14Sunflower Oil

Maria A. Grompone

1. HISTORICAL REVIEW

Sunflower (Helianthus annuus L.), one of the most ancient oilseed species in North

America, belongs to the family Compositae (Asteraceae) and the genus Helianthus.

Cultivation of sunflower dates from times earlier than 3000 B.C., as indicated by

archeological evidence obtained in sites once inhabited by the Hopi Indians, in

the north of Arizona.

According to other archaeological findings and traditional tales, sunflower was

cultivated by indigenous people throughout central North America (from New

Mexico to the Dakotas) and eastward (Pennsylvania and Ontario). It appears that

sunflower was domesticated in America even before corn was. Single-head plants

were preferred by the indigenous people, who differentiated them from multiple-

head plants growing wildly. Some tribes ate fruits directly, or ground into a meal

that was baked in the form of bread. Other tribal practices included boiling of

heads, and crushed roots, for the treatment of disease and bites. The oil extracted

from seeds was used as body and hair ointment. Seeds, petals, and pollen were used

in the preparation of facial and body makeup, and for dying cloth and utensils (12).

Sunflower was introduced into Europe by the Spanish explorers returning to the

continent at the beginning of the 1500s A.D. The first scientific review of American

plants was made by Sevillan doctor Nicolas Bautista Monardes (15081588), who

wrote Historia medicinal de las cosas que se traen de nuestras Indias Occidentales

(A medical review of things brought from the West Indies, published in Seville in

Baileys Industrial Oil and Fat Products, Sixth Edition, Six Volume Set.Edited by Fereidoon Shahidi. Copyright # 2005 John Wiley & Sons, Inc.

655

three volumes, in 1565, 1571, and 1574). It was in this study that sunflower was first

mentioned. Monardes, who never traveled to America, described those plants that

reached him and which he grew in a Botanic Garden designed for this purpose. He

also gathered information that he obtained from navy captains, missionaries, and

travelers.

There is also a description of sunflowercontemporaneous with the work of

Monardesin a herbarium made by Rembert Dodoens in 1568. Even though this

and other later herbaria attribute the origin of sunflower to Peru and Central

America, it is now believed to have originated in North America.

Starting from Spain, sunflower crops spread rapidly through France and Italy,

and toward the north and east of Europe. In several regions, it was a source of

smoking leaves, flowers for consumption in salads, or for the manufacture of paint,

edible, and medicinal seed, and cooking oil. But it was, perhaps, the beauty in the

inflorescence of sunflowers that interested the first growers, large and bright yellow,

always facing the sun. Hence, the name of the genus, Helianthus, derived from the

Greek helios meaning sun and anthos meaning flower; and its Spanish, English,

French, and German words: girasol, sunflower, tournesol and Sonnenblumen.

It was not until the eighteenth century that sunflower seeds were used as oilseed.

According to records, the first patent of oil extraction for industrial use was granted

to Arthur Bunyan in 1716 in England, where reference is made to an English seed

that could be pressed yielding sweet oil of great value for those interested in the

manufacture of wool, paint, leather, and so on. Seeds of double- and single-head

flowers, known as sunflowers, were indicated for oil extraction (2).

In Russia, it was introduced by Peter I the Great, Czar between 1682 and 1725,

who, having seen sunflowers in the Netherlands, took seeds to Russia. It was in

Russia where the most important development took place in the use of sunflower

as both food and oil source. The Russian Orthodox Church banned the consumption

of several foods during Lent and Advent (periods of the religious calendar dedi-

cated to fasting and penitence), including several sources of oil. As the ban did

not include sunflower seeds, they were adopted as an oil source.

Rapidly, sunflower spread through Russia, the earliest records of cultivation dat-

ing from 1770. The extraction of oil from sunflower seeds was first suggested in

1779, according to Russian Academy proceedings. The cultivated area increased

rapidly as a result of the development of the sunflower oil extraction industry,

Russia being the worlds first and largest sunflower producer until current times.

Once the value of the crop had been recognized, commercial production was started

in 1880 over 150,000 hectares, a figure that reached one million hectares toward

1910. Pioneering and fundamental research work has been carried out in Russia

since 1860 concerning the improvement of seed for oil content.

Toward the end of the nineteenth century, improved Russian cultivars were intro-

duced in the Balkans leading to the expansion of sunflower crops. The crop did not

reach northern Europe owing to the lack of cultivars adapted to cold climates.

Sunflower was the main Russian crop already at the beginning of the twentieth

century. In 1912, scientist V. S. Pustovoit started research work in the fields of the

Kuban region. Krasnodar was Russias experimental oilseed selection center, since

656 SUNFLOWER OIL

1924. The Pustovoit All Union Research Institute was founded in 1932 and named

after V. S. Pustovoit for his valuable contributions (Pustovoit was in charge of the

Breeding Department until his death in 1972). Pustovoits work led to an improve-

ment in the oil content and seed yield. The average oil content of a Russian cultivar

was 330-g oil per kilogram seed in 1940, reaching values as high as 550 g per kilo-

gram in strains developed by Pustovoit in 1965.

Hybridization of sunflower resulting from natural cross-breeding, performed in

seed-producing fields with parents planted in alternating lines, led to major

advances in research. It enabled improvements of yield in USSR cultivars and rapid

disease control, as well as increases of oil content and other issues of agronomical

interest. Most remarkable among these open-pollinated varieties was the Peredo-

vik, named after the Russian agronomist. Two major events in the 1960s had a

marked effect on the sunflower industry worldwide: the introduction of USSR cul-

tivars of high oil content, and the discovery of cytoplasmic male sterility and ferti-

lity-restoring genes. Male sterile sunflowers were obtained in 1968 by Leclercq

from the offspring of an interspecific hybrid between the cultivated sunflower

and wild sunflower Helianthus petiolaris. The identification of fertility-restoring

genes of several breeders led to hybrids of special characteristics. Open-pollinated

cultivars were rapidly replaced by hybrids of higher yield, uniformity, and disease

resistance. Currently, hybrid seeds are widely used for cheap and efficient produc-

tion throughout the world (3).

Sunflower crops cultivated in North America are derived from seeds introduced

by eastern European immigrants toward the end of the nineteenth century; hence,

the name Russian Peanuts. Russian emigrants in the United States and Canada

grew strains such as Giant or Mammoth Russian in gardens for the production of

edible seeds. These served as a base for the development of improved cultivars for

commercial production. The cultivated area in the United States reached 200,000

acres in 1968; most of which was destined to the production of seed for manufac-

ture of food for human consumption, and to the bird meal market (4).

An open-pollinated Russian-bred cultivar of high oil content (Peredovik variety,

4045%) was introduced in the United States in 1966 (3). Commercial production

of oilseed-type sunflower was started with the Peredovik variety among other cul-

tivars, and since 1966, several research programs in the United States have sought

to improve sunflower hybrids for oil yield.

Around 1960, the USSR interrupted the supply of sunflower oil to Europe,

because of the high internal demand, including satellites, thus leaving an unat-

tended sector in the European market, where consumption of tallow and butter

were then indicated as causes of coronary disease. The high content of polyunsatu-

rated fatty acids (PUFA) of sunflower oil naturally interested many American and

Canadian oil industries, with the consequent increase in sunflower production in the

late 1970s (1).

Russian immigrants carrying sunflower seeds introduced the crop into Argentina

in the nineteenth century, for human consumption of seeds. Cultivation of the crop

was performed at small-scale initially, and it was not until the world economic

crisis of 1930 that it was first sown intensively to supply the internal market, in

HISTORICAL REVIEW 657

replacement of imported oils. Around 1500 metric tons (MT) of sunflower oil were

produced in Argentina in 1930, a figure that reached 5000 MT in 1945. New, disease-

resistant varieties were developed as a result of the work of Experimental Stations

of Argentinean National Institute of Agrarian Technology (INTA) and of private

seed breeders. The appearance of hybrids characterized the Argentinean market

in the period after 1975, although the first hybrid had been launched in 1972.

Almost 100% of the cultivated area is currently sown with hybrids. A higher

seed and oil production capacity, together with the introduction of specialized

upgraded technology, led to an increase in oil yield per hectare in Argentinean plan-

tations. Seed yield levels increased from 0.73 tons per hectare in 19771978

2,200,000 hectares of sunflower plantations producing 1,600,000 tons of seed

to 1.38 tons per hectare in 1987-19882,117,000 hectares (2,915,000 tons) (1,2).

2. SUNFLOWER CROPS

2.1. General Characteristics

The genus Helianthus comprises 68 known species divided into two major separate

groups: the North American and the South American species. North American sun-

flower species spread throughout the United States, reaching Canada and Mexico.

Both groups do not seem to relate to each other; in South America, they appear to

have originated by parallel evolution of the genus Viguiera (1).

Sunflower is a highly cross-pollinated crop. Wild sunflowers have several flowers

or heads and depend on the work of insects for pollination. Wild sunflowers are the

genetic base of current commercial sunflowers of a single flower or head per plant.

Sunflower is an annual crop. Plants reach 13 m in height. The head is composed

of a large number of tiny flowers that are tubular in shape (700 to 4000 single blos-

soms) forming a disk, those in the outer row having long strap-shaped corollas that

form the rays of the composite flower. Plants have a large number of flowers clus-

tered in a capitulum, inflorescence, or head. The back of the head is covered with

small green bracts. Radial structures in the shape of petals are displayed over the

bracts. These are known as ray flowers, and they do not have a reproductive func-

tion other than serving as a signal for bees and other pollinizer insects. Toward the

disk center, are a large number of complete tiny flowers known as disk florets. Each

of these flowers is capable of bearing an achene or seed (a fruit from a strict bota-

nical viewpoint).

