Sorbitol

Chemical properties

Sorbitol occurs as an odorless, white or almost colorless, crystalline, hygroscopic powder.

Occurrence

Sorbitol is one of the most widely found sugar alcohols in nature with relatively high concentrations occurring in apples, pears, plums, peaches and apricots. Also reported found in several varieties of berries, seaweed and algae.

The Uses of Sorbitol

Sorbitol is highly hygroscopic and has a pleasant, sweet taste. It maintains moistness in shredded coconut, pet foods, and candy. In sugarless frozen desserts, it depresses the freezing point, adds solids, and contributes some sweetness. It is used in low-calorie beverages to provide body and taste. It is used in dietary foods such as sugarless candy, chewing gum, and ice cream. It is also used as a crystallization modifier in soft sugar-based confections.
Besides, it can be used in manufacture of sorbose, ascorbic acid, propylene glycol, synthetic plasticizers and resins; as humectant (moisture conditioner) on printing rolls, in leather, tobacco. In writing inks to insure a smooth flow and to prevent crusting on the point of the pen. In antifreeze mixtures with glycerol or glycols.

Background

A polyhydric alcohol with about half the sweetness of sucrose. Sorbitol occurs naturally and is also produced synthetically from glucose. It was formerly used as a diuretic and may still be used as a laxative and in irrigating solutions for some surgical procedures.

Definition

Sorbitol is a hexahydric alcohol that occurs in rose hips and rowan berries. It can be synthesized by the reduction of glucose. Sorbitol is used to make vitamin C (ascorbic acid) and surfactants. It is also used in medicines and as a sweetener (particularly in foods for diabetics). It is an isomer of mannitol.

Production Methods

Sorbitol occurs naturally in the ripe berries of many trees and plants. It was first isolated in 1872 from the berries of the Mountain Ash (Sorbus americana).
Industrially, sorbitol is prepared by high-pressure hydrogenation with a copper–chromium or nickel catalyst, or by electrolytic reduction of glucose and corn syrup. If cane or beet sugars are used as a source, the disaccharide is hydrolyzed to dextrose and fructose prior to hydrogenation.

Pharmaceutical Applications

Sorbitol is widely used as an excipient in pharmaceutical formulations. It is also used extensively in cosmetics and food products. It may also be used analytically as a marker for assessing liver blood flow.

Safety Profile

Mildly toxic by ingestion. Human systemic effects by ingestion: hypermotility and diarrhea. Mutation data reported. When heated to decomposition it emits acrid smoke and irritating fumes.

Safety

Sorbitol is better tolerated by diabetics than sucrose and is widely used in many sugar-free liquid vehicles. However, it is not considered to be unconditionally safe for diabetics.
Reports of adverse reactions to sorbitol are largely due to its action as an osmotic laxative when ingested orally,(17–19) which may be exploited therapeutically. Ingestion of large quantities of sorbitol (>20 g/day in adults) should therefore be avoided.

Side Effects

There are no formal recommendations for sorbitol intake. Fermentation of sorbitol in the large intestine can create gastrointestinal discomfort including bloating, gas and diarrhea. But these effects are not the same for everyone. Therefore, the FDA requires a label statement regarding potential laxative effects for foods that might lead to eating 50 grams of sorbitol in a day.
For those following a low Fermentable Oligosaccharides Disaccharides Monosaccharides And Polyols (FODMAP) diet, food sources of sorbitol are monitored because sorbitol is a type of polyol.

Storage

Sorbitol is chemically relatively inert and is compatible with most excipients. It is stable in air in the absence of catalysts and in cold, dilute acids and alkalis. Sorbitol does not darken or decompose at elevated temperatures or in the presence of amines. It is nonflammable, noncorrosive, and nonvolatile.

Incompatibilities

Sorbitol will form water-soluble chelates with many divalent and trivalent metal ions in strongly acidic and alkaline conditions. Addition of liquid polyethylene glycols to sorbitol solution, with vigorous agitation, produces a waxy, water-soluble gel with a melting point of 35–40℃. Sorbitol solutions also react with iron oxide to become discolored.
Sorbitol increases the degradation rate of penicillins in neutral and aqueous solutions.