12 Sesame Oil Lucy Sun Hwang National Taiwan University Taipei, Taiwan 1. INTRODUCTION Sesame (Sesamum indicum L.) is believed to be one of the most ancient crops culti- vated by humans (1). It was first recorded as a crop in Babylon and Assyria over 4000 years ago. The seeds of the crop are used both as condiment and oil source. The Babylonians made wine and cakes with sesame seeds, whereas sesame oil was used for cooking, medicinal, and cosmetic purposes. Ancient Indians used sesame oil as lighting oil, and sesame seeds were commonly used in the religious rites of Hindus. The Chinese believed that sesame seeds could promote health and longevity. Sesame seed has higher oil content (around 50%) than most of the known oil- seeds although its production is far less than the major oilseeds such as soybean or rapeseed due to labor-intensive harvesting of the seeds. Sesame oil is generally regarded as a high-priced and high-quality oil. It is one of the most stable edible oil despite its high degree of unsaturation. The presence of lignan type of natural antioxidants accounts for both the superior stability of sesame oil and the beneficial physiological effects of sesame. In Asia, sesame oil is obtained by pressing the roasted oilseeds and consumed as a naturally flavored oil without refining. In the western world, sesame oil is extracted by a multiple-step mechanical expeller and either the virgin oil or the Bailey’s Industrial Oil and Fat Products, Sixth Edition, Six Volume Set. Edited by Fereidoon Shahidi. Copyright # 2005 John Wiley & Sons, Inc. 537
Transcript
12Sesame Oil
Lucy Sun Hwang
National Taiwan University
Taipei, Taiwan
1. INTRODUCTION
Sesame (Sesamum indicum L.) is believed to be one of the most ancient crops culti-
vated by humans (1). It was first recorded as a crop in Babylon and Assyria over
4000 years ago. The seeds of the crop are used both as condiment and oil source.
The Babylonians made wine and cakes with sesame seeds, whereas sesame oil
was used for cooking, medicinal, and cosmetic purposes. Ancient Indians used
sesame oil as lighting oil, and sesame seeds were commonly used in the religious
rites of Hindus. The Chinese believed that sesame seeds could promote health and
longevity.
Sesame seed has higher oil content (around 50%) than most of the known oil-
seeds although its production is far less than the major oilseeds such as soybean or
rapeseed due to labor-intensive harvesting of the seeds. Sesame oil is generally
regarded as a high-priced and high-quality oil. It is one of the most stable edible
oil despite its high degree of unsaturation. The presence of lignan type of natural
antioxidants accounts for both the superior stability of sesame oil and the beneficial
physiological effects of sesame.
In Asia, sesame oil is obtained by pressing the roasted oilseeds and consumed
as a naturally flavored oil without refining. In the western world, sesame oil is
extracted by a multiple-step mechanical expeller and either the virgin oil or the
Bailey’s Industrial Oil and Fat Products, Sixth Edition, Six Volume Set.Edited by Fereidoon Shahidi. Copyright # 2005 John Wiley & Sons, Inc.
537
refined oil is used for salad dressing. After pressing out oil, the remaining sesame
meal contains high-quality protein suitable for human consumption as well as ani-
mal feed. It is also a good source of water-soluble antioxidants.
In this chapter, the properties and processing of sesame oil will be presented, and
the antioxidative components and their effects on oil stability and health will be
summarized.
2. BOTANY OF SESAME
Sesame (Sesamun indicum. L., synonymous with Sesamun orientale L.), also
known as benniseed (Africa), benne (Southern United States), gingelly (India), gen-
gelin (Brazil), sim-sim, semsem (Hebrew), and tila (Sanskrit), is the world’s oldest
oil crop. It belongs to the Tubiflorae order, Pedaliaceae family, which comprises
of 16 genera and some 60 species (2). There are 37 species under the Sesamum
genus (3). Among the 37 species, only Sesamum indicum is widely cultivated.
The wild species such as S. angustifolium, S. calycium, S. baumii, S. auriculatum,
S. brasiliense, S. malabaricum, S. prostratum, S. indicatum, S. radiatum, S. occiden-
tale, and S. radiatum are cultivated in Africa, India, or Sri Lanka in small areas.
The wild species, although low in oil contents, may contribute to favorable agro-
nomic characters (such as resistance to disease, pests, and drought) when used in
plant breeding.
As most of the wild species of sesame were found in Africa, it is generally
believed that sesame originated in Africa. India may also be the origin of some
species (S. capense, S. prostratum, and S. schenckii) of sesame (2, 4). The sesame
species in the Middle East are similar to Africa; they are believed to be spread from
Africa via Egypt (2). Sesame seeds were brought to India and Burma from Africa
and the Middle East (4). Cross-fertilization of the species from Africa and India
results in a large variety of sesame species. India, therefore, became the secondary
center of diversity. Both China and Japan are the major consumers of sesame
seeds; their sesame seeds were introduced from the Middle East as early as in
500 to 700 B.C. Sesame was brought to the United States by slaves from Africa
in the late seventeenth century. The sesame seeds are still known as benne in
the southern parts of United States, a term similar to the African name of sesame
(benniseed).
Sesame grows in tropical and subtropical areas about 40�N latitude to 40�Slatitude (5). Sesame indicum L. is the commonly cultivated species of sesame. It
has 26 somatic chromosomes (2n ¼ 26). Sesame is an annual, erect herb that
may grow between 50 cm and 250 cm in height, depending on the variety and grow-
ing conditions. The stems (Figure 1) may have branches and are obtusely quadran-
gular, longitudinally furrowed, and densely hairy. The extent of hairiness on the
stem can be classified as smooth, slightly, and very hairy; it is related to the variety
of sesame. The degree and type of branching of the stem are also important varietal
characters (6).
538 SESAME OIL
Sesame leaves are hairy on both sides and are highly variable in shape and size
not only among different varieties but also on the same plant. The lower leaves are
opposite, ovate, sometimes palmately lobed or palmately compound, dull green
in color, 3–17.5 cm long and 1–7 cm wide, and coarsely serrate, and the petiole
is 5 cm in length. The upper leaves are alternate or subopposite, lanceolate, and
entire or with a few coarse teeth, and the petiole is 1–2 cm long. The arrangement
of leaves influences the number of flowers born in the axils and thus the seed yield
per plant.
Sesame has large, white, bell-shaped flowers. The flowers are zygomorphic, in
axils of upper leaves, born singly or 2�3 together, short-pedicelled, and geniculate.
The calyx is small and five parted, and the segments are ovate-lanceolate and 0.5–
0.6 cm long. The corolla is tubular-campanulate, 3–4 cm long, widened upward,
two-lipped, five-lobed with middle lower lobe longest, pubescent outside, white,
pink, or purplish in color with yellow or purple blotches, spots, and stripes
on inner surface. The stamens are four in number, didynamous, and inserted on
the base of the corolla; the anthers are sagittate. The ovary is superior and two-
celled (7).