Those flowers that form the rays are generally sterile, and although they have

vestigial styles and stigmas, they do not possess anthers. Flowers yielding seed

are complete, each with a tubular corolla and an anther. Sunflower heads will follow

the sun cycle until practically all flowers comprising the head have been pollinated.

After that, they remain in a fixed position, facing eastward. Around 70 days are

required from sowing to flowering of the crop. Seeds reach maturity at 130 days

and can be harvested 10 days later (45).

Sunflower grows in moderate climates (temperate to temperate-hot), especially

in America, Europe, and China, predominantly at temperatures between 20C and

658 SUNFLOWER OIL

25C, with an optimum temperature of 2728C. It grows well in dry, sunnyweather, in deep soils capable of supplying abundant water. The oil content of seeds

is lower in regions of extreme heat. The crop has high resistance to temperature

fluctuations between night and day varying between 8C and 34C (1, 5).The highest yield in seed is achieved at temperatures between 18C and 25C

through the period from formation to filling of the seed. Humidity conditions are

critical during both 1520-day periods prior to and after flowering. Improved filling

of the seed takes place in periods without rain. Pollination is nearly all cross-type,

i.e., from one flower to another. Crossing within one head is scarce. Insects, in par-

ticular bees, are the main fertilization agent (2).

Climatic conditions in Argentina are ideal for cultivation of sunflower in view of

the varying degrees of influence of the Atlantic Ocean. The buffering of thermal

extremes between summer and winter (mean values in winter and summer of

8C and 28C), the circulation of east winds (allowing a rainfall range from 500to 1100 mm annually), and the span of the period free of frost (over 6 months)

are major climatic factors contributing to ensure the establishment and success of

the cycle of sunflower (6). In Argentina, the sunflower is grown between latitudes

26S (Chaco) and 39S (southern Buenos Aires), over an area averaging 2.93 mil-lion hectares for 19902000 summer seasons. The cultivation environments include

subtropical (northern Argentina) and temperate (central and southern) climate (7).

Sunflowers are ripe when the back of the head has turned from green to yellow

and the bracts are turning brown. Harvest is done when the seed reaches commer-

cial ripeness, that is, allowing time for the seed to dry from a 35% moisture content

of heads at physiological maturity down to 11%. The harvest of seed-loaded, heavy

fruits is advanced to prevent seeds falling off (2, 8).

Drying agents such as magnesium chlorate may be used as an aid to advance

harvesting. This practice readily reduces the moisture content of heads, stems,

and leaves, but seeds retain most of their moisture. Artificial drying of seeds is often

necessary prior to storage.

Seeds must be stored with moisture levels lower than 9.5% to avoid undesired

enzymatic reactions. Some of these reactions start within 12 hours after harvesting

for seeds with moisture higher than 20% (5). Seeding and harvesting periods

obviously differ according to hemisphere of producer country. For Argentina and

Uruguay, in the South Hemisphere, seeding is in October and harvesting between

February and April, and in Australia, harvesting is between January and May. For

countries in the Northern Hemisphere, such as ex-USSR, seeding is done in March

and harvesting is between August and October; in the United States seeding is in

April or May and harvesting is in September or October; in Spain and Italy, harvest-

ing is in August (1, 5).

2.2. Yield of Sunflower Crops

Seed yield varies according to region. Maximum yield values in 1994 were

obtained in Italy (2596 kg/ha), Greece (2577 kg/ha), and Austria (2544 kg/ha);

minimum values were obtained in Tanzania (370 kg/ha). These values have been

SUNFLOWER CROPS 659

increased in the last years as a result of genetic improvements. Figure 1 shows the

evolution of yield levels in major producer countries, as well as world average

values (1, 5).

2.3. Structure of Sunflower Seeds

An achene, the seed of sunflower, is pointed at the base and rounded at the top. Seed

size ranges between 10 and 15 mm in length and between 4 and 12 mm in width,

appearing to be four-sided in cross-section. The outer layer, the pericarp or hull,

represents 1845% of the total achene weight. The white papery layer immediately

beneath the pericarp, the testa or seedcoat, is made up of three parenchyma layers,

the inner layer being spongy in texture. The endosperm comprises a single layer

of cells rich in protein, firmly attached to the hull, and an embryo, commonly referred

to as kernel. The embryo consists of two cotyledons attached to a protruding

radicle (9).

There are two basic types of sunflower: (1) oilseed type and (2) nonoil type, the

latter supplying the bird meal and confectionary markets. The first hybrid oilseed

types bore small black seeds with a thin hull (representing 2025% of total seed

weight) with a 40% oil content. The non-oilseed type is somewhat different; it

has a larger seed with a thicker black-and-white-striped hull (representing 40

45% of total seed weight), which is weakly attached to the kernel and can easily

be removed. These seeds contain 30% of oil.

The size of oil-type seeds varies according to cultivar and according to the seeds

position in the head, those on the periphery being larger. Besides affecting the oil

content, the position of seeds in the head influences the fatty acid composition.

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1930 1940 1950 1960 1970 1980 1990 2000

Seed

yie

ld (k

g/ha)

worldArgentinaUSAexUSSR

Figure 1. Evolution of seed yield (kg/ha) in the most important producer countries, as well as

world average values (1, 5).

660 SUNFLOWER OIL

Internal seeds contain less oil than those in intermediate or external zones. The con-

tent of linoleic and palmitic acids increases, and the content of oleic acid decreases

from the perimeter toward the flower head center (10).

One thousand seeds of most currently used hybrids weigh from 30 to 80 g. Hull

color ranges from completely white to black, with gray- or brown-striped inter-

mediates. Both hull thickness and structure, as well as other seed characteristics,

depend on variety and ambient growth conditions (9).

The hull is mainly composed of fibrous substances, lignin and cellulosic materi-

als in equal proportions. Kernels of oilseed-type sunflower contain nearly all of the

oil of seeds, besides proteinaceous substances and carbohydrates. The kernel repre-

sents 70% of the seed, with an oil content of approximately 55%, amounting to 40%

with respect to the whole seed. The protein content ranges between 20% and 35%,

amounting to up to 57% on a water-and-oil-free basis (1, 5, 11).

A commonly occurring hull and kernel composition is shown in Figures 2 and 3,

respectively, as well as of sunflower meal in Figure 4. Data correspond to a fully

dehulled meal, a condition difficult to obtain in practice (1, 5, 11).

2.4. The Influence of Ambient Factors on Sunflower Seed Oil

The oil content of sunflower seeds varies during the development of the seed:

increasing from the fourteenth to the thirty-fifth day after flowering, when the

seed is physiologically mature. The oil content remains steady after reaching matur-

ity. Oil composition also changes during the formation and ripening stages of the

seed. The linoleic acid content increases from the fourteenth day after flowering

while the oleic acid content decreases; also, saturated fatty acids decrease slightly

(12).

protein3%

fiber61%

N-free extract31%

oil3%

ash3%

Figure 2. Hull composition (1, 5, 11).

SUNFLOWER CROPS 661

Ambient factors, such as temperature and light, affect the oil composition of sun-

flower seeds. Robertson and Russell (13) studied the effect of climatic conditions

(temperature difference between night and day in Canada, Minnesota, and California)

on the composition of sunflower oil, finding that linoleic acid increased propor-

tionally with increasing temperature difference. Robertson and Green (14) studied

the effect of sowing time on oil content and composition. Eleven different hybrids

oil67%

protein21%

N-free extract6%

fiber3%

ash3%

Figure 3. Kernel (dehulled seed) composition (1, 5, 11).

oil1%

protein63 %

fiber9%

N-free extract 19%

ash8%

Figure 4. Composition of fully dehulled meal (1, 5, 11).

662 SUNFLOWER OIL

were used. Sowing was performed in February and August in Florida. The results

show that the oleic acid content is lower (average: 19.4%) and that the linoleic acid

content is higher (average: 68.4%) for seeds sown in August (lowest mean tempera-

ture from flowering to maturity, 18C). Seeds harvested in plantations sown at thebeginning of April (highest mean temperature from flowering to maturity, 27C)have a lower content of linoleic acid (average: 36.3%) and a higher average content

of oleic acid (54.6%). This indicates that adjustments in seeding time in Florida

may lead to sunflower oil of different compositions.

Average temperature from flowering to ripening appears to be a major factor

affecting the fatty acid composition of sunflower oil (15). The oleic/linoleic ratio

was correlated with average temperature for different sunflower plantations across

Spain, average temperature being related not only to latitude, but also to other geo-

graphic factors that determine a microclimate of the crops. An increase in tempera-

ture resulted in a decrease in the linoleic acid content and an increase in the oleic

acid content. The linoleic acid content ranged from 48.7% in seeds grown in war-

mer weather in the south of Spain to 70.2% for colder weather plantations. The

addition of the contents of linoleic and oleic acids is not constant with temperature,

the increase in oleic acid being greater than the decrease in linoleic acid, with a

partial compensation by a reduction in the stearic acid content, suggesting the con-

version of stearic acid to oleic acid. The above mechanism is related to the effect of

temperature on the activity of desaturase enzymes converting oleic into linoleic

acid.

