Characterization of sugars

Sugars are compounds made of C, H, and O. We divide them into simple (monosaccharides) and complex ones, including disaccharides and polysaccharides. 

Monosaccharides are sugars having 3-7 carbon atoms in the molecule. From the nutritional point of view, the most important are 6-carbon sugars 






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Disaccharides are composed of two molecules of simple sugars linked by a glycosidic bond. These are 

– maltose – consisting of two molecules of glucose, 

– sucrose – consisting of one glucose molecule and one fructose molecule, 

– lactose – consisting of one molecule of glucose and one galactose, 

– cellobiose – consisting of two glucose molecules connected by a b-glycosidic bond. 


Polysaccharides consist of many linked glycoside molecules of simple sugars.

The most important are starch and glycogen, which are made up of many thousands of glucose molecules connected by a-glycosidic bond and cellulose composed of many glucose molecules connected by a b-glycosidic bond 

Glucose is grape sugar. It is found in vegetable juices, honey, fruits and flowers. In animals and humans, it is stored as a spare form (glycogen) in the muscles and liver. In human blood it is about 0.1%. 

Fructose is a fruit sugar. It is contained in honey and fruits. In the human body it is rapidly metabolized or converted to glucose. 

Galactose – a component of milk sugar – lactose, rarely occurs in the free state. 

Mannose – a component of sugars combined with proteins. 

Sucrose – cane or beet sugar. It is commonly used to sweeten drinks and dishes. 

Lactose – sugar contained in milk. 

Maltose – malt sugar (malt is included in cereal grains of barley) 

Starch – is contained in cereal grains, potatoes, legume seeds (peas, beans). 

Cellulose – is the main building material for plants. 


Cellulose, pectins, hemicelluloses, lignin, gums and sluices are so-called fiber.

It is not digested in the human digestive tract due to the lack of adequate enzymes. It is very important, although it does not have a nutritional function. It improves intestinal peristalsis, thus preventing the retention of food and its decay. It also has the ability to bind water, so it increases the volume of feces to prevent colon cancer. Absorbs cholesterol on its surface, acting counter-atherosclerosis. Fiber is also a nutrient for symbiotic bacteria living mainly in the large intestine. These bacteria are a source of valuable vitamins, amino acids and hormones. 

Our diet should be rich in complex sugars, primarily in the starches, which are contained in dark, wholegrain bread, pasta, groats, pulses, fruits and vegetables. Starch digestion takes place gradually, and the released glucose slowly penetrates into the blood. You should limit the intake of simple sugars and sucrose, because they do not require digestion (or are digested easily like sucrose) and quickly pass into the bloodstream. Large intake may lead to hyperglycaemia (increased blood sugar levels). The correct blood sugar level is 90-125 mg / dl. The daily requirement of the body for carbohydrates is 5-6 g / kg of body weight and depends on the amount of energy consumed. Excess sugars in the diet (especially simple ones) are converted into fats, which are stored in adipose tissue. 



Glucose, also known as grape sugar with the formula C6H12O6, is a simple sugar found in all living organisms both in free form and as a component of many more complex agents. In plants, glucose is formed by photosynthesis. Animals and human beings meet their glucose demand by taking it in free form as well as as a component of compound sugars, along with food. Glucose supplies the main part of energy to life processes. It is also a substrate in many metabolic reactions. Glucose in the human body is the only simple sugar found in a greater quantity, because all other sugars that we eat are converted into glucose by the liver. In the human body is the only form of transport of sugars and its concentration in the blood must be kept constant (about 0.1 in relation to body weight). The decrease in the concentration of this sugar increases the excitability of certain brain cells, which may be manifested in cramps, seizures, loss of consciousness and even death. In turn, in certain disorders of the sugar metabolism in the body, called diabetes, glucose in the blood stays at an elevated level. Constant blood glucose concentration is preserved thanks to the highly complex biochemical mechanism. 



Fructose, also called fruit sugar, is another very widespread simple sugar. Fructose is a ketosis. It has the same sum pattern as glucose, but the other mutual arrangement of atoms in the molecule. Fructose is thus a glucose isomer. In the free state occurs in many fruits and honey. Fructose is an easily digestible food ingredient. They are used as a sweetening agent in diabetes and in the treatment of myocardial insufficiency. Fructose is the sweetest of sugars. In fact, not all sugars are equally sweet. To sweeten a specific portion of food with fructose, it is enough to take it almost twice less than sucrose. Speaking of the ability to sweeten, it is worth realizing that there are chemical compounds – having nothing to do with sugars – characterized by a huge sweetness. The popular saccharin, a synthetic sweetener, used by people with diabetes, is sweeter than ordinary sugar 550 times. In other words, you would have to spill over half a ton of our sugar used in the household to get the sweetening effect of one kilogram of saccharin. 




