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Ethnobotanical Leaflets 14: 381-89. 2010. Physicochemical
Parameters and Antimicrobial Activities of Oil Extracted from Ginger Abitogun A.S1. and Badejo
O.F2. 1Department of
Science Laboratory Technology, Rufus Giwa
Polytechnic, P. M. B. 1019, Owo, Ondo State, Nigeria 2Department of
Food Science and Technology, Rufus Giwa
Polytechnic, P. M. B. 1019, Owo, Ondo State, Nigeria *Email: adeboabitogun@yahoo.com Issued April 1,
2010 Abstract Ginger rhizome was obtained in Owo, Ondo State, Nigeria. The
rhizomes were prepared for use by sun-drying and milled to flour. A soxhlet apparatus was used for the extraction of the oil.
The residual oil obtained was assessed for physicochemical parameters and
fatty acid composition. The antimicrobial activities were carried out using
four species of bacteria. The results of the assessment showed that: moisture
content was 0.352%, specific gravity 0.97, refractive index 1.47, fire point
330oC, flash point 240 oC, smoke point(185 oC,
and turbidity 20jtu. Others were free fatty acid 2.37% (Oleic acid), acid
value 4.74 % (Oleic acid), saponification value
213.18MgKOH/g oil, peroxide value 82.00Meq peroxide/Kg, iodine value 87.82
and the yield was 7.15%. The yield indicated that ginger rhizome was not a
good source of oil. Also, the assessment indicated that the oil can supply
essential fatty acid needed in the body. In conclusion, the oil possessed
some inhibitory characteristics. Key words:
Ginger, extraction, oil, physicochemical, fatty acid composition, microbial
activities. Introduction Lipids are important nutritional
components in cereal, grain and seed of major fruits. They solubilized
vitamins A, B ,E and K, which are necessary for proper maintenance of
health and a source of essential fatty acids, thus contributing to several
metabolic functions (Lawson 1995). Lipids can be referred to as heterogeneous
collection of biochemical substances, which have in common the property of
being soluble in organic polar solvent and insoluble or sparingly soluble in
water (Gunstone, et al, 2004). The term lipids covers edible fats, oils and waxes
of plants and animals origin and certain related compounds, which includes
phospholipids and steroid (Anonymous 2002). Some organic polar compounds that
form part of the food store of the seeds, nuts and roots have deferring
levels of food and medical values. This chemical constituent can be obtained
from oily part of the seed and root when extracted (Lusas
2002). The spice ginger is the underground
rhizome of the ginger plant, known botanically as Zingiba officinale. This plant originates from
Indian, China and Java, however, it is widely grown in African countries
including Nigeria. Ginger is a perennial herb and grows to about 3-4 feet
high with a thick spreading tuberous rhizome. Ginger produces clusters of
white and pink flower buds that bloom into yellows. Every year it shoots up a
stalk with narrow spread shaped leaves as well as white or yellow flowers
growing directly from the root. It is a spice vegetable substances because
they have a distinctive flavor and aromas, thus, they are used to season
food. Other examples were dove, cinnamon, nutmeg, pepper, garlic, onion and
curry (Guralink 1984). The characteristic odour and flavor of ginger is caused by a mixture of zingerone, shogaols and gingerols. The dried rhizome contains volatile oils and
its extractives are the essentials oils and oleoresins, these extractives are
reformulated to produce secondary products such as essence, emulsion and fat
based spices (Health and Reinccius 1986). In
Nigeria Ginger is used as spices and sometimes, they can be stewed in boiling
water to make ginger tea and the oil from it are used for medical purposes
(Bode 2003). The pungent taste of ginger is due to
non volatile phenyl propernoid derived compounds,
particularly gingers and shogoals which form gingerols when ginger is dried or cooked. Zingerone is also produced from gingerols
during this process; this compound is less pungent and has a spicy sweet
aroma (Govindarajan 1982). Photochemical studies
showed that the plants is rich in a large number of substances including zingiberene, bisabolene, also gingerols and shogaols Masucla et al.,
(2004), Jolad et
al., (2005). These compounds have been reported to display diverse
biological activities such as antioxidant (Jolad et al., 2005) and anti-inflammatory as
reported by Frondoza et al., (2004) and Young et
al., (2005). Ginger is one of the most commonly used herbal supplements
and it’s substantially use in folks remedies for difference medical
conditions has been documented. Traditionally ginger has been used to treat a
wide range of ailments including gastrointestinal disorder such as stomach
aches, abdominal spasm, nausea and vomiting as well as in arthritis and
motion sickness (Langner et al., 1998 and White 2007).
