Edited by Roberto Eusebio
Carbohydrates, also called (improperly) carbohydrates, are chemical substances composed of carbon, hydrogen and oxygen, and can be defined as aldehyde and ketone derivatives of polyvalent alcohols.
Functionality
requirement
Because the body has the ability to synthesize carbohydrates from other nutrients, carbohydrates cannot properly be considered essential nutrients; however, there is a need to maintain the blood sugar level within a range of values appropriate to the needs of the central nervous system and erythrocytes (red blood cells).
The total recommended intake of carbohydrates is around 40-60% of the total energy. However, the consumption of simple sugars should not exceed 10-12% of total calories. The simple added sugars, in fact, provide only energy, while the foods containing complex carbohydrates - in addition to supplying slower-release energy than simple ones - also provide other fundamental nutrients for the general balance of the diet. This aspect is relevant above all in the case in which it is necessary to maintain the global energy supply within relatively modest limits, as also required by the current lifestyle, characterized on average by a sedentary lifestyle.
Chemicals of carbohydrates and food sources
They are chemical substances composed of carbon, hydrogen and oxygen and can be defined as aldehyde and ketone derivatives of polyvalent alcohols. In relation to their complexity they are classified into:
1) Monosaccharides: they contain from 3 to 9 carbon atoms and are the simplest structures belonging to the family of carbohydrates. Monosaccharides of biological importance include glucose, fructose and galactose. Glucose is scarcely present in nature, except for very small amounts in fruit and vegetables. Fructose is present as such in fruit and honey.
2) Disaccharides: they can be considered as the union of two molecules of monosaccharides bound together by glycosidic bonds. Disaccharides of biological importance include sucrose, lactose and maltose. Sucrose is composed of glucose and fructose and is found in fruit, especially beet and cane, from which it is extracted to produce table sugar. Lactose is contained in milk and is made up of glucose and galactose. Maltose (glucose and glucose) comes from the fermentation (or digestion) of starch.
3) Oligosaccharides: the term oligosaccharides is generally used for compounds formed from 3 to 10 monosaccharides. The oligosaccharide family includes sugars such as raffinose, stachiosio and non-digestible verbascose, composed of galactose, glucose and fructose and contained mainly in legumes. The production of gas following the fermentation of these sugars in the large intestine explains the meteorism caused above all in some subjects by the consumption of leguminous products.
4) Polysaccharides: the term polysaccharides is generally used for compounds formed by more than 10 monosaccharides. Starch is the reserve (energetic) polysaccharide of the plant world. The main sources of starch are cereals (bread, pasta, rice) and potatoes. It is present in the form of granules with a semi-crystalline structure: cooking food alters this structure (gelatinization process), making the starch digestible; on the contrary, the cooling of food, which leads to partial phenomena of starch recrystallization, partially reduces its digestibility.
Glycogen is a polysaccharide carbohydrate of animal origin. It is therefore found in meat foods (horse meat, liver), but its content is devoid of nutritional significance being present in very small quantities: after the death of the animal, glycogen turns rapidly into lactic acid due to anoxia ( absence of oxygen).