The fruit of sesame is a capsule (2–5 cm long and 0.5–2 cm in diameter), and it
is erect, oblong, brown or purple in color, rectangular in section, deeply grooved
with a short, triangular beak (Figure 2). The capsules may have four, six or eight
rows of seeds in each capsule (Figure 2). Most of the sesame capsules have four
rows of seeds, with a total of 70 seeds per capsule. The capsules with a wider
Figure 1. The plant of sesame.
BOTANY OF SESAME 539
diameter will usually have higher rows of seeds and the total number of seeds per
capsule can be as high as 100�200. When the fruit is ripened, it dehisces by split-
ting along the septa from top to bottom (so called ‘‘open sesame’’).
Sesame seeds are small (3�4 mm long and 1.5–2 mm wide), flat, ovate (slightly
thinner at the hilum than at the opposite end), smooth, or reticulate. The color varies
from white, yellow, gray, red, brown, to black. The weight of 1000 seeds is around
2.5 to 3.5 g. Sesame seeds consists of testa (exo and endo), endosperm, and coty-
ledon (Figure 3). The oil drops are located in the cotyledon. It is generally believed
that the light-colored seeds with thin coats are higher in quality and oil content than
the dark-colored seeds.
Although sesame seeds are higher in oil contents than most other oilseeds and
sesame oil has good flavor and oxidation stability, sesame seeds have never been a
major oil source. The low yield (400–500 kg/ha) of sesame seeds and the labor-
intensive harvesting procedure are the limiting factors. When sesame capsules
Figure 2. Sesame fruits with four (A) or eight (B) rows of seeds in each capsule.
Figure 3. Structure of the sesame seed (A) and the oil drops in cotyledon (B).
540 SESAME OIL
are mature, they are fragile and will burst open easily, scattering the seeds on the
ground and thus difficult to collect. Harvesting of sesame seeds is usually per-
formed by cutting the plant stalks and stacking them vertically under the sun
with the cut-ends downward in the threshing yard. Each dried stalk is then shaken
or beaten over a cloth to catch the seeds that fly out from the dried capsules. The
plant breeders have been trying to develop sesame varieties that do not dehisce
when the capsules are mature and thus can be adapted to mechanical harvest
(8–10). In the middle of the twentieth century, horticulturists developed sesame
with ‘‘papershell capsules,’’ which is indehiscence allowing mechanical harvesting
and is easier to thresh than the normal type (11). Until today, however, more than
99% of the sesame produced in world is still harvested manually. Numerous efforts
have been made to move sesame from a labor-intensive harvest crop to a mecha-
nically harvest crop for the past 60 years. Considerable progress was made between
1940 and 1965, but there was still a limited amount of manual labor necessary in
the harvest. The first completely mechanized cultivars were developed in the early
1980s, and there has been continuing progress. Progress in mechanizing sesame has
been slow because of the need to combine many characters in order to compromise
between machine-harvesting and plant characteristics such as seed yield and qua-
lity, disease resistance, insect resistance, hail resistance, and drought resistance.
Sesame can become a major oilseed only with lower price achieved by increasing
yields and reducing production costs (12).
3. WORLD PRODUCTION
3.1. Sesame Seed
Sesame ranks eighth in the world production of edible oil seeds. The total annual
production of sesame seeds is around 3 million metric tons (MT) worldwide from
2000 to 2002. This number has increased 33% since 1990. Figure 4 shows the total
tonnage together with the total area of world sesame production from 1990 to 2003.
It is evident that there is a steady increase of both the seed production and the area
of harvest. The highest sesame seed production reached 3.2 million MT in 2001,
with a total harvesting area of 7.5 million hectares (ha) worldwide. The average
yield of sesame seed is around 400 kg/ha worldwide (Table 1). Among the five
continents, Asia has the highest area of harvest (4.6 million ha), which produces
2 million MT of sesame seed annually. Europe has the lowest quantity of seed pro-
duction (only 0.057% of the world total) but the highest yield (4968.5 kg/ha)
of sesame seed. This yield is ten times that of Asia where more than 70% of world’s
sesame seeds are produced. Africa, the origin of sesame seed, is the second
largest sesame-producing continent. It has, however, the lowest yield (only
328 kg/ha) of sesame seed.
China, India, Sudan, Myanmar, and Uganda are the world’s major sesame seed
producing countries. In 2003, China produced 825 thousand MT of sesame seed and
was the world’s largest sesame-producing country followed by India (620,000 MT),
WORLD PRODUCTION 541
Myanmar (225,000 MT), Sudan (122,000 MT), and Uganda (106,000 MT). These
five countries together supply nearly 70% of the world’s total sesame seed
(Figure 5). Figure 6 shows the fluctuation in annual seed production by these coun-
tries from 1990 to 2003. As the crop yield is very dependent on moisture, the seed
production can vary up or down in any given year due to rainfall. According to
FAO statistics (13), the yield of sesame seed in China grew rapidly from around
700 kg/ha in 1990 to 1099 kg/ha in 2003, whereas India remained around 300 kg/
ha for the past 15 years. Sudan is the lowest among the five major sesame producing
countries in per hectare yield (150�220 kg/ha) followed by Mayamar (170
�380 kg/ha). Uganda has a relatively high yield (500 kg/ha) of sesame seed, but
the area of harvest is the lowest among the five countries.
Seed production
Area of harvest
Ton
nage
( 1
06M
t )
0
0.5
1
1.5
2
2.5
3
3.5
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
Years
0
1
2
3
4
5
6
7
8
Are
a (1
06ha
)
(Data source: FAOSTAT database)
Figure 4. World production of sesame seed (1990–2003). (This figure is available in full color at
http://www.mrw.interscience.wiley.com/biofp.)
TABLE 1. Production of Sesame Seed in the Five Continents in 2003.1
Continent Seed Production (1000 Mt) Area of Harvest (1000 ha) Yield (kg/ ha)
Africa 603.827 (21.835%)2 1840.382 (27.547%) 328.099
Asia 2014.492 (72.846%) 4602.432 (68.889%) 437.702
Europe 1.575 (0.057%) 0.317 (0.005%) 4968.454
North and Central
America 65.870 (2.382%) 127.254 (1.905%) 517.626
South America 79.655 (2.880%) 110.485 (1.654%) 720.958
——————————————————————————————————————————–
World Total 2765.419 (100%) 6680.870 (100%) 413.931
1Based on FAOSTAT database (2003).2Data in parenthesis are the percentage of total.
