Uses Of Hydrogenation Of Oils Biology Essay

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What are fats and oils? Triacylglycerols , also called triglycerides, are compounds in which the three OH groups of glycerol are esterified with fatty acids. If the three fatty acid components of a triacylglycerol are the same, the compound is called a simple triacylglycerol. Mixed triacylglycerols, on the other hand, contain two or three different fatty acid components and are more common than simple triacylglycerols. Not all triacylglycerol molecules from a single source are necessarily identical. Substances such as lard and olive oil, for example, are mixtures of several different triacylglycerols.

Triacylglycerols that are solids or semi solids at room temperature are called fats. Fats are usually obtained from animals and are composed largely of triacylglycerols with either saturated fatty acids or fatty acids with only one double bond. The saturated fatty acid tails pack closely together, giving the triacylglycerols relatively high melting points at room temperature.

Liquid triacylglycerols are called oils. Oils typically come from plant products such as corn , soybeans, olives, and peanuts. They are composed primarily of triacylglycerols with unsaturated fatty acids that cannot pack tightly together. Consequently they have relatively low melting points, causing them to be liquids at room temperature.

Cis and trans fats

Trans fat is the commonly known as unsaturated fat can be monounsaturated or polyunsaturated. Unsaturated fat is a molecule in one or more double bonds between carbon atoms exists. Since the carbon atoms are bonded to each other by double bonds, there are fewer bonds connected to hydrogen, meaning there are lesser hydrogen atoms, hence unsaturation.

Cis and trans are terms denoting the arrangement of chains of carbon atoms across the double bond. In the cis arrangement, chains are on the same side of the double bond, resulting in a kink. In the trans arrangement, chains are on the opposite sides of the double bond, and is straight.

Every fat molecule has three hydrocarbon chains. By hydrogenation, hydrogen atom is added to cis unsaturated fats, and double bonds are eliminated, and the fat is converted into partially or completely saturated fats. The completely saturated fats having high melting point, are more suitable for baking purposes and the saturation results in extended shelf life.

Partial hydrogenation converts a part of cis isomers into trans unsaturated fats instead of hydrogenating them completely while complete hydrogenation converts them into a saturated hard fat .

A molecule can be either Cis or Trans, depending on the conformation of the double bond even if it has the same number of atoms with a double bond in the same location.

Hydrogenation of an unsaturated fatty acid refers to the addition of hydrogen atoms to the acid, causing the conversion of double bonds into single bonds as carbon atom acquires new hydrogen atoms and it is tetravalent.

Partial hydrogenation results in the addition of hydrogen atoms at some of the empty positions, with a corresponding reduction in the double bond count. Commercial hydrogenation is typically partial in order to obtain a malleable mixture of fats which is solid at room temperature, but melts upon baking (or consumption).

Hydrogenated oils

We can convert unsaturated vegetable fats and oils into fats and oils of higher melting point through partial or complete hydrogenation.

In this process the sparging (the oil is heated to near the smoke point under vacuum,and water is introduced at the bottom of the oil. The water is immediately converted to steam, which bubbles through the oil, carrying with it any chemicals which are water soluble) of oil is done, in the presence of a catalyst, at high temperature and pressure with hydrogen.

The catalyst is usually a powdered nickel compound. As each double bond breaks, two hydrogen atoms each form single bonds with the two carbon atoms. This process is called saturation. The degree of saturation is directly proportional to the oil’s viscosity and melting point.

Steps involved in the manufacture of hydrogenated oils

Preparation of seeds which involves heating and dehulling, followed by chopping and grinding, and enzyme deactivation of the seeds as enzymes can influence quality.

Extraction from seeds is next. Extraction is done either by mechanically pressing or by mixing with solvents like hexane and heptane.

Degumming is then done which includes removal of phosphates, waxes, and other impurities by treating crude oil with water, salt solutions, dilute acids, or alkalis. For example, caustic soda(sodium hydroxide or a mixture of sodium hydroxide and sodium carbonate) is used to remove free fatty acids that can cause rancidity and decrease the quality of oil.

Other advantages of degumming:

It is essential to remove the lecithin which can cause rancidity.

Gum removal

Significantly decrease refinery waste load.

Oil becomes suitable for team refining as non volatile impurities such as phosphatides are reduced.

Improves acidulation performance.

Bleaching is done to remove color pigments.

Deoderization is then done to remove undesirable odors and tastes from the oil.

Hydrogenation is done to convert liquid oils into hard fats by adding hydrogen to the fat molecule. Hydrogenation can be of varying degrees according to the needs. The hydrogenated fats are desirable for its melting point, allowing for high temperature cooking and frying. Hydrogenation also provides liquid oils the property of spread ability. During complete hydrogenation all double bonds are saturated with hydrogen.


