Information AboutStarch |
| CATEGORIES ABOUT STARCH | |
| nutrition | |
| printing | |
| polysaccharides | |
| edible thickening agents | |
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The word is Derived from Middle English ''sterchen'', meaning to stiffen, which is appropriate since it can be used as a thickening agent when dissolved in water and heated. The chemical formula for Starch is (C6H10O5)n, Raven, P.; Evert, R.; Eichhorn, S. (1999) ''Biology of Plants'' (6th edition) p. 910 Worth Publishers. ISBN 1-57259-041-6, as it is a Polymer of Glucose . In terms of Human Nutrition , starch is by far the most important of the Polysaccharides . It constitutes more than half the carbohydrates even in many 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 Adhesive s, Paper , Textile s 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 Taste less and Odour less. 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 , Seed s, Rhizome s or Tuber s of Plant s. 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 , 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. Resistant Starch is starch that escapes digestion in the small intestine of healthy individuals. NON-FOOD APPLICATIONS Papermaking is the largest non-food application for starches globally, consuming millions of metric tons annually. In a typical sheet of copy paper for instance, the starch content may be as high as 8%. Both chemically modified and unmodified starches are used in papermaking. In the wet part of the papermaking process, generally called the “wet-end”, starches that have been chemically modified to contain a cationic or positive charge bound to the starch polymer, and are utilized to associate with the anionic or negatively charged paper fibers and inorganic fillers. These cationic starches impart the necessary strength properties for the paper web to be formed in the papermaking process (wet strength), and to provide strength to the final paper sheet (dry strength). In the dry end of the papermaking process the paper web is rewetted with a solution of starch paste that has been chemically, or enzymatically depolymerized. The starch paste solutions are applied to the paper web by means of various mechanical presses (size press). The dry end starches impart additional strength to the paper web and additionally provide water hold out or “size” for superior printing properties. Corrugating glues are the next largest consumer of non-food starches globally. The corrugating glues generally contain a mixture of chemically modified and unmodified starches that have been partially gelatinized to form an opaque paste. This paste is applied to the flute tips of the interior fluted paper to glue the fluted paper to the outside paper in the construction of cardboard boxes. This is then dried under high heat, which provides the box board strength and rigidity. Another large non-food starch application is in the construction industry where starch is used in the sheet rock or wall board manufacturing process. Chemically modified or unmodified starches are added to the rock mud containing primarily gypsum. Top and bottom heavyweight sheets of paper are applied to the mud formulation and the process is allowed to heat and cure to form the eventual rigid wall board. The starches act as a glue for the cured gypsum rock with the paper covering and also provide rigidity to the board. Clothing starch or '''laundry starch''' is a liquid that is prepared by mixing a vegetable starch in water (earlier preparations also had to be boiled), and is used in the Laundering of Clothes . Starch was widely used in Europe in the 16th and 17th centuries to stiffen the wide collars and Ruffs of fine linen which surrounded the necks of the well-to-do. During the 19th century and early 20th century, it was stylish to stiffen the collars and sleeves of men's Shirt s and the ruffles of girls' Petticoat s by applying starch to them as the clean clothes were being Ironed . Aside from the smooth, crisp edges it gave to clothing, it served practical purposes as well. Dirt and Sweat from a person's neck and wrists would stick to the starch rather than fibers of the clothing, and would easily wash away along with the starch. After each laundering, the starch would be reapplied. Starch is also used to make some Packing Peanut s, and some Dropped Ceiling tiles. |
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