Products
Starch is available as a pure substance in grocery stores (e.g., Maizena, Epifin), pharmacies, and drugstores, among other places.
Structure and properties
Starch is a polysaccharide and a carbohydrate composed of D-glucose units that are α-glycosidically linked. The contains amylopectin (about 70%) and amylose (about 30%), which have different structures. Amylose consists of unbranched chains, whereas amylopectin is branched. Starch is usually extracted from tubers or from the clods of grasses (caryopses). Typical examples are potato starch (Solani amylum), maize starch (Maydis amylum), rice starch (Oryzae amylum) and wheat starch (Tritici amylum). Another example is cassava starch. Starch serves as an energy store for plants. It is roughly equivalent to glycogen in humans. Starch exists as an odorless and tasteless powder that crunches between the fingers when rubbed. It is virtually insoluble in cold water.
Effects
Starch has binding, swelling, stabilizing, and thickening properties. When added to warm water, it forms a viscous solution that solidifies into a gel or paste when cooled. In the mouth and intestines, starch is broken down by the enzyme amylase.
Fields of application (selection)
- Starches are found in many foods, for example, in wheat, corn, and potatoes. They are a component of staple foods such as flour, bread and cereals.
- For the production of processed foods, for example, for the preparation of sauces, creams and soups, for shortbread and biscuit dough, for meat, baby food and for beer production.
- As a pharmaceutical excipient, for example, as a filler, as a disintegrant, as a binder, as an ointment base.
Adverse effects
Starch has a high caloric value of about 360 to 380 kcal per 100 g.