542 SESAME OIL
In 2000, the world trade of sesame seed was 620,000 MT, which was 21.5%
of the total production. Japan imported 165,000 MT (26% of the world imports)
and was the largest importer of sesame seed. South Korea was the second
largest importer (70,000 MT) followed by United States (49,000 MT), Taiwan
(35,000 MT) and Egypt (34,000 MT). Although China and India are the top two
sesame seed producers, most of the seeds are consumed locally. Only 12�15%
of the sesame seeds produced in India were exported in the past ten years. China
was the world number one sesame seeds exporting country, which exported
Sudan(122,000 Mt)
4%
India(620,000 Mt)
22%
Uganda(106,000 Mt)
4%
Others(866,888 Mt)
32%
China(825,531 Mt)
30%
Myanmar(225,000 Mt)
8%
(Data source: FAOSTAT database)
Figure 5. Major sesame seed-producing countries and their percentage shares of the world
production in 2003.
Ton
nage
(10
6M
t)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
Years
China
India
Sudan
Myanmar
Uganda
(Data source: FAOSTAT database)
Figure 6. Major sesame seed-producing countries (1990–2003). (This figure is available in full
color at http://www.mrw.interscience.wiley.com/biofp.)
WORLD PRODUCTION 543
17�25% of its sesame production before 1996. Because of the fast economic
growth in China, domestic demand of sesame seed increased tremendously
after 1996. Although China became the world’s biggest sesame seed producer since
1997 (Figure 6), the export of sesame seed from China dropped from 119,000 MT
(in 1996) to 41,000 MT (in 1997). Starting from 1996, Sudan became the world’s
top sesame exporting country followed by India and China.
3.2. Sesame Oil
Each year, the world consumes close to 120 million MT of edible fats and oils (14).
Soybean oil is the leading oil that accounts for 30% of the world production of
edible fats and oils. In 2003, it is closely followed by palm oil, whereas rapeseed
oil ranked third has only one-third of the production tonnage of soybean oil.
Sesame oil, with an annual production of 760,000 MT in 2003, is the twelfth largest
vegetable oil produced in the world, higher in quantity than olive oil and safflower
oil (13). The production of sesame oil increased 20% in the recent 10 years, it was
632,000 MT in 1992. China has almost doubled the production of sesame oil
(from 142,000 to 210,000 MT), whereas India has decreased the production by
44% (from 236,000 to 131,000 MT) in the above period. Both China and India
are the largest producers of sesame oil, together they account for nearly half of
the total world production of sesame oil. Besides China and India, Myanmar,
Sudan, and Japan are the top five sesame oil producers.
4. CHEMICAL COMPOSITION
Sesame seed contains high levels of fat and protein. The chemical composition of
sesame seed varies with the variety, origin, color, and size of the seed. The fat con-
tent of sesame seed is around 50% whereas the protein content is around 25%.
Table 2 lists the proximate composition of sesame seeds from different sources.
Sesame seed contains about 5% of ash, whereas the fiber and carbohydrate contents
show large variation. Crude fiber from one variety of Nigerian black sesame
was reported to have 19.6% of crude fiber (15), whereas one variety of Taiwanese
TABLE 2. Proximate Composition of Sesame Seed (%).
Crude Crude
Sesame Crude Fat Protein Carbohydrate Fiber Ash Moisture Reference
Black sesame 35.8 17.2 9.19 19.6 4.01 4.73 15
White sesame 34.6 20.8 9.19 14.2 10.1 4.14 15
Brown sesame 41.3 20.2 10.3 18.6 5.19 4.12 15
Yellow sesame 53.8 22.0 6.85 13.0 6.09 4.28 15
Black sesame 48.4–56.7 22.8–30.3 3.4–10.8 2.8–7.2 4.4–5.5 4.6–6.4 16
White sesame 50.1–51.7 22.6–24.1 7.9–13.2 5.3–7.5 4.2–4.5 4.4–4.7 16
Brown sesame 46.3–53.1 21.8–27.6 4.7–13.6 3.7–7.3 3.9–5.4 5.0–8.2 16
Nigerian sesame 51.5 20.0 12.5 6.0 5.0 5.0 17
whole seed
Dehulled seed 55.0 24.3 10.4 2.0 3.0 5.3 17
544 SESAME OIL
black seed contained only 2.81% of crude fiber (16). The carbohydrate content
ranged from 3% to 14% (15–17).
Sesame seed has about 17% seed weight as hull, which is high in oxalic acid
(2�3%), calcium, and crude fiber. Oxalic acid could complex with calcium and
reduce its bioavailability; indigestible fiber would reduce the digestibility of pro-
tein. Sesame seed hull is therefore recommended to be removed if sesame meal
is used for human food (18). When sesame seed is properly dehulled, the oxalic
acid content can be decreased to less than 0.25% of the seed weight (19). After
dehulling, the fat and protein contents are raised, whereas the fiber, ash, and carbo-
hydrate contents are lowered (Table 2).
4.1. Content of Oil
Sesame seed is a rich source of edible oil. It contains more oil than the major oil-
seeds, such as soybean, rapeseed-canola, sunflower seed, and cotton seed. The oil
content of sesame seed varies with the variety of sesame; it may range from 28%
to 59% (20–22). The wild seeds contain less oil (around 30%) than the cultivated
seeds because the oil content is an important criterion for seed selection in agri-
culture practice. In general, the cultivated seed has around 50% oil, whereas the
color of the seed coat exhibits slight influence on the oil content. Black seeds
appear to contain slightly less oil than the white and brown seeds in the Japanese
strains (Table 3). The oil content was found to be influenced also by the growing
condition, daily mean temperature, and the cumulative degrees of daily temperatures
during reproductive stage, which showed negative correlation with the oil content
(23).
TABLE 3. Oil Content of Sesame Seed.
Sesame Color of Seed Oil Content
Species Coat (% Seed) Reference
Sesamum indicum L.
Sudan strainsa Black 50.7 20
Sudan strains Brown 52.3 20
Sudan strains White 47.4 – 55.5 20
Japanese strainsb Black 43.4 – 51.1 21
Japanese strains Brown 50.5 – 56.5 21
Japanese strains White 51.8 – 58.8 21
Turkish strainsc Black 43.3 – 48.2 22
Turkish strains Brown 42.8 – 46.9 22
Turkish strains White 43.1– 46.3 22
Sesamum alatum T.d Brown 28.1– 29.8 20
Sesamum radiatum S. and T.d Black 30.3 – 33.4 20
Sesamum angustifolium E.d Black 29.2–29.7 20
a The cultivated species of sesame grown in Sudan.b Forty-two species of sesame grown in Japan.c The cultivated species of sesame grown in Turkey.d The wild species of sesame grown in Sudan.
