and chemical properties
sucrose is most often prepared as a fine, colorless, odorless crystalline powder
with a pleasing, sweet taste. Large crystals are sometimes precipitated from water
solutions of sucrose onto a string (or other nucleation surface) to form rock
candy, a confection.
other carbohydrates, sucrose has a hydrogen to oxygen ratio of 2:1. It consists
of two monosaccharides, Î±-glucose and fructose, joined by a glycosidic bond between
carbon atom 1 of the glucose unit and carbon atom 2 of the fructose unit. What
is notable about sucrose is that unlike most polysaccharides, the glycosidic bond
is formed between the reducing ends of both glucose and fructose, and not between
the reducing end of one and the nonreducing end of the other. The effect of this
inhibits further bonding to other saccharide units. Since it contains no free
anomeric carbon atom, it is classified as a nonreducing sugar.
melts and decomposes at 186 °C to form caramel, and when combusted produces carbon,
carbon dioxide, and water. Water breaks down sucrose by hydrolysis, however the
process is so gradual that it could sit in solution for years with negligible
change. If the enzyme sucrase is added however, the reaction will proceed rapidly.
sucrose with sulfuric acid dehydrates the sucrose and forms elemental carbon,
as demonstrated in the following equation:
- C12H22O11 + H2SO4 catalyst --->12 C + 11 H2O
production and use
is the most common food sweetener in the industrialized world, although it has
been replaced in industrial food production by other sweeteners such as fructose
syrups or combinations of functional ingredients and high intensity sweeteners.
is the most important sugar in plants, and can be found in the phloem sap. It
is generally extracted from sugar cane or sugar beet and then purified and crystallized.
Other (minor) commercial sources are sweet sorghum and sugar maples.
is ubiquitous in food preparations due to both its sweetness and its functional
properties; it is important to the structure of many foods including biscuits
and cookies, ice cream and sorbets, and also assists in the preservation of foods.
As such it is common in many processed and so-called junk foods.
as a macronutrient
beings, and in fact most other mammals except felines, which lack the ability
to taste sweetness will typically accept food sweetened with sucrose even if they
are not hungry. In mammals, sucrose is very readily digested in the stomach into
its component sugars, by acidic hydrolysis. This step is performed by a glycoside
hydrolase, which catalyzes the hydrolysis of sucrose to the monosaccharides glucose
and fructose. Glucose and fructose are rapidly absorbed into the bloodstream in
the small intestine. Undigested sucrose passing into the intestine is also broken
down by sucrase or isomaltase glycoside hydrolases, which are located in the membrane
of the microvilli lining the duodenum. These products are also transferred rapidly
into the bloodstream. Sucrose is digested by the enzyme invertase in bacteria
and some animals.Acidic hydrolysis can be used in laboratories to achieve the
hydrolysis of sucrose into glucose and fructose.
is an easily assimilated macronutrient that provides a quick source of energy
to the body, provoking a rapid rise in blood glucose upon ingestion. However,
pure sucrose is not normally part of a human diet balanced for good nutrition,
although it may be included sparingly to make certain foods more palatable. Overconsumption
of sucrose has been linked with some adverse health effects. The most common is
dental caries or tooth decay, in which oral bacteria convert sugars (including
sucrose) from food into acids that attack tooth enamel. Sucrose, as a pure carbohydrate,
has a high food energy content (4 kilocalories per gram or 17 kilojoules per gram),
and thus can make a diet hypercaloric even in small amounts, contributing to obesity.
The rapidity with which sucrose raises blood glucose can cause problems for people
suffering from defects in glucose metabolism, such as persons with hypoglycemia
or diabetes mellitus. Sucrose can contribute to development of the metabolic syndrome.
An experiment with rats that were fed a diet one-third of which was sucrose may
serve as a model for the development of the metabolic syndrome. The sucrose first
elevated blood levels of triglycerides, which induced visceral fat and ultimately
resulted in insulin resistance.
Satoshi Fukuchi (2004). "Role of Fatty Acid
Composition in the Development of Metabolic Disorders in Sucrose-Induced Obese
Rats". Experimental Biology and Medicine 229 (6): 486-493. PMID
J.; Edelman, J., Hough, L. (1973). Sugar - Chemical, Biological and Nutritional
Aspects of Sucrose. The Butterworth Group. ISBN