Starch

Starch (CAS# 9005-25-8) is a complex carbohydrate which is soluble in water; it is used by plants as a way to store excess glucose and can be used as a thickening agent when dissolved and heated. The word is derived from Middle English sterchen, meaning to stiffen. The formula for Starch is C6H10O5.

In terms of human nutrition, starch is by far the most important of the polysaccharides. It constitutes more than half the carbohydrates even in affluent diets, and much more in poorer diets. It is supplied by traditional staple foods such as cereals, roots and tubers.

Starch (in particular cornstarch) is used in cooking for thickening foods such as sauce. In industry, it is used in the manufacturing of adhesives, paper, textiles and as a mold in the manufacture of sweets such as wine gums and jelly beans. It is a white powder, and depending on the source, may be tasteless and odourless.

Starch contains a mixture of two molecules: amylose and amylopectin. Usually these are found in a ratio of 30:70 or 20:80, with amylopectin found in larger amounts than amylose.

Starch is often found in the fruit, seeds, rhizomes or tubers of plants. The major resources for starch production and consumption worldwide are rice, wheat, corn, and potatoes. Cooked foods containing starches include boiled rice, various forms of bread and noodles (including pasta).

As an additive for food processing, arrowroot and tapioca are commonly used as well. Commonly used starches around the world are: arracacha, buckwheat, banana, barley, cassava, kudzu, oca, sago, sorghum, sweet potato, taro and yams. Edible beans, such as favas, lentils and peas, are also rich in starch.

When a starch is pre-cooked, it can then be used to thicken cold foods. This is referred to as a pregelatinized starch. Otherwise starch requires heat to thicken, or "gelatinize." The actual temperature depends on the type of starch.

A modified food starch undergoes one or more chemical modifications that allow it to function properly under high heat and/or shear frequently encountered during food processing. Food starches are typically used as thickeners and stabilizers in foods such as puddings, custards, soups, sauces, gravies, pie fillings, and salad dressings, but have many other uses.