Oil cactus pear (Opuntia ficus-indica L.)

Abstract

Seeds and pulp of cactus pear (Opuntia ficus-indica L.) were compared in terms of fatty acids, lipid classes, sterols, fat-soluble vitamins and β-carotene. Total lipids (TL) in lyophilised seeds and pulp were 98.8 (dry weight) and 8.70 g/kg, respectively. High amounts of neutral lipids were found (87.0% of TL) in seed oil, while glycolipids and phospholipids occurred at high levels in pulp oil (52.9% of TL). In both oils, linoleic acid was the dominating fatty acid, followed by palmitic and oleic acids, respectively. Trienes, γ- and α-linolenic acids, were estimated in higher amounts in pulp oil, while α-linolenic acid was only detected at low levels in seed oil. Neutral lipids were characterised by higher unsaturation ratios, while saturates were higher levels in polar lipids. The sterol marker, β-sitosterol, accounted for 72% and 49% of the total sterol content in seed and pulp oils, respectively. Vitamin E level was higher in the pulp oil than in the seed oil, whereas γ-tocopherol was the predominant component in seed oil and δ-tocopherol was the main constituent in pulp oil. β-Carotene was also higher in pulp oil than in seed oil. Oils under investigation resembled each other in the level of vitamin K1 (0.05% of TL). Information provided by the present work is of importance for further chemical investigation of cactus pear oil and industrial utilisation of the fruit as a raw material of oils and functional foods.

Full text

Oil cactus pear (Opuntia ficus-indica L.)
Mohamed Fawzy Ramadan*,Jo
¨rg-Thomas Mo
¨rsel
Institute of Food Chemistry, Technical University of Berlin, TIB 4/3-1, Gustav-Meyer-Allee 25, D-13355 Berlin, Germany
Received 5 August 2002; received in revised form 13 November 2002; accepted 13 November 2002
Abstract
Seeds and pulp of cactus pear (Opuntia ficus-indica L.) were compared in terms of fatty acids, lipid classes, sterols, fat-soluble
vitamins and b-carotene. Total lipids (TL) in lyophilised seeds and pulp were 98.8 (dry weight) and 8.70 g/kg, respectively. High
amounts of neutral lipids were found (87.0% of TL) in seed oil, while glycolipids and phospholipids occurred at high levels in pulp
oil (52.9% of TL). In both oils, linoleic acid was the dominating fatty acid, followed by palmitic and oleic acids, respectively. Tri-
enes, g- and a-linolenic acids, were estimated in higher amounts in pulp oil, while a-linolenic acid was only detected at low levels in
seed oil. Neutral lipids were characterised by higher unsaturation ratios, while saturates were higher levels in polar lipids. The sterol
marker, b-sitosterol, accounted for 72% and 49% of the total sterol content in seed and pulp oils, respectively. Vitamin E level was
higher in the pulp oil than in the seed oil, whereas g-tocopherol was the predominant component in seed oil and d-tocopherol was
the main constituent in pulp oil. b-Carotene was also higher in pulp oil than in seed oil. Oils under investigation resembled each
other in the level of vitamin K
1
(0.05% of TL). Information provided by the present work is of importance for further chemical
investigation of cactus pear oil and industrial utilisation of the fruit as a raw material of oils and functional foods.
#2003 Elsevier Science Ltd. All rights reserved.
Keywords: Cactus pear; Opuntia ficus-indica L.; Seed oil; Pulp oil; Fatty acids; Lipid classes; Sterols; Tocopherols; b-carotene; Vitamin K
1
.
1. Introduction
The potential supply of lipid from fruits and fruit by-
products may be enormous and should to be investi-
gated. Palm and coconut oils are good examples of
commercially successful oils extracted from fruit flesh.
