The Full Wiki

Fat: Wikis

  
  
  

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Did you know ...


More interesting facts on Fat

Include this on your site/blog:

Encyclopedia

From Wikipedia, the free encyclopedia

Types of fats in food
See also

Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Chemically, fats are generally triesters of glycerol and fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure and composition. Although the words "oils", "fats", and "lipids" are all used to refer to fats, "oils" is usually used to refer to fats that are liquids at normal room temperature, while "fats" is usually used to refer to fats that are solids at normal room temperature. "Lipids" is used to refer to both liquid and solid fats, along with other related substances. The word "oil" is used for any substance that does not mix with water and has a greasy feel, such as petroleum (or crude oil) and heating oil, regardless of its chemical structure.[1]

Fats form a category of lipid, distinguished from other lipids by their chemical structure and physical properties. This category of molecules is important for many forms of life, serving both structural and metabolic functions. They are an important part of the diet of most heterotrophs (including humans). Fats or lipids are broken down in the body by enzymes called lipases produced in the pancreas.

Examples of edible animal fats are lard (pig fat), fish oil, and butter or ghee. They are obtained from fats in the milk, meat and under the skin of the animal. Examples of edible plant fats are peanut, soya bean, sunflower, sesame, coconut, olive, and vegetable oils. Margarine and vegetable shortening, which can be derived from the above oils, are used mainly for baking. These examples of fats can be categorized into saturated fats and unsaturated fats.

Contents

Chemical structure

A triglyceride molecule

There are many different kinds of fats, but each is a variation on the same chemical structure. All fats consist of fatty acids (chains of carbon and hydrogen atoms, with a carboxylic acid group at one end) bonded to a backbone structure, often glycerol (a "backbone" of carbon, hydrogen, and oxygen). Chemically, this is a triester 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.

A fat's constituent fatty acids may also differ in the number of hydrogen atoms that are bonded to the chain of carbon atoms. Each carbon atom is typically bonded to two hydrogen atoms. When a fatty acid has this typical arrangement, it is called "saturated", because the carbon atoms are saturated with hydrogen; meaning they are bonded to as many hydrogens as possible. In other fats, a carbon atom may instead bond to only one other hydrogen atom, and have a double bond to a neighboring carbon atom. This results in an "unsaturated" fatty acid. More specifically, it would be a "monounsaturated" fatty acid, whereas, a "polyunsaturated" fatty acid would be a fatty acid with more than one double bond. Saturated and unsaturated fats differ in their energy content and melting point. Since an unsaturated fat contains fewer carbon-hydrogen bonds than a saturated fat 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. But the rigid double bond in an unsaturated fat fundamentally changes the chemistry of the fat. 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 rather than naturally occurring. 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.[2]

Importance for living organisms

Vitamins A, D, E, and K are fat-soluble, meaning they can only be digested, absorbed, and transported in conjunction with fats. Fats are also sources of essential fatty acids, an important dietary requirement.

Fats play a vital role in maintaining healthy skin and hair, insulating body organs against shock, maintaining body temperature, and promoting healthy cell function.

Fats also serve as energy stores for the body, containing about 37.8 kilojoules (9 Calories) per gram of fat[3]. They are broken down in the body to release glycerol and free fatty acids. The glycerol can be converted to glucose by the liver and thus used as a source of energy.

Fat also serves as a useful buffer towards a host of diseases. When a particular substance, whether chemical or biotic—reaches unsafe levels in the bloodstream, the body can effectively dilute—or at least maintain equilibrium of—the offending substances by storing it in new fat tissue. This helps to protect vital organs, until such time as the offending substances can be metabolized and/or removed from the body by such means as excretion, urination, accidental or intentional bloodletting, sebum excretion, and hair growth.

While it is nearly impossible to remove fat completely from the diet, it would be unhealthy to do so. Some fatty acids are essential nutrients, meaning that they can't be produced in the body from other compounds and need to be consumed in small amounts. All other fats required by the body are non-essential and can be produced in the body from other compounds.

Adipose tissue

The obese mouse on the left has large stores of adipose tissue. For comparison, a mouse with a normal amount of adipose tissue is shown on the right.

In animals, adipose, or fatty tissue is the body's means of storing metabolic energy over extended periods of time. Depending on current physiological conditions, adipocytes store fat derived from the diet and liver metabolism or degrade stored fat to supply fatty acids and glycerol to the circulation. These metabolic activities are regulated by several hormones (i.e., insulin, glucagon and epinephrine). The location of the tissue determines its metabolic profile: "Visceral fat" is located within the abdominal wall (i.e., beneath the wall of abdominal muscle) whereas "subcutaneous fat" is located beneath the skin (and includes fat that is located in the abdominal area beneath the skin but above the abdominal muscle wall). Visceral fat was recently discovered to be a significant producer of signaling chemicals (ie, hormones), among which are several which are involved in inflammatory tissue responses. One of these is resistin which has been linked to obesity, insulin resistance, and Type 2 diabetes. This latter result is currently controversial, and there have been reputable studies supporting all sides on the issue.