The disucciner with the greatest practical application is sucrose, i.e. the everyday nutrition sugar known from everyday life. Because sucrose is a disaccharide, it’s easy to guess that its molecule consists of two molecules of sugars – a simple glucose molecule and a fructose molecule. However, the total sucrose pattern is not simply doubling the glucose or fructose pattern. When the two molecules of sugars combine in a two-bowl, a water molecule is separated. Thus, the sucrose total formula takes the form C12H22O11. Sucrose, a white, crystalline substance, perfectly soluble in water, was known in India and China several thousand years ago. In 1494, the cultivation of sugar cane was transferred to Santo Domingo, and then to Cuba, Brazil and Mexico. In the sixteenth, sugar was brought to Europe, but its high price forced to look for a plant rich in this compound and well enduring a cold climate. In 1747 A. Marggraf won a crystalline sucrose from sugar beet. 

In Poland, sucrose was used quite late, because only in the early nineteenth century. Previously, the sweetener was honey bee. Obviously, global sugar production exceeds 100 million tons per year. Poland is one of the sucrose producers of sucrose. 




Lactose (milk sugar) C12H22O11, disaccharide build. from D-galactose and D-glucose residues found in the milk of all mammals (human milk 6.7%, cow 4.5%), obtained as whey by-product in the cheese industry; lactose is white crystalline. a substance with a slightly sweet taste (3 times less sweet than sucrose); in water, it is not fermented by ordinary yeast; it is used as a component of milk and baby foods as well as a filler in the farm industry; lactose can not be eaten by people whose body is unable to absorb the resulting galactose, it accumulates in the body and is the cause of the disease – galactosemia. 




Maltose (malt sugar) C12H22O11, a disaccharide composed of two molecules of D-glucose; formed from starch and glycogen under the action of diastase or amylase enzyme or as an intermediate hydrolysis; further acid hydrolysis of maltose or the action of the maltase enzyme leads to D-glucose; maltose is a white, crystalline substance, less sweet than sucrose (0.6 sweetness of sucrose); its large amounts are found in malt and intermediate products of the fermentation industry (mash, wort, starch syrup). 




Cellulose is a plant polysaccharide composed of several thousand glucose molecules connected in a non-branched chain. Pure cellulose is a white, water-soluble substance. It is a podtaval element of the plant cell wall, gives the tissues mechanical strength and flexibility. Some plant fibers (flax, cotton) are almost pure cellulose; in wood, the cellulose content reaches 50 percent. For this reason, cellulose is the largest organic compound on Earth. 

It is worth knowing that no mammal produces the cellulase enzyme needed to digest cellulose. Thus, in the human gastrointestinal tract and carnivorous animals, cellulose is not degraded. In contrast, herbivores can digest it, because in their digestive tract there are bacteria and protozoa that produce the enzyme needed. 




Skrobie is also a plant polysaccharide. Similar to cellulose is composed only of glucose molecules, but they combine in a different way. In addition, the starch is a mixture of two unopened amylose polysaccharides 7 and branched amylopectin 8. Starch is the most important spare polysaccharide in plants that store it in fruits, seeds, roots and rhizomes. Starch grains and potato tubers are particularly rich in starch. Starch occurs in the form of grains with a characteristic appearance, different for individual plant species. It is a white solid, devoid of taste and smell. Insoluble in cold water, in a hot form creates a colloidal solution called starch glue, which, after cooling, thickens. This phenomenon is used in the preparation of jelly and pudding. The characteristic feature of starch is its ability to create a violet-blue color with iodine. Under the influence of heating, its color disappears to appear again after cooling the gruel. 



We divide the starch into 

amylose – a non-branched starch component. It consists of glucose molecules ranging from several hundred to several thousand. Amylose molecules, although not branched, do not form a long chain, but have a screw shape. There are 6 units of glucose per bolt. 

amylopectin – a branched starch component. Simple chains with a length of several dozen to several hundred glucose residues are linked together to form a branched structure. Branches in the amylopectin molecule appear on average every 8 – 10 glucose residues. 


The third important glucose, consisting solely of glucose molecules, is glycogen, also known as animal starch. The comparison to starch results, firstly, from the structural similarity of glycogen to amylopectin, and secondly, from its function. Glycogen is the main form of sugar storage in animals and in this respect is equivalent to starch in plants. Occur mainly in the liver (up to 6 percent of its mass) and in the muscles (about 1 percent). Due to the greater amount of muscle mass, muscle glycogen is a 3 to 4-fold greater mass than hepatic glycogen. 

Muscle glycogen is a source of glucose processed in the muscles themselves. This process aims to energize the energy needs of the muscles in their work. Liver glycogen stores the glucose necessary to maintain a constant, physiological concentration of this compound in the blood between meals. This is not a big store. For a dozen or so hours they will not get sugar in the body in meals, and the liver will become almost completely devoid of glycogen. And then the body incorporates other metabolic mechanism mechanisms. 


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