboxyl group of an aldehydes of ketone.
Carbohydrate in Human Nutrition

Carbohydrate in general

Carbohydrate are organic compounds containing carbon, hydrogen and oxygen, and they may be simple or complex molecules.

Historically, the term “carbohydrate” has been used to classify all compounds with the general formula Cn(H2O)n as the hydrates of carbon.

Carbohydrates are polyhydroxy compounds appearing commonly in nature, either as relatively small molecules or as large quantities extending to macromolecular levels (polysaccharides).

Important food carbohydrates include simple sugars, dextrin, starches, cellulose, hemicellulose, pectins and gums.

They are an important source of energy or fiber in the diet, and they also are important constituent of foods because of their functional properties.

Some common sources of carbohydrate are bread, potatoes, grains, cereals and rice.

Carbohydrates may be used as sweeteners, thickeners, stabilizers, gelling agents, and fat replacers.

Sugars are formed in green plants as early products of photosynthesis from carbon dioxide and water and are then converted into organic plant constituents through a variety of biosynthetic pathways.

The simplest carbohydrates are known as monosaccharides or sugars, and they have the general formula CnH2nOn. The most common ones contain six carbon atoms.

Disaccharides contain two sugars units, trisachharides contain three, oligosaccharides contain several units, and polysaccharides are complex polymers containing as many as several thousands units linked together to form a molecule.

Oligosaccharides such as raffinose and stachyose are found in small amounts in legumes. Examples of polysaccharides include starch and glycogen, which are the storage forms of carbohydrates in plants and animal, respectively.

Finally, sugar alcohols, such as sorbitol and mannitol, are alcohol forms of glucose and fructose, respectively.

Complex carbohydrates, the most efficient fuel for body cells, should supply the largest portion of the daily caloric intake – about 70%.

These foods are more abundant and less expensive than foods high in proteins and/or fats.

Complex carbohydrates satisfy the appetite, curing the tendency to over eat. They maintain an even energy level, curbing the desire for snacks.

They are ideal energy source foods of great benefit to the obese and diabetic.
Carbohydrate in general

Fats

Fats
Fats are glyceryl ester of fatty acids. Fats, as do carbohydrates, contains the element of carbons, oxygen and hydrogen, but proportion of oxygen in fats is less, and it to be said that fats are fuel foods of more concentrated type than are carbohydrates.

Carbohydrates and fats are interchangeable as fuel foods, but it can be shown, by calorimetry, that fats produce more than twice the heat energy produced by carbohydrates.

One grams of fats yields 9 cal, while 1 gram of carbohydrates yields 4 cal. An additional advantage of fat from the view point of energy availability is that it stores well in large amount of adipose tissue. Thus fat, considered to be a reserve from of fuel for the body.

Paradoxically, this is not advantageous in affluent societies where the problem is not availability of food energy, but rather health hazard of obesity.

Fats may occur in foods as materials that are solid at room temperature or as oils that are liquid at room temperature.

Solid fat contain comparatively small amounts of fatty acids with two or more groups of adjacent carbons that are not fully saturated with hydrogen.
Fats

Glycogen

Glycogen
Glycogen is produced in the liver from glucose. And it is stored in the liver, as well as in the muscle where it is available for immediate use as energy.

Both liver and the muscles can store only a limited amount of glycogen; therefore, when an excess of carbohydrates is ingested, there will be a tendency to develop an excess of glycogen.

The excess carbohydrates will then be converted to fat and stored in body as fat.

The body maintains equilibrium between glucose, the energy-producing sugar, and glycogen, which can be converted to glucose as the glucose in the blood used up to produce energy.

The production of energy from glucose involves oxidation of sugar with the release of water and carbon dioxide, which are easily removed from the body.
Glycogen

Carbohydrates

What is carbohydrates?
In order to carry out its day to day physiological functions and maintain a constant body temperature (due to invariably in a environment of changing temperatures), the body requires a constant source of energy.

Beyond it continuing maintenance needs for energy, the body periodically needs relatively larger amounts of energy to do work or to engage in other vigorious physical activites.

Human derives derive their energy mainly from carbohydtares (55-65%), although they can also utilise fats and proteins fo this purpose.
The carbohydrates are a class of chemical compounds that consists of carbon, oxygen and hydrogen.

The carbohydartes that are important in nutrition include the sugars, the starches, the dexrins and glycogen. Cellulose, pectin, and other carbohydrates are not important nutritonally.
Food Science

Functions of Carbohydrate

Functions of Carbohydrate
The main function of carbohydrate is to provide energy. Each gram of starch or sugar gives four calories to the body.