See also

References

  1. ^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1. OCLC 32308337. 
  2. ^ Mozaffarian D, Katan MB, Ascherio A, Stampfer MJ, Willett WC (13 April 2006). "Trans Fatty Acids and Cardiovascular Disease". New England Journal of Medicine 354 (15): 1601–1613. doi:10.1056/NEJMra054035. PMID 16611951.  PMID 16611951
  3. ^ NASA Energy

1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

FAT (O.E. fdett; the word is common to Teutonic languages, cf. Dutch vet, Ger. Fett, &c., and may be ultimately related to Greek rim/ and irtapos, and Sanskrit pivan), the name given to certain animal and vegetable products which are oily solids at ordinary temperatures, and are chemically distinguished as being the glyceryl esters of various fatty acids, of which the most important are stearic, palmitic, and oleic; it is to be noticed that they are non-nitrogenous. Fat is a normal constituent of animal tissue, being found even before birth; it occurs especially in the intra-muscular, the abdominal and the subcutaneous connective tissues. In the vegetable kingdom fats especially occur in the seeds and fruits, and sometimes in the roots. Physiological subjects concerned with the part played by fats in living animals are treated in the articles Connective Tissues; Nutrition; Corpulence; Metabolic Diseases. The fats are chemically similar to the fixed oils, from which they are roughly distinguished by being solids and not liquids (see Oils). While all fats have received industrial applications, foremost importance must be accorded to the fats of the domestic animals - the sheep, cow, ox and calf. These, which are extracted from the bones and skins in the first operation in the manufacture of glue, are the raw materials of the soap, candle and glycerin industries.


<< Sir John Fastolf

Fatalism >>


Bible wiki

Up to date as of January 23, 2010

From BibleWiki

(Heb. heleb) denotes the richest part of the animal, or the fattest of the flock, in the account of Abel's sacrifice (Gen 4:4). It sometimes denotes the best of any production (Gen 45:18; Num 18:12; Ps 8116; Ps 14747). The fat of sacrifices was to be burned (Lev 3:9ff; Lev 4:8; Lev 7:3; Lev 8:25; Num 18:17. Comp. Ex 29:13ff; Lev 3:3ff).

It is used figuratively for a dull, stupid state of mind (Ps 1710).

In Joel 2:24 the word is equivalent to "vat," a vessel. The hebrew word here thus rendered is elsewhere rendered "wine-fat" and "press-fat" (Hag 2:16; Isa 63:2.

This entry includes text from Easton's Bible Dictionary, 1897.

what mentions this? (please help by turning references to this page into wiki links)

This article needs to be merged with FAT (Jewish Encyclopedia).

Simple English

The word "fat" can also mean that someone is obese.
mouse on the left has a lot of adipose tissue. In many animals, adipose tissue is used to store energy. For comparison, a mouse with a normal amount of adipose tissue is shown on the right.]]

Fat is something found in foods, and it is the most concentrated kind of energy that a human can use. It has 9 kilocalories in one gram. The other two types of energy that humans can use are carbohydrates and proteins. Those each have 4 kilocalories in one gram.

Fats can be solid (firm) or fluid at room temperature. For example, cooking oil is a type of fluid fat. Butter is a solid fat. Some fats come from animals, others come from plants. Fat from plants is called vegetable fat. Examples of vegetable fats are margarine and vegetable oil. Examples of animal fats are butter, cream and lard.

The different types of fats are saturated, unsaturated and trans fats. Trans fats are created in the food industry by treating other types of fats and giving them a different structure. This happens when oil is hardened to make margarine, for example. Many restaurants also use trans fats for deep-frying food. Trans fats are the most unhealthy fats to eat and can cause heart disease.

Fats are usually not soluble in water, but they can be dissolved in other organic solvents. Fats are triesters of fatty acids and glycerol.

Fat is important for the human body because it gives much energy and helps the body use the vitamins in the food. It is also good for the skin and hair. Olive oil is an especially healthy fat. Many types of fish also contain healthy fat, for example salmon, sardines, herring, and tuna. But if too much fat collects in the body, a person can become too heavy. The energy that fat gives the body must be used up by moving or working. Some vegetables like celery or carrots contribute much less to the bodies fat supply. Though being very important for the human body, it can be harmful in large amounts.








Got something to say? Make a comment.
Your name
Your email address
Message