Understanding Starches: Key to Sustained Energy and Nutritional Balance

Starches, a type of carbohydrate, are foundational to a balanced diet, providing sustained energy and essential nutrients. As complex carbohydrates, starches consist of long chains of glucose molecules, which require a gradual breakdown in the digestive system. Enzymes in the mouth and intestines convert these chains into simpler sugars, primarily glucose, which then enters the bloodstream to fuel bodily functions. This process allows for a steady release of energy, unlike simple sugars that lead to quick spikes and crashes. This sustained energy release from starches is ideal for supporting physical activity and mental focus throughout the day.

Starches are found in a range of whole foods, with primary sources being grains (like rice, wheat, and corn), root vegetables (such as potatoes, sweet potatoes, and yams), and legumes (like beans and lentils). Each source provides distinct nutritional benefits. Whole grains, for instance, are rich in fiber, which aids digestion and regulates blood sugar by slowing glucose absorption. Fiber also promotes satiety, helping with weight management and reducing cravings for unhealthy snacks. Additionally, whole grains and starchy vegetables deliver important vitamins and minerals, including B vitamins for energy production, iron for oxygen transport, and magnesium for muscle and nerve function.

However, not all starches are equally beneficial. Refined starches, like those in white bread, pastries, and processed snacks, lack fiber and other nutrients stripped away during processing. These refined starches cause rapid spikes in blood sugar, potentially leading to insulin resistance, weight gain, and an increased risk of chronic diseases such as diabetes and heart disease. The rise of ultra-processed foods, high in refined starches, has been linked to higher rates of obesity and metabolic disorders globally.

For optimal health, nutritionists recommend prioritizing whole, minimally processed sources of starch, such as quinoa, oats, and legumes, and reducing intake of refined starches. Incorporating a variety of whole grains, legumes, and starchy vegetables supports long-term health by balancing energy levels, promoting digestive health, and supplying essential nutrients for overall well-being.
Understanding Starches: Key to Sustained Energy and Nutritional Balance

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

Starch in potato

Starch granule morphology varies with plant genotype and cultural practices. It also depends on the biochemistry of the chloroplast/amyloplast and the physiology of the plant. The major part of potato carbohydrate is present as starch.

Starch is the main component of potato accounting for 17.5% on a fresh weight basis. Raw potato is high in resistant starch because the starch is encapsulated in granules. This changes when potato is cooked and the starch is gelatinized and can be modified by further treatments.

Starch in potato contains 16-24% amylose, 70-80% amylopectin and several percent of an immediate substance called ‘thylmol-amylopectin’ which differs from amylose and amylopectin in structure and properties.

Cooking either peeled or an unpeeled potato increases the digestibility of potato starch. Potatoes judge to be adequately cooked at 25 to 30 min had slightly lower digestibly than those ‘overcooked’ at 40 min.
Starch in potato

Carbohydrates in biological system

Carbohydrates are polyhydroxy aldehydes, ketones, alcohol, acids, their simple derivatives and their polymers having linkages of the acetal type.

Carbohydrates are an essential component of the human diet responsible for supplying energy to the host and its complex gastrointestinal microflora, but also for having an overall role in physiology including maintaining gastric function, hepatic metabolism and glycosylation of lipids and proteins necessary for other physiological functions.

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.

Carbohydrate-containing foods are vehicles for important micronutrients and phytochemicals. Dietary carbohydrate is important to maintain glycemic homeostasis and for gastrointestinal integrity and function.

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.

There are many researches linking the consumption of complex nonstarch polysaccharides with a reduced risk of chronic disease including diabetes, cardiovascular and cancers.
Carbohydrates in biological system

Nutritional value of peanut

Peanuts are grown in tropical and subtropical climates. They need much sunshine, warm temperature, moderate rainfall and a frost-free growing period of 4 to 5 months.

Peanuts are rich in oil: 100 pounds of whole nuts yields 32 pounds of oil and small podded varieties contain 50% oil.

The oil contains 76% to 82% unsaturated fatty acid that is fatty acids with double bonds. Monounsaturated fatty acids represent 48.4% of the total; polyunsaturated fatty acids, 33.6 percent and saturated fatty acids, 18%.