Future edible oil supplies may depend on the discovery
and development of similar types of plants. A listing of
the lipid content and fatty acid composition of oils
extracted from new plant sources would be an impor-
tant first step in this search. Furthermore, a relatively
untapped source of lipid and protein raw material is the
by-product of fruit-processing plants. Millions of
pounds of fruit seeds are discarded yearly, resulting in
disposal problems, while proper utilisation of these
waste products could lead to an important new source
of oil and meal (Kamel & Kakuda, 2000). A multi-
ingredient fruit, such as cactus or prickly pear (Opuntia
ficus-indica L.) (Fig. 1), holds promising answers for
tailor-made nutraceuticals and functional foods by
embracing essential ingredients, such as taurine, amino
acids, readily absorbable carbohydrates, minerals, vita-
min C and soluble fibres (Stintzing, Schieber & Carle,
2000, 2001). Cactus pear grows wild in arid and semi-
arid regions, where the production of more succulent
food plants is severely limited; it is a delicacy in Mexico,
United States, Mediterranean countries and South
Africa (Gurbachan & Felker, 1998). Low water exi-
gency and a high water-use efficiency ratio favour the
extension of cactus production, as underlined by the
Food and Agriculture Organisation (Barbera, Inglese, &
Pimienta-Barrios, 1995). Under optimal conditions,
annual production of cactus pear can reach 50 tons/
hectare (Dominguez-Lopez, 1995; El-Kossori, Villaume,
El-Boustani, Sauvaire, & Mejean, 1998). Therefore, it
will be an important fruit for recovery in arid and semi-
arid areas.
Both nopal and cactus pear fruit are consumed as
fresh vegetables, added to casseroles, cooked, canned,
or used in salads, syrups, alcoholic drinks, fruit juices
and in cheese production (Gurbachan & Felker, 1998).
0308-8146/03/$ - see front matter #2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0308-8146(02)00550-2
Food Chemistry 82 (2003) 339–345
www.elsevier.com/locate/foodchem
* Corresponding author. Tel.: +49-30-31472813; fax: +49-30-
31472823.
E-mail address: hassanienmohamed@hotmail.com
(M. F. Ramadan).

Juice obtained from the strained pulp is suggested to be
a good source for natural sweeteners and colorants
(Saenz, Estevez, Sepulveda, & Mecklenburg, 1998; Tur-
ker, Coskuner, Ekiz-Hi, Aksay, & Karababa, 2001). On
the other hand, in most medicinal research involves the
leaves rather than the fruit (El-Kossori et al., 1998).
Experimental evidence showed that cactus pear could
reduce glucose and cholesterol levels in human blood
and modify low density lipoprotein (LDL) composition
(Frati, 1992; Gurbachan & Felker, 1998; Stintzing et al.,
2001).
The proximate composition of prickly pear cactus (O.
ficus-indica L.) has been investigated (Dominguez-
Lopez, 1995; El-Kossori et al., 1998; Stintzing et al.,
2000, 2001). Seeds constitute about 10–15% of the
edible pulp and are usually discarded as waste after
extraction of the pulp. According to literature data
(Sawaya & Kahn, 1982; Pimienta-Barrios, 1994; Stintz-
ing et al., 2000), oil processed from the seeds constitutes
7–15% of whole seed weight and is characterised by a
high degree of unsaturation wherein linoleic acid is the
major fatty acid (56.1–77%). The sterols in seed oil are
composed of b-sitosterol as the sterol marker, followed
by campesterol, then stigmasterol. Information on the
lipid composition of seed oil, however, is still inade-
quate and data available are incomplete. Moreover, no
data about the lipid constitution in the seedless part of
the pulp are yet available. In the present study, we ana-
lysed the seeds and soft parts, to obtain an informative
profile of lipids in cactus pear which will serve as a basis
for further detailed chemical investigation and nutri-
tional evaluation. The results will be important as an
indication of the potential nutraceutical and economic
utility of cactus pear as a new source of fruit oils and to
address stability issues and the potential for their delivery
in functional foods.
2. Material and methods
2.1. Materials
Three kilogrammes of freshly harvested cactus pear
(ca. 11 fruits per kilogramme) fruits were purchased
from a local market, Berlin, Germany, in 2001. Stan-
dards used for sterols (ST) characterisation, cholesterol,
b-sitosterol, stigmasterol, lanosterol, ergosterol, cam-
pesterol, 5-avenasterol and 7-avenasterol, were pur-
chased from Supelco (Bellefonte, PA, USA). Standards
used for characterisation of vitamin E (a-, b-, g- and d-
tocopherol), b-carotene and vitamin K
1
(2-methyl-3-
phytyl-1,4-naphthoquinone) were purchased from
Merck (Darmstadt, Germany). Reagents and chemicals
used were of the highest purity available.
