 Wet-rendered lard, from pork fatback. | |
| Fat composition | |
|---|---|
| Saturated fats | |
| Total saturated | 38–43%: Palmitic acid: 25–28% Stearic acid: 12–14% Myristic acid: 1% |
| Unsaturated fats | |
| Total unsaturated | 56–62% |
| Monounsaturated | 47–50%: Oleic acid: 44–47% Palmitoleic acid: 3% |
| Polyunsaturated | Linoleic acid: 6–10%[1] |
| Properties | |
| Food energy per 100 g (3.5 oz) | 3,770 kJ (900 kcal) |
| Melting point | backfat: 30–40 °C (86–104 °F) leaf fat: 43–48 °C (109–118 °F) mixed fat: 36–45 °C (97–113 °F) |
| Smoke point | 121–218 °C (250–424 °F) |
| Specific gravity at 20 °C (68 °F) | 0.917–0.938 |
| Iodine value | 45–75 |
| Acid value | 3.4 |
| Saponification value | 190–205 |
| Unsaponifiable | 0.8% |
Animal fats arelipids derived fromanimals which are used by the animal for a multitude of functions, or can be used by humans for dietary, sanitary, and cosmetic purposes. Depending on the temperature of the fat, it can change between a solid state and a liquid (oil) state. Chemically, both fats and oils are composed oftriglycerides.[2][3] Although many animal parts and secretions may yield oil, in commercial practice, oil is extracted primarily fromrendered tissuefats from livestock animals likepigs,chickens andcows. Dairy products yield animal fat and oil products such asbutter.
Animal fats are composed oftriglycerides, which are a type ofester molecule in whichglycerol is bonded to threefatty acids.[3] The three fatty acids that bond to the glycerol will determine the complexity and type of the triglyceride. If the three fatty acids are the same, then the triglyceride will be considered a simple triglyceride.[3] However, most triglycerides contain differing fatty acids, causing them to have differing characteristics. Animal fat is a combination of many different triglycerides.[2] Fatty acids can be broken down into two categories, saturated andunsaturated fats. Most animal fats aresaturated fats.[4]
Fat serves many purposes within an animal's body. Some of these include insulating the body to regulate internal body temperature, serving as an energy reserve, and cushioning the feet.[5] Many mammalian animals that live in cold regions of the globe, including both aquatic and terrestrial ecosystems, have developed a thick layer of fat just below the skin calledblubber.[6] This blubber helps these animals to reduce the amount of heat that is lost to the colder outside environment. Fat is a poor conductor of heat; therefore, it allows the heat that the animal produces to remain in their body for a longer period of time.[5][6] Fat is also used by animals for the storage of energy. The type of fat that is used for energy storage is known asadipose tissue.[7] This adipose tissue is made upadipocytes which store the energy in thechemical bonds of triglycerides.[5][7][8] For example, prior to an animal going through hibernation, an animal will build up large reserves of adipocytes to ensure it has the energy to survive the long slumber.[7][9] Fat is also used by animals to create foot pads.[10] These foot pads aid in the longevity and health of the animal by absorbing the impacts that occur when the animal walks, runs, or jumps. These foot pads are present in many animals includingcats,dogs,horses, and even larger mammals likeelephants.[5][10]
Many animal fats and oils are consumed directly, or indirectly as ingredients in food. Animal fats are commonly consumed as part of awestern diet in their semi-solid form as eithermilk,butter,lard,schmaltz, anddripping or more commonly as filler in factory-produced meat, andfast-food products.[11] Certain fats, such asgoose fat, have a highersmoke point than other animal fats, but are still lower than many vegetable oils such as olive oravocado.[12]
The oils serve a number of purposes in this role:
Secondly, oils can be heated and used to cook foods. Suitability for this purpose depends onflash point.
There are many other human uses for animal fat, a few of these uses come fromtallow. One of the uses of tallow is the production of soap through a process calledsaponification. The tallow is boiled or heated along withlye, resulting in the production of a rough soap as well as glycerol.[citation needed] The soap is then put through a purification process until it becomes a usable sanitary product.[13] Tallow is also used in the production of many skincare and cosmetic products.[14][15] Tallow contains vitamins E, D, K, and A as well asconjugated linoleic acid which have all been shown to have benefits to skin health.[15]
