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 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, usually in a medical or biochemical context. The word "oil" is also used for any substance that does not mix with water and has a greasy feel, such as petroleum (or crude oil), heating oil, and essential oils, regardless of its chemical structure.
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, fish oil, butter/ghee and whale blubber. They are obtained from fats in the milk and meat, as well as from under the skin, of an animal. Examples of edible plant fats include peanut, soya bean, sunflower, sesame, coconut and olive oils, and cocoa butter. Vegetable shortening, used mainly for baking, and margarine, used in baking and as a spread, can be derived from the above oils by hydrogenation.
These examples of fats can be categorized into saturated fats and unsaturated fats. Unsaturated fats can be further divided into cis fats, which are the most common in nature, and trans fats, which are rare in nature but present in partially hydrogenated vegetable oils.
Famous quotes containing the word fat:
“I pray we are still a young and courageous nation, that we have not grown so old and so fat and so prosperous that all we can think about is to sit back with our arms around our money bags. If we choose to do that I have no doubt that the smoldering fires will burst into flame and consume usdollars and all.”
—Lyndon Baines Johnson (19081973)
“Marty: Im just a fat little man. A fat ugly man.
Mrs. Pilletti: Youre not ugly.
Marty: Im ugly! Im ugly! Im ugly!”
—Paddy Chayefsky (19231981)
“O why do you walk through the fields in gloves,
Missing so much and so much?
O fat white woman whom nobody loves,
Why do you walk through the fields in gloves,
When the grass is soft as the breast of doves
And shivering sweet to the touch?”
—Frances Cornford (18861960)