- Food chemistry
Food chemistry is the study of
chemicalprocesses and interactions of all biological and non-biological components of foods. The biological substances include such items as meat, poultry, lettuce, beer, and milkas examples. It is similar to biochemistryin its main components such as carbohydrates, lipids, and protein, but it also includes areas such as water, vitamins, minerals, enzymes, food additives, flavours, and colours. This discipline also encompasses how products change under certain food processingtechniques and ways either to enhance or to prevent them from happening. An example of enhancing a process would be to encourage fermentation of dairyproducts with microorganismsthat convert lactoseto lactic acid; an example of preventing a process would be stopping the browning on the surface of freshly cut Red Deliciousapples using lemon juice or other acidulated water.
History of food chemistry
Food chemistry's history dates back as far as the late 1700s when many famous chemists were involved in discovering chemicals important in foods, including
Carl Wilhelm Scheele(isolated malic acidfrom apples in 1785), and Sir Humphry Davy(published the first ever book on agricultural and food chemistry in 1813 titled "Elements of Agricultural Chemistry, in a Course of Lectures for the Board of Agriculture" in the United Kingdomwhich would serve as a foundation for the profession worldwide, going into a fifth edition.
In 1874 the Society of Public Analysts was formed, with the aim of applying analytical methods to the benefit of the public [Proc. Soc. Analyt. Chem p. 234] . It's early experiments were based on bread, milk and wine.
It was also out of concern for the quality of the food supply, mainly food adulteration and contamination issues that would first stem from intentional contamination to later with chemical
food additivesby the 1950s. The development of collegesand universitiesworldwide, most notably in the United States, would expand food chemistry as well with research of the dietary substances, most notably the Single-grain experimentduring 1907-11. Additional research by Harvey W. Wileyat the United States Department of Agricultureduring the late 19th century would play a key factor in the creation of the United States Food and Drug Administrationin 1906. The American Chemical Societywould establish their [http://membership.acs.org/a/agfd/ Agricultural and Food Chemistry Division] in 1908 while the Institute of Food Technologistswould establish their [http://www.ift.org/divisions/food_chem/ Food Chemistry Division] in 1995.
A major component of food is
water, which can encompass anywhere from 50% in meatproducts to 95% in lettuce, cabbage, and tomatoproducts. It is also an excellent place for bacterialgrowth and food spoilage if it is not properly processed. One way this is measured in food is by water activitywhich is very important in the shelf life of many foods during processing. One of the keys to food preservationin most instances is reduce the amount of water or alter the water's characteristics to enhance shelf-life. Such methods include dehydration, freezing, and refrigeration.
Comprising 75% of the biological world and 80% of all food intake for human consumption, the most common known human carbohydrate is
starch. The simplest version of a carbohydrate is a monosaccharidewhich possesses the properties of carbon, hydrogen, and oxygenin a 1:2:1 ratio under a general formula of CnH2nOn where n is a minimum of 3. Glucoseis an example of a monosaccharide as is fructose. Combine them in the picture shown to the right and you have sucrose, one of the more common sugarproducts around.
A chain of monosaccharides form to make a
polysaccharide. Such polysaccharides include pectin, dextran, agar, and xanthan.
Sugar content is commonly measured in degrees
The term lipid comprises a diverse range of
moleculesand to some extent is a catchall for relatively water-insoluble or nonpolarcompounds of biological origin, including waxes, fatty acids (including essential fatty acids), fatty-acid derived phospholipids, sphingolipids, glycolipids and terpenoids, such as retinoids and steroids. Some lipids are linear aliphaticmolecules, while others have ring structures. Some are aromatic, while others are not. Some are flexible, while others are rigid.
Most lipids have some polar character in addition to being largely nonpolar. Generally, the bulk of their structure is nonpolar or
hydrophobic("water-fearing"), meaning that it does not interact well with polar solvents like water. Another part of their structure is polar or hydrophilic("water-loving") and will tend to associate with polar solvents like water. This makes them amphiphilicmolecules (having both hydrophobic and hydrophilic portions). In the case of cholesterol, the polar group is a mere -OH ( hydroxylor alcohol).
