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The groundnut or peanut is a legume and belongs to the family of beans.It has a high nutritional value and is therefore considered as nut. Groundnut oil is organic oil derived from groundnuts. It is the only nut that grows underground. In South East Asian cuisine peanut oil is popular just as olive oil is in the Mediterranean region. Among edible vegetable oils only soybean oil exceeds the production of groundnut oil making it one of the most produced oils in the world. Groundnut oil is pale in colour, bland in taste, has pleasant aroma and is of light consistency.
Extraction of groundnut oil: There are three methods used for extracting groundnut oil namely, hydraulic, expeller and solvent extraction. The peanuts are first shelled by passing them through shellers or hullers and then cleaned.  The hydraulic method of extraction consists of pressing the shelled peanuts or kernels while adding steam and heat. The expeller method is more popular in which the peanuts are fed into a grinder and pressure is added as the screw turns. A perforated screen separates the oil from the solid mass left behind. The solvent method is the most expensive. It involves the use of solvent such as hexane to extract oil. This method is sometimes combined with the expeller method. The oil content of the kernels is between 42 and 50 percent if extracted by expeller method but can go up 55 to 60 percent if obtained by heat and using a solvent. Solvent extracted oil needs to be refined to remove traces of solvent before it is used for edible purposes.
Fatty Acids and Groundnut Oil: Groundnut oil contains high amounts of energy and fat-soluble vitamins such as A, D, E and K. It is also rich in monosaturated fatty acids called oleic fatty acids. It is the presence of this fatty acid that imparts health promoting qualities in peanut oil. Though fatty acids are a major component of any oil form, it is the oleic form, also found in large quantities in olive oil that make this oil healthy and a good substitute for olive oil. This form of fatty acid has shown to reduce cholesterol levels. Phytosterols present in peanut oil has the ability to absorb dietary cholesterol in the blood, thereby protecting against cardiovascular disease.
Health benefits of Groundnut Oil: Groundnut or peanut oil is also known to contain good amount of beta-sitosterol as a natural compound in peanuts. Research studies have proved that this compound can protect against colon, breast and prostate cancer by inhibiting cell division and stimulating tumour cell death. Groundnut oil is well balanced oil but it lacks anti-oxidants and micronutrients that are present in some other oils such rice bran oil. Groundnut oil can be harmful for those who are allergic to nuts or suffer from any nut allergy. But research indicates that refined peanut oil does not cause allergy because the protein content is low. However, it is the unrefined variety that causes health problems. The newer variety developed in economically advanced nations has over 80 percent monosaturated fatty acids bringing it at par with olive and sunflower oil. Groundnut contains more protein then meat, two and half more than eggs and more than any other vegetable food. The proteins in groundnut are well balanced. Its oil has many beneficial properties too.
Cooking and Groundnut Oil: Groundnut oil is known as an excellent all-rounder with the advantage of having no distinct flavour yet being luscious at the same time. It is perfect for making mayonnaise with a dash of olive oil added. It is extremely beneficial for cooking oriental dishes where the use of olive oil is restricted. It has a high smoke point, making it a good oil for frying. In fact, its having a smoke point of 450 degrees Celsius makes it ideal for foods that require deep frying. It imparts a slightly earthy, nutty flavour. Refined peanut oil is also used in a wide range of manufacture food products such as biscuits, cakes and muffins.
Some Other Uses: Groundnut oil can also serve as a beauty aid. A teaspoon of refined groundnut oil mixed with an equal quantity of lime juice can be applied on the face at bedtime. It keeps the face fresh, skin glowing and prevents acne. Peanut oil is rich in vitamin E and is readily absorbable with good capacity for conditioning. Because of these properties groundnut oil is favoured for use in massage oils and in making soaps. It is a cost effective base for most soap recipes. The oil is used in the manufacture of margarines and shortenings, and as a salad oil. The press cake is used for cattle feed.
Storage: Groundnut oil can be found in most well stocked grocery stores. This oil also has a longer shelf life because it contains smaller amount of polysaturated fatty acids that are prone to oxidation. Groundnut oil should be stored in a cool, dark place away from direct heat or sunlight.
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