Polyunsaturated fat in the context of Linoleic acid

An unsaturated fat is a fat or fatty acid in which there is at least one double bond within the fatty acid chain, which makes the fatty acid chain, which is basically a chain of hydrocarbons, an alkene. A fatty acid chain is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond.

A saturated fat has no carbon-to-carbon double bonds, so the maximum possible number of hydrogen is bonded to carbon, and thus, is considered to be "saturated" with hydrogen atoms. To form carbon-to-carbon double bonds, hydrogen atoms are removed from the carbon chain. In cellular metabolism, unsaturated fat molecules contain less energy (i.e., fewer calories) than an equivalent amount of saturated fat. The greater the degree of unsaturation in a fatty acid (i.e., the more double bonds in the fatty acid) the more susceptible it becomes to lipid peroxidation (rancidity). Antioxidants can protect unsaturated fat from lipid peroxidation.

Ostrich oil is an oil derived from the fat of ostriches. Ostrich oil is composed of 36.51% of saturated fat, 46.75% of monounsaturated fat, and 18.24% of polyunsaturated fat. Ostrich oil contains fatty acids, such as omega-3, omega-6, and omega-9. It also contains vitamins and minerals like vitamin E and selenium, which serve as natural antioxidants. Emu oil in the USA has a similar composition to ostrich oil, but ostrich oil has a higher omega-3 content, containing 2.1% compared to 0.25% in emu oil.

Ostrich oil has antibacterial properties, and is used for various skincare purposes, such as inflammation reduction. Due to the moisturizing properties, ostrich oil is currently used in cosmetic formulations and food chemistry. Ostrich oil is also used in the food industry as it has fatty acids and tocopherols, and a low cholesterol content.

The germ of a cereal grain is the part that develops into a plant; it is the seed embryo. Along with bran, germ is often a by-product of the milling that produces refined grain products. Cereal grains and their components, such as wheat germ oil, rice bran oil, and maize bran, may be used as a source from which vegetable oil is extracted, or used directly as a food ingredient. The germ is retained as an integral part of whole-grain foods. Non-whole grain methods of milling are intended to isolate the endosperm, which is ground into flour, with removal of both the husk (bran) and the germ. Removal of bran produces a flour with a white rather than a brown color and eliminates fiber. The germ is rich in polyunsaturated fats (which have a tendency to oxidize and become rancid on storage) and so germ removal improves the storage qualities of flour.

omega−3 oils, ω−3 fatty acids or n−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond three atoms away from the terminal methyl group (numbered ω, the last letter of the Greek alphabet) in their chemical structure. They are widely distributed in nature, are important constituents of animal lipid metabolism, and play an important role in the human diet and in human physiology. The three types of omega−3 fatty acids involved in human physiology are α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA can be found in plants, while DHA and EPA are found in algae and fish. Marine algae and phytoplankton are primary sources of omega−3 fatty acids. DHA and EPA accumulate in fish that eat these algae. Common sources of plant oils containing ALA include walnuts, edible seeds and flaxseeds as well as hempseed oil, while sources of EPA and DHA include fish and fish oils, and algae oil.

Almost without exception, animals are unable to synthesize the essential omega−3 fatty acid ALA and can only obtain it through diet. However, they can use ALA, when available, to form EPA and DHA, by creating additional double bonds along its carbon chain (desaturation) and extending it (elongation). ALA (18 carbons and 3 double bonds) is used to make EPA (20 carbons and 5 double bonds), which is then used to make DHA (22 carbons and 6 double bonds). The ability to make the longer-chain omega−3 fatty acids from ALA may be impaired in aging. In foods exposed to air, unsaturated fatty acids are vulnerable to oxidation and rancidity.