CHEMICAL COMPOSITION 545
Table 4 lists the chemical and physical properties of sesame oil (24).
4.2. Fatty Acid Composition
Sesame oil belongs to the oleic-linoleic acid group. It has less than 20% saturated
fatty acid, mainly palmitic (7.9�12%) and stearic (4.8�6.1%) acids. Oleic acid and
linoleic acid constitute more than 80% of the total fatty acids in sesame oil. Unlike
other vegetable oils in this group, the percentages of oleic acid (35.9–42.3%) and
linoleic acid (41.5–47.9%) in the total fatty acids of sesame oil are close (Table 5).
Table 5 lists the first FAO/WHO Codex Alimentarius Standard of the sesame
oil fatty acid composition as reported by O’Connor and Herb (25) and the most
recent Codex Standard (24). Besides the four major fatty acids, there are low
TABLE 4. Chemical and Physical Characteris-
tics of Sesame Oil (24).
Properties Range
Relative density 0.915 – 0.924
(20�C/water at 20�C)
Refractive index 1.465 –1.469
(ND 40�C)
Saponification value 186 –195
(mg KOH/g oil)
Iodine value 104 –120
Unsaponifiable matter �20
(g/kg)
TABLE 5. Fatty Acid Composition of Sesame Oil (% Total Fatty Acids).
Total sterols (mg/kg) 4500–19000 4335–6764 3420–10005
a Expressed as a percentage of total sterols.b The cultivated species of sesame grown in Sudan.c The wild species of sesame grown in Sudan.
CHEMICAL COMPOSITION 547
nasterol, and �7-stigmasterol present in descending abundance. Only a trace
amount (<0.5%) of cholesterol was found in sesame oil. Oils from the wild species
of sesame contain higher levels of sterols, especially �5-and �7-avenasterols.
These two sterols having the �24;28 ethylidene side chain showed antipolymeriza-
tion effects that could protect vegetable oils from high-temperature oxidation (28).
Phytosterols and cholesterol have similar structures; phytosterols are therefore
competitors of cholesterol absorption. Consumption of phytosterol may lower
blood cholesterol and thus protect from cardiovascular diseases (29). Phytosterol,
especially, b-sitosterol, inhibits the growth of human colon cancer cell (30), pros-
tate cancer cell (31), and breast cancer cell (32).
4.4. Tocopherols
Sesame oil is well known for its oxidative stability; one of the reasons for this
extra-stability is attributed to its tocopherol content. The total tocopherol content
of sesame oil ranges from 330-mg/kg to 1010-mg/kg oil according to the Codex
Standard. Sesame oil from black sesame seeds contains less tocopherols than oils
from brown or white sesame seeds (Table 7). The wild species of sesame, Sesamum
angustifolium E. and Sesamum radiatum S. and T., have higher levels of total
tocopherol (760 mg/kg and 810 mg/kg, respectively) in the oil than the cultivated
species (486–680 mg/kg) although they have a black seed coat. Regardless of the
species and the color of seed coat, g-tocopherol is the predominant tocopherol
in sesame oil, whereas d-tocopherol accounted for less than 5% of the total toco-
pherols. a-Tocopherol is present in sesame oil in trace amount only. Among the
different tocopherol isomers, g-tocopherol is a more potent antioxidant in oils
(33), but it has lower Vitamin E value in biological systems than a-tocopherol (34).
TABLE 7. Levels of Tocopherols in Sesame Oil.
Tocopherol (mg/kg Oil)
Sesame Color of —————————————————
Species Seed Coat a g d Total Reference
Sesamum indicum L.
Japanese strainsa Black 5.2 468.5 12.2 485.9 26
Brown 6.2 517.9 13.6 537.7 26
White 3.8 497.8 20.5 522.1 26
Sudan strainsb Black NDd 527.0 12.6 540 27
Brown 4.8 663.7 11.6 680 27
White 3.1 603.9 13.0 620 27
Sesamum alatum T.c Brown 2.9 310.1 7.0 320 27
Sesamum radiatum S. and T.c Black 6.5 800.3 3.2 810 27
Sesamum angustifolium E.c Black ND 754.7 5.3 760 27
Codex standard — ND–3.3 521–983 4–21 330–1010 24
a The cultivated species of sesame grown in Japan.b The cultivated species of sesame grown in Sudan.c The wild species of sesame grown in Sudan.dND: Not detected.
548 SESAME OIL
4.5. Protein
The protein content of sesame seed is approximately 25% with a range of 17�31%
depending on the source of the seed. Sesame protein is low in lysine (3.1% protein),
but it is rich in sulfur-containing amino acids methionine and cystine (6.1%), which
are often the limiting amino acids in legumes. Comparing with the standard
values recommended by FAO and WHO for children, sesame protein is borderline
deficient in other essential amino acids such as valine, threonine, and isoleucine.
Sesame seed protein, however, contains an adequate amount of tryptophanm, which
is limiting in many oilseed proteins. Because of its characteristic amino acid
composition, sesame seed protein is regarded as an excellent protein source for
supplementing many vegetable proteins such as soybean and peanut to increase
their nutritional value.
The protein efficiency ratio (PER) of sesame seed protein is 1.86 (35). The PER
value can be raised to 2.9 when sesame seed protein is supplemented with lysine
(36). El-Adawy (37) added sesame products including sesame meal, sesame protein
isolate, and protein concentrate to red wheat flour to produce flour blends. It was
found that water absorption, development time, and dough weakening were increas-
ed as the protein level increased in all blends; however, dough stability decreased.
Sesame products could be added to wheat flour up to 16% protein without any detri-
mental effect on bread sensory properties. The addition of sesame products to red
wheat flour increased the contents of protein, minerals, and total essential amino
acids; the in vitro protein digestibility also increased significantly.
Inyans and Nwadimkpa (17) investigated the protein functionality of dehulled
sesame seed flour. They reported that the emulsification capacity was higher at
alkaline condition and ranged from 25-ml oil/g at pH 4 to 66-ml oil/g at pH 10.
The highest foaming capacity (315%) was observed at pH 2. Protein solubility
ranged from 7.9% at pH 2 to 14.2% at pH 10. The viscosity of the flour dispersion
ranged from 2.5 cps at 1% concentration to 7.0 cps at 10% concentration. The se-
same flour could impart desirable characteristics when incorporated into products
such as ice cream, frozen dessert, sausage, baked food, and confectionary.
When sesame seeds were boiled or allowed to sprout, in order to reduce bitter
taste, there was a slight increase in protein content of sprouted seeds and the foam-
ing capacity of flour from boiled seeds was increased (38). The emulsion stability
was improved after sprouting or boiling, whereas the emulsion capacity was low-
ered after boiling. The bitter taste was not detected in flour from boiled seed but
still persisted in that from sprouted seed.