There are studies on the medicinal
values, proximate composition, antioxidant activities of ginger therefore,
the study looks into the physicochemical properties, fatly and composition as
well as microbial activities of ginger rhizome oil. Material
and Methods The ginger rhizome used for this study
was obtained Owo, The moisture content and specific
gravity were determined according to AOAC (1990), while the refractive index
was measured using Abbey Refractometer coupled with
thermometer (ASTM 1985). The colour was determined
using lovibond tintometer
in half inch cell. The colour was calculated based
on the expression (5R + Y) – B, where R stands for red pigments, Y for yellow
pigments and blue for blue pigments. The flash point, fire point were
measured using Gallenkamp Authomatic
pensky – Martens flash points and fire points
taster with thermometer, the smoke point was determined using clevland open cup apparatus. The temperature at which
turbidity is first detectable was also measured using Palm tester turbidity
tube (ASTM 1985). The chemical parameters of the crude
oil were determined using standard method AOAC. (1990). the parameters
determined were; free fatty acid, acid value, saponification
value, peroxide value, and iodine value. Analytical test method for fatty
acid methyl esters were analyzed using Agilent 6890 series. Gas
chromatography filled with a flame ionization detector and enhanced
integrator, nitrogen gas was used as carrier gas. The column initial
temperature was 2500C moving at 120C per minute to a
final temperature of 3000C, while the injection and the detector
were maintained at 2500C and 3000C respectively. The
peaks were compared with standard fatty acid methyl ester (ASTM 1985). Antibacterial
activities Bacterial
Strain Klebsiella pneumoniae,
Strephylococcus aureus,
Escherichia coli and Pseudomonas aeruginosa
were obtained from the culture collections of the Federal Medical Centre, Owo, Ondo State, Nigeria. Media
and Inocula Nutrient agar was used as basal
medium. The test strains were cultured over night at 370C in
Nutrient agar, and then colonies obtained were suspended in nutrient broth to
obtain homogenous suspension of the inocula. Disc
Diffusion Method The agar disc diffusion method was
employed for the determination of antimicrobial activities of the tested oil
sample as described by Harrigan and McCancc (1979). A suspension of the tested micro organism
(0.1ml) was spread on the solid media plates. Sterile filter paper disc (5min
in diameter) were soaked with about 159 litres of
each of the oil sample and placed on the inoculated plates and were incubated
at 370C for 24 hours, the diameters of the inhibition zones were
measured in millimeters. All tests were carried out in duplicates and their
mean values were recorded. Results
and Discussion Table 1 depicts the
physicochemical parameters of crude Ginger oil. Physicochemical
characteristics of oils are those characteristics for the confirmation of the
identity and edibility of oil. The identity characteristics determined were;
specific gravity, refractive index, moisture content, iodine value saponification value and fatty acid composition, while
the quality characteristics determined were; moisture content, colour, free fatty acid, acid value, and peroxide value.