The two major carbohydrates of peanuts are starch, present primarily in starch grains in the two large cotyledons of the seed, and sugars (mostly sucrose) present in the honeycomb network surrounding the fat deposits.

Peanuts have fiber, plus a good amount of protein to build a better body. Peanuts generally contain higher amounts of protein (25.80 g/100 g) than three nuts (7.91-21.22 g/100g).

100 grams of raw nuts contains about 705 mg of potassium and 18 mg of sodium. They also have a good supply of niacin and a bit of thiamine for more energy. They are rich in fiber, a good source of B-group vitamins, vitamin E and a source of iron and zinc.

Nutritional value of peanut

Classification of carbohydrates

The word ‘carbohydrate’ was coined more than 100 years ago to disrobe a large group of compounds of the general formula Cn(H2O)n. Sugars, starches and fiber are the main forms in which carbohydrates occurs in food.

Carbohydrates can be classified based on their chemical structure and/or based on their physiological effects.  The classification of carbohydrate is a complicated subject due to in part to the numerous classification schemes or systems used in the past.

There are three main groups, monosaccharide, or simple sugars; oligosaccharides, of which the most prevalent in nature are the disaccharides; and polysaccharides the most complex of the carbohydrates.

All carbohydrates must be reduced to simple sugars (monosaccharides in the intestine before they can be absorbed into the bloodstream).

The most basic or simple form of carbohydrate is the monosaccharide. Typical monosaccharide are of the empirical formula (CH2O)n where n is a value between 3 and 9. The basic or archetypal monosaccharide is the six-carbon simple carbohydrate glucose. Glucose, a simple sugar, is the form in which carbohydrates circulate in the bloodstream.

Polysaccharides are large polymers of monosaccharides. Polysaccharides may consist of straight chains or branched chains having hundreds or ten thousands of monosaccharides joined together through glycosidic bonds.
Classification of carbohydrates

Popcorn nutrition

Nutritionally, air-popcorn made without oil or salt, is the best choice. Air-popped popcorn is virtually oil free: one cup provides only 30 calories and 0.4 g of fat.

Otherwise, make the popcorn with a popper which calls for only teaspoon of oil and make that oil of heart-healthy polyunsaturated or monounsaturated oil such as canola or safflower. One cup salted and with butter, provides 154 calories and 14 g of fat.

People who ate popcorn had a significantly higher total whole grain intake than non-popcorn eaters.

Popcorn contains high levels of complex carbohydrate and provides six times the amount of fiber as an equivalent amount of broccoli. The nutrient content of popcorn may be quite variable due to potential differences in varieties, soil types, growing conditions and the amount of weed seeds and foreign material in cull popcorn.

It has high proportion of hard starch which on heating, expands rapidly, resulting in an explosive rupture of the epidermis and starch granules.

Movie theater popcorn is often buttered in addition to being cooked in shortening which is saturated fat.
Popcorn nutrition 

Fibers in food

Dietary fiber includes the nondigestible carbohydrates. The major portion of dietary fiber in foods is derived from the plant cell walls in foods. These may be either water soluble or water insoluble. Soluble dietary fiber tends to dissolve or swell in water while insoluble dietary fiber remains relatively unchanged.

Gel-forming soluble fibers are readily broken down by bacteria residing in the colon, as opposed to insoluble fibers, which are largely non-fermentable. Both have nutritional significance.

The water insoluble group such as cellulose and hemicellulose are found in the outer layers of whole grains, the strings of celery, the hulls of seeds and the skins of corn kernels. These fibers retain their structure and rough texture even after hours of cooking.

The water-soluble fibers such as those found in the brans of some cereals (e.g., oats and rice) and in pectin are believed to lower the levels of serum cholesterol by binding with bile acids and causing removal of cholesterol in the feces.

Dietary fiber exerts a wide range of physiological effects when consumed, and its complex nature is responsible for a range of physical and chemical properties that are responsible for these physiological effects.

Dietary fibers are now accepted to an important ingredient of a healthy diet, and are thought to reduce the probability of cancer induction in the digestive organs.

Dietary fibers shorten the time food remains in the digestive organs, and as a result a carcinogen will remain in contact with these organs for a shorter period.