5. SESAME LIGNANS AND LIGNAN GLYCOSIDES
5.1. Lignans
Sesame oil contains high levels of unsaturated fatty acids (more than 80% of total
fatty acids); however, it is highly resistant to oxidative deterioration as compared
with other edible vegetable oils (39, 40). The superior oxidative stability is not
SESAME LIGNANS AND LIGNAN GLYCOSIDES 549
only attributed to the presence of tocopherols, but it is mainly associated with the
unique group of compounds-lignans (41). Lignans are compounds formed by oxi-
dative coupling of r-hydroxyphenylpropane. They are widely distributed in all parts
of plants. Oilseeds such as sesame and flaxseed are well known to contain abundant
lignans (42). Two types of lignan compounds existed in sesame seeds, the oil solu-
ble lignans and the water soluble lignan glycosides. In raw sesame seed, sesamin
and sesamolin are the two major lignans. Sesamin has been found in other plants,
whereas sesamolin is characteristic of sesame and has not been found in plants
other than Sesamum. Fukuda et al. (43) determined the lignan contents of 14 vari-
eties of commercial sesame seeds grown in Japan and noticed that sesamin content
was always higher than sesamolin content and that the average ratio of sesamolin to
sesamin in the black varieties (0.6�1.0) was greater than the white varieties
(0.2�0.5). Other types of lignans such as sesamol, P1, sesamolinol, and sesaminol
were only present in minor quantity as shown in Table 8 (43). The structures of the
sesame lignans are illustrated in Figure 7.
Tashiro et al. (21) further investigated the oil and lignan (sesamin and sesamolin)
contents in 42 strains of Sesamum indicum L. originated from different parts of the
world. The strains included white-, brown-, black-, and yellow-colored seed types.
The results of this study indicated that the sesamin content in the oil ranging from
0.07% to 0.61% with an average of 0.36%, whereas the sesamolin content was low-
er (ranging from 0.02% to 0.48% with an average of 0.27%). There was a signifi-
cant positive correlation between the oil content of the seed and the sesamin content
of the oil, whereas no correlation existed between the oil and the sesamolin
TABLE 8. Lignan Contents in Different Strains of Sesame Seeds.a,b
aData adapted from (43).bUnit: mg/100-g oil.cND: Not detected.
550 SESAME OIL
contents. It was also noticed that the black seed types contained significantly less
oil and a high ratio of sesamolin to sesamin. In the wild species of sesame seeds,
Fukuda et al. (43) found that an Indian variety had an extreme low sesamolin con-
tent (only 14% of its sesamin content), whereas one variety from Borneo contained
OO
O
OO
OH
O
O
O
OO
OO
O
OO
OO
O
OO
O
O
O
O O
OO
O
OO
OCH3
O
O
OCH3
H3CO
H3CO
OO
OCH3O
OO
OH
OO O
O
OH OH
Sesamin Episesamin Sesamolin
Sesangolin 2-episesalatin Sesamol
Sesaminol Sesamol dimer(direct-linked)
Figure 7. Structures of lignans.
SESAME LIGNANS AND LIGNAN GLYCOSIDES 551
several times more sesamin (1152.3 mg/100 g oil) and sesamolin (1360.7 mg/100 g
oil) than in other species. Kamal-Eldin and Appelqvist (27) determined the contents
of sesamin and sesamolin in three wild species of Sesamum. They reported that S.
radiatum was extremely high in sesamin (2.40% in oil) but contained only a minor
amount of sesamolin (0.02%), whereas S. alatum contained minor amounts of sesa-
min and sesamolin (both were 0.01%); S. angustifolium possessed reasonable
amounts of both sesamin (0.32%) and sesamolin (0.16%).
Other types of lignans were found in wild species of Sesamum. Sesangolin was
present in S. angolense (44) and was the major lignan in S. angustifolium, which
contained 3.15% sesangolin in its oil (27). 2-Episesalatin occurred in S. alatum
(45) and was its most abundant lignan present at 1.37% in its oil (27). The struc-
tures of sesangolin and 2-episesalatin are shown in Figure 7. The contents of
different lignans present in sesame oil are listed in Table 9.
5.2. Lignan Glycosides
Lignan glycosides are the glycosilated forms of lignans; they are water soluble.
Although most lignans are found in the oil-soluble part of sesame seed, lignan
glycosides are present in sesame meal. Sesaminol, sesamolinol, and pinoresinol
OO O
O
OH OH
CH2
OO O
O
O OO
O
OH
OO
OO
O
OCH3
OH
O O
OCH3
OH
O
OCH3
OH
O
OO
O
O
OCH3
OH
P-1
Sesamol dimer(Methylene-bridged)
Sesamol dimerquinone Samin
Sesamolinol Pinoresinol
Figure 7. (Continued)
552 SESAME OIL
glucosides (Figure 8) are the major lignan glycosides in sesame. Acetone extract of
sesame seed contained sesamolinol and sesaminol (46, 47), and it was revealed that
they were released after treating defatted sesame seed flour with b-glucosidase (48).
Later, three pinoresinol diglucosides (KP1, KP2, and KP4) and one pinoresinol tri-
glucoside (KP3) were isolated from the ethanol extract of sesame seed (49, 50).
Kuriyama et al. (51) analyzed the lignan glycosides composition of white sesame
seed with high-performance liquid chromatography (HPLC) and found eight lignan
glycosides. There were two pinoresinol glucosides with two or three glucose
units, three sesaminol glucosides with one to three glucose units, two sesamolinol
glucosides with one or two glucose units, and one P-1 glucoside with two glucose
units. The total contents of lignan glycosides in white sesame seed were around
100–170-mg/100-g seed, with sesaminol triglucoside the most predominant one.
In black sesame seed, the lignan glycosides content varied greatly with the
species of the sesame (from 6.4 to 361.3-mg/100-g seed), whereas sesaminol tri-
glucoside was still the major lignan glycoside (52). This effect of sesame variety
on the lignan glycoside contents was also noticed by Ryu et al. (53). They reported
that a significant difference existed between the black and white sesame seeds in
their sesaminol contents, which were analyzed after hydrolysis of the sesaminol
glucosides. White sesame seeds contained an average of 84.5-mg sesaminol in
100-g seed (ranging from 32.5 to 98.5 mg/100 g), and black sesame seeds contained
113.2 mg/100 g of sesaminol in average with a range of 41.5 to 134.5-mg/
100-g seed. Table 10 lists the contents of sesaminol glucosides in various sesame
seeds.
TABLE 9. Levels of Lignans in Sesame Oil.
Lignan Contents (% Oil)
Color of ———————————————————————— Reference
Sesame Species Seed Coat Sesamin Sesamolin Sesamol Sesangolin 2-Epsesalatin
Sesamum indicum L.