There are traces of moisture in the oil. The colour
was determined to be 38units. The high colour might
be as a result of high red pigment of the oil. However, the colour can be reduced during further processing. The
yield was 7.15±2.70%. The oil content was low in compare with 31.45% reported
for Luffa cylindrical (Abitogun
and Olumayede 2008). However, the oil content was
higher than 2.9% reported for pigeon pea (Oshodi
and Eperigin 1993). The specific gravity
and refractive index were determined to be 0.91 and 1.47 respectively. The
refractive index is the degree of the deflection of a beam of light that
occur when it passes from one transparent medium to the other. It increases
with the length of chains and with the number of carbon atom present (Pearson
1976), therefore, the refractive index of 1.47 determined for the sample is
evidence that the sample might be long carbon chain with double bond. The
result of the flash, smoke and fire points were; 2400C, 1850C
and 3300C respectively. This implies that the oil has a combustion
characteristic. These values compares favourably
with the value reported foe crude soybean oil (Salunke
et al., 1992). The value obtained
for free fatty acid and acid value were; 2.27±0.5 and 4.74±0.34% Oleic acid
respectively. Free fatty acid and acid value are the measure of amount of
fatty acid which is insoluble in water. Since most fatty acid present in
neutral oil are not soluble in water, some are relatively high, while some
are relatively low fatty acid (Lillian 1978). The low free fatty
acid and acid value was an indication that the oil can be refined to edible
vegetable oil. However, the free fatty acid compares favourably
with 1-2.8%Oleic acid reported for crude soybean oil by Salunkhe
et al., (1992). Saponification
value measures the numbers of milligrams of Potassium hydroxide require saponifying 1g of oil. The oil with low molecular weight
fatty acid will consequently have high saponification
value (Pearson 1976). The saponification value of
213.18±1.8Mg KOH/100g obtained for the sample suggests that the sample might
be low molecular fatty acid triglyceride. Thus, it may not find application
in soap and sampoo industries. However this value
is higher than 179.52Mg KOH/100g reported for Luffa bean oil (Abitogun and Olumayede
2008). The unsaturated glyceride of oil is the ability to absorb a definite
amount of iodine (Gunstone 2004). The iodine value
was 87.82±1.32. This shows that the oil is non-drying oil and apart from
this, it implies that the oil is more of unsaturated acid and it does not
congeal at ordinary temperature. Peroxide value measures the degree of rancidity
in oil (Bernardini 1973, Gunstone
2004). The result of the peroxide value was 82.00±2.12Meq peroxide/Kg. This
implies that the oil is susceptible to oxidative rancidity. It also gave an
insight to presume that the oil contain high level of unsaturated hydrocarbon
thus, it might not be stable in air at ordinary temperature. Table 2 presents the fatty acid
composition of ginger oil. The fatty acid detected and there values were; caprylic 1.37%, capric 4-14%, lauric 8.93%, myristic 3.75%, palmitic 23.96%, stearic 3.50%,
arachidic 0.90% and lignoceric
2.28% acids. Others were; oleic 23.09%, linoleic
23.09% and lnolenic acids 5.64%. The summary of
fatty acids in the oil was as follows; total saturated fatty acid was 45.12%,
while the total unsaturated fatty acids were 51.64%. The fatty acids that
were not detected and those with infinitesimal values form the 3.24%
difference. Palmitic, oleic and linoleic
acids dominate the fatty acids. Early experiments showed that palmitic, myristic and lauric acids raised plasma cholesterol more than those
with either shorter or longer chains (Bonanome and
Grundy 1988). It has been re-established that stearic
consumption is associated with lower level of total and low density
lipoprotein cholesterol than those on similar intakes of palmitic
acid. Indeed the cholesterol-lowering effect was similar to that seen in
oleic acid. The effect of lauric acid is less
pronounced than those of myristic and palmitic acids (Cox 1999). However, saturated fatty acid
plays an important role in the structure of tissue as reported by Gunstone et al.,
(2004). The high level of lnoleic and oleic acids
confirm that the oil is liquid oil than solid oil; hence, it cannot easily
congeal at ordinary temperature. It also implies that the consumption of this
oil can prevent the risk of heart problems. Table 3 shows the antibacterial activity
of ginger oil. The diameters of inhibition in (mm) were measured, the result
for each organism were; staphylococcus aureus (15±1.6),
Klebsiella eshericha
(10±2.2), Pseudominas aeruginosa
(10±1.2) and Escherichia coli
(8±1.5). The highest activity was recorded in Staphylococcus aureus while Escherichia
coli recorded the lowest activity. The oil has inhibitory power over Staphylococcus aureus
and less effect on the remaining organisms. The inhibitory characteristics
are as a result of the presence of saturated