Sesame seeds

A small seed that is half oil

Sesame seed comes from Sesamum indicum, an annual herb of the family Pedaliaceae that the older literature also calls Sesamum orientale. It goes by several names: gingelly, til, benniseed and simsim, and in the Mizo language of north-east India chhawhchhi. The seeds ripen in small capsules and come in pale, brown and black forms; the colour is one of the first things a cook or buyer notices, though it says little about flavour on its own.

What makes sesame unusual is its oil. Texas A&M's production guide puts the seed at about half oil by weight, calls anything below 50 percent unacceptable for the crop and says most current varieties give 50 to 55 percent; Oklahoma's extension sheet on sesame oil gives a wider range of 40 to 60 percent oil together with about 25 percent protein. That composition is why one seed serves as topping, paste, oil and the pressed meal left behind. A pressed meal is no longer the seed, a paste is not the oil, and the nutrient figures of one cannot be carried over to another.

Sesame is also one of the most drought-tolerant crops in cultivation. Texas guidance says it needs 110 to 150 frost-free days, germinates poorly when the soil is below about 70 °F, and does best with daily average temperatures of 86 to 92 °F. Plants use about half the water of cotton and a quarter of the water of corn, and suit regions with 16 to 18 inches of annual rain, but they die if left standing in water for more than a few hours.

An old crop with a South Asian start

The crop's origin is a question that archaeobotanists argued over for a long time. Many scholars had suggested that sesame was first domesticated in Africa. Dorian Fuller's 2003 review of the evidence, drawing on finds from 22 sites, concluded otherwise. Cultivated sesame derives from wild populations native to South Asia, especially the western Indian peninsula, the Punjab and parts of Pakistan, where a wild plant known as Sesamum malabaricum or S. mulayanum, which Fuller treats as synonyms, still grows. Genetic diversity is much higher in South Asia than elsewhere, which points the same way.

The wild type resembles the crop but has smaller, highly rugose seeds with sharp margins, usually purple rather than white flowers, lobed leaves and longer beaked capsules. It grows in the wet tropical regions of the western Indian peninsula, often as a weed of wasteland, and in semi-arid zones of the northwest. Some South Asian landraces keep a few of these features, such as black seeds with a somewhat rugose coat, which is part of the evidence that the crop descends from this plant. Because spontaneous populations readily establish themselves around fields, it is hard to say how much of the wild plant's range is true wild and how much is feral escape from cultivation.

The oldest charred seeds come from northwestern South Asia. Sesame seeds from the Harappan city of Harappa were once dated to the late fourth millennium BC, but Fuller notes that the date was a guess made before radiocarbon dating; the layer belongs to the mature Harappan period, between 2500 and 2000 BC. A better-documented find at the Harappan site of Miri Qalat in Baluchistan dates to the same period, and sesame is absent from the site's earlier layers back to 4000 BC, so it arrived there with the Harappans. In the second millennium BC the crop turns up across India: Sanghol in Punjab (1900 to 1400 BC), Malhar in the Gangetic basin at about 1600 BC, Imlidh-Kurd before 1300 BC, and Inamgaon in Maharashtra at 1500 to 900 BC.

West of the Indus the record is thinner but clear. Charred seeds from Abu Salabikh in Iraq show sesame in Mesopotamia by about 2300 BC, which supports reading the Assyrian word shamas-shammu and perhaps the earlier Sumerian she-gish-i as sesame. By about 1400 BC it was grown in Bahrain, and a burnt storage context at Sabir in Yemen of about 900 BC held large quantities of sesame beside linseed and mustard. Oil-pressing equipment at Karmir Blur shows that sesame oil was being pressed in the early first millennium BC. Textual evidence in Egypt appears in the Greek period, from the fourth to the first century BC. Egypt's earlier record is more contested. Seeds from the tomb, from Deir el Medina and from Amarna suggest sesame reached Egypt by the later fourteenth century BC, though some Egyptologists doubt that the New Kingdom word for an edible oil refers to sesame. The seeds from Tutankhamun's tomb have a distinctly reticulate coat, which is unusual for cultivars but is a feature of the wild type and of some Indian landraces, so it does not argue against their identification.

Fuller's review points out two cautions. One is that sesame is hardly a domesticate in the strict sense, because its capsules split as they ripen and seed is lost, a problem breeders still fight; the other is that the earliest finds come from northwestern South Asia but that region need not be where the crop was first grown. The African evidence that does exist is late: the earliest seeds south of Egypt come from Qasr Ibrim in Nubia at 300 to 500 AD, and by the twelfth century Arabic sources attest the crop in West Africa. In short, sesame is old, South Asian in origin, and widely carried by about 2000 BC, but the first field has not been found.

Capsules, shatter and harvest

Harvest decides how much of the crop reaches the market. Ripe capsules split, and in older varieties much of the seed fell to the ground before it could be gathered. Texas growers once lost heavily to shatter, until the discovery of an indehiscent gene in 1943 and a seamless gene in 1986 led to varieties that open slightly and keep their seed, even through six weeks of rain; strictly indehiscent lines held their seed too well and were abandoned commercially because they were hard to thresh without damage.

Growers plant seed three-quarters of an inch to an inch and a half deep once the soil has held an average of 68 °F at eight in the morning for ten days, about two to three weeks later than cotton. Dryland yields in Texas ran from 300 to 1,200 pounds an acre and irrigated crops from 800 to 1,700 pounds. A commercial variety takes 90 to 110 days to physiological maturity and then 20 to 40 days to dry down in the field. Combines are run slowly with loose concaves so that no more than two seeds in a hundred are broken, and the seed is cleaned afterwards in separate equipment. Seed must be kept from rain and dew, because wet seed heats faster than most seed. Dark seed spoils the white lots, since the colour of black seed bleeds into the kernel and cannot be removed by dehulling; optical sorting removes it.