Eleven strains Black 0.24 0.27 — — — 21
(0.07–0.40) (0.13–0.40)
Twelve strains Brown 0.36 0.30 — — — 21
(0.11–0.61) (0.13–0.42)
Fifteen strains White 0.44 0.25 — — — 21
(0.12–0.61) (0.02–0.48)
Japanese strains Black 0.45 0.54 NDa — — 26
Japanese strains Brown 0.46 0.66 ND — — 26
Japanese strains White 0.66 0.42 ND — — 26
Sudan strains Black 0.45 0.54 — ND ND 27
Sudan strains Brown 0.46 0.66 — ND ND 27
Sudan strains White 0.23–0.72 0.39–0.41 — ND ND 27
Sesamum alatum T.b Brown 0.01 0.01 — ND 1.37 27
Sesamum radiatum
S. and T.b Black 2.4 0.02 — ND ND 27
Sesamum angustifolium E.b Black 0.32 0.16 — 3.15 ND 27
aND: Not detected.bThe wild species of sesame grown in Sudan.
SESAME LIGNANS AND LIGNAN GLYCOSIDES 553
TABLE 10. Contents of Sesaminol Glucosides in Different
Sesame Seeds.a
Sesaminol Glucosides (mg/100g Seed)
————————————————————
Color of Seed Coat Meanb Range CV (%)c
Black ðn ¼ 10Þd 113.2�� 41.5–134.5 23.5
Brown ðn ¼ 5Þ 78.5� 39.4–91.4 8.9
White ðn ¼ 10Þ 84.5� 32.5–98.5 11.8
aData adapted from (53).bMean values bearing different superscripts are different significantly at 1% level.cCV: coefficient of variance.dn: represents the number of samples analyzed.
aData adapted from (94).bThe extracted oil was stored at 65�C for 35 days.cResults are mean values of three determinations � SD. Values in each column with different superscripts (d-g ) are significantly ðp < 0:05Þ different from one another. Values
of fresh and stored oil with different superscripts (x and y ) are significantly ðp < 0:05Þ different from each other.
sesaminol and its epimer did not decrease by deodorization as much as sesamol. In
refined unroasted sesame oil, sesaminol, epi-sesaminol, and g-tocopherol are thus the
antioxidative substances responsible for its excellent oxidative stability (41).
Shahidi et al. (94) investigated the effect of different processing methods, in-
cluding roasting (200�C for 20 min), steaming (100�C for 20 min), roasting
(200�C for 15 min) plus steaming (100�C for 7 min), and microwaving
(2450 MHz for 15 min) on the endogenous antioxidants in the resultant sesame
oil and upon storage. Sesamin content in oil was well retained (nearly 90%) in
oil from coated seed immediately after processing, but the decrease was more
pronounced (nearly 50%) in oil from dehulled seed especially after the oil was
stored (65�C for 35 days). The roasting process resulted in the highest loss of
sesamin. The corresponding changes in sesamolin contents were more drastic
than sesamin (Table 12).
The changes of sesame lignans during processing is summarized in Figure 11.
Recently, Asakura et al. (95) have prepared the ortho methylene-bridged and
direct-link oligomers from sesamol. The structures are shown in Figure 7. The
methylene-bridged oligomers showed much stronger antioxidant activities on
the autoxidation of lard than the sesamol monomer because of a greater average
number of hydroxyl groups per sesamol unit. The direct-linked oligomers prepared
in acidic conditions were better antioxidants for lard than the sesamol monomer,
whereas oligomers prepared under neutral and alkaline conditions did not improve
the antioxidant effect of sesamol.
7. NUTRITIONAL CHARACTERISTICS
7.1. Effect on Polyunsaturated Fatty Acid Metabolism
Linoleic acid and a-linolenic acid are essential fatty acids and are the important
fatty acids involved in the metabolic pathway of prostaglandin synthesis.
Epi-sesamin Sesamin Epi-sesamin
Sesamol Sesamolin Sesamol Sesamol dimer
bleaching Sesaminol
Sesamol dimer
decomposition Samin and sesamol
Sesamoldimmer quinone
Roasted Sesame Oil Sesame Seed Refined Sesame Oil
roasting deodorizaiton
heating deodorizaiton roasting
[o]
[o]
(heat stable)
(heat unstable)
Figure 11. Changes of sesame lignan during processing.
564 SESAME OIL
Converting linoleic acid to g-linolenic acid and dihomo-g-linolenic acid (DGLA) is
catalyzed by �6-desaturase, whereas �5-desaturase catalyzes the transformation of
DGLA to arachidonic acid. Shimizu et al. (96) reported that sesame oil could cause
an accumulation of DGLA acid in the cell. Sesamin was discovered to be the active
component in sesame oil; it can inhibit the activity of �5-desatursase (97). When
rats were fed sesamin, there was an accumulation of DGLA in liver phospholipids
and the ratio of DGLA to arachidonic acid increased. Arachidonic acid is the
precursor of eicosanoids such as 2 series’ prostaglandin and 4 series’ leukotriene.
Consequently, sesamin tended to reduce the production of eicosanoids from
arachidonic acid (98), and the plasma concentration of PGE2 was decreased (99).
Fujiyama-Fujiwara et al. (100) also reported that sesame lignans (sesamin and epi-
sesamin) inhibited �5 desaturation from DGLA ðn-6Þ to arachidonic acid ðn-6Þ, but
not from 20 : 4ðn-3Þ to eicosapentaenoic acid (EPA, n-3) in cultured rat hepatocytes,
and Umeda-Sawada et al. (101) confirmed this finding in vivo and also found that
dietary sesame lignans decreased arachidonic acid content and increased n-6/n-3
ratio. Umeda-Sawada et al. (102) further examined the effect of dietary sesame lig-
nans on hepatic metabolism and n-6/n-3 ratio of essential fatty acids in rats; they
concluded that sesame lignans could inhibit extreme changes of n-6/n-3 ratio and
function to bring it close to the appropriate n-6/n-3 ratio. Epidemiological and clin-
ical studies have shown that the plasma n-6/n-3 ratio is associated with the preva-
lence of thrombosis (99, 103). Therefore, sesame lignans would be beneficial to the
prevention of thrombosis.
7.2. Hypocholesterolemic Effect of Sesame Lignans
Sesame oil was reported to lower the absorption of fatty acid and cholesterol in
lymph by 50% when rats were fed diet containing 24% sesame oil as compared
with control diet containing no sesame oil (104). As the lymphatic system is the
major route for the transport of absorbed fatty acids and cholesterol, serum and liver
cholesterol levels were significantly reduced, especially LDL-cholesterol (105).
