Sesame oil is an edible vegetable oil derived from sesame seeds. Besides being used as a cooking oil, it is used as a flavor enhancer in many cuisines, having a distinctive nutty aroma and taste. The oil is one of the earliest-known crop-based oils. Worldwide mass modern production is limited due to the inefficient manual harvesting process required to extract the oil.
Historically, sesame was cultivated more than 5000 years ago as a drought-tolerant crop and was able to grow where other crops failed. Sesame seeds were one of the first crops processed for oil as well as one of the earliest condiments. Sesame was cultivated during the Indus Valley Civilisation and was the main oil crop. It was probably exported to Mesopotamia around 2500 BC.
Sesame seeds are protected by a capsule which only bursts when the seeds are completely ripe. This is called dehiscence. The dehiscence time tends to vary, so farmers cut plants by hand and place them together in an upright position to continue ripening until all the capsules have opened. The discovery of an indehiscent mutant (analogous to nonshattering domestic grains) by Langham in 1943 began the work towards development of a high-yielding, dehiscence-resistant variety. Although researchers have made significant progress in sesame breeding, harvest losses due to dehiscence continue to limit domestic US production.
Sesame seeds are primarily produced in developing countries, a factor that has played a role in limiting the creation of large-scale, fully automated oil extraction and processing techniques. Sesame oil can be extracted by a number of methods, depending on the materials and equipment available.
Tanzania remains the largest producer of sesame oil and also dominates the global consumption of this product. The African and Asian regions constitute the fastest developing sesame oil markets. The steady growth in demand being observed here is in line with rising household income figures and urbanization, as well as an increase in the use of sesame oil for food products and Asian dishes.
In developing countries, sesame oil is often extracted with less-expensive and manually intensive techniques such as hot water flotation, bridge presses, ram presses, the ghani process, or by using a small-scale expeller. In developed countries sesame oil is often extracted using an expeller press, larger-scale oil extraction machines, or by pressing followed by chemical solvent extraction.
Sesame oil can also be extracted under low-temperature conditions using an expeller press in a process called cold pressing. This extraction method is popular among raw food adherents because it avoids exposing the oil to chemical solvents or high temperatures during extraction.
While some manufacturers will further refine sesame oil through solvent extraction, neutralization and bleaching in order to improve its cosmetic aspects, sesame oil derived from quality seeds already possesses a pleasant taste and does not require further purification before it can be consumed. Many consumers prefer unrefined sesame oil due to their belief that the refining process removes important nutrients. Flavour, which was traditionally an important attribute, was best in oils produced from mild crushing.
Sesame oil is one of the more stable natural oils, but can still benefit from refrigeration and limited exposure to light and high temperatures during extraction, processing and storage in order to minimize nutrient loss through oxidation and rancidity. Storage in amber-colored bottles can help to minimize light exposure.
Sesame oil is a polyunsaturated (PUFA) semi-drying oil. Commercial sesame oil varies in colour from light to deep reddish-yellow depending on the colour of the seed processed and the method of milling. Provided the oil is milled from well-cleaned seed, it can be refined and bleached easily to yield a light-coloured limpid oil. Sesame oil is rich in oleic and linoleic acids, which together account for 85% of the total fatty acids. Sesame oil has a relatively high percentage of unsaponifiable matter (1.5-2.3%). In India and in some other European countries it is obligatory to add sesame oil (5-10%) to margarine and generally to hydrogenated vegetable fats which are commonly used as adulterants for butter or ghee.
Sesame seed market
The market for sesame oil is mainly located in Asia and the Middle East where the use of domestically produced sesame oil has been a tradition for centuries. About 65 percent of the annual US sesame crop is processed into oil and 35 percent is used in food.
There are many variations in the colour of sesame oil: cold-pressed sesame oil is pale yellow, while Indian sesame oil (gingelly or til oil) is golden, and East Asian sesame oils are commonly a dark brown colour. This dark colour and flavour are derived from roasted/toasted sesame seeds. Cold-pressed sesame oil has a different flavour than the toasted oil, since it is produced directly from raw, rather than toasted, seeds.
Sesame oil is traded in any of the forms described above: Cold-pressed sesame oil is available in Western health shops. Unroasted (but not necessarily cold-pressed) sesame oil is commonly used for cooking in South India, the Middle East, halal markets and East Asian countries.
The only essential nutrient having significant content in sesame oil is vitamin K, providing 17% of the Daily Value per 100 grams (ml) consumed supplying 884 calories (table). For fats, sesame oil is approximately equal in monounsaturated fat (oleic acid, 40% of total) and polyunsaturated fat (linoleic acid, 42% of total), together accounting for 80% of the total fat content (table). The remaining oil content is primarily the saturated fat, palmitic acid (about 9% of total, USDA table).
One type of sesame oil, a pale yellow liquid with a pleasant grain-like odor and somewhat nutty taste, is used as frying oil. A second type of oil, amber-colored and aromatic, is made from pressed and toasted sesame seeds and is used as a flavoring agent in the final stages of cooking.
Despite sesame oil’s high proportion (41%) of polyunsaturated (omega-6) fatty acids, it is least prone, among cooking oils with high smoke points, to turn rancid when kept in the open. This is due to the natural antioxidants, such as sesamol, present in the oil.
Light sesame oil has a high smoke point and is suitable for deep-frying, while dark sesame oil (from roasted sesame seeds) has a slightly lower smoke point and is unsuitable for deep-frying. Instead it can be used for the stir frying of meats or vegetables, sautéing, or for the making of an omelette.
Sesame oil is most popular in Asia, especially in Korea, China, and the South Indian states of Karnataka, Andhra Pradesh, and Tamil Nadu, where its widespread use is similar to that of olive oil in the Mediterranean.
- East Asian cuisines often use roasted sesame oil for seasoning.
- The Chinese use sesame oil in the preparation of meals.
- In Japan, rāyu is a paste made of chili-sesame oil seasoning and used as a spicy topping on various foods, or mixed with vinegar and soy sauce and used as a dip.
- In South India, before the advent of modern refined oils produced on a large scale, sesame oil was used traditionally for curries and gravies. It continues to be used, particularly in Tamil Nadu and Andhra Pradesh, mixed with foods that are hot and spicy as it neutralizes the heat. It is often mixed in with a special spice powder that accompanies idli and dosa as well as rice mixed with spice powders (such as paruppu podi).
- a solvent in injected drugs or intravenous drip solutions,
- a cosmetics carrier oil,
- coating stored grains to prevent weevil attacks. The oil also has synergy with some insecticides.
Low-grade oil is used locally in soaps, paints, lubricants, and illuminants.
As with numerous seed and nut foods, sesame oil may produce an allergic reaction, although the incidence of this effect is rare at approximately 0.1% of the population. Reports of sesame allergy are growing in developed countries during the 21st century, with the allergic mechanism from oil exposure expressed as contact dermatitis, possibly resulting from hypersensitivity to lignin-like compounds.
Although preliminary research on the potential effect of sesame oil on inflammation and atherosclerosis has been conducted, as of 2017, there was insufficient quality of the studies to allow any conclusions.
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