Saccharose

Sucrose, or sucrose, is a disaccharide made up of glucose and fructose.

Its chemical name is α-D-Glucopyranosyl - (1→2) - β-D-Fructofuranoside, and its formula is C₁₂H₂₂O₁₁.

It is a disaccharide that has no reducing power over Fehling's reagent and Tollens' reagent.

Sucrose crystal is transparent, the white color is caused by multiple diffraction of light in a group of crystals.

common sugar or table sugar is the sweetener most commonly used to sweeten foods and is usually unrefined sucrose. In nature it is found in 20% of the weight of sugar cane and 15% of the weight of sugar beets, from which table sugar is obtained. Honey is also a fluid that contains a large amount of partially hydrolyzed sucrose.

Structure and function

Sucrose, table sugar or cane sugar, is a disaccharide of glucose and fructose. It is synthesized in plants, but not in higher animals. In a sucrose molecule there are a total of 45 atoms, since its formula is C₁₂H₂₂O ₁₁. It does not contain any free anomeric carbon atoms (negative in Fehling's reagent), since the anomeric carbons of its two constituent monosaccharide units are linked together, covalently through an O-glycosidic bond. For this reason, sucrose is not a reducing sugar and does not have a reducing end.

Its short name can be written as Glc(a -1à 2)Fru or as Fru(b 2à 1)Glc. Sucrose is a main intermediate product of photosynthesis, in various plants it is the main form of transport of sugar from the leaves to other parts of the plant. In plant sprouts, stored fats and proteins are converted to sucrose for transport out of the developing plant.

A curious thing about sucrose is that it is triboluminescent, which means that it produces light by mechanical action. It has a rotary power of +66.

Link characteristics

The bond that joins the two monosaccharides is of the O-glycosidic type. Furthermore, this bond is dicarbonyl since the two reducing carbons of both monosaccharides form the alpha(1-2) bond of alpha-D-glucose and beta-D-fructose.

The enzyme in charge of hydrolyzing this bond is sucrase, also known as invertase, since hydrolyzed sucrose is also called invert sugar.

Sucrose's main function in the human body is to help generate energy and transport carbohydrates.

Sucrose as a nutrient

Sucrose is used in foods for its sweetening power. Its caloric value is even below the "4 kilocalories/gram" of carbohydrates in general; being in the case of sucrose 1,619 kJ or 387 Kcal / 100 grams. Upon reaching the stomach, it undergoes acid hydrolysis and a part is broken down into its glucose and fructose components. The rest of the sucrose passes into the small intestine, where the enzyme sucrase converts it into glucose and fructose.

There are many controversies about the harm caused by sucrose consumption, and several theories about it. The biggest debate is focused on the production of cavities, type 2 diabetes (in no case does type 1 diabetes have to do with sugar consumption), obesity, arteriosclerosis, and other pathologies.

However, its specific properties as a nutrient for the human body have been highlighted: it is easily digested and does not generate toxic products during its metabolism.

The glycemic index that it may contain is discussed, but in general it is assumed that it is very high, because after its consumption, the blood glucose level increases significantly, triggering a high secretion of insulin, which with the time can be harmful to health. Due to its pleasant taste, human beings tend to consume it excessively, which rarely occurs in nature. However, in industrialized society, its availability is high and its price is low, so it easily exceeds the reasonable limits of its consumption. As a result, sucrose is limited in the diet for health reasons, since uncontrollably high consumption produces a high glycemic load.

Sucrose metabolism

Sacarosa granulada.

In humans and other mammals, sucrose is broken down into its two constituent monosaccharide sugars, glucose and fructose, by the action of the enzymes sucrase or isomaltase (glucosidases), which are located in the cell membrane of microvilli. duodenum. As a result, glucose and fructose molecules are absorbed into the bloodstream.

Consuming large amounts of sucrose is linked to diseases such as tooth decay, because bacteria in the mouth convert sugars into acids that attack tooth enamel.

Sucrose, as a pure carbohydrate, contains 3.94 kilocalories per gram, or 17 kilojoules per gram. When large amounts of sucrose-containing foods are consumed, beneficial nutrients can be displaced from the diet, contributing to health problems. It has been suggested that the sucrose contained in beverages (such as soft drinks) is related to obesity and could be related to insulin resistance.

Sucrose may contribute to the development of metabolic syndrome. In an experiment, rats that were fed a diet in which one-third of their food was sucrose first showed elevated levels of triglycerides, which generated visceral fat, followed by insulin resistance. Another study in rats found that a diet high in sucrose developed hypertriglyceridemia, hyperglycemia, and insulin resistance.

Precautions

When sucrose is heated, it melts into a liquid state. Due to its low melting point, this process occurs very quickly, and it adheres to the container that contains it easily.

As mentioned, excessive consumption can cause obesity, type 2 diabetes, cavities, or even tooth loss. There are people who suffer from sucrose intolerance, due to a lack of the enzyme sucrase, and who cannot take sucrose, since it causes intestinal problems.

Commercial use

Sucrose is the most widely used sweetener in the industrialized world, although it has been partly replaced in industrial food preparation by other sweeteners such as glucose syrups, or by combinations of functional ingredients and high intensity sweeteners.

It is usually extracted from sugar cane, beetroot or corn and then purified and crystallized. Other (minor) commercial sources are sweet sorghum and maple syrup.

The extensive use of sucrose is due to its sweetening power and its functional properties such as consistency. For this reason it is important for the structure of some foods including rolls and cookies, fruit ice creams and sorbets, it is also an aid in food preservation, being an additive commonly used in the preparation of so-called junk food.