The consumptions of fiber is recommended, although not to excess. It appears that excessive amounts of dietary fiber may interfere with the retention of minerals required by the body.
Fibers in food

Digestion and absorption of carbohydrates

The carbohydrates in the diet are broken down by the enzymes on the mouth, pancreas and intestinal epithelium.

Digestion resumes in the small intestine where more polysaccharide splitting enzymes from the pancreas break the carbohydrate down completely into disaccharides. The enzyme released through the common bile duct into the small intestine.

Then enzymes on the surface of the cells of the small intestine break these into simple sugars or monosaccharaides.  Maltose is split into two glucose molecules; lactose is split into one glucose and one galactose; and sucrose into one glucose and one fructose.

However the great majority of carbohydrates in human meal are digested and absorbed as glucose, if a blood glucose levels are measured before such a meal and at half hourly intervals thereafter, it would show a rise in blood glucose, peaking at about the half hour mark and returning to fasting levels almost as quickly.

If a person were to abstain from carbohydrates for considerable periods say a week, the blood glucose levels would still be normal in spite of a minimal or zero intake.

The active absorption of glucose across the intestinal mucosa is thought to be by phosphorylation in the mucosal cell.

The body’s capacity to maintain blood glucose within specific limits is achieved by a variety of hormones, the two most important of which are insulin and glucagon. Both are secreted by the pancreas into bloodstream, as required.

When the blood glucose level arises, the body adjusts by storing the excess. The frost organ to detect the excess glucose is the pancreas, which releases the hormone insulin in response.
Digestion and absorption of carbohydrates

Carbohydrate as a source of energy

Fats and carbohydrates are equally important sources of energy when the body at rest and at low-levels of exercise, such as a slow walks.

During short term, intense exercise, carbohydrates are the main source of energy. Carbohydrates are made of carbon, hydrogen and oxygen and are classified as either simple or complex, based on the number of sugar molecules present.

Carbohydrate in the form of glycogen is the most readily available energy source. Compared to fat, carbohydrate provides energy more quickly, can be used whether or not oxygen is present and serves as the sole source of energy for the central nervous system.

During prolonged exercise, fats become the main energy source, and the shift from carbohydrate to fat utilization (carbohydrate sparing) is enhanced by physical training.

For the people of many countries, 80% of their total daily calories come from complex carbohydrates.

Carbohydrate such as starches and sugars are an efficient and readily available energy source especially for the brain. They are also necessary for fat and protein metabolism. Carbohydrates provide energy with 4 calories per gram.

Plentiful stores of carbohydrates in the body are important for excelling in physical activity, especially endurance exercise. During exercise utilization of carbohydrate accelerates an increased release for glucose from the liver is functionally important to maintain blood glucose homeostasis and to possibly attenuate muscle glycogen glycogen depletion.

If inadequate carbohydrate is available, the body burns protein for energy. This protein comes from food and from the body’s own muscle tissue.

Therefore, in cases of inadequate carbohydrate and protein intake, not only would muscle wasting occur, but adequate proteins would not be available for repair of body tissue.
Carbohydrate as a source of energy 

What does polysaccharide mean?

Polysaccharides are a class of biopolymers constituted with simple sugar monomers. It represents most of the structural and energy reserve carbohydrates found in nature.

Unlike protein, polysaccharides generally do not have definite molecular weight.

Many polysaccharides exist in the plant and animal kingdoms. However, only a few of these are known to be significant in mammalian nutrition, either as dietary constituents or as human cell metabolites.

The most common digestible polysaccharides in plant is starch, a polymer of glucose. It is composed of amylose and amylopectin. Starch is the energy compound stored predominantly in seeds and tubers. Glycogen is the animal counterpart of starch, but with shorter, more numerous branches.

The composition of starches also differs somewhat, but all types contain both amylase, a straight chain polymer of glucoses, and amylopectin, a branch chain polymer.

The average chain contains 20 to 25 glucose units with approximately 5 to 8 glucose molecules between branching points within the chain. On hydrolysis in the intestinal tract, starch yields dextrin and maltose and, eventually glucose.

Cellulose, the most abundant polysaccharide, is the structural component of plant tissues. It is the structural component of plant cell was, which consist of long chain of glucose residues.