Research carried out with sunflower crops grown in controlled temperature

chambers 20/10C (day/night) and 30/20C (day/night) with equal light intensityand photoperiod, demonstrated a decrease in the linoleic/oleic ratio with increasing

temperature (16). An increase in temperature also leads to a slight decrease in the

stearic acid content. Similar results were obtained by authors in different countries,

like France, Italy, Japan, the United States, Canada, and so on (17). This is because

those enzymes involved in the sequence of steps leading to the formation of linoleic

acid are alike in all higher plants; that is, all oilseed crops have a common enzyme

base catalyzing the synthesis of fatty acids, producing varying amounts of 16:0,

18:0, 18:1, 18:2, and 18:3.

Among a number of studies carried out in different regions worldwide, the com-

position of sunflower seeds was determined for six different Argentinean regions

(18). For the latitudes considered, according to region, mean ambient temperature

during the development period of seed decreased from 28C to 20C southward.The linoleic acid content was found to decrease, and the oleic acid content

increased with increasing temperature. A similar behavior was observed for sun-

flower seeds grown in Japan (19).

2.5. Sunflower Associations

The International Sunflower Association (ISA), with main offices in Paris aims to

enhance international cooperation toward the improvement of cultivation, growth,

and technical and nutritional levels, besides promoting and facilitating close

SUNFLOWER CROPS 663

cooperation relations among researchers. ISA holds an International Conference on

Sunflower every four years.

In addition, there is a national association in different countries. The U.S.

National Sunflower Association (NSA) with main offices in Bismarck, North Dakota,

promotes the production and trade of sunflower products both at national and inter-

national levels. Founded in 1981, it currently has 20,000 members. The Australian

Sunflower Association was established in 1976; the membership of the ASA

consists of growers, researchers, and personnel from all facets of the industry. The

National Sunflower Association of Canada (NSAC) was founded in 1996, with

105 members in 1999. The Argentinean Sunflower Association (ASAGIR), created

in 1980, hosted the Eleventh International Conference on Sunflower in 1985.

3. CHEMICAL AND PHYSICAL PROPERTIES OF REGULARSUNFLOWER OIL

3.1. Composition of Regular Sunflower Oil

Sunflower oillike most vegetable oilsis composed mainly of triacylglycerols

(9899%), and a small fraction of phospholipids, tocopherols, sterols, and waxes

(all of the latter are commonly referred to as the unsaponifiable fraction).

3.1.1. Sunflower Fatty Acids Regular sunflower oil is characterized by a high

concentration of linoleic acid, followed by oleic acid. Saturated fatty acids (mainly

palmitic acid and stearic acid) do not amount to more than 15% of the fatty acid

content. Table 1 shows the variation range of major fatty acids in regular sunflower

oil (9, 20).

Two facts regarding the composition of regular sunflower oil are worth noting

from the nutritional viewpoint: It provides an essential fatty acid (linoleic acid),

and it has a low content of palmitic acid compared with other oils (palmitic acid

is believed to increase LDL-C in blood).

The reported composition of regular sunflower oil has changed with adjustments

of analytical methods and the samples considered. This is reflected in the variation

ranges approved successively by the Codex Alimentarius Comission. The values

approved in 1981 and 1993 (21) are compiled in Table 2, as well as the current

TABLE 1. Variation Range for Major Fatty Acids (%)

of Regular Sunflower Oil (9, 20).

Fatty Acid AOCS (20) Merrien (9)

16:0 58 57

18:0 2.57.0 46

18:1 1340 1525

18:2 4074 6270

18:3

value of 1999 (Codex-Stan 210-1999). The Codex Alimentarius Commission

(Codex) was established in 1962 by two United Nations organizations, the Food

and Agriculture Organization (FAO) and the World Health Organization (WHO).

Codex is the major international organization for encouraging fair international

trade in food and protecting the health and economic interests of consumers. The

Codex Committee on Fats and Oils (CCFO) was established to elaborate worldwide

standards for fats and oils and their products. The Codex Alimentarius is thus taken

as reference.

According to the composition indicated by the Codex Alimentarius (Codex-Stan

210-1999), the saturated fatty acid content of regular sunflower oil is lower than

that in corn (maximum 22%), cottonseed (maximum 32%), peanut (maximum

28%), and soybean (maximum 20%) oils, and higher than the saturated content

of safflower (maximum 12%) and rapeseed (maximum 12%) oils. The linolenic

acid content (18:3) of regular sunflower oil is fairly low (always lower than

0.3%), giving the oil a good oxidative stability.

The variation ranges of fatty acids in regular sunflower oil have also changed in

several countries. The Canola Council of Canada revised the table of composition

of edible oils prepared in 1979, based on a study carried out by the POS Pilot Plant

Corporation in Saskatoon, Saskatchewan, Canada. POS analyzed ten vegetable oils

and three animal fats supplied by food processing and manufacturing enterprises of

Canada and the United States, according to one issue of Canada Digest (22). Aver-

age regular sunflower oil compositions are shown in Table 3 for Canada and the

United States, as well as for Argentina (2, 23).

TABLE 2. Variation Range for Fatty Acids (%) of Regular Sunflower Oil According

to Standards Approved by the Codex Alimentarius Commission in Different Years.

Fatty Acid 1981 1993 1999

12:0 ND0.1

14:0

3.1.2. Triacylglycerol Composition Figure 5 shows the composition in major

triacylglycerols (above 1%) of regular sunflower oil [based on Prevot (17)]. As

expected from its high linoleic acid content, the main triacylglycerol is trilinolein

(36.3%), followed by oleo-dilinolein (29.1%); triolein being practically nonexistent

(0.6%). Thus, the percentage of triacylglycerols (TAG) with four or more double

bonds is higher than 80%. This TAG distribution is responsible for the low solidi-

fication point of regular sunflower oil (16C to 19C), allowing, for example,storage of mayonnaise manufactured with regular sunflower oil in a refrigerator

without breakage of the emulsion (unlike the case of other oils such as peanut oil).

Rossell et al. (24) analyzed the triacylglycerols of 20 regular sunflower oil sam-

ples, regarding the total number of carbon atoms. The content of 54-carbon TAG

was 75.179.5%. The composition of these triacylglycerols is OOO, SOL, OOL,

SLL, OLL, and LLL. Grouping the data provided by Prevot (17) in the same man-

ner, the 54-carbon TAG content would be 82.1%. Thus, the results of both works

are to a large extent in agreement.

TABLE 3. Average Composition (%) of Regular Sunflower Oil for Canada/United States

(normalized to 100%) and Argentina, Elaborated in Different Years (2, 22, 23).

Canada/U.S. 1979 Canada/U.S. 1994 Argentina 1981 Argentina 1998

Fatty Acid (22) (22) (23) (2)

saturated 11 12 8.7 10.1

18:1 20 16 24.0 26.8

18:2 69 71 66.0 62.2

0

5

10

15

20

25

30

35

40

SOL POL OOL SLL PLL OLL LLLTriacylglycerol

Perc

enta

ge

Figure 5. Composition in major triacylglycerols (above 1%) of regular sunflower oil [based on

(17)]. (Key: P palmitic acid, S stearic acid, O oleic acid, L linoleic acid.)

666 SUNFLOWER OIL

The 1,2,3-random hypotheses assumes that one pool of fatty acids is randomly

distributed to all three positions of the glycerol molecules in an oil. The fatty acid

compositions of the sn-1, sn-2, and sn-3-positions would thus be equivalent. Figure 6

shows the theoretical composition of regular sunflower oil as calculated by the

equations of random distribution. Calculation of the random distribution was based

on the following composition: 11% saturated fatty acids (Sat), 20% oleic acid (O),

and 69% linoleic acid (L). The TAG composition of a regular sunflower oil deter-

mined experimentally is also shown; there is no indication of the overall fatty acid

composition (17). Differences between both compositions are not great, in particu-

lar, taking into account the fact that the fatty acid composition may differ for the

oils considered.

Fatty acids are not randomly distributed in natural oils. Saturated fatty acids are

almost exclusively concentrated in the sn-1,3 positions and are practically nonexis-

tent in the sn-2 position (taxonomic pattern). Linoleic acid clearly has a higher

occurrence in the sn-2 position. For example, out of a total 16.239.3% linoleic

acid in peanut oil, the sn-2 position has 27.267.8%, clearly showing the concen-

tration of linoleic acid in this position (24).

Table 4 shows the fatty acid distribution in the sn-2 position with respect to the

composition of the sn-1 and sn-3 positions (25) or with respect to the overall com-

position of the sunflower oil samples analyzed (24). Occurrence of 18:2 is slightly

higher in the sn-2 position than it would be if distributed in equal proportions

among all three positions. The occurrence of linoleic acid is also slightly higher

in the sn-2 position than in the sn-1,3 positions by a ratio of 1.27. As the content

of linoleic acid is particularly high in regular sunflower oil, the preferential distri-

bution of linoleic acid is less apparent than for other vegetable oils. Saturated fatty

0

5

10

15

20

25

30

35

40

SatOL OOL SatLL LLO LLL

Perc

enta

ge

experimental

random

Figure 6. Triacylglycerol composition of regular sunflower oil as calculated from random

distribution and experimentally determined (17). (Key: Sat saturated acid, O oleic acid,L linoleic acid.)

CHEMICAL AND PHYSICAL PROPERTIES OF REGULAR SUNFLOWER OIL 667

acids have a tendency to concentrate in the sn-1 and sn-3 positions, hardly ever

occurring in the sn-2 position. Oleic acid occurs equally among all three positions.

However, differences are small, resulting in an apparent agreement between the

TAG profile determined experimentally and the fatty acid distribution calculated

on a supposed random distribution (as indicated in Figure 6).