Whole seed, paste, oil and meal

Most sesame eaten in the United States is whole seed, scattered on buns and snack foods, which Texas guidance gives as the primary use. Ground to a paste, sesame becomes tahini, which is normally made with hulled and lightly roasted seed; ingredient lists should still be read, since not every paste follows one recipe. Sweetened and pounded, it makes halva and similar confectionery.

Oil is the most processed form. A pale refined oil pressed from raw seed is used for cooking and frying. An amber oil pressed from toasted seed has a strong nutty aroma and serves as a seasoning rather than a frying medium. The pressing leaves a meal, whose composition differs from that of the whole seed. Sesame also contains lignans, a group of compounds that includes sesamin and sesamolin.

Heat changes those lignans. A comprehensive review of sesame lignans reports that roasting converts sesamolin into sesamol, and that refining alters the lignan profile, so a toasted oil does not have the same chemistry as raw seed. The review also finds that the lignan contents of sesame samples vary and that comparisons do not support a universal ranking of black, white and brown seed.

Sesame in condiments and ferments

Sesame is rarely a fermented food in itself. Its role in ferments and condiments is as an oily, aromatic ingredient that carries other flavours, and the best-documented examples are dry seasonings. Gomasio, the Japanese sesame and salt condiment (gomashio), pairs tan or black seeds with salt. In one preparation both are toasted separately and then ground together by hand in a suribachi, the ridged Japanese mortar. Grinding breaks the hulls and releases oil, giving a coarse, fragrant powder that is sprinkled over grains and vegetables. Japan's Ministry of Agriculture describes a Hokkaido serving of sekihan, the festive red rice, topped with black sesame ground with salt.

The Mizo people of north-east India ferment sesame. Their word for it is chhawhchhi, and it comes in two kinds, chhibung and chhipui. Chhi-um, the fermented sesame, is made from chhibung: the seed is heated, crushed in a wooden mortar and kept in a closed container on top of the fireplace, and after three days it is used as a taste enhancer. Chhipui is heated and pounded with salt until it turns oily and sticky and is eaten as a side dish; the stickiness comes from released oil and does not signal fermentation. Ai-um combines sesame with crab: thumb-sized river crabs are killed with hot water, ground and mixed thoroughly with chhawhchhi, kept in a closed container above the fireplace and opened after about three days, and the paste is then dried in the sun or over the fire and served as a side dish.

Sesame garum, a Goodlok seasoning, uses sesame seed as a named input alongside barley-groat koji, the base of a fermented liquid seasoning; the producer does not publish the proportions or the process.

Sesame as an allergen

Sesame is a recognised food allergen, and its presence matters whether a food shows visible seeds or contains tahini, oil or paste. In the United States, sesame became the ninth major food allergen when the FASTER Act took effect on 1 January 2023, so packaged foods must declare it in the ingredient list or in a Contains statement; products sold before that date did not have to be relabelled. Other jurisdictions have their own rules, and unpackaged foods may be subject to different requirements. A sesame declaration and a gluten or barley declaration answer different questions about a finished food: the gluten declared on that garum belongs to the barley-groat koji and not to the seed.

Keeping sesame and keeping it safe

The oil that makes sesame valuable also makes it prone to going rancid. Keep seed in a closed container and cool, and treat whole seed, paste and oil as different foods with different keeping times; the sources give no single figure. A toasted aroma is a flavour, and stale oil is a fault. Wet seed deteriorates quickly: a Kansas case in which a hard freeze caught green plants with wet seed led to rancidity weeks later, whereas dry seed showed no problem.

Dryness does not make sesame sterile. A review of sesame food safety identifies Salmonella as the main hazard in seed and sesame products and traces it to outbreaks, including 47 confirmed cases in five European countries in 2016 and 2017 linked to sesame paste from Greece and seed from Nigeria, and 135 confirmed cases between January 2019 and October 2021 linked to halva and tahini imported from Syria. Sesame products have a water activity below 0.70 and several months of shelf life, which stops bacteria from growing but not from surviving, and the oil can shield them from heat treatment and irradiation. Many sesame foods are eaten as they are, without a further step that would inactivate bacteria, so the safety of the supply chain matters more than any step in the kitchen.

What the sources leave open

The date and place of first domestication remain open, as does the route sesame took between the Indus and Mesopotamia. The Mizo methods are traditional household practice with no measured acidity or safety limits, and the recipe for sesame garum is unpublished.

Sesame on breads

Whole sesame seeds are also a topping for breads in several documented preparations. A recipe published by Thessaloniki’s Network of Creative Cities of Gastronomy dips shaped koulouri rings in sugared water, coats them in sesame and bakes them at 200 °C for about 15 minutes. Luay Ghafari’s home recipe for ka'ak al-Quds mixes untoasted sesame with honey and hot water, then dips the shaped rings in the mixture before baking; this is a contemporary recipe, not a complete history of Palestinian bread practice.

Judy’s Shanghai da bing recipe brushes the folded dough with water, adds toasted sesame seeds and bakes the pancakes. The Woks of Life describes da bing as one of Shanghai’s breakfast foods, often served with you tiao. These examples show different uses for whole sesame on bread; they do not establish one method for every sesame-topped bread.