Lipids in food include the oils of such grains as corn,
soybean, from animalfats, and are parts of many foods such as milk, cheese, and meat. They also act as vitamin carriers as well.
Proteins compose over 50% of the dry weight of an average living cell and are very complex macromolecules. They also play a fundamental role in the structure and function of cells. Comprised mainly of carbon, hydrogen,
oxygen, and some sulfur, they also may contain iron, copper, phosphorus, or zinc.
In food, proteins are essential for growth and survival and vary depending upon a person's age and
physiology(e.g., pregnancy). Proteins in food are commonly found in peanuts, meat, poultry, and seafood. They are also involved in ELISAtest for food allergydetermination as well.
Enzymes are biochemical
catalystsused in converting processes from one substance to another. They are also involved in reducing the amount of time and energy required to complete a chemical process. Many aspects of the foodindustry use catalysts, including baking, brewing, dairy, and fruit juices, to make cheese, beer, and bread.
nutrientsrequired in small amounts for essential metabolic reactions in the body. These are broken down in nutrition as either watersoluble ( Vitamin C) or fatsoluble ( Vitamin E). An adequate supply of vitamins can prevent such diseases as beriberi, anemia, and scurvywhile an overdose of vitamins can produce nauseaand vomitingor even death.
Dietary minerals in foods are large and diverse with many required to function while other trace elements can be hazardous if consumed in excessive amounts. Bulk minerals with a
Reference Daily Intake(RDI, formerly Recommended Daily Allowance (RDA)) of more than 200 mg/day are calcium, magnesium, and potassiumwhile important trace minerals (RDI less than 200 mg/day) are copper, iron, and zinc. These are found in many foods, but can also be taken in dietary supplements.
Food coloring is added to change the
colorof any foodsubstance. It is mainly for sensory analysispurposes. It can be used to simulate the natural color of a product as perceived by the customer, such as red dye like FD&CRed No.40 ( Allura Red AC) to ketchupor to add unnatural colors to a product like Kellogg's Froot Loops. Caramelis a natural food dye; the industrial form, caramel coloring, is the most widely-used food coloring and is found in foods from soft drinks to soy sauce, bread, and pickles.
Flavor in food is important in how food smells and
tastes to the consumer, especially in sensory analysis. Some of these products occur naturally like saltand sugar, but flavor chemists (called a " flavorist") develop many of these flavors for food products. Such artificial flavors include methyl salicylatewhich creates the wintergreenodor and lactic acid which gives milk a tart taste.
Food additives are substances added to food for preserving flavors, or improving taste or appearance. These processes are as old as adding
vinegarfor picklingor as an emulsifierfor emulsionmixtures like mayonnaise. These are generally listed by " E number" in the European Unionor GRAS(" Generally recognized as safe") by the United States Food and Drug Administration.
*Fennema, O.R., Ed. (1985). "Food Chemistry - Second Edition, Revised and Expanded." New York: Marcel Dekker, Inc.
*Francis, F.J. (2000). "Harvey W. Wiley: Pioneer in Food Science and Quality." In "A Century of Food Science." Chicago: Institute of Food Technologists. pp. 13-14.
*Potter, N.N. and J.H. Hotchkiss. (1995). "Food Science, Fifth Edition." New York: Champman & Hall. pp. 24-68.
*U.S. Food and Drug Administration. (1993). "Everything Added to Food in the United States." Boca Raton, FL: C.K. Smoley (c/o CRC press, Inc.).
* [http://membership.acs.org/a/agfd/ American Chemical Society Agricultural and Food Chemistry Division website.]
* [http://www.ift.org/divisions/food_chem/ Institute of Food Technologists Food Chemistry Division website.]
* [http://www.publicanalyst.com/ Association of Public Analysts]
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