2.2. Methods
2.2.1. Extraction of total lipids (TL)
Intact fruits were carefully selected according to the
degree of ripeness measured by fruit colour (red to pur-
ple), the pH value of the pulp (pH 6.05) and the total
titratable acidity (0.39%). Fruits were brushed under
distilled water, air-dried and hand-peeled. Seeds were
isolated by pressing the whole edible pulp and rinsing
the residue with distilled water. The two fractions (pulp
and seeds) were separately lyophilised (Alpha 1-5, Mar-
tin Christ, Osterode am Harz, Germany) to 10–25% of
the original weight, depending on the fruit fraction and
composition. Three samples (5 g each sample) of lyo-
philised seeds and pulp were ground (Analysenmu
¨hle
A10, Janke & kunkel GmbH, Staufen Br., Germany),
and the lipid was isolated using a chloroform/methanol
extraction procedure (Yang & Kallio, 2001). The sam-
ples were homogenised in methanol (50 ml) for 1 min in
a blender, chloroform (100 ml) was added and homo-
genisation was continued for a further 2 min. The mix-
ture was filtered and the solid residue resuspended in
chloroform/methanol (2:1, v/v, 150 ml) and homo-
genised for 3 min. The mixture was filtered again and
washed with fresh solvent (2:1, v/v, 150 ml). The com-
bined filtrates were cleaned with a repeat addition of 0.2
volumes of 0.75% aqueous sodium chloride solution.
The samples were thoroughly mixed without shaking,
the layers allowed to separate and the chloroform layer
recovered. The purified lipids were collected in a flask
and subsequently treated with sodium sulphate to
remove traces of water; after filtration, the extract was
taken to dryness on a rotary evaporator at 40 C. Total
lipids recovered were weighed and stored in chloroform
at20 C until analysed.
Fig. 1. Cactus pear (Opuntia ficus-indica L.) fruits are uniocular,
polyspermic, egg-shaped fleshy berries and highly appealing because of
their attractive colours. Fruit weights range from 100 to 150 g,
depending on origin and cultivar. Small barbed spines on the pericarp,
the glochids, consist of pure crystalline cellulose. The pericarp and the
edible pulp from the ripe fruits have cherry-red or purple hues con-
taining numerous small brown seeds.
340 M.F. Ramadan, J.-T. Mo
¨rsel / Food Chemistry 82 (2003) 339–345

2.2.2. Gas liquid chromatography analysis of fatty acid
methyl esters
Fatty acids were transesterified into methyl esters
(FAME) by heating in boron trifluoride (10% solution
in methanol, Merck, Darmstadt, Germany) according
to the procedure reported by Metcalfe, Schmitz, and
Pleca (1966). FAME were identified on a Shimadzu GC-
14A equipped with flame ionisation detector (FID) and
C-R4AX chromatopac integrator (Kyoto, Japan). The
flow rate of the carrier gas helium was 0.6 ml/min and
the split value with a ratio of 1:40 was used. A sample of
1ml was injected on a 30 m 0.25 mm 0.2 mm film
thickness Supelco SP
TM
-2380 (Bellefonte, PA, USA)
capillary column. The injector and FID temperatures
were set at 250 C. The initial column temperature was
100 C programmed by 5 C/min until 175 C and kept
10 min at 175 C, then 8 C/min until 220 C and kept
10 min at 220 C. A comparison of the retention times
of the samples with those of authentic standard mixture
(Sigma, St. Louis, MO, USA; 99% purity specific for
GLC), run on the same column under the same condi-
tions, was made to facilitate identification. The quanti-
fication of each fatty acid was carried out by comparing
the peak of its methyl ester with that of methyl
nonadecanoate without application of any correction
factor.
2.2.3. Column chromatography fractionation of the main
lipid classes
Total lipid (30 mg per g of adsorbent) in chloroform
was separated into neutral lipids (NL), glycolipids (GL)
and phospholipids (PL) by passing through a glass col-
umn (20 mm dia 30 cm) packed with a slurry of acti-
vated silicic acid (70 to 230 mesh; Merck, Darmstadt,
Germany) in chloroform (1:5, w/v) according to Rou-
ser, Kritchevsky, Simon, and Nelson (1967). NL were
eluted with three-times the column volume of chloro-
form; GL were eluted with 5-times the column volume
of acetone and PL with four times the column volume
of methanol. Solvents were evaporated by using a
rotary evaporator and the percentage of each fraction
was determined gravimetrically. The respective residue
was dissolved in chloroform and stored at 20 Casa
lipid fraction.