3.1.3. Nonacylglycerol Components of Regular Sunflower Oil

3.1.3.1. Phospholipids The phospholipid content of crude sunflower oil ranges

between 0.5% and 1.2%. Oils extracted by solvent generally have a higher content

of phosphlipids than those obtained by pressing. Major phospholipids are phospha-

tidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidic

acid. Most are hydratable and may be removed from the crude oil through a

water-degumming process (See Section 5.3.1.)

3.1.3.2. Tocopherols Tocopherols are heterocyclic compounds with a phenolic

group and a substituted side chain of branched hydrocarbon. Their high solubility

in oil is caused by a long alkyl side chain. The Codex Alimentarius (Codex-Stan

210-1999) indicates levels of tocopherols and tocotrienols in crude regular sun-

flower oil (mg/kg), compiled in Table 5.

TABLE 4. Distribution of Fatty Acids in the sn-2 Position with Respect to the sn-1 and

sn-3 Positions (25) or with Respect to the Overall Sunflower Oil Composition (24).

Alvarez-Ortega et al. (25) Rossell et al. (24)

sn-1 sn-3 sn-2 overall sn-216:0 9.2 0.5 5.76.9 0.20.4

18:0 6.1 0.4 3.06.3 0.10.3

18:1 34.0 34.7 14.034.4 12.131.3

18:2 50.7 64.2 55.573.2 66.287.4

TABLE 5. Levels of Tocopherols

and Tocotrienols in Crude Regular

Sunflower Oil (ppm), According

to the Codex-Stan 210-1999.

Content (ppm)

Alpha-tocopherol 403935

Beta-tocopherol ND45

Gamma-tocopherol ND34

Delta-tocopherol ND7.0

Alpha-tocotrienol ND

Gamma-tocotrienol ND

Delta-tocotrienol ND

Total 4401520

ND nondetectable.

668 SUNFLOWER OIL

The biological value of tocopherols differs according to isomer. Their

importance as Vitamin E activity is the following: alpha> beta> gamma> delta.Vitamin E functions primarily as an antioxidant, especially in preventing oxidation

and peroxidation of polyunsaturated fatty acid units of membrane phospholipid

(within and on the plasma membrane of cells). The value of regular sunflower

oil as a source of Vitamin E is enhanced by a high content of alpha-tocopherol.

Similar conclusions can be found in the literature for tocopherols of Argentinean

sunflower oil: 700 ppm of total tocopherols, 91% of which corresponds to alpha-

tocopherol (2).

Tocopherols also function as free radical scavengers. The alpha form has the

highest Vitamin E activity, and gamma-tocopherol has the highest antioxidant activ-

ity. In one study, sunflower tocopherols were added to stripped soybean oil, and

soybean tocopherols were added to stripped sunflower oil. The stability pattern

of sunflower oilgenerally less stable than soybean oilmimicked that of soybean

oil. With the added sunflower tocopherols, the stability pattern of soybean oil

resembled that of sunflower oil. The results suggest that gamma-tocopherol is a

better antioxidant than the alpha isomer (26). Other authors, however, attribute a

higher antioxidant activity to alpha-tocopherol. Disagreement with respect to the

relative antioxidant activity of tocopherol homologs may be because of differences

in the degree of unsaturation of the substrates used, the degree of oxidation

achieved in the measurement, and the method of oxidation analysis.

Figure 7 shows a comparison of maximum values for major tocopherols in crude

regular sunflower, peanut, soybean, corn, and cottonseed oils, according to the

Codex Alimentarius (Codex-Stan 210-1999). Among these, regular sunflower oil

has the highest tocopherol level. In general, gamma-tocopherol is the most widely

occurring isomer in vegetable oils.

0

500

1000

1500

2000

2500

3000

3500

4000

corn soybean sunflower peanut cottonseed

Cont

ent (p

pm)

total alpha

gamma delta

Figure 7. Maximum values of major tocopherols (ppm) of crude sunflower, peanut, soybean,

corn, and cottonseed oils, according to the Codex Alimentarius (Codex-Stan 210 -1999).

CHEMICAL AND PHYSICAL PROPERTIES OF REGULAR SUNFLOWER OIL 669

3.1.3.3. Sterols Sterols are polycyclic alcohols derived from sterane. Sterols con-

stitute most of the unsaponifiable fraction of an oil. The sterol profile is character-

istic of each oil. The Codex Alimentarius (Codex-Stan 210-1999) indicates the total

sterol content (ppm) and the percentages of each sterol type in regular sunflower oil,

as shown in Table 6.

Among vegetable oils, regular sunflower oil is characterized by a medium sterol

content. According to the Codex Alimentarius (Codex-Stan 210-1999), the oils with

the highest sterol content are rapeseed oil (low erucic acid), with 480011,300-ppm

sterols; corn oil with 800022,100 ppm, and sesame oil with 450019,000 ppm.

In regular sunflower oil, the main component is b-sitosterol, followed by -7-stigmasterol. The latter may be used as a tracer for detection of adulterations in sun-

flower oil, as most vegetable oils (except safflower oil) have fairly low amounts of

-7-stigmasterol (less than 7%).

3.1.3.4. Other Components of the Unsaponifiable Matter The unsaponifiable

matter in a crude regular sunflower oil is usually in the range of 0.51.5% (9,

17), or lower than 15 g/kg according to the Codex-Stan 210-1999. In addition to

sterols (around 2.44.6 g/kg) and tocopherols and tocotrienols (0.41.5 g/kg), there

are minor components of sunflower oil. Aliphatic compounds and terpenoids occur

naturally in oils. Of the terpenoid family, squalene is the most widely occurring

compound. The occurrence of squalene in regular sunflower oil is fairly low:

0.0080.019% (5) or 1520 mg/100 g (9). The aliphatic alcohol content is 100-

mg/100-g oil (9).

Carotenoids and chlorophylls are the major lipochromes of vegetable oils. Crude

regular sunflower oil is not particularly rich in carotenoids (as palm oil is) or in

chlorophylls (like rice bran, rapeseed, olive, and avocado oils). This gives crude

regular sunflower oil its light-amber color, turning to pale yellow upon the bleach-

ing operation.

TABLE 6. Levels of Desmethylsterols

in Crude Regular Sunflower Oil,

as a Percentage of Total Sterols and Total

Sterol Content (ppm), According to

Codex-Stan 210-1999.

Cholesterol (%)

3.2. Chemical Characteristics of Regular Sunflower Oil

The Codex Alimentarius (Codex-Stan 210-1999) indicates the characteristics of

crude regular sunflower oil: (1) saponification value 188194-mg KOH/g oil;(2) iodine value (calculated from the fatty acid composition) 118141. However,Merrien (9) reports an iodine value of 120134, and Bockisch (5) reports a value in

the range of 110143 (Wijs method).

3.3. Physical Characteristics of Regular Sunflower Oil

3.3.1. Refractive Index The refractive index is a characteristic property of fats

and oils and may be used as a fast measurement of the advance of a hydrogenation

operation. The Codex Alimentarius (Codex-Stan 210-1999) indicates a refractive

index (nD) of regular sunflower oil in the range of 1.4611.468 at 40C; Merrien

(9) reports the range 1.4741.476 at 20C.

3.3.2. Density Determinations of the content of tanks or flow rates are usually

based on methods of volumetric dosing. These methods are used to facilitate equip-

ment automation. However, mass determinations based on volume measurements

will depend on the nature and temperature of an oil.

The Codex Alimentarius (Codex-Stan 210-1999) indicates a relative density of

regular sunflower oil in the range of 0.9180.923 (20C/water at 20C). The valuessuggested by the Codex do not differ appreciably from the expected values for most

vegetable oils.

Figure 8 shows the temperature dependence of the density (g/mL) of an Indian

edible sunflower oil [based on Subrahmanyam et al. (27)].

0.88

0.89

0.9

0.91

0.92

0.93

0.94

0.95

0.96

30 10 10 30 50 70 90Temperature (C)

Den

sity

(g/cc

)

Figure 8. Temperature dependence of the density (g/cc) of an Indian edible sunflower oil [based

on (27)].

CHEMICAL AND PHYSICAL PROPERTIES OF REGULAR SUNFLOWER OIL 671

3.3.3. Viscosity The viscosity of an oil is a fundamental parameter when pump-

ing is required. The viscosity of a vegetable oil will depend on the fatty acid com-

position. Oils with hydroxylated fatty acids (like castor oil and lesquerelle oil) have

a particularly high viscosity.

Figure 9 shows the temperature dependence of the dynamic viscosity (cP) of

refined sunflower oil. The curve corresponding to the crude oil is along the same

curve [based on Abramovic and Klofutar (28)].

3.3.4. Specific Heat and Combustion Heat The specific heat of sunflower oil

at constant pressure is 2.197 J/kg C (29). The energy content or combustion heat ofan oil is a major parameter when used as an energy source. The gross heat contents

of all vegetable oils are fairly close to each other. Ali and Hanna (30) report a gross

heat content of regular sunflower oil of 39,575 kJ/kg, and Bhattacharyya and Reddy

(31) a value of 39,486 kJ/kg.

3.3.5. Smoke Point, Flash Point, and Fire Point The smoke point, flash point,

and fire point of an oil are relevant parameters in deep-fat frying processes. The

fatty acid composition of the oil is not relevant (unless the oil has short-chain fatty

acids, as is the case of butter or coconut oil). The most important effect is generally

that of free fatty acids (FFA) in the oil. The following values have been reported for

fully refined sunflower oil (with 0.10% free fatty acids): smoke point 209C;flash point 316C; fire point 341C (5).