Cellulose is not attacked by digestive enzymes of the human and although it provides bulk to the diet it does not contribute significantly to the nutrition of body cells.

It is fully permeable to water and solutes and therefore does not affect exchange of materials between the cells and the environment. Cellulose tends to be affected little by usual acid hydrolysis and requires the action of strong mineral acids.

Plants also contain indigestible hemicellulose, which are unrelated chemically to cellulose and are homopolysaccharides containing D-xylose. Homopolysaccharides are defined as polysaccharides formed from only one type of monosaccharide.

Pectin, present in fruit, is an indigestible heteropolymer and contains arabinose, galactose, and galacturonic acid. In general, heteropolysaccharides contain two or more different monosaccharides.
What does polysaccharide mean?

Monosaccharides: the basic unit of carbohydrates

Carbohydrates are the most abundant organic compounds in the plant world. The simpler members of the carbohydrate family are often referred to as saccharides because of their sweet taste. Saccharum in Latin mean ‘sugar’.

Monosaccharides are, as the name implies, the simplest of the carbohydrate and cannot be broken into smaller molecules of other carbohydrates.

Monosaccharides have a general formula Cx(H2O)y with one of the carbons being the carbonyl group of either an aldehyde or a ketone. Therefore, monosaccharides can be a polyhydroxy aldehyde or a polyhydroxy ketone.

The most common monosaccharides have three to nine carbon atoms. The three most common monosaccharides are glucose, fructose and galactose.

Glucose 
Glucose is a natural sugar found in food and also produced in the body form other simple and complex carbohydrates. Glucose containing six carbons that is present in the blood, also known as dextrose or blood sugar.

Fructose
Fructose or fruit sugar occurs naturally in fruits and honey and is converted to glucose in the body. It is often added to foods in the forms of high-fructose corn syrup. It is also called levulose or fruit sugar.

Galactose
Galactose is produced from milk sugar in the mammary glands of lactating animals and is converted to glucose in the body.

All other carbohydrates are made up of monosaccharides linked together. For instance, disaccharides are composed of two monosaccharides linked together.

A molecule of lactose, the sugar found in milk is made of two monosaccharides, galactose and glucose. Both sucrose and lactose are disaccharides.

When a large number of monosaccharides are linked together as in a molecule of starch, the result is called polysaccharide.
Monosaccharides: the basic unit of carbohydrates

Carbohydrate group of food

Carbohydrates are polyhydroxy aldehydes, ketones, alcohols, acids, their simple derivatives and their polymers having linkages of the acetal type. Most carbohydrates conform to the general formula (CH2O)n, but the classification of carbohydrates includes compounds that are not true hydrates as the names implies. 

For example, deoxyribose contains 5 carbon atoms, 10 hydrogen, but only 4 oxygen rather than 5 as is customary for pentose. Moreover, some compounds that are properly classified as carbohydrates in terms of chemical properties contain nitrogen or sulfur addition to carbon, hydrogen, and oxygen.

Carbohydrate biosynthesis in plants starting from carbon disaccharide and water with the help of light energy i.e. photosynthesis is the basis for the existence of all other organisms which depend on the intake of organic substance with food.

The major carbohydrate containing foods in the human diet are: cereal, sweeteners, root crops, pulses, vegetables, fruit, and milk products. Carbohydrates play a major role in human diets, comprising some 40-75% of energy intake. Their nutritional energy value amounts to 17 kJ/g or kcal/g. Their most important nutritional property is digestibility in the small intestine.

Carbohydrates can be classified based on their chemical structure and/or based on their physiological effects. There are three main groups, monosaccharide, or simple sugars; oligosaccharides, of which the most prevalent in nature are the disaccharides; and polysaccharides the most complex of the carbohydrates. 

Defining carbohydrates by chemical structure, does not take into account their physiological differing response, such as differences in satiety value, gastric emptying times and effects on glucose and insulin levels.

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.

Many starches do not have the functional properties needed to impart or maintain desired qualities on food products. As a result, some starches have been modified to obtain the functional properties required. These type modified starches, also known as derivates.

Sucrose ranks next in important comprising about 25% of carbohydrates intake. In the last 70 years the intake of complex carbohydrates in the diet of United States has decreased, and the intake of sucrose has markedly increased.
Carbohydrate group of food