2.2.4. High temperature gas liquid chromatography
analysis of sterols (ST)
Separation of ST was performed after saponification
of the oil samples without derivatization (Ramadan &
Mo
¨rsel, 2002b). After the addition of cholesterol acetate
(1.5 mg; Sigma, MO, USA) as an internal standard,
lipids (250 mg) were refluxed with 5 ml ethanolic KOH
solution (6%, w/v) and a few anti-bumping granules for
60 min. The unsaponifiables were first extracted three
times with 10 ml of petroleum ether; the extracts were
combined and washed three times with 10 ml of neutral
ethanol/water (1:1, v/v), then dried overnight with
anhydrous sodium sulphate. The extract was evapo-
rated in a rotary evaporator at 25 C under reduced
pressure, then ether was completely evaporated under
nitrogen. Gas chromatography analyses of unsaponifi-
ables were carried out using a Mega Series (HRGC
5160, Carlo Erba Strumentazione; Milan, Italy) equip-
ped with FID. The column was a ID phase DB 5,
packed with 5% phenylmethylpolysiloxan (J&W scien-
tific; Falsom, CA, USA), 30 m length, 0.25 mm i.d., 1.0
mm film thickness with carrier gas (helium) flow of 38
ml/min and split-splitless injection. The detector and
injector were set at 280 C. The oven temperature was
kept constant at 310 C and the injected volume was 2
ml. All ST homologues eluted within 45 min and total
analysis was set at 60 min to assure the elution of all ST.
The quantification of sterol compounds was carried out
with a cholesterol acetate internal standard and calcu-
lated by applying the detector response of sitosterol.
The repeatability of the analytical procedure was tested
and the relative standard deviation of three repeated
analyses of a single sample was <5%. Quantitative
analyses were performed with a Shimadzu (C-R6A
Chromatopac; Kyoto, Japan) integrator.
2.2.5. Normal phase high performance liquid chromatography
(NP-HPLC) separation, identification and quantification
of fat-soluble vitamins (FSV) and -carotene
2.2.5.1. Procedure. NP-HPLC was selected to avoid
extra sample treatment (e.g. saponification). Analysis
was performed with a solvent delivery LC-9A HPLC
(Shimadzu, Kyoto, Japan). The chromatographic sys-
tem included a model 87.00 variable wavelength detec-
tor and a 250 4 mm i.d. LiChrospher-Si 60, 5 mm,
column (Knauer, Berlin, Germany). Separation of all
components was based on isocratic elution where the
solvent flow rate was maintained at 1 ml/min at a col-
umn back-pressure of about 65–70 bar. The solvent
system selected for tocopherols elution was isooctane/
ethylacetate (96:4, v/v) with detection at 295 nm. An
isooctane/isopropanol (99:1, v/v) mixture was used to
elute b-carotene (detection at 453 nm) and vitamin K
1
(detection at 244 nm). Twenty ml of the diluted solution
of TL in the selected mobile phase were directly injected
into the HPLC column. FSV and b-carotene were iden-
tified by comparing their retention times with those of
authentic standards.
2.2.5.2. Preparation of standard curves. Standard solu-
tions of vitamins were prepared by serial dilution to
concentration of approximately 5 mg/ml of vitamin E,
0.7 mg/ml of b-carotene and, 1.4 mg/ml of vitamin K
1
.
Standard solutions were prepared daily from a stock
solution which was stored in the dark at 20 C.
Twenty ml was injected and peaks areas were determined
to generate standard curve data.
M.F. Ramadan, J.-T. Mo
¨rsel / Food Chemistry 82 (2003) 339–345 341

2.2.5.3. Quantification. All quantitation was by peak
area using a Shimadzu C-R6A chromatopac integrator
(Kyoto, Japan). Standard curves (concentration versus
peak area) were calculated from six concentration levels
by linear regression. Based on the established chroma-
tographic conditions, repeated injections of different
concentrations of the standard FSV and b-carotene
were made three times onto the HPLC system. All work
was carried out under subdued light conditions. All the
experiments were repeated at least twice when the var-
iation on any one was routinely less than 5% and mean
values are given.
