Gelatin, << JEHL uh tuhn, >> is a protein substance that comes from animal skins and bones. It is made by boiling collagen, a protein found in bone, cartilage, and other connective tissue. When dry, gelatin is a tasteless, odorless, nearly white powder. Gelatin readily dissolves in hot water and, upon cooling, forms a stiff, elastic gel.
To make gelatin from bones, a manufacturer first crushes the raw bones into small pieces, cooks them in hot water, and then vigorously rinses them to remove fat. The degreased bones are dried in hot air and soaked in an acid solution for several days to dissolve calcium and other minerals. The remaining material is then washed repeatedly with fresh water. Next, the manufacturer typically treats the material with either mineral acid or an alkali such as lime to convert collagen to gelatin.
After the acid or alkali is neutralized, the gelatin is dissolved in hot water. The resulting solution is filtered to remove solid impurities. The gelatin is then concentrated, typically with an evaporator that boils off the water. The solution is then sterilized by exposing it to high temperatures for several seconds. Next, it is cooled and fed through devices called extruders to form noodlelike threads that are spread onto a dryer belt. After hot-air drying, the gelatin is ground into a fine powder.
Gelatin on its own has little nutritional value, but it is an important food ingredient. It is the main ingredient of gelatin desserts and marshmallows. It is used as a thickener in ice cream, yogurt, jams, cream cheese, and margarine. Gelatin-based foods can be good for sick people and children because gelatin can be easily digested. The photographic industry uses gelatin for coating films and photographic papers. Both soft and hard medicinal capsules are made of gelatin, but the soft capsules, used for oils, have glycerin added. Scientists use gelatin as a medium for growing bacteria.