Polyunsaturated fats and oils are easily oxidized by O2 by means of a radical chain reaction. In the initiation step, a radical removes a hydrogen from a methylene group that is flanked by two double bonds. This is the most easily removed hydrogen because the resulting radical is resonance-stabilized by both double bonds.

The resulting radical reacts with O2, forming a peroxy radical with conjugated double bonds. The peroxy radical removes a hydrogen from a methylene group of another molecule of fatty acid, forming an alkyl hydroperoxide. The two propagating steps are repeated over and over.

The reaction of fatty acids with O2 causes them to become rancid. The unpleasant taste and smell associated with rancidity are the results of further oxidation of the alkyl hydroperoxide to shorter chain carboxylic acids that have strong odors. The same process contributes to the odor associated with sour milk.

Rancidity is due to the presence of volatile, bad smelling acids and aldehydes. These compounds result (in part, at least) from attack by oxygen at reactive allylic positions in the fat molecules.

Hydrogenation reduces rancidity

Hydrogenation slows down the development of rancidity presumably by decreasing the no of double bonds and hence the no of allylic positions.

Uses of hydrogenation

Hydrogenated oils are used in deep frying restaurants, as they can be used for longer than most conventional oils before becoming rancid.

The fat industry uses hydrogenation to provide fats some special properties like allowing margarine to be taken out of the refrigerator and immediately spread on a slice of bread.

By some minor changes to the chemical composition of hydrogenated fat , they also found such hydrogenated fat provided superior baking properties as compared to natural vegetable oils like Lard. Because of these properties, margarine has replaced butter fat.

Other use of hydrogenation is hydrogenation in petroleum refining, as production of gasoline involves cracking by destructive hydrogenation (hydrogenolysis), in which large molecules are broken down to smaller ones and reacted with hydrogen.

Why hydrogenated oils are harmful?

During hydrogenation, hydrogenation gas is fused into heated oils and attached to fatty acids. Hydrogenation removes all of the good nutrients out of the oil (essential fatty acids like Omega 3s).

The hydrogenation is done using metal catalysts like aluminum, nickel, and cobalt which are all toxic to the body. The body does not recognize the new molecular structure of the oil (which now closely resembles the chemical make up of stearic acid, used to make candles) and cannot break it down.

During the hydrogenating process, all the enzymatic activity in the oil is neutralized. Remember that this hydrogenated oil is only one molecule away from plastic and plastic does not breakdown, it lasts for millennia which is one reason that even our oceans are starting to turn to plastic.

The more enzyme dead food and ingredients you consume, the more your own body has to create and use up its own food enzymes during digestion. The act of digestion is a strenuous one on the body and requires a lot of Chi, nutrients and enzymes to take place. This places a large strain on your internal organs, especially the pancreas which has to create the necessary food enzymes for digestion. An overworked pancreas is actually one of the major causes of type II diabetes which is basically pancreatic failure.

As the body sends more enzymes (digestive acids) into the stomach to try and digest this plastic like oil, the internal stomach temperature rises. This is another way that these unhealthy oils can lead to cancer as cancer is classified as a "Yang" or "Fire" symptom in Chinese medicine. It can take thousands of degrees to break down plastic. The body is often only partially successful at breaking down and digesting hydrogenated oils.

Directly promotes heart disease

Promotes cancers: breast cancer, prostate cancer, colon cancer

Results in low birth weight infants

Raises LDL (bad) cholesterol and lower HDL (good) cholesterol

Raises blood sugar levels and promotes weight gain

Interferes with the absorption of essential fatty acids and DHA

Impairs brain function and damages brain cells

Accelerates tumor growth

Accelerates the progress of type-2 diabetes

Raises serum cholesterol

Impairs immune system function

Promotes attention deficit hyperactivity disorder (ADHD)

Impairs development of the brains of fetuses

Causes gallbladder disease

Causes liver disease

Causes 30,000 deaths per year in the United States alone

Clogs blood, makes blood cells stick together

Blocks the body's creation of natural pain-reducing hormones (eicosanoids)

Causes the creation of free radicals that promote inflammation

Creates nutritional deficiencies of healthy oils and essential fatty acids (EFAs)

Promotes cystic fibrosis

Lowers essential fatty acids in the breast milk of nursing mothers

Clogs artery walls and promotes atherosclerosis

Cause gum disease and rotted teeth

Lowers tissue oxygen intake

Causes infertility

Directly damages blood vessels

Causes high blood pressure

Weaken cell walls and compromises cellular structure

Causes dandruff and acne