Sources of starch

Starch derived from Middle English sterchan, meaning to stiffen, which is appropriate since it can be used as a thickening agent when dissolved in water and heated. In several languages, starch is known as sago or sagu; consequently, in English sago now refers to several different starches (see Sago (disambiguation)). Starch is basically long chains of glucose molecules which all have different heights and weights.

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Granules of wheat starch, stained with iodine, photographed through a light microscope

Starch is a white powder, and depending on the source, may be tasteless and odorless. Microscopically, starch grains are fine crystals or lumps; the precise form of these grains varies within the plant kingdom. Today, commercial starches include cornstarch, arrowroot, potato starch, sago and tapioca. Historically they included Florida arrowroot.

[edit] Uses

Starch in its basic refined form is used in cooking to thicken foods such as sauces. 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 also used in the form of flakes, sticks, and pearls (tapioca and sago).

[edit] Food

Starch is by far the most consumed polysaccharide in the human diet. Traditional staple foods such as cereals, roots and tubers are the main source of dietary starch.

The technical term for a colorless, tasteless, odorless, and edible starch is a fecula.

Starch is often found in the fruit, seeds, rhizomes, and tubers of plants, and is the major source of energy in these food items. The major resources for starch production and consumption worldwide are rice, wheat, corn, and potatoes. Fresh chestnut has twice as much starch as potato. As the chestnut ripens, some of its starch is gradually converted into sugars.^[2] 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, regular household potatoes, 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, which 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.

Resistant starch is starch that escapes digestion in the small intestine of healthy individuals.

Plants use starch as a way to store excess glucose, and thus also use starch as food during mitochondrial oxidative phosphorylation.

Starch

Starch, CAS# 9005-25-8, chemical formula (C₆H₁₀O₅)_n, is a polysaccharide carbohydrate consisting of a large number of glucose monosaccharide units joined together by glycosidic bonds. All plant seeds and tubers contain starch which is predominantly present as amylose and amylopectin. Depending on the plant, starch generally contains 20 to 25 percent amylose and 75 to 80 percent amylopectin.^[1].