"Oils" is usually used to refer to fats that are liquids at normal room temperature.
"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.
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 containing about 37.8 kilojoules (9 calories) per gram of fat. 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.
Fats and oils are the fatty acid esters of glycerol. Chemically, they are triglycerides, triesters of glycerol.
"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.
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 containing about 37.8 kilojoules (9 calories) per gram of fat. 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.
Fats and oils are the fatty acid esters of glycerol. Chemically, they are triglycerides, triesters of glycerol.
- Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. Glycerol can be used as a laxative when introduced into the rectum in suppository or small-volume (2–10 ml) (enema) form; it irritates the anal mucosa and induces a hyperosmotic effect.
- Ethers contain an ether group — an oxygen atom connected to two alkyl or aryl groups — R–O–R'. They are formed from the reaction of the carboxylic acid and an organic alcohol. That is, esters are formed by condensing an acid with an alcohol. Esters with low molecular weight are commonly used as fragrances and found in essential oils and pheromones. Phosphoesters form the backbone of DNA molecules. Nitrate esters, such as nitroglycerin, are known for their explosive properties, while polyesters are important plastics, with monomers linked by ester moieties.
As a simple visual illustration, if the fatty acids each seen as a horizontal line; the glycerol "backbone" would be the vertical line that joins the horizontal lines - "ester" bonds. 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.
Milk is an emulsion or colloid of butterfat globules within a water-based fluid that contains dissolved carbohydrates and protein aggregates with minerals. The fat-soluble vitamins A, D, E, and K along with essential fatty acids such as linoleic and linolenic acid are found within the milk fat portion of the milk.
Butterfat, the fatty portion of milk, is a triglyceride derived from fatty acids such as myristic, palmitic, and oleic acids. Each fat globule is surrounded by a membrane consisting of complex lipids such as phospholipids, along with proteins. These act as emulsifiers which keep the individual globules from coalescing and protect the contents of these globules from various enzymes in the fluid portion of the milk.
The fatty acids of butterfat are typically composed as follows (by mass fraction):
Saturated fatty acids:
- Palmitic acid: 31%
- Myristic acid: 12%
- Stearic acid: 11%
- Lower (at most 12 carbon atoms) saturated fatty acids: 11%
- pentadecanoic acid and heptadecanoic acid: traces
Unsaturated fatty acids:
- Oleic acid: 24%
- Palmitoleic acid: 4%
- Linoleic acid: 3%
- Linolenic acid: 1%
Milk and cream are sold according to the amount of butterfat they contain. In U.S., the federal standards for butterfat content of dairy products are:
- Low fat milk contains between 0.5–2%; 1% and 2% varieties are widely marketed
- Whole milk contains at least 3.25%
- Sherbet contains 1–2%
- Ice cream contains at least 10%
- Half and half contains 10.5–18%
- Light whipping cream (often called simply "whipping cream") contains 30–36%
- Swiss cheese contains at least 43% relative to the total solids
- Cheddar cheese contains at least 50% relative to the total solids
- Butter (including whipped butter) contains at least 80%
Melting point, is 82.4-96.8°F (28-36°C), measures the temperature range at which a solid becomes a liquid. Solid Fat Index (SFI) is an empirical measure of solid fat content at standardized temperature check points. Butter's SFI curve illustrates that butter will only partially solidify at room temperature.
(Ref:
1.http://www.eatwisconsincheese.com/wisconsin/other_dairy/butter/butter_basics/physical_chemical_characteristics.aspx
2.http://hypertextbook.com/facts/2003/JessicaCheung.shtml)
