How do you do a chemical extraction on food?

Question

How do you do a chemical extraction on food?

Answer 1

You need to know what kind of molecule you want to extract,the solvent to be used is related to it, and its acid -base properties are also to be considered.

Answer 2

Food consists of proteins, fats and carbohydrates, usually disperced in water. Fats are the easiest to extract. The food is dried and then mixed with a nonpolar solvent. "Like dissolves like" in layman's terms, so any nonpolar fats will wash away from the food with nonpolar solvents. The solvent can be evaporated and the fat weighed to obtain a percentage. Proteins are frequently estimated by a process which discintegrates the sample with powerful acids, distills the nitrogen as ammonia and then preforms an acid titration. The amount of ammonia is porportional to the protein, which contains nitrogen. Carbohydrates are sometimes estimated using High Pressure Liquid Chromatography (HPLC). Chromatography is a process which separates compounds based on molecular weight. A solution flows through an absorbant matrix and individual chemicals separate and can be identified. HPLC can also be used to determine individual proteins based on molecular weight.