The flash point is also an important parameter when considering the possibility

of using an oil as an alternative diesel fuel in ignition engines. The flash points of

all vegetable oils are far above that of diesel fuel, reflecting the nonvolatile nature

0

10

20

30

40

50

60

20 25 30 35 40 45 50 55 60Temperature (C)

Dyn

amic

Visc

osity

(cP)

Figure 9. Temperature dependence of the dynamic viscosity (cP) of refined sunflower oil [based

on (28)].

672 SUNFLOWER OIL

of vegetable oils. Ali and Hanna (30) report a value of 274C for the flash point ofregular sunflower oil.

3.3.6. Melting Characteristics

3.3.6.1. Cloud Point and Pour Point The cloud point is the temperature at which

solids first become visible when an oil is cooled. The pour point is the temperature

at which the amount of solids out of solution is sufficient to gel the liquid; thus, it is

the lowest temperature at which the oil is fluid.

The above parameters are relevant when pumping oils at low temperatures or for

their use as alternative diesel fuel in ignition engines. The cloud points and pour

points of the vegetable oils are higher than for diesel fuel.

Widely varying values have been reported in the literature for regular sunflower

oil. For example, Bockisch (5) reports a cloud point of 10C (and a solidificationpoint in the range 16 to 18C). Ali and Hanna (30) report a cloud point of 7.2Cand a pour point of 15.0C. Differences between reported cloud points are possi-bly caused by a varying degree of winterization of the oils considered.

3.3.6.2. Thermal Behavior of Regular Sunflower Oil Crude regular sunflower oil

is a liquid at room temperature. The refined oil resists refrigerator temperatures

without the appearance of turbidity. These characteristics make it suitable as salad

oil. The thermal behavior of an oil may be determined within wide temperature

ranges through methods of nuclear magnetic resonance (NMR) or through differen-

tial scanning calorimetry (DSC). Both methods allow the evaluation of indices

related to the solid content as a function of temperature.

-60 -40 -20 0 20 40Temperature (C)

Pow

er Sunflower oil

Soybean oil

Figure 10. Thermograms of a refined sunflower oil and of a refined soybean oil (32).

CHEMICAL AND PHYSICAL PROPERTIES OF REGULAR SUNFLOWER OIL 673

The thermogram of an oil determined by DSC allows the study of thermal beha-

vior, and the evaluation of the solid percentage from the area of peaks. This infor-

mation is characteristic of the fatty material considered. The thermograms of a

refined regular sunflower oil and a refined soybean oil (32) are compared in Fig-

ure 10. It is clear that melting of sunflower oil is practically complete above 15C.Soybean oil, however, has a second, smaller peak between 5C and 5C, whichcorresponds to a higher content of saturated fatty acids. Figure 11 shows the solid

content as a function of temperature for both oils, as determined by partial integra-

tion of peaks in the above thermograms (32).

4. SUNFLOWER SEED OF MODIFIED FATTY ACID COMPOSITION

Until two decades ago, the fatty acid composition of vegetable oils was closely

related with their origin. The fatty acid profile of sunflower oil was thus defined

within natural variation ranges. Current practices, however, are widely based on

the production of oilseed of modified fatty acid composition. Several methods

have been developed to this end.

The genetic diversity of wild sunflower allowed researchers to obtain a number

of varieties of defined characteristics. The North Central Regional Plant Introduc-

tion Station (Iowa), which gathers dozens of species, has distributed materials to

researchers and companies interested in either the study or use of these materials.

The sunflower germplasm collection of the U.S. Department of Agriculture

(USDA) is the largest and most complete collection worldwide, including wild

materials from 48 U.S. states, as well as samples from Canada and Mexico. The

0

20

40

60

80

100

-60 -40 -20 0 20 40Temperature (C)

SFI

Sunflower oil

Soybean oil

Figure 11. Solid fat content (SFI) of a refined regular sunflower oil and a refined soybean oil

(32).

674 SUNFLOWER OIL

program of the U.S. Department of Agriculture/Agricultural Research Service

(USDA/ARS) evaluates wild material according to oil content and composition.

Most breeding programs are aimed at the development of hybrids, although other

projects are for the improvement of open-pollinated varieties and synthetic culti-

vars. In view of the improvements in yield, disease resistance, uniformity, and

self-compatibility achieved in some modifications, open-pollinated varieties have

been replaced by hybrids. Varieties have been produced with increased oil content

of seeds and/or improvements in oil composition.

Inbreeding has been used since 1920 for the improvement of sunflower, the most

common method consisting in the self-pollination of those phenotypically desirable

plants within the existing cultivars. The progeny of the best plants are sown in the

following season, and the selection procedure is continued among the resulting pro-

geny. A variation of recurrent selection, the method of reserves, developed by Pus-

tovoit in the USSR, consists of the evaluation of progeny and subsequent cross-

pollination among superior progenies.

In order to obtain hybrid seeds, self-pollination and pollination by a sibling plant

must be avoided. It is sought to develop a female parental line accepting pollen

from other lines (cross-pollination), without reproduction of its own line. This

can be achieved directly through emasculation, i.e., elimination of the pollen-

bearing organ, usually at the expense of large labor requirements. Other methods

can be used to induce male sterility.

Modifications in the characteristics of sunflower are obtained through crosses to

recombine genes from two sexually compatible parents. Both for self pollination

and for controlled crosses, it is important that heads be isolated before flowering

to avoid natural cross-pollination.

Emasculation of the female parent is used for the production of artificial hybrids.

Acid-induced male sterile plants pollinated without emasculation are also used.

These hybrids were produced by natural crossing in seed production fields (breed-

ing nursery), with the two parents planted in alternating groups of rows. The first

hybrid cultivars were introduced in Canada for commercial production in 1946 (4).

Cytoplasmic male sterility of sunflower was discovered in 1958, whereby one

factor in the cell cytoplasm leads to the male-sterility in all plants of the second

generation. However, as a result of the pollination of fertile ordinary lines, plants

will still bear some fertile progeny. Patrice Leclercq, in France, in 1969, reported on

cytoplasmic male sterility obtained in the progeny of a cross of Helianthus petio-

laris Nutt and Helianthus annuus. In 1970, fertility restorer lines were found. Two

years later, hybrid seeds produced by this system were made available to farmers. In

1976, 80% of the U.S. sunflower harvest had been produced on hybrid seed.

The production of single crosses or three-way hybrids using cytoplasmic male

sterility and nuclear fertility restorer system is widely used. Genic male sterility

was used for the production of hybrid seeds in the early 1970s in France and

Romania. The first hybrids produced in this way were introduced in the United

States in 1972 (4).

Various genetically different types of cultivar are commercially available. In

open-pollination varieties, each individual is genetically different from another

SUNFLOWER SEED OF MODIFIED FATTY ACID COMPOSITION 675

among the population. This results in a high level of adaptation to different envir-

onment conditions on the one hand, but it may also cause handling difficulties

because of the lack of phenotypical uniformity. Open-pollination varieties may

be recovered yearly by the producer, the regular purchase of new seed being neces-

sary only for maintenance of purity and type.

Commercial hybrid cultivars include single and three-way hybrids. The former

type is produced by crossing two lines, resulting in genetically identical individuals;

the latter are developed by crossing a single hybrid with a homozygote line. Seed

must be procured yearly by the producer in both cases.

The production of high-quality hybrid seeds does not only depend on the use of

parental lines of superior class, but also on the degree of isolation of the cultivation

field from other sunflower plantations, including wild varieties. The isolation con-

ditions cannot be accurately established, in view of the role of insects as pollination

agent, and the long viability period of pollen; yet, recommendations have been

made.

Genetic variation occurring naturally within crop species is scarce. Additional

genetic modification strategies are required to generate variants of a certain fatty

acid profile. Such variants may be included in crossing programs for the develop-

ment of cutivars or strains of interest. Modifications in the fatty acid profile of an oil

may be achieved through techniques of mutagenesis, Stable genetic mutations may

be induced by use of chemical mutagens, such as ethyl methyl sulfonate. This pro-

cedure was used in the USSR to develop sunflower seeds of improved oleic acid

content.

4.1. Modification of the Saturated Fatty Acid Content

The consumption of fat of high saturated fatty acid content has been associated with

increased risk of coronary heart disease. Traditional sunflower oil contains around

1112% saturated fatty acids, a considerably low value among vegetable oils.

Canola oil has 7% and safflower oil less than 10% of saturated fatty acids, both

being strong competitors of the edible oil market.

Since 1992, the National Sunflower Association (NSA) has supported a cultiva-

tion program developed by researchers of the USDA/ARS for a reduction of the

saturated content of sunflower oil. New germplasm stocks with reduced content

of palmitic and stearic acids were made available. They were developed through

continuous selection starting from a sunflower accession collected in Egypt around

1950. Several private companies have also carried out investigations aiming at

obtaining hybrids of low saturated fatty acid content (6% or lower). Cultivators

of Pioneer Hi-Bred International Incorporation managed to reduce the stearic

acid content to 1.5% for commercial products. SVO Enterprises and Triumph

Seed Company developed research lines aiming at reducing the saturated quantity

in high-oleic sunflower oil (3334).

With a view to finding new industrial uses of vegetable oils, the saturated fatty

acid content may also be increased. Three high stearic acid sunflower mutants, hav-

ing as much as 28%, 15%, and 14% of stearic acid in the seed lipids have been

676 SUNFLOWER OIL

biochemically characterized (35). An increased solid content of the oil could be

obtained in the oil without requiring hydrogenation, although such an increase

may not meet nutritional standpoints.

