[Chemistry Class Notes] Fatty Acid Pdf for Exam

Fatty acids in plants, animals, and microorganisms make the essential components of lipids (fat-soluble components of living cells). A fatty acid generally consists of a straight chain of an even number of carbon atoms, with hydrogen atoms along the chain length and at one end of the chain and at the other end of a carboxyl group (-COOH). It is that group of carboxyls that makes it an acid (carboxylic acid). The acid is saturated if the carbon-to-carbon bonds are all single; if any of the bonds are double or triple, the acid is unsaturated and more reactive.

List of Fatty Acids

1. Palmitic acid

2. Stearic acid

3. Oleic acid

4. Linolenic acid

Fatty Acids Examples

The 16- and 18-carbon fatty acids, better known as palmitic acid and stearic acid, are among the most commonly distributed fatty acids. In the lipids of most species, both palmitic and stearic acids exist. Palmitic acid makes up as much as 30 percent of body fat in animals. It accounts for between 5 and 50 percent of the lipids in vegetable fats, with palm oil being particularly abundant. In certain vegetable oils (e.g. cocoa butter and shea butter), stearic acid is abundant and makes up a relatively high proportion of the lipids present in ruminant tallows.

Essential Fatty Acids

Essential fatty acids, or EFAs, are fatty acids that must be consumed by humans and other animals because they are required by the body for good health but can not be synthesized. 

Fatty acids needed for biological processes are referred to by the term “essential fatty acid” but do not include fats that only serve as fuel. In the sense of being a distilled essence, essential fatty acids should not be confused with essential oils, which are “essential”

Here is an Example of Two Essential Fatty Acids

Linoleic acid (an omega-6 fatty acid) and alpha-linolenic acid are not synthesized by many species (an omega-3 fatty acid). However, for cellular processes and the development of other essential omega-3 and omega-6 fatty acids, certain fatty acids are needed. Thus, they are called essential fatty acids since they need to be taken in via the diet. Omega-6 and omega-3 fatty acids derived from linoleic acid and alpha-linolenic acid, respectively, are conditionally required by many mammals; they are produced from their parent fatty acids in the body, but not always at levels sufficient to maintain optimum health or development.

Classification of Fatty Acids

In many ways, fatty acids are classified: by length, by saturation vs unsaturation, by the content of even vs odd carbon, and by linear vs branched. 

1. Fatty Acid Length 

• Fatty acids with aliphatic tails of five or fewer carbons are short-chain fatty acids (SCFA) (e.g. butyric acid). 

• Medium-chain fatty acids (MCFA) are fatty acids with 6 to 12 carbon aliphatic tails that are capable of forming medium-chain triglycerides. 

• Long-chain fatty acids (LCFA) are fatty acids containing from 13 to 21 carbon aliphatic tails. 

• Very long-chain fatty acids (VLCFA) are fatty acids of 22 or more carbons with aliphatic tails.

2. Saturated Fatty Acids 

Saturated fatty acids do not have double bonds of C=C. “They have the same CH3(CH2)nCOOH formula, with “n” variations. Stearic acid (n = 16), which is the most common form of soap when neutralized with lye, is an important saturated fatty acid.

3. Unsaturated Fatty Acids

Unsaturated fatty acids have double bonds of one or more C=C. Either cis or trans isomers can be given by the C=C double bonds. 

A configuration of cis means that on the same side of the chain, the two hydrogen atoms adjacent to the double bond hold out. The rigidity of the double bond freezes its conformation and causes the chain to bend in the case of the cis isomer and restricts the fatty acid’s conformational freedom.

By comparison, a trans arrangement implies that the two hydrogen atoms that are adjacent lie on opposite sides of the chain. They do not induce any bending of the chain as a result, and their form is identical to straight saturated fatty acids.

List of Unsaturated Fatty Acids

1. Crotonic acid.

2. Myristoleic.

3. Palmitoleic acid.

4. Oleic acid.

Applications of Fatty Acids

A large variety of commercial uses are available for fatty acids. They are used not only in the manufacture of various food products, for instance, but also in soaps, detergents, and cosmetics. Soaps are fatty acid salts of sodium and potassium. Some skincare items contain fatty acids, which can help keep the look and function of the skin healthy. Fatty acids are also commonly marketed as dietary supplements, particularly omega-3 fatty acids.

Did You Know?

1. Omega 3 Fatty Acids

They are a class of fatty acids found in fish oils that reduce cholesterol and LDL (low-density lipoproteins) levels in the blood, especially in salmon and other cold-water fish. (The “bad” cholesterol is LDL cholesterol.) 

2. Trans Fatty Acids

Trans fatty acids (trans fats) are made to solidify liquid oils by hydrogenation. They increase the shelf life of oils and are found in some margarine, crackers, cookies, and snack foods, and in vegetable shortenings. Trans fatty acid consumption raises blood levels of LDL-cholesterol (‘bad’ cholesterol) and increases the risk of coronary heart disease.