Starch in food

Plants use water, carbon dioxide and energy from the sun to form simple sugars through a process called photosynthesis. When the sugar chains gather in large quantities inside a plant’s cells, they form starch grains, also called starch granules.

Starch is deposited in granules in almost all green plant and in various types of plant tissues and organs, e.g leaves, roots, shoots, fruits, grains and stems.

Grains are the riches food source of starch, providing much of the food energy for people all over the world. Starch may be produced from potatoes, rice, tapioca, or wheat by methods similar to corn, except that with potatoes and tapioca it is not necessary to degerm the product.

Starch is valuables because it can break down into simple sugars that provide human with sustained energy and keep them feeling full and satisfied.
Starch in food

Carbohydrates content in rice

As a food material rice is nutritious and easily digestible. In comparison with other grains it is poor in nitrogenous material and fat, and correspondingly rich in non-nitrogenous substances or carbohydrates.

Cleaned rice contains 79% carbohydrate. Carbohydrate of rice is predominantly starch, with small portions of pentosans, hemicelluloses and sugars. As in most starches, both of the major components (amylase and amylopectin) occur generally in rice starch.

Sugars comprise some 0.3 to 0.5% of white rice and about 0.6 to 1.4%b of brown rice. Reducing sugars (maltose) increase and non-reducing sugars (sucrose) decrease during storage. The degradation of carbohydrates to CO2 is usually very small, but it may become significant at moisture more than 14%.

The changes of free carbohydrate content are greatly influenced by temperature. Maillard’s browning reaction between free carbohydrates and free amino acids may play a significant role in CO2 formation.

Fiber is a carbohydrate and is also a carbohydrate blocker. In other words, it slows down the absorption of digestible carbohydrates.
Carbohydrates content in rice

Glycosidic bond of sugar unit

Polysaccharides chains are generally formed by a repeated sequence of monomers or oligomers. Few monosaccharides exist in the free state. They generally occur linked by glycosidic bond to one another or to an aglycones.

The term ‘glycosidic bond’ is used for the bond between the anomeric C-atom and the glycosidic O (N-, S,) atom.

While the term ‘glycosidic linkage is used to define a set of all bonds that connects to monosaccharide rings.

It is a bond that links two sugar units together; it is formed between the free carbonyl group of one sugar and a hydroxyl group of another sugar; the orientation (α or β) and position (eg. 1,4) of the link must be specified. The structure of a di-, oligo- or polysaccharide sugar is based on the bonding of two monosaccharides.

In the case of a disaccharide, two monosaccharides are joined with loss of one molecule of water. This joining occurs between two –OH groups, one of each monosaccharide.
Glycosidic bond of sugar unit

Sugar compounds

Sugars and carbohydrates are now commonly referred termed saccharides. The name derived from the Latin word saccharum, meaning ‘sugar’.

The compound sugars are made up of two or more molecules of monosaccharides and are further divided into two broad categories: oligosaccharides and polysaccharides.

Oligosaccharides and polysaccharides comprise two, several or many monomeric sugars covalently linked to each other by glycosidic bonds. Glycosidic bonds may have one of two orientations, termed alpha and beta.

Oligosaccharides, which are composed of two to nine, include sucrose (a disaccharide) and raffinose (a tri-saccharide).

The most common of the oligosaccharides is sucrose which contains two glycosidic-linked sugars, glucose and fructose. Some oligosaccharides serve storage functions a-in cells (e.g. sucrose, raffinose), whereas others accumulate as breakdown products from polysaccharides (e.g. maltose from starch, cellobiose from cellulose).

The polysaccharides are yield more than 1o molecules of monosaccharides on hydrolysis. They may be separated into three broad groups:
Homopolysaccharides (one kind of monosaccharide unit)
Heteropolysaccharides (two or more kinds of monosaccharides)
Nitrogen containing polysaccharides

Homopolysaccharides are composed of just one type of monosaccharide and heteropolysaccharides are built from more than one type. Typically, heteropolysaccharides molecule will be constructed from very few different monosaccharides.

The monosaccharides and disaccharides are sweet tasting and soluble in water. In contrast, the polysaccharides are colloidal, dispersible under certain conditions in water tasteless and vary greatly in digestibility.
Sugar compounds 

The sugar of sorbitol

Sorbitol is a fined chemical that can be obtained after catalytic hydrogenation of glucose solution derived from starch. It is often used as vehicle in syrups and elixirs containing antihistamines, phenobarbital, vitamin B12 and other drugs.

Sorbitol is widely used in the pharmaceutical industry as a sweetening agent, moistening agent and a diluents.

Sorbitol is a sugar alcohol occurs naturally in the many stone fruits such as plums and ripe berries of many fruits, trees and plants.

The body can make it from glucose. It was first isolated in 1872 from the berries of the European mountain ash. The body only partly absorbs sorbitol. The unabsorbed part pulls water into the large intestine, causing distention that stimulates the muscle of the bowel and translates into the urge to have a bowel movement.

Sorbitol also acts as a fuel for bacteria that create lots of nasty gas.

Sorbitol is metabolized in the liver to fructose, but is also eliminated unchanged by the kidneys.

Sorbitol has a caloric value of 4 kcal/g and is better tolerated by diabetics than sucrose: however, because some of it is metabolized to glucose it is no unconditionally safe for diabetics.

Sorbitol can be found in some laxatives that treat constipation and it’s often used as a sweeteners in ‘diet’ foods and sugar free chewing gum.

Sorbitol can be found in toothpaste and other oral care products as the primary sweetener. The role of oral care products is to prevent tooth decay.

Sorbitol does not lower the pH of the mouth and cannot be utilized by the microorganisms that dominate in dental plaque, so it will not promote the growth of bacteria that can lead to tooth decay.

The sugar of sorbitol