HYDROGENATION OF OIL
Hydrogenated oil is oil in which the essential fatty acids have been converted to a different form chemically, which has several effects on the oil.
Hydrogenated oil is made by forcing hydrogen gas into oil at high pressure. The hydrogenation of oils converts liquid oils into hard fats by adding hydrogen to the fat molecule. Oils can be hydrogenated to varying degrees, depending on the hardness. The most common forms are shortening, margarines, and the partially hydrogenated fats used for frying and in processed foods. These fats are desirable for its melting point, allowing for high temperature cooking and frying.
When hydrogenated oil is made, these healthy fats are converted into a new type of fatty acid, known as a trans fat.
Trans fatty acids work to increase LDL, or "bad" cholesterol, and they also decrease HDL cholesterol, which is "good" cholesterol.
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Hydrogenated oil is far more shelf stable, and will not go rancid as quickly as untreated oil. It also has a higher melting point, and is often used in frying and pastries for this reason.
The following steps are taken to process oils found on supermarket shelve:
- Preparation of seeds begins with heating and dehulling, followed by chopping or grinding, to break the cell walls, freeing the oil to make the penetration of solvents into the cells easier. This is accomplished by rolling or flaking, but it is still not enough to release all of the oil. Therefore, a thermal or conditioning step is required. In addition, all oil seeds have enzymes that can influence quality. During processing, the object is to deactivate these enzymes early by means of heat. For example, with canola or rapeseed, the enzyme myrosinase can influence quality because it catalyses hydroysis of glucosinolates to give glucose, sulphate, isothiocyanates, oxazolinine thiones, and other compounds. Some of these compounds act as a catalyst poison during hydrogenation of oil for margarine production.
- Extraction from seeds is accomplished either by mechanically pressing or by mixing with such gasoline-like solvents as hexane and heptane (which are lung irritants and nerve depressants). At this stage, if the chemical extraction method is used, the oil is extremely flammable, and some factories have been known to blow up or catch on fire. Later, the oils are steam heated to evaporate the solvents at temperatures around 300°F. Most of the solvents are evaporated, but not all. The primary objective of this step is to produce a clean, crude oil product. Be aware that, at this stage, the oil can now be bottled and sold as "unrefined oil" in health food stores and delicatessens. Oil designated for more refining goes through more processing procedures. After being mashed and cooked for up to two hours at varying temperatures, depending on the seed type, mechanically pressed seeds are subject to additional heating during the "auger" process, where the average temperature reaches about 120°C (248°F) with higher temperatures and pressures producing more oil. At this temperature, however, oil reacts with oxygen more than 100 times faster than at room temperature, producing fatty acid damage. In some cases, after mechanical pressing, the oil is filtered and sold as unrefined oil, but more often, the oil undergoes further refining.
- Degumming is a treatment of crude oils and water, salt solutions, dilute acids, or alkalis used in order to remove phosphates, waxes, and other impurities. Caustic soda, (often sodium hydroxide -- commonly known as Drano -- or a mixture of sodium hydroxide and sodium carbonate) is one such substance used to remove free fatty acids that can cause rancidity and decreases the quality of the oil. Alkali solutions combine with the free fatty acids to form soaps and also helps to remove toxic substances that are naturally present in many plants. Temperatures again have reached 75°C (167°F). At this stage, the oil still has its pigmentaion of red, yellow, or greenish hue, which is also deemed undesireable. Degumming converts the phosphatides to hydrated gums which are insoluble in oil and readily separated as sludge. The hydrated gums are vacuum dried for crude lecithin processing. This process also involves the addition of phosphoric acid and water at temperatures of 60°C (140°F).
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The industry's rationale for the degumming process is as follows:
- It is necessary to remove the lecithin, which can cause rancidity of the oil.
- It satisfies export oil requirments for a product free of impurities that settle out during shipment.
- Gum removal prior to alkali refining often improves yield because the phosphates can act as emulsifiers in a caustic solution, increasing the neutral oil contained in the soapstock.
- It substantially decreases refinery waste load because of the lower neutral oil losses and the reduction of gums discharged.