Crude lignan fraction separated from sesame oil was found to have a weak but signi-
ficant hypocholesterolemic activity (98). The cholesterol-lowering activity depen-
ded on the dietary level of the lignans. With purified sesame lignan (sesamin),
the hypocholesterolemic effect was clearly demonstrated (106). As shown in
Table 13, sesamin (0.5%) significantly reduced the serum cholesterol in rats fed
a cholesterol-enriched diet (Exp. I) or a commercial chow diet (Exp. II). Sesamin
lowered intestinal absorption of cholesterol by precipitating cholesterol from the
bile acid micelles, and thus the serum cholesterol level is reduced. Table 13 also
shows that liver cholesterol concentration was also significantly lowered when
rats were fed a sesamin-containing diet because of the reduction in the activity
of liver microsomal 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-
CoA reductase), the key enzyme in the cholesterol synthesis pathway of liver. Sesa-
min thus possess a unique function in that it can simultaneously inhibit cholesterol
synthesis and absorption. It is, therefore, a potential hypocholesterolemic agent of
natural origin.
NUTRITIONAL CHARACTERISTICS 565
The hypocholesterolemic effect of sesamin could be enhanced by a-tocopherol
(107). Data shown in Table 14 clearly indicated that rats fed sesamin together with
tocopherol (1%), the serum cholesterol-lowering effect of sesamin, could be
demonstrated at a much lower level (0.05%). This synergistic effect was found to
be related to both the levels of sesamin and cholesterol in the diet. The combination
of a-tocopherol with sesamin has a practical value for the treatment of hyper-
cholesterolemia. The cholesterol-lowering effect of sesamin has also been demon-
strated in humans with dietary supplementation of sesamin at 64.8-mg/day
level (108).
With regard to the mechanism underlying the hypocholesterolemic effect of
dietary sesamin, Hirose et al. (109) demonstrated in rats that it increased fecal
TABLE 14. Combined Effects of Sesamin and a-Tocopherol
1Data adapted from (106).2Values are means � SEM (n ¼ 6 � 8). Values with different letters are significantly different in each
experiment ðp < 0:05Þ. Male Wistar rats were fed experimental diets for 4 weeks.
566 SESAME OIL
cholesterol excretion and reduced the hepatic activity of HMG-CoA reductase. In
addition, Ashakumary et al. (110) examined the effect of sesame lignan (a 1 : 1
mixture of sesamin and episesamin) on hepatic fatty acid oxidation in rats. They
concluded that sesame lignan greatly increased the activity and gene expression
of hepatic fatty acid oxidation enzymes and thus increased the rate of fatty acid
b-oxidation through the activation of peroxisome proliferator activated receptor
(PPAR)a. Sesame lignan was also demonstrated to decrease the hepatic fatty acid
synthesis in rats by decreasing the activity and gene expression of many hepatic
enzymes involved in fatty acid synthesis (111) because sesame lignan contains
both sesamin and episesamin. The effect of each component was examined by
Kushiro et al. (112). They found that episesamin caused a larger magnitude of
increase in the activity and gene expression of enzymes in fatty acid oxidation
than sesamin. Sesamin and episesamin showed no difference, however, in lowering
the activity and gene expression of hepatic lipogenic enzymes.
7.3. Effect on Vitamin E
Sesame seed has long been regarded as a health food for longevity. Namiki et al.
(113–115) examined the effect of sesame seed in aging by using a senescence-
accelerated mouse, and they have found that the advancement of senescence was
suppressed by long-term feeding of sesame seed. Vitamin E is recognized as a
food component that may exert an anti-aging effect (116). Sesame seed, however,
contains mainly g-tocopherol whose Vitamin E activity is only 6–16% that of
a-tocopherol (117, 118), although it exhibits a stronger antioxidative activity in
vitro than a-tocopherol (119, 120). The effects of sesame seed and sesame lignans
on Vitamin E activity were, therefore, studied extensively to elucidate if sesame is a
good source of Vitamin E.
Yamashita et al. (121) first reported that sesame seed and its lignans could raise
the bioactivity of g-tocopherol to almost the same level as a-tocopherol in rats.
Later, they reported that sesame seed lignans could also act synergistically with
a-tocopherol to enhance its Vitamin E activity in rats fed a low a-tocopherol diet
(122). Kamal-Eldin et al. (123) showed that feeding rats with sesamin, a lignan
from sesame oil, increased g-tocopherol and g-/a-tocopherol ratio in the plasma,
liver, and lung. Sesamin appears to enhance the bioavailabity of g-tocopherol in
rat plasma and tissues, and this effect persists in the presence of a-tocopherol. Diet-
ary sesame seed can also elevate the tocotrienol concentration in the adipose tissue
and skin of rats fed tocotrienol-rich diet (124). The effect of sesame lignans on the
levels of tocopherols was also demonstrated in humans. In a study with 40 healthy
Swedish women (mean age 26), serum g-tocopherol concentrations were raised sig-
nificantly after consuming a diet that contained 22.5 g/day of sesame oil (125).
Coonery et al. (126) gave muffins containing equivalent amounts of g-tocopherol
from sesame seeds, walnuts, or soy oil to nine volunteers; they observed that con-
sumption of as little as 5 mg of g-tocopherol per day over a 3-day period from
sesame seeds but not from walnuts nor soy oil significantly elevated serum g-toco-
pherol levels in the volunteers.
NUTRITIONAL CHARACTERISTICS 567
7.4. Effect on Blood Pressure
Sesamin, the most abundant lignan present in sesame seed and sesame oil, was
demonstrated to suppress the development of hypertension in rats induced by
deoxycorticosterone acetate (DOCA) and salt (127). Dietary sesamin was also
reported to effectively prevent the elevation of blood pressure and cardiac hypertro-
phy in two-kidney, one-clip (2k, 1c) renal hypertensive rats (128). In the stroke-
prone spontaneously hypertensive rats (SHRSP), sesamin feeding was much
more effective as an anti-hypertensive regimen in salt-loaded SHRSP (with 1%
salt in drinking water) than in unloaded SHRSP (129).
7.5. Antioxidative Effect in Biological System
In the development of atherosclerosis, oxidative modification of low-density lipo-
protein (LDL) is the critical step and is therefore a target for interventions aimed at
slowing down the progression of atherogenesis (130). Antioxidants such as Vitamin E,
probucol, and N,N0-diphenylphenylenediamine (DPPD) were suggested to prevent
the oxidation of LDL (131–133). Sesame oil is highly resistant to oxidative dete-
rioration because of the presence of endogenous antioxidants such as sesaminol,
sesamolinol, pinoresinol, and P1. Sesaminol exerted a strong inhibitory effect on
the 2,20-azobis (2,4-dimethylvaleronitrile) (AMVN)-induced peroxidation of LDL
by acting as a chain breaker in the lipid peroxidation cascade in vitro (134). In inhi-
biting either Cu2þ-induced or 2,20-azobis (2-amidinopropane) dihydrochloride
(AADH)-induced lipid peroxidation in LDL, sesaminol was found to be more effec-
tive than a-tocopherol and probucol. Sesaminol was also the strongest antioxidant
among the sesame lignans (sesamolinol, pinoresinol, and P1) for protecting LDL
from oxidative modification (135). The reason for the strong antioxidative effect
of sesaminol is possibly because of its highly lipophilic nature that makes it act
within the LDL particle to exert a sparing effect on tocopherol (122, 123).