3. Results and discussion
3.1. General
For a plant to be suitable for oil production, it must
meet the following two criteria: (i) the oil content must
reach the minimum for commercially viable exploita-
tion, and (ii) the plant must be suitable for high acreage
cultivation. The only exceptions are plants that contain
oils or fats unique in their composition or with proper-
ties that cannot be found elsewhere (Bockisch, 1998).
Cactus pear pulp which resembles the edible part of the
fruit can be divided into seeds (ca. 15%) and strained
pulp (ca. 85%), the latter being the basis for fruit and
juice products. It was found that seeds contain the
maximum amount of oil (98.8 g/kg dry weight) while
TL, recovered from lyophilised strained pulp, accounted
for 8.70 g/kg. It is well known that the mesocarp, or
pulp, of fruits generally contains very low levels of lipid
materials (0.1–1.0%) and, as such, does not constitute
an important source of edible or industrial oils (Kamel
& Kakuda, 2000). Amounts of oil recovered from seeds
which represent a potential source of oil, are in agree-
ment with literature data (Pimienta-Barrios, 1994;
Sawaya & Kahn, 1982). The levels of total lipids, how-
ever, may depend on fruit cultivar, degree of ripeness
and fruit processing or storage conditions.
3.2. Lipid classes and their fatty acid composition
The levels of lipid classes in cactus pear seed and pulp
oils and fatty acid profile of these classes are shown in
Table 1. Among the TL present in the seeds, a sig-
nificant amount of NL was found (87.0% of TL), while
polar lipids were recovered at higher levels in pulp oil
(52.9% of TL). In both oils, GL resemble PL in the low
unsaturation ratios, whereas NL were characterised by
high level of unsaturated fatty acids. Fatty acid profile
of seed oil evinces the lipids as a good source of the
nutritionally essential linoleic acid and unsaturated oleic
acid, wherein the ratio of linoleic acid to oleic acid was
about 3:1. In both seed and pulp oils, linoleic acid was
the dominating fatty acid, followed by palmitic and
oleic acids, respectively. Previous data on cactus pear
seed oil showed a rather similar pattern in that linoleic
acid was the fatty acid marker (Sawaya & Kahn, 1982).
In the polar lipid classes of seed oil, unsaturated fatty
acids were also predominant, while saturates (palmitic
and stearic acids) ranged from 28.9 to 30.0%. The fatty
acids identified in the pulp oil contained myristic and g-
linolenic acid (GLA, C18:3n-6) in addition to the fatty
acids identified in the seed oil. Of the three saturates
estimated in pulp oil, palmitic was the most pre-
dominant fatty acid (34.4% of total FAME). The
majority of fatty acids detected in polar fractions in
pulp oil were also saturated fatty acids that comprised
more than 45%. Concerning the polyunsaturated fatty
acids (PUFA), especially trienes, the two oils are dis-
tinctly different, wherein GLA and a-linolenic were
estimated in higher amounts in pulp oil, while a-lino-
lenic was only detected at low level in seed oil. Unlike
seed oil, which contains very low levels of trienes, pulp
oil could be a good source of this unique type of PUFA.
Interest in the PUFA as health-promoting nutrients has
expanded dramatically in recent years. Although GLA
was identified at low level, a great deal of interest has
been placed in the few oils that contain GLA. The
sources of natural GLA are few and at present only
borage (21–25%), evening primorse, hemp and hopseed
oils are well known (Kamel & Kakuda, 2000). Further-
more, the need for o-3 fatty acids relates to the forma-
tion of their long-chain polyunsaturated metabolites.
These play a critical role, as structural lipids, but also as
substrates for signalling molecules, such as pros-
taglandins and leukotrienes (O’Keefe, 1998; Riemersma,
2001). A rapidly growing literature illustrates the bene-
fits of PUFA in alleviating cardiovascular complaints,
inflammatory conditions, heart diseases, atherosclerosis,
autoimmune disorder, diabetes and other diseases. In
addition, presence of these fatty acids in human milk is
associated with better performance of breast-fed infants
than those on infant formula. Pregnant and lactating
women, therefore, are encouraged to ensure their diet-
ary intake of appropriate amounts of PUFA (Finley &
Shahidi, 2001; Riemersma, 2001). The fatty acid com-
position (and high amounts of PUFA) makes the cactus
pear a special fruit for nutritional applications.