- It prepares the oil for steam refining. Degummed oil is more suitable to this physical refining technique because of the significant reduction in such nonvolatile impurities as phosphatides and metallic prooxidants.
- It results in improved acidulation performance. The soapstock from alkali refining is easier to acidulate because of lower emulsifier content, and the acid water has less impact on the wastewater treatment systems.
- Bleaching oils is necessary because they have a strong yellow or reddish pigment that is considered undesirable. In the bleaching process, oils are heated to temperatures of 175°-225°C, for about 4 hours, and mixed with a type of clay substance that will absorb the unwanted pigment. Most of the spent clay is then filtered from the oil. During this phase, some of the polyunsaturated fatty acids may undergo oxidation and toxic peroxides, forming conjugated fatty acids.
- Deoderization is done through pressurized steam distillation at temperatures of 240°-270°C (464-518°F) for 30 to 60 minutes, which removes undesirable odors and tastes from the oil. : When temperatures go above 150°C (302°F), unsaturated fatty acids become mutagenic. Above 160°C(320°F), trans fatty acids begin to form. Above 200°C (392°F), trans fatty acids multiply substantially, and, above 220°C, the rate of trans fatty acids explodes.
Deoderizing reduces the content of many other substances, including residues, toxins, and products of oxidation formed during the bleaching stage, as well as removing sulphur, monoglycerides, sterols, beta carotene, and tocopherols (Vitamin E). The oil is now tasteless and cannot be distinguished from other oils derived from seeds or plants. At this point, despite all of the heating involved, the oils can still be sold as "cold-pressed" since there is no accepted definition of the term. Preservatives are added such as synthetic antioxidants, BHT (butylated hydroxytoluene), BHA (butylated hydroxyanisole, propyl gallate, TBHQ (teriary butyhydroquinone), citric acid, or methylsilicone. A defoamer may also be added to prevent turbidity when refrigerated.
- Hydrogenation: After all this, oils not designated for sale, go on to more processing in the form of hydrogenation to make margarines, shortenings, and shortening oils. The hydrogenation of oils converts liquid oils into hard fats by adding hydrogen to the fat molecule. Oils can be hydrogenated to varying degrees, depending on the hardness. The most common forms are shortening, margarines, and the partially hydrogenated fats used for frying and in processed foods. These fats are desirable for its melting point, allowing for high temperature cooking and frying.
Hydrogenation involves the artificial saturation of fully refined oils to harden them into spreadable products. All oils sold in supermarkets and convenience stores are processed in the above manner. "ALL" includes safflower, walnut, sunflower, corn, grape seed, soybean, sesame, rice bran, canola, almond, peanut, avocado, and others including blends. Olive oil is the only oil sold on supermarket shelves that is not heated above 150°C. However, it is a poor source of essential fatty acids, containing on average 10% LA and 0.5% LNA.
After the refining process above, oils are put under pressure, using hydrogen gas at temperatures of 120-210°C (248-410°F) in the presence of a metal catalyst (nickel, platinum, or copper) for six to eight hours. A nickel catalyst is actually 50% nickel and 50% aluminum. Remnants of both metals remain in the final products of hydrogenated or partially hydrogenated goods. During complete hydrogenation, all double bonds are saturated with hydrogen. This means there are no unsaturated fatty acids, no w6's, and no w3's. In some partially hydrogenated margarines, the trans fatty acid content can be more than 60%. Partially hydrogenated oils are found in French fries (37.4%), candies (38.6%), and bakery products (33.5%). A completely hydrogenated oil is now a hard fat containing no essential fatty acid activity, causing a nation-wide deficiency of the essential fatty acids.
USES OF HYDROGENATION OF OIL
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Hydrogenation of oil used for various purposes as follows:
Coconut oil is commonly used in cooking, especially when frying. In communities where coconut oil is widely used in cooking, the unrefined oil is the one most commonly used. Coconut oil is commonly used to flavor many South Asian curries.
Hydrogenated or partially-hydrogenated coconut oil is often used in non-dairy creamers, and snack foods.
Industrial and commercial Uses
Hydrogenated oil is used in a variety of industrial and home products. Cosmetics and polishes are the most common sources of hydrogenated oil in the home.
