Most organic acids are very weak. A neutralization reaction occurs and leaves the organic equivalent of a salt. Esters usually have a pleasant fruit-like flavor. Carbohydrates are compounds of carbon, hydrogen, and oxygen that have two atoms of hydrogen for each atom of oxygen. Two simple sugars are often linked to form a disaccharide .
Polysaccharides are complex sugars consisting of chains of the simple sugars.
In living things, polysaccharides serve both as structural components and as a source of stored energy. Starch is another polysaccharide of 300 to 1000 glucose units that is used to store energy. Chitin is another polysaccharide used by insects and sea creatures with shells to form a strong outer layer. Glycogen is a polysaccharide used to store energy in the liver and muscles of animals. Sugars are used by animals and plants which recover the energy of formation by a controlled process of oxidation.