4.2. High-Oleic Sunflower

The typical sunflower oil composition is 6672% linoleic acid, 12% saturated acids

(palmitic and stearic), 1620% oleic acid, and less than 1% a-linolenic acid. Anincrease in low-density lipoprotein cholesterol (LDL-C) and a decrease of high-

density lipoprotein cholesterol (HDL-C) are believed risk factors of coronary heart

disease (CHD). Diets rich in saturated fat increase plasma total and LDL-C. Tradi-

tional high-linoleic sunflower oil has always been regarded as healthy because of its

high content of polyunsaturated fatty acids (PUFA) and relatively low content in

saturated fatty acids.

The substitution of saturated fatty acids by PUFA in a diet leads to a reduction of

total cholesterol and LDL-C. It has been suggested that a high intake of polyunsa-

turated fatty acids leads to a decrease of HDL-C. Some authors have proved this

theory based on rather unrealistic high PUFA in the diet (PUFA/MUFA> 3). Othershave found statistically nonsignificant decrease values for HDL-C in more realistic

high PUFA diets. An increased intake of monounsaturated fatty acids (MUFA) also

leads to a decrease in total cholesterol and of LDL-C levels without reducing HDL-

C even with fairly high MUFA intake values. As oleic acid is more stable against

oxidation than linoleic acid, consumption of MUFA has further advantages over

PUFA. It is recommended to avoid foods containing peroxidized lipids, as these

might be initiators of pathologic processes. In view of the considerations above,

new genetic strategies were started toward a high-oleic sunflower oil (HOSO).

There is also controversy over the importance of MUFA over PUFA from the

metabolic viewpoint. Great emphasis is placed on the distinction between the n-3

PUFA and those of the n-6 family. An increased intake of n-3 and a reduced intake

of n-6 are recommended in light of the competitive metabolism of both families

of fatty acids. As linoleic acid is a n-6 parent, a reduction of its intake favors the

n-3/n-6 ratio; on the other hand, it is also an essential fatty acid.

High-oleic sunflower oil, with very low PUFA levels, may well suit the require-

ments of processors, but it does not support the work of nutritionists who recom-

mend n-6/n-3 ratios within the range 5 to 10. In addition, HOSO does not represent

an increased intake of family n-3 fatty acids as recommended by nutritionists, the

linolenic acid content being very low for all types of sunflower oil.

K. I. Soldatov, in Russia, developed high-oleic sunflower seeds through the treat-

ment of normal seed with a chemical mutagen (dimethyl sulfate). Through pro-

grams of selected breeding, a number of plants containing seed with as much as

8090% oleic acid were obtained. L. N. Kharachenko, also in Russia, studied the

standard Peredovik progeny and the Pervenets progenyobtained from treatment

of seeds of the former variety with a chemical mutagen. It seems that modifications

in the seed genotype of high-oleic Pervenets are responsible for an irreversible

blockage of the desaturating enzyme system. G. N. Fick developed progenies of

SUNFLOWER SEED OF MODIFIED FATTY ACID COMPOSITION 677

cultivar Pervenets in plantations in the United States, Argentina, and Chile and

incorporated the dominant genes into hybrids that were suitable for commercial

production. High-oleic seeds were first grown commercially in the United States

in 1984 (3637).

The Lubrizol Corporation obtained U.S. patents (granted to Sigco and inventor

Gerhardt N. Fick) for sunflower seeds and oils of oleic acid content of 80% or

higher and linoleic/oleic ratios lower than 0.09Patent 4,627,192 for seed granted

on December 9, 1986, and Patent 4,743,402 for oils granted on May 10, 1988. SVO

Enterprises, a division of Agrigenetics Company, which is a part of The Lubrizol

Corporation, has produced high-oleic sunflower oil trademarked under the name

Trisun in the United States (3334, 38).

High-oleic sunflower oil is sold in Australia under the name Sunolaa regis-

tered trademark of Meadow Lea Foods. The seed variety was bred by Australian

farmers through traditional selective breeding techniques. The first Sunola crop

was developed in Queensland. The oils fatty acid composition is 85% monounsa-

turated, 8% polyunsaturated, and 7% saturated. The composition of oil extracted

from Sunola seed in the first stages of ripening resembles that of regular sunflower

varieties. Only when the synthesis of oil has actually started (some three weeks

after flowering) does the oleic acid content start to increase considerably and the

linoleic content start to decrease rapidly (39).

A further approach to modified sunflower oils was made by the Agriculture

Canada Research Station in Saskatoon (Saskatchewan) from two different types

of dwarf early-ripening sunflower trademarked under the name Sunola (Western

Grower Seed Corp. was created for commercialization and further improvement

of Sunola). One of these types was regular high-linoleic Sunola, which was first

produced commercially in 1993. The hybrid was specially developed for farmers

in regions of the west of Canada where cultivation of sunflower was nonexistent

because of a short growing season. The fatty acid composition of this oil is 72

74% linoleic acid (owing to the colder growth conditions), 14% oleic acid, and

12% saturated acids. The other hybrid is high-oleic Sunola sunflower, whose pro-

duction started in 1995. The ripening time of high-oleic Sunola is about 100 days

(three weeks shorter than for most sunflower crops). The fatty acid composition is

87% oleic acid, 5% linoleic acid, and 78% total saturated acids. Seeds of this type

are smaller than regular sunflower seeds, the hull being slightly lighter and bearing

a narrow stripe (3334, 40).

As both Sunola crops are special, care must be taken against contamination with

traditional sunflower or canola. However, this is rarely the case, as Sunola is grown

in northern areas of the United States, where regular sunflower is not grown and in

areas of southern Canada that are too hot and dry for the development of canola

crops.

It is worth noting that the name Sunola for modified oils is used in Australia for

high-oleic sunflower oil, whereas, in Canada, it is a registered trademark of two oils

of different composition: one of higher linoleic acid content than traditional sun-

flower and another of high-oleic type. Care must be taken that this should not

lead to confusion. Canadian Western Grower Seed Corporation has also developed

678 SUNFLOWER OIL

lines of Sunola with higher oleic acid content to be introduced in the cosmetics mar-

ket. One of these has as much as 88% oleic acid.

Purdy (37) reported on the fatty acid composition and other analytical character-

istics of high-oleic sunflower oil of the Pervenets variety cultivated in three regions

of the United States. The oil content of seeds ranged between 43.3% and 47.9%

(dry basis), the hull accounting for 2433% of total seed weight. Table 7 shows

the fatty acid composition of high-oleic sunflower oil (37, 41 43).

Table 8 shows the chemical and physical characteristics of crude high-oleic sun-

flower oil according to the Proposed Draft Amendment to the Codex Standard for

Named Vegetable Oils (Alinorm 01/17). The Active Oxygen Method (AOM) value

for refined oil extracted from seed of high-oleic Pervenets variety is 5156 hours,

compared with 13 hours for regular oils (37). In another study, Purdy (36) extracted

oil from high-oleic Pervenets seed and from high-linoleic seed. The saturated fatty

acid content of these oils varies only slightly (811%); the main variation occurs in

the oleic/linoleic ratio. Table 9 shows AOM values for refined sunflower oils as a

TABLE 7. Fatty Acid Composition (%) of High-Oleic Sunflower Oil (37, 41, 43).

Fatty Acid Vermeersch (41) Krawczyk (43) Purdy (37)

16:0 3 6.7 2.74.2

18:0 5 3.45.0

18:1 83 80.0 80.586.7

18:2 9 12.0 4.08.5

TABLE 8. Chemical and Physical Characteristics

of Crude High-Oleic Sunflower Oil (Codex Alimen-

tarius, Alinorm 01/17).

Relative density (25C/water at 20C) 0.9090.915Refractive index (ND 25C) 1.4671.471Saponification value (mg KOH/g oil) 182194

Iodine value 7890

Unsaponifiable matter (g/kg)

function of the oleic acid content. Data presented show that the oxidative stability

of this oil is enhanced considerably with an increase in the oleic acid content. Table 10

shows the triacylglycerol composition of high-oleic oil (derived from Pervenets)

and of regular sunflower oil, with practically no occurrence of saturated fatty acids

in the sn-2 position for either oil (25).

Although the content of oleic acid is high in both high-oleic sunflower oil and

olive oil, there is a higher content of saturated acids in olive oil. Their MUFA con-

tents are similar, but the composition of triacylglycerols differs widely (Table 11).

Whereas the triacyglycerol OOO (O oleic) is the main species in both oils, HOSOhas a higher content, olive oil, in contrast, having a higher proportion of POO

(P palmitic). Further differences are in the fatty acids occupying those positionsother than sn-2, which is occupied by oleic acid in both oils. In addition, HOSO has

a higher proportion of linoleic acid in position sn-2, whereas olive oil has more a-linolenic acid (44)

Another major difference between olive oil and HOSO is a most distinct flavor

of olive oil that characterizes it from HOSO and other oils. Extra virgin olive oil,

TABLE 10. Fatty Acid and Triacylglycerol Composition

(%) of Regular Sunflower Oil and of High-Oleic Sunflower

Oil [based on (25)].

Regular Oil High-Oleic Oil

Fatty Acid: % %

16:0 6.8 5.3

18:0 5.0 3.8

18:1 31.4 88.3

18:2 55.4 1.4

Triacylglycerol: % %

sn-1 sn-316:0 9.2 5.1

18:0 6.1 5.8

18:1 34.0 87.4

18:2 50.7 1.6

sn-2

16:0 0.5 0.3

18:0 0.4

18:1 34.7 98.6

18:2 64.2 1.1

TABLE 11. Composition in Major Triacylglycerols (%) of Olive

Oil and High-Oleic Sunflower Oil (HOSO) [Based on (44)].