In an industrial setting, hydrogenated oil is used in electrical equipment, carbon paper, lubricants and greases for machinery.
Since hydrogenated oil is not water-soluble, it protects items against moisture.
Cosmetics and skin treatments
Coconut oil is excellent as a skin moisturizer and softener. A study shows that extra virgin coconut oil is effective and safe when used as a moisturizer, with absence of adverse reactions.
Fractionated coconut oil is also used in the manufacture of essences, massage oils and cosmetics.
In India and Sri Lanka, coconut oil is commonly used for styling hair, and cooling or soothing the head.
Also in cosmetics, hydrogenated castor oil is considered to be organic. Since the hydrogenation process uses natural hydrogen gas that is mixed with natural castor bean oils, it is commonly found in both organic and non-organic cosmetics.
Soaps and detergents
Coconut oil is used as a base oils for soap, shampoo and detergent making.
Coconut oil is used in oil lamps.
In diesel engines
Coconut oil has been tested for use as a feedstock for biodiesel to be used as a diesel engine fuel. In this manner it can be applied to power generators and transport using diesel engines. Since straight coconut oil has a high gelling temperature (22-25°C), a high viscosity, and a minimum combustion chamber temperature of 500°C (932°F) (to avoid polymerization of the fuel), coconut oil is typically transesterified to make biodiesel. Use of B100 (100% biodiesel) is only possible in temperate climates as the gel point is approximately 10°C (50 degrees Fahrenheit). The oil needs to meet the Weihenstephan standard for pure vegetable oil used as a fuel otherwise moderate to severe damage from carbonisation and clogging will occur in an unmodified engine.
The Philippines, Vanuatu, Samoa, and several other tropical island countries are using coconut oil as an alternative fuel source to run automobiles, trucks, and buses, and to power generators. Coconut oil is currently used as a fuel for transport in the Philippines. Further research into the oil's potential as a fuel for electricity generation is being carried out in the islands of the Pacific. In the 1990s Bougainville conflict, islanders cut off from supplies due to a blockade used it to fuel their vehicles.
Coconut oil has been tested for use as an engine lubricant; the producer claims the oil reduces fuel consumption, smoke emissions and allows the engine to run at a cooler temperature.
Transformer oil acts as an insulating and cooling medium in transformers. The insulating oil fills up pores in fibrous insulation and also the gaps between the coil conductors and the spacing between the siding and the tank, and thus increases the dielectric strength of the insulation. A transformer in operation generates heat in the winding, and that heat is transferred to the oil. Heated oil then flows to the radiators by convection. Oil supplied from the radiators, being cooler, cools the winding. There are several important properties such as dielectric strength, flash point, viscosity, specific gravity and pour point and all of them have to be considered when qualifying an oil for use in transformers. Normally mineral oil is used, but coconut oil has been shown to possess all the properties needed to function as an environmentally friendly and economic replacement to mineral oil for this purpose.
Also Hydrogenation reactions are important in petroleum refining; production of gasoline by cracking involves destructive hydrogenation (hydrogenolysis), in which large molecules are broken down to smaller ones and reacted with hydrogen. Most hydrogenation reactions are reversible and proceed to favorable equilibria at high pressure and moderate temperature.
We conclude, therefore, that when we hydrogenate fats, we do not only change their molecular structure, but we change their entire character and we destroy essential nutrients.
`[Vitamins] . . . can be eliminated by such modern food processing as milling of grains, polishing of rice, and hydrogenation or chemical hardening of plant or animal fats.
`The process of hydrogenation whereby oil is cooked at high temperatures under pressure in the presence of a catalyst and elemental hydrogen, results in saturations of the oil and the formation of unnatural isomeric forms. The vitamins and nutritional mineral factors are also destroyed in the process, and the resulting dark and smelly grease is bleached and deodorized to become a white, tasteless, synthetic fat that can be flavored, coloured and sold to imitate butter, or used for lard or other shortening or frying fat. It is my serious contention that hydrogenated fats are not one iota better or more beneficial or acceptable to the human body than mineral oil [motor oil].