3.3. Sterols composition
Sterols comprise the bulk of the unsaponifiables in
many oils. They are of interest due to their impact on
health. Recently, sterols have been added to vegetable
oils as an example of a successful functional food
(Ntanios, 2001). This type of product is now available
and has been scientifically proven to lower blood LDL-
cholesterol by around 10–15% as part of a healthy diet
(Jones et al., 2000). The contents and compositions of
342 M.F. Ramadan, J.-T. Mo
¨rsel / Food Chemistry 82 (2003) 339–345

most of the sterols in the cactus pear seed and pulp oils
are presented in Table 2. High levels of sterols were
estimated in both oils, which made up 9.33 g/kg seed oil
and 22.8 g/kg pulp oil. The latter were characterised by
high amounts of unsaponifiables (87.2 g/kg TL), while
unsaponifiable residues accounted for 20.1 g/kg seed oil.
b-Sitosterol, campesterol, stigmasterol, lanosterol and
5-avenasterol were among the major components. In
both oils, the sterol marker was b-sitosterol, which
comprised ca. 72% and 49% of the total sterol content
in seed and pulp oils, respectively. The next major
component was campesterol and these two major com-
ponents constituted ca. 90% of the total sterols. Other
components, e.g., stigmasterol and lanosterol, were
present is approximately equal amounts (3.0% of total
sterols) in the both samples. Moreover, 5-avenasterol
was present at levels of 3.1 and 6.2% of total sterols in
seed and pulp oils, respectively. A small amount of 7-
avenasterol (0.53%) was identified in the seed oil, but
not detected in the unsaponifiable residues of pulp oil.
3.4. Fat-soluble vitamins (FSV) and -carotene
composition
Nutritionally important components, such as car-
otenes and tocopherols (vitamin E), improve stability of
the oil. Carotenoids, as singlet oxygen quenchers, protect
oils from photo-oxidation, whereas their role in auto-
xidation is associated with the presence of tocopherols
(Psomiadou & Tsimidou, 2001). Data about the qualita-
tive and quantitative composition of vitamins E, K
1
and b-carotene are summarised in Table 2. The NP-
HPLC technique was used to eliminate column con-
tamination problems and allow the use of a general lipid
Table 1
Levels of total lipids, lipid classes (g/kg) and fatty acid composition of cactus pear (Opuntia ficus-indica L.) seed and pulp oils
Lipid class Seed oil Pulp oil
TL NL GL PL TL NL GL PL
98.8
a
6.26 870
b
39.8 52.3
b
3.13 70.7
b
4.55 8.70
a
0.89 462
b
21.3 293
b
11.5 236
b
12-7
Fatty acid relative content (%)
C14:0 nd
c
nd nd nd 1.130.09 0.89 0.06 1.00 0.08 1.20 0.10
C16:0 20.12.26 18.0 1.77 24.62.89 26.8 2.94 34.4 3.12 28.93.71 42.14.15 43.44.18
C16:1n-7 1.800.11 2.01 0.16 1.62 0.06 0.77 0.04 1.62 0.06 1.92 0.12 1.46 0.09 1.30 0.07
C18:0 2.720.13 2.07 0.08 4.320.27 3.23 0.21 2.37 0.10 2.140.08 2.290.08 2.850.07
C18:1n-9 18.31.58 19.3 1.66 17.7 1.49 15.6 1.23 10.8 0.98 10.2 1.03 11.5 1.09 10.4 1.12
C18:2n-6 53.54.89 56.1 4.95 50.2 4.56 49.7 4.35 37.0 3.87 45.9 4.26 28.0 3.12 27.7 3.08
C18:3n-6 nd nd nd nd 0.680.05 0.45 0.06 0.79 0.09 0.65 0.08
C18:3n-3 2.580.16 2.52 0.12 1.56 0.09 3.90 0.28 12.0 1.05 9.60 0.86 12.9 0.98 12.5 0.99
Total saturates 22.82.36 20.0 2.25 28.92.58 30.0 2.67 37.9 3.09 31.92.96 45.44.23 47.44.36
Total monoenes 20.11.89 21.3 2.16 19.31.96 16.3 1.86 12.4 1.09 12.11.06 12.91.00 11.70.96
Total dienes 53.54.89 56.1 4.95 50.24.56 49.7 4.35 37.0 3.87 45.94.26 28.03.12 27.73.08
Total trienes 2.580.16 2.52 0.12 1.560.09 3.90 0.28 12.7 1.09 10.00.93 13.71.05 13.11.06
U/S
d
3.38 4.00 2.46 2.33 1.63 2.13 1.20 1.10
Results are given as mean SD from triplicate estimations.
a
g/kg of seed or pulp dry weight.
b
g/kg of total lipids.
c
Not detected.
d
Unsaturation ratio=(16:1+18:1+18:2+18:3)/(14:0+16:0+18:0).
