Fats

A "Fat" in food contains 9kcal of energy (9Calories).
 * Fats** consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. [|Chemically], fats are [|triglycerides] , [|triesters] of [|glycerol] and any of several [|fatty acids] . Fats are typically solid at room temperature but may be liquid depending on the shape and amount of hydrogen bonds.

Fat is a component in food. Some foods, including most fruits and vegetables, have almost no fat. Other foods have plenty of fat. They include nuts, oils, butter, and meats like beef. The name — fat — may make it sound like something you shouldn't eat. But fat is an important part of a healthy diet. And little kids, especially, need a certain amount of fat in their diets so the brain and nervous system develop correctly. That's why toddlers need to drink whole milk, which has more fat, and older kids can drink low-fat or skim milk.
 * Fats** and **oils** are made from two kinds of molecules: **glycerol** (a type of alcohol with a hydroxyl group on each of its three carbons) and three **fatty acids** joined by dehydration synthesis. Since there are three fatty acids attached, these are known as [|**triglycerides**] . “Bread” and pastries from a “bread factory” often contain mono- and diglycerides as “dough conditioners.” Can you figure out what these molecules would look like? The main distinction between fats and oils is whether they’re solid or liquid at room temperature, and this, as we’ll soon see, is based on differences in the structures of the fatty acids they contain.

A fat can be a Triglyceride, Triester, glycerol, or fatty acids. Obesity is the number one cause of death in the United States. For fats there are four main fatty acids. The fatty acids are Monosaturated fat, Saturated fat, poloyunstrated fat and trans fat. The fats that raise HDL Levels and Lowers LDL Level are Monosaturated fats and poloyunstrated fat. As for the bad fats that Raises LDL and lowers HDL are Saturated fat and Trans fat

Chemical structure
A [|triglyceride] molecule There are many different kinds of fats, but each is a variation on the same chemical structure. All fats are derivatives of fatty acids and glycerol. The molecules are called triglycerides, which are triesters of glycerol (an ester being the molecule formed from the reaction of the carboxylic acid and an organic alcohol). As a simple visual illustration, if the kinks and angles of these chains were straightened out, the molecule would have the shape of a capital letter E. The fatty acids would each be a horizontal line; the glycerol "backbone" would be the vertical line that joins the horizontal lines. Fats therefore have "ester" bonds. The properties of any specific fat molecule depend on the particular fatty acids that constitute it. Different fatty acids are composed of different numbers of carbon and hydrogen atoms. The carbon atoms, each bonded to two neighboring carbon atoms, form a zigzagging chain; the more carbon atoms there are in any fatty acid, the longer its chain will be. Fatty acids with long chains are more susceptible to intermolecular forces of attraction (in this case, van der Waals forces ), raising its melting point. Long chains also yield more energy per molecule when metabolized.



Saturated and unsaturated fats
A fat's constituent fatty acids may also differ in the C/H ratio. When all three fatty acids have the formula CnH(2n+1)CO 2 H, the resulting fat is called "saturated". Values of n usually range from 13 to 17. Each carbon atom in the chain is saturated with hydrogen, meaning they are bonded to as many hydrogens as possible. Unsaturated fats are derived from fatty acids with the formula CnH(2n-1)CO 2 H. These fatty acids contain double bonds within carbon chain. This results in an "unsaturated" fatty acid. More specifically, it would be a monounsaturated fatty acid. Polyunsaturated fatty acids would be fatty acids with more than one double bond; they have the formula, CnH(2n-3)CO 2 H and CnH(2n-5)CO 2 H. Unsaturated fats can be converted to saturated ones by the process of hydrogenation. This technology underpinned the development of margerine. Saturated and unsaturated fats differ in their energy content and melting point. Since unsaturated fats contain fewer carbon-hydrogen bonds than saturated fats with the same number of carbon atoms, unsaturated fats will yield slightly less energy during metabolism than saturated fats with the same number of carbon atoms. Saturated fats can stack themselves in a closely packed arrangement, so they can freeze easily and are typically solid at room temperature. For example, animal fats tallow and lard are high in saturated fatty acid content and are solids. Olive and linseed oils on the other hand are highly unsaturated and are oily.

Trans fats
There are two ways the double bond may be arranged: the isomer with both parts of the chain on the same side of the double bond (the // cis //-isomer), or the isomer with the parts of the chain on opposite sides of the double bond (the // trans //-isomer). Most //trans//-isomer fats (commonly called trans fats ) are commercially produced. Trans fatty acids are rare in nature. The//cis//-isomer introduces a kink into the molecule that prevents the fats from stacking efficiently as in the case of fats with saturated chains. This decreases intermolecular forces between the fat molecules, making it more difficult for unsaturated cis-fats to freeze; they are typically liquid at room temperature. Trans fats may still stack like saturated fats, and are not as susceptible to metabolization as other fats. Trans fats may significantly increase the risk of coronary heart disease.