About 65 top 80 –percent of energy is supplied by the carbohydrates, mainly in the form of starch.

Some of this energy is used as glucose to supply immediate energy needs of the body, a small portion is stored as glycogen (about 350 g) mainly in the muscles and liver; and any excess intake is converted to fat and stored as adipose tissue.

Glucose is the source of energy for the central nervous system.

Another important function is to spare proteins for their main function of tissue building and maintenance. It is important to supply sufficient carbohydrates and fats to meet the essential energy needs of the body, otherwise proteins are metabolized to meet energy requirement of the body.

A third functions is related to proper utilization of fat from the diet. It is that fats burn in the flame of carbohydrates, indicating the need for major part of energy to be supplied in the form of carbohydrates.

Certain carbohydrates have special role in the body. Lactose aids the absorption of calcium, Ribose a five carbon sugar, is a part of the important compounds DNA and RNA.

Cellulose and other indigestible carbohydrates aid the movements of food through the digestive tract by their capacity to absorb water and help to maintain muscle tone.
Functions of Carbohydrate

Summary of Protein and Carbohydrate

Summary of Protein and Carbohydrate
Protein
Proteins are composed of intercoiling strands, in turn composed of amino acids.

• The proteins function to regulate specific steps in metabolism – one step, one protein. Hence, many proteins are needed.

• The variety of protein structures is made possible by the order and arrangement of the amino acid building blocks.

• At any time, body protein is being both synthesized and degraded, an inefficient process which leads to urinary loss of the breakdown products of the amino acid building blocks.

• This loss is obligatory and necessities regular replenishment – hence the nutritional necessity for protein in the diet.

Carbohydrate
Carbohydrate are composed of sugar molecules, single, paired or in long strands. Dietary carbohydrates are predominantly starch, with some sucrose and lactose.

• Starch is digested to glucose units, which are observed to be used for energy or for the synthesis of fats.

• Rising blood glucose levels after a meal stimulates insulin release which disposes of this load. Falling blood glucose levels stimulates glucagon, which maintains a basic minimum level of glucose in the blood.

• Although sucrose is well tolerated, lactose is poorly tolerated by many people who lack the enzyme to digest it. Both these substances yield glucose or glucose-like compounds on digestion.

Summary of Protein and Carbohydrate

Carbohydrate Functions in Human Body

Carbohydrate Functions in Human Body
In order to carry put its day to day physiological functions and maintain a constant body temperature (invariably in an environment of changing temperature, usually less than that of body temperature), the body requires a constant source of energy.

Beyond its continuing maintenance needs for energy, the body periodically needs relatively larger amounts of energy to do work or to engage in other vigorous physical activities.

Human derive their energy mainly from carbohydrate (55 – 65%), although they can also utilize fats and proteins for this purpose.

The carbohydrates are a class of chemical compounds that consist of carbon, oxygen and hydrogen.

The carbohydrates that are important in nutrition include the sugars, the starches, the dextrin, and glycogen. Cellulose, pectin, and other carbohydrate are not important nutritionally.
Carbohydrate Functions in Human Body

How Important of Carbohydrates to Our Body?

How Important of Carbohydrates to Our Body?
The word carbohydrate was originally derived from the fact that the greater part of the compound in this class had the empirical formula Cn(H20)n. The value of n ranged from three to many thousands.

This formula is now considered too restrictive, and more useful definitions might be “polyhydroxy aldehydes or ketones and their derivatives”. This latter definition encompasses deoxy sugars, sugar alcohols, sugar acids, and amino sugars.

Carbohydrates occur in fruits and vegetables as storage reserves in seeds, roots, and tubers; in the sap; and as constituents if the structural tissues. They are also found in milk, blood, and tissues of animals.

Carbohydrates are the most abundant food in the world and the most economical as an energy food source. In the American diet, carbohydrate foods constitute approximately 50% of the daily caloric intake.

However, carbohydrates make up an even greater proportion of the diet of peoples of other countries where cereals are a staple. In addition to their value as an expensive source of energy, carbohydrates are important for several reasons.

The body needs carbohydrates in order to use fat efficiently. Many foreign substances are removed from the body through the intermediate formation of glycosides of glucoronic acid. Diseases such as diabetes develop when the body is unable to utilize sugar properly. Some carbohydrates have an effect on the type of bacteria that will grow in the intestine. In some of the lower animals (crab and lobster), a major constituent of the exoskeleton is a polymer of glucosamine.
How important of Carbohydrates to Our Body?