The in vivo antioxidative activity of sesame lignan was examined in an animal
model (136). When SD rats were fed a diet containing 1% sesamolin, the lipid per-
oxidation activity (measured as 2-thiobarbituric acid reactive substances, TBARS)
in the liver and kidney was significantly lowered. The amount of 8-hydroxy-20-deoxyguanosine, a DNA base-modified product generated by reactive oxygen spe-
cies and a good marker for oxidative damage (137), was also significantly lower in
the sesamolin-fed rats. Sesamolin is one of the major sesame lignans present in the
oil fraction of sesame; however, it does not possess any appreciable in vitro anti-
oxidant activity (138). The significant in vivo antioxidative activity of sesamolin
came from its metabolites, sesamol and sesamolinol, when sesamolin was supple-
mented in rats diet (136). Feeding rats with a diet containing 40% of dietary energy
as either sesame, soybean, olive, or canola oils for 7 weeks, sesame oil was shown
to be the most effective one in lowering lipid peroxidation (139). Sesame seeds rich
in sesame lignans, sesamin and sesamolin, could lower the activities of enzymes
involved in fatty acid synthesis, and thus the serum triacylglycerol levels were
lower in rats fed diets high in sesame lignans (140).
568 SESAME OIL
Sesame seeds contain two types of lignans, the oil-soluble lignans such as sesa-
min and sesamolin and the water-soluble lignan glycosides including pinoresinol
glucosides (141) and sesaminol glucosides (142). Both of the glucosides were lower
in peroxyl radical scavenging activity than their corresponding aglycones because
of the lack of phenolic group. Using hypercholesterolimic rabbit as the animal
model, Kang et al. (143) were able to demonstrate that dietary defatted sesame flour
(containing 1% sesaminol glucoside ) could decrease the peroxidation in liver and
serum. Sesaminol, the principal metabolite of sesaminol glucoside and the active
antioxidant, was found in abundant quantities in the serum and liver of rabbit
(143). In an insulin-resistance animal model, rats were fed with high fructose
diet in order to develop insulin-resistance, which was accompanied by a high oxi-
dative stress status (144). When the insulin-resistant rats were given 1.0 g/kgBW of
crude lignan glycosides, liver TBARS were significantly lowered and the insulin
sensitivity was improved, indicating an alleviation of oxidative stress (145).
7.6. Effect on Cancer
Antioxidants are well recognized to play an important role in the defense against
oxidative stress, which may cause damage to membrane, nucleic acid, and protein
resulting in circulatory ailments, senility, mutation, and cancer (146). As sesame
lignans possess antioxidative ability, their effect on the model systems for in vivo
peroxidation, such as the peroxidation of ghost membranes of rabbit erythrocyte
and the peroxidation of rat liver microsome, were investigated (147). Sesame
lignans were found to suppress lipid peroxidation equal to or stronger than toco-
pherol in these systems. One of the sesame lignan, sesaminol, was observed to
be as strongly suppressive as tocopherol in mutagenicity of E. Coli WP2s induced
by peroxidation of membrane lipid of erythrocytes (147).
As mentioned earlier that sesame lignans, especially sesamin and epi-sesamin,
could influence the metabolism of polyunsaturated fatty acid and the production of
prostaglandins. As prostaglandin is one of the most influential factors for mammary
carcinogenesis, Hirose et al. (99) studied the effect of sesamin on dimethylbenz-
anthracene (DMBA)-induced mammary cancer. Their results showed that sesamin
at a dietary level of 0.2% considerably reduced the cumulative number and
mean number of mammary cancer; the effectiveness of sesamin was similar to a-
tocopherol.
The anti-tumor promotion activity of topically and orally admistered sesame
components was tested in ICR mice using a two-stage skin tumorigenesis model
(148). Skin tumor was initiated with 7,12-dimethylbenz [a]-anthracene (DMBA)
and promoted with 12-o-tetra-decanoylphorbol-13-acetate (TPA). The sesame com-
ponents applied topically after TPA treatment were able to delay the formation of
papilloma remarkably. It was suggested that sesame components had radical
scavenging ability toward the reactive oxygen species or peroxidized molecules
generated by TPA. Therefore, the inhibition of tumorigenesis by sesame compo-
nents was the result of metabolic inactivation. When sesame components were
admistered orally, the formation of skin papilloma was also inhibited effectively,
NUTRITIONAL CHARACTERISTICS 569
indicating that the sesame components could be absorbed and remained active even
after passing through digestive organs (149).
Sesamin, however, did not significantly reduce the number of N-nitrosobis-
(2-oxopropyl)-amine(DOP)-induced pancreatic cancer in hamsters (150). It was
noticed that 2% sesamol in the diet exerts forestomach carcinogenic activity in
rats and mice (151). Fortunately, human beings do not have a forestomach and daily
ingestion of sesamol is much lower than 2%.
7.7. Effect on Liver Function
Sesamin fed to rats at a level above 0.5% caused a temporary liver enlargement
because of an increase in liver phospholipids; no specific histological changes
were observed, and the activities of serum GOT and GPT remained unchanged
(99, 106). It was suggested that sesamin could act as a stimulus to the liver function,
particularly in the endoplasmic reticula. When mice were exposed to a high concen-
tration of carbon tetrachloride or continuously inhaled ethanol to cause liver
damage, sesamin was able to improve the liver function (152). Furthermore, rats
previously given sesamin were found to reduce their plasma ethanol levels more
rapidly than the control rats. This effect of sesamin on alcohol metabolism was
studied in human trials. Male adults given sesamin (100 mg/day for 7 days) were
found to have a significantly faster rate of ethanol reduction in their blood (153).
The effect of dietary sesamin and sesaminol on the ethanol-induced modulation
of immune indices related to food allergy has also been studied. Although chronic
ethanol drinking would increase the plasma IgA, IgM, and IgG concentrations,
0.2% sesamin in the diet could suppress this increase of IgA and IgM, whereas
sesaminol was not effective. In addition, the increase in relative liver weight
because of ethanol consumption was alleviated by dietary supplementation of
sesamin but not by sesaminol (154).
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570 SESAME OIL
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