Table 2
Sterols and fat-soluble vitamin profile (g/kg) of cactus pear (Opuntia ficus-indica L.) seed and pulp oils
Compound Seed oil Pulp oil Compound Seed oil Pulp oil
Cholesterol nd
a
nd a-Tocopherol 0.0560.003 0.849 0.09
Ergosterol nd nd b-Tocopherol 0.0120.002 0.126 0.01
Campesterol 1.660.21 8.74 0.75 g-Tocopherol 0.330 0.03 0.079 0.006
Stigmasterol 0.300.04 0.73 0.08 d-Tocopherol 0.005 0.001 4.220 0.17
Lanosterol 0.280.05 0.760.07 Total vitamin E 0.403 0.04 5.274 0.36
b-Sitosterol 6.750.89 11.21.21
5-Avenasterol 0.290.03 1.43 0.13 b-Carotene 0.047 0.008 0.420 0.05
7-Avenasterol 0.050.006 nd Vitamin K
1
0.5250.06 0.532 0.08
Results are given as mean S.D. from triplicate estimations.
a
Not detected.
M.F. Ramadan, J.-T. Mo
¨rsel / Food Chemistry 82 (2003) 339–345 343

extraction for FSV as well as b-carotene isolation
(Ramadan & Mo
¨rsel, 2002a). In our study, saponifica-
tion of oil samples was not required, which allowed
shorter analysis time and greater vitamin stability dur-
ing analysis. All tocopherol derivatives were identified
in both samples (Fig. 2). Vitamin E levels were extre-
mely high in the pulp oil (ca. 0.52% of TL), but only
0.04% of TL in the seed oil. Although, there are certain
differences in the levels of the separated individual
tocopherols, g-tocopherol seems to be the major com-
ponent in seed oil, while d-tocopherol was the main
constituent in pulp oil. Both tocopherol markers com-
prised more than 80% of total vitamin E content in
both oils. a-Tocopherol was the second major compo-
nent in both oils, accounting for 14–16% of the total
vitamin E content. High levels of vitamin E, detected in
the oils, may contribute to great stability toward oxida-
tion. Evaluation of carotenoid levels was restricted to b-
carotene, which accounted for 0.42 g/kg in pulp oil, but
less than this in the seed oil. Carotenoids may be the
reason of the dark orange hues of cactus pear pulp oil,
while seed oil is characterised by light yellow hues. The
level of pigments, however, depends on the stage of fruit
ripeness, the extraction process and storage conditions.
Thus, oils extracted from older fruits may contain more
carotene pigments and oils from younger fruits more
chlorophyll pigments. The vitamin K
1
(phylloquinone)
profile involves 2-methyl-3-phytyl-1,4-naphthoquinone
in the plant. The phylloquinone requirement of the
adult human is extremely low. However, relatively few
values for dietary items are available (Suttie, 1985). Oils
under investigation resemble each other in the levels of
phylloquinone (Table 2), which accounted for more
than 0.05% of TL in each oil. Addition of phylloqui-
none-rich oils in the processing of foods that are other-
wise poor sources of vitamin (for example, peanut and
corn oils) could make them potentially important diet-
ary sources of the vitamin.
4. Conclusions
The trend towards natural ingredients and products
promoting health is likely to increase. The data
obtained will be important as an indication of the
potentially nutraceutical and economic utility of cactus
pear as a new source of fruit oils and functional foods.
Moreover, these results provide useful information for
the industrial application of cactus pear fruits. Evi-
dently fruit pulp provides low yields of oil, but is a rich
source of essential fatty acids, sterols, carotenes and fat-
soluble vitamins. Utilisation of the entire pulp makes
commercialisation of oil more economic, reduces wastes
from seeds and procures hitherto neglected substances
for technological and nutritional purposes. Addition of
cactus pear oil to mixed dishes and desserts could have
an impact on the amount of essential ingredients in diet.
Furthermore, it can be assumed that deoiled pulp will
yield a more stable juice.
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