Major Triacylglycerols (%) Olive Oil HOSO

POO 30.5 12.1

OOO 49.9 65.1

OLL 0.3 3.1

O oleic, P palmitic, L linoleic.

680 SUNFLOWER OIL

being the preference of so many gourmets worldwide, is considered the finest

choice oil.

The similarity in the fatty acid composition of HOSO and olive oil may lead

to cases of adulteration or fraud, in view of the price difference between the

two oils. These adulterations may be difficult to detect through conventional analy-

tical methods. The nature of an oil can be traced through a study of its sterol

composition.

The sterol composition of both oils is compared in Table 12. Clearly, for HOSO,

b-sitosterol is the sterol with the highest occurrence (4270% of total sterols), fol-lowed by 7-stigmasterol (6.524%), campesterol (513%), and stigmasterol (4.513%). Although there are differences in the sterol composition of both oils, they are

not large enough to enable easy analysis.

Several studies have been aimed at the detection of a fraudulent addition of

vegetable oils to olive oil. In particular, different analytical methods can be applied

to determine blends of regular and high-oleic sunflower oil with olive oil. The mini-

mum sunflower oil detection level depends on the analytical method used. For

example, a minimum detectable level of 0.7% of regular or high-oleic sunflower

oil may be achieved through methods of sterol analysis, and analysis of the fatty

acids will not enable detection of additions below 20% (45).

High-oleic sunflower oil is widely used as salad oil and cooking oil, because of

its composition, light flavor. A high content of oleic acid provides enhanced oxida-

tive stability in frying processes. In addition, it does not require partial hydrogena-

tion for an increase in product shelf-life, with the additional nutritional advantages.

The effect of trans-fatty acids generated as byproducts of hydrogenation processes

on the plasma lipoprotein profile is as adverse as that of saturated fatty acids, both

increasing the concentration of LDL-C and reducing that of HDL-C (44).

High-oleic sunflower oil is sprayed on cereals, crackers, and cookies to retain

freshness and crispness. It is also used in the manufacture of non-dairy creamers,

snack foods, and frozen desserts. Special properties of oleic acid make high-oleic

sunflower oil a choice ingredient for cosmetic formulations. The AOM value of

TABLE 12. Sterol Composition (as Percentage of Total Sterols)

of High-oleic Sunflower Oil (According to Codex Alimentarius,

Alinorm 01/17) and Olive Oil (20).

Sterol Composition High-Oleic Sunflower Oil (Codex) Olive Oil (20)

Campesterol (%) 5.013.0 4.0Stigmasterol (%) 4.513.0

Florasun-90 (of International Flora Technologies Ltd.) is higher than 90 hoursa

high value compared with less than 40 hours for high-oleic rapeseed oil and about

20 for sesame oil. Research has indicated that the oil is not skin-irritating or sensi-

tizing. It may be used in suntanning products and cosmetics with a high content of

natural lipids, such as bath oils, massaging oils, skin-care products, lipstick, and

cosmetic cream bases (33, 34).

High-oleic sunflower oil is currently used in the manufacture of a lubricant for

diesel and gas motors. The product, denominated Helianthe, is commercialized by

the Tecnol Society (France). It is composed of 7080% high-oleic sunflower oil and

2030% additives. Helianthe is a formulation type 5W40, with a high viscosity

index and high fluidity at ignition (41).

4.3. Mid-Oleic Sunflower

The production of high-oleic sunflower oil with 80% or higher oleic acid content

was protected under patents. However, the patent holder agreed to license breeding

material for the development of mid-oleic sunflower seed. In July 1995, the NSA

decided to redirect efforts toward an increase in oleic acid. It was established that

mid-oleic sunflower should contain 65% oleic acid, no higher than 10% saturated

acids, and the rest being linoleic acid, a balance that, according to research, pro-

vides in-process functionality in frying.

Breeding a mid-oleic sunflower requires at least one oleic parent. The USDA/

ARS Northern Crop Science Laboratory in Fargo, North Dakota, provided private

companies with crossing lines of mid-oleic sunflower. Hybrid seeds were developed

by traditional crossing methods; no hybrids of transgenic sunflower were used. The

mid-oleic concentration appears to be controlled by a partially dominant major

gene and one or more dominant minor modifier genes (46, 47).

In a market accustomed to HOSO and traditional high-linoleic sunflower, the

name NuSun seemed suitable and was trademarked by the NSA. Seed and other

companies using the name NuSun in their commercial products should have author-

ization of the NSA. NuSun contains less than 10% saturated, 5075% monounsa-

turated, and 3032% polyunsaturated fatty acids, with less than 1% linolenic acid (46).

Harvests of NuSun were first commercialized in 1999. In 2000, Procter & Gam-

ble chose NuSun for the manufacture of Pringles chips in North America, part of

Europe, and Asia, finding a low rate of formation of polar compounds as compared

with other oils, an important factor for extending product shelf-life (46, 48).

Figure 12 shows the fatty acid composition (%) of regular, mid-oleic, and high-

oleic sunflower oils according to the Proposed Draft Amendments to the Standard

for Named Vegetable Oils (Report of the Eighteenth Session of the Codex Commit-

tee on Fats and Oils, London, 2003). Table 13 shows the composition in major tria-

cylglycerols of mid-oleic sunflower oil, compared with the composition of regular

sunflower oil (49). Clearly, there is a difference in the unsaturated triacylglycerol

composition of both oils: mid-oleic sunflower oil has a higher content of OOO, and

regular sunflower oil is richer in LLL and LLO (the addition of both contents

amounting to 60.3%).

682 SUNFLOWER OIL

Figure 13 shows the composition in major triacylglycerols of mid-oleic sun-

flower oil (49), as compared with the calculated composition from a random distri-

bution. The triacylglycerol distribution does not fit the random model, the main

differences being in the levels of OOL and OOO, the main triacylglycerols. In con-

trast, as shown in Figure 6, the fatty acid distribution in regular sunflower oil TAG

differs only slightly from the random distribution. Table 14 shows the chemical and

physical characteristics of crude mid-oleic sunflower oil according to the Proposed

TABLE 13. Composition in Major Triacylglycerides (%) of

Mid-Oleic Sunflower Oil, as Compared with the Composition

of Regular Sunflower Oil [Based on (49)].

Triacylglycerols Mid-Oleic Regular

LLL 11.5 32.4

LLO 12.1 27.9

LLP 4.1 10.7

LOO 8.3 6.7

LLS 2.7 7.4

LOP 2.6 4.8

OOO 40.2 1.7

LOS 1.6 2.2

POO 5.7 0.6

SOO 5.4 0.4

L linoleic, O oleic, P palmitic, S stearic.

0

10

20

30

40

50

60

70

80

90

100

minimum maximum minimum maximum minimum maximum

regular mid-oleic high-oleic

Perc

enta

ge

16:0 18:0

18:1 18:2

Figure 12. Fatty acid composition (%) for regular, mid-oleic, and high-oleic sunflower oil (based

on the Proposed Draft Amendments to the Standard for Named Vegetable Oils Committee on

Fats and Oils, 2003).

SUNFLOWER SEED OF MODIFIED FATTY ACID COMPOSITION 683

Draft Amendments to the Standard for Named Vegetable Oils (Report of the Eight-

eenth Session of the Codex Committee on Fats and Oils, London, 2003).

Table 15 shows the sterol composition of mid-oleic sunflower oil according to

the Proposed Draft Amendments to the Standard for Named Vegetable Oils (Report

of the Eighteenth Session of the Codex Committee on Fats and Oils, London,

2003). Clearly, b-sitosterol is the sterol with the highest occurrence (5658% oftotal sterols), followed by campesterol (9.19.6%) and stigmasterol (9.09.3%).

b-sitosterol is the main sterol in all three types of sunflower oil (regular, mid-oleic,and high-oleic).

4.4. Semi-Dwarf and Dwarf Sunflower

The search for sunflower varieties of defined characteristics was also aimed at a

reduction of plant size and adaptation to other climates. Short-stature cultivars in

0

5

10

15

20

25

30

35

40

45

SatOL SatLL Sat OO OOL LLO LLL OOO

Perc

enta

ge

experimental

random

Figure 13. Triacylglycerol composition of mid-oleic sunflower oil as calculated from random

distribution and experimentally determined (49). (Key: Sat saturated acid, O oleic acid,L linoleic acid.)

TABLE 14. Chemical and Physical Characteristics

of Crude Mid-oleic Sunflower Oil (According to the

Proposed Draft Amendments to the Standard for

Named Vegetable Oils, 2003).

Relative density (25C/water at 20C) 0.9140.916Refractive index (ND 25C) 1.4611.471Saponification value (mg KOH/ g oil) 190191

Iodine value 94122

Unsaponifiable matter (g/kg)

sunflower are classified as semi-dwarf (typical 1.20 m to 1.50 m high) and dwarf

(typical 0.80 m to 1.20 m high) types. Dwarf cultivars were developed more

recently and include dwarf hybrids and dwarf open-pollinated cultivars.

Two types of hybrid denominated Sunola and Sunwheat were developed in

Canada to address the handling problems caused by traditional hybrids, requiring

special machinery adapted only to the long growing season areas in southeastern

Saskatchewan. These new hybrids are 2535% shorter than regular sunflower

(hence the denomination miniature or dwarf), allowing use of the same machinery

as is used for cereal or canola production. Both early maturing types offer producers

in short-growing-season areas the opportunity to diversify rotations.

Sunola is a miniature type of sunflower developed by the Agriculture Canada

Research Station in Saskatoon as a sowing alternative for areas where growth of

traditional sunflower is not viable. It is the result of persistent selection of open-

pollinated varieties. Plant height is small (6090 cm), and heads are 813 cm in

diameter. Ripening time is 99103 daysthree weeks shorter than for most sun-

flower varieties. Sunola has a high oil content (similar to that of the best hybrids)

and a higher content of linoleic acid (7274%) than any other commercial

sunflower.

Sunwheat is a dwarf hybrid of sunflower, having leaves and heads of similar size

to other hybrids, but short (96120 cm). Ripening time is 100110 days, and the oil

content is slightly lower than that of Sunola. It is appropriate for cultivation in bar-

ren areas and has a higher resistance to extreme-heat summer periods.

5. EXTRACTION AND PROCESSING OF SUNFLOWER OIL

The procedures used for the extraction and processing of sunflower oil are broadly

the same as for other seed oils. Focus will be made on those operations or details

specific of the production of sunflower oil. Sunflower oil is usually extracted

through pressing of seed and later extraction by solvent. The crude oil is usually

subjected to traditional refining stages. Otherwise, cold-pressed sunflower oil is cur-

rently valued as a new extra virgin oil.

TABLE 15. Sterol Composition (as Percentage

of Total Sterols) of Mid-Oleic Sunflower Oil

(According to the Proposed Draft Amendments

to the Standard for Named Vegetable Oils, 2003).

Sterol Composition Mid-Oleic Sunflower Oil (%)

Campesterol 9.19.6

Stigmasterol 9.09.3

b-Sitosterol 56585-Avenasterol 4.85.3

7- Stigmasterol 7.77.9

7-Avenasterol 4.34.4Others 5.45.8

EXTRACTION AND PROCESSING OF SUNFLOWER OIL 685

5.1. Preparation of Sunflower Seeds for Extraction

Figure 14 shows normal stages in the preparation of sunflower seed. Once har-

vested, sunflower seeds are cleaned, dried, and stored. Seeds must be dehulled prior

to pressing and oil extraction stages. Depending on processing plant, seeds may be

cracked before the dehulling stage to reduce seed size and help remove the hull.

Kernels may be further broken and subjected to two conditioning stages: cooking

and flaking. Thermal conditioning or cooking is directed to an adjustment of the

moisture content (generally to 34.5%) and the temperature (generally 100C) ofmeats. The last stage in the preparation of seed is the conversion of the cracked,

dehulled, and conditioned meat into a flake. As these stages are common to a num-

ber of oilseeds, only those aspects specific of sunflower seeds are considered,

namely, in the drying and dehulling stages.

Sunflower seed

Cleaning

Drying

Storage

Dehulling

Conditioning

Cracking

Pre-treated seed to oil extraction

Hull

Cracking

Figure 14. Preparatory treatment of sunflower seed for extraction.

686 SUNFLOWER OIL

5.1.1. Drying of Sunflower Seeds The moisture content of sunflower seed

must be reduced to around 89% prior to storage. Different authors indicate slightly

varying levels: 15% (50), 910% (51), 8.5% (52), and 10.5% (5). In order to prevent

losses caused by unfavorable climatic conditions, seeds are usually harvested with

moisture contents above the recommended levels for storage.

When seed moisture is higher than the recommended value, enormous spoilage

of the seeds by microbiological attack is possible. Fungi may also grow explosively

over the surface of seeds, with the consequent increase in temperature caused by

biological activity. Such temperature increase leads to ideal life conditions for ther-

mophilic bacteria; their metabolism contributes further to a temperature increase.

Enzyme and mold activity reduces the quality and the yield of the extracted oil.

Seed moisture is normally expressed as weight percentage of the whole seed. As

water is insoluble in seed lipids, the moisture content is concentrated in the nonfatty

parts of the seed. The water content calculated on a nonfatty basis is defined as cri-

tical moisture. The critical moisture of sunflower seeds is 16%, although a max-

imum 15% is recommended for storage.

As the content of nonfatty materials in sunflower seeds decreases as the oil con-

tent increases, the moisture content corresponding to one critical moisture value is

inversely related to the oil content, as shown in Table 16 [based on Muller (50)]. For

critical moisture levels above 15%, the rate of respiration of seeds increases.

Respiration is accompanied by an exothermic transformation of organic substances

of seeds, creating conditions that may lead to spontaneous combustion (50).

Drying of seed may be performed at room temperature with no additional equip-

ment, or with hot-air dryer. The first stage of drying consists of the removal of

external moisture from the fresh seeds. Internal water diffuses outward, evaporating

in the external part of seeds. After a certain time, seeds reach a hygroscopic equili-

brium state at which the moisture content remains constant. The equilibrium

depends on ambient temperature and relative humidity of the surrounding air.

Figure 15 is a representation of these values for different temperatures: 10C,25C, and 40C [based on Mazza and Jayas (51)].

The equilibrium moisture of seeds is modified upon dehulling. Equilibrium

moisture values for undehulled sunflower seeds, hulls, and kernels are compared

as a function of the relative humidity of the surrounding air at 25C (Figure 16).The initial moisture content of all seeds was 5% (dry basis). Those samples stored

at a relative humidity below 33% reached the equilibrium by desorption, and those

at a relative humidity above 33% reached the equilibrium by adsorption (51).

TABLE 16. Critical Moisture of Sunflower Seeds with Different Oil and Moisture Content

[Based on (50)].

Oil Content (%) Nonfat Content (%) Moisture (%) Critical Moisture (%)

35 65 9.75 15

40 60 9.00 15

45 55 8.25 15

48 52 7.80 15

EXTRACTION AND PROCESSING OF SUNFLOWER OIL 687

5.1.2. Dehulling of Sunflower Seeds With approximately 30% of hull, sun-

flower seeds must be dehulled prior to processing. The high wax content of hulls,

which would otherwise be transferred to the oil during extraction, is one major

reason for dehulling. The wax content of an oil extracted from undehulled seed

is approximately five times higher than for oils extracted from dehulled seed.

However, a small fraction of hull (less than 15%) is left with the seed for easy

percolation during the process of extraction by solvent. Seed moisture is usually

reduced to values below 8% for hulls to turn more brittle and be easily removed.

0

5

10

15

20

25

0 20 40 60 80 100relative humidity (%)

equ

ilibriu

m m

oist

ure

cont

ent (%

) 10C

25C

40C

Figure 15. Equilibrium moisture (%) of sunflower seed with hull as a function of air relative

humidity (%) for three temperatures [based on (51)].

0

5

10

15

20

25

30

0 20 40 60 80 100relative humidity (%)

equ

ilibriu

m m

oist

ure

cont

ent (%

) seeds

kernels

hulls

Figure 16. Equilibrium moisture (%) of sunflower seeds with hull, hulls, and kernels as a function

of air relative humidity (%) at 25C [based on (51)].

688 SUNFLOWER OIL

Genetic improvements of sunflower seeds have been aimed at increasing oil con-

tent, but also leading to a decrease in the amount of hull. The seed pericarp is thin-

ner and more firmly attached to the kernel in improved varieties. The hullability

of improved seeds, i.e., the ease with which hulls can be cracked and removed from

the seed, is lower than that of seeds with hull of higher thickness.

Dehulling consists of mechanical removal of the pericarp (hull) of seeds. The

most widely used method consists of colliding of seeds at high speed against a

hard surface by centrifugal effect, leading to the cracking of seeds. Loose hull

bits are separated from partially dehulled seed. In addition to the size and shape

of seeds, the moisture content is a most relevant parameter in the dehulling process.

A decrease in moisture content facilitates hull removal, the effect being greater for

hybrids of higher oil content. However, a decrease in moisture also leads to an

increase in the amount and composition of fines. Therefore, it is necessary to deter-

mine the optimum value of seed moisture for maximum hullability and a reduction

in the amount of fines.

5.2. Sunflower Oil Extraction

Partially dehulled sunflower seed is generally used for oil extraction, with 8%

moisture and 10% residual hull content, approximately. The process employs

mechanical pressing followed by hexane extraction. Figure 17 represents a diagram

of the unit operations involved.

Pre-treated seed

Hot pressing

Pressed oil Expander

Solvent extraction

Desolventization Pelleting

SUNFLOWER MEAL

Extracted oil

CRUDE SUNFLOWER OIL

Figure 17. Production of crude sunflower oil.

EXTRACTION AND PROCESSING OF SUNFLOWER OIL 689

Extraction of sunflower oil is generally carried out in two stages. The first stage

consists of mechanical extraction using screw-presses (expellers). The meal

obtained in the pressing stage, containing 1520% of oil, is subjected to extraction

by solvent (normally hexane). The solvent must then be eliminated from both meal

and oil. Oils obtained through pressing are of better quality than those obtained by

solvent extraction. However, both are blended before storage. Pressed oils are

sometimes commercialized separately from solvent extracted oils. The solvent-

extracted meal is obtained as a byproduct of this stage.

5.3. Treatment of Crude Oil

Figure 18 shows a diagram of alkali refining and physical (steam) refining of sun-

flower oil. The traditional method, alkali refining, involves degumming, neutraliza-

tion with alkali, bleaching, dewaxing, and deodorization. A pre-dewaxing stage

may be performed after neutralization to reduce the wax content to 100150

ppm, in addition to a stage of winterization after bleaching for removal of the

remaining waxes. Physical refining includes the following stages: degumming,

bleaching, dewaxing, and deodorization. Also for physical refining, a combined

stage of predewaxing and degumming makes post-dewaxing easier and less costly.

Crude sunflower oil

Degumming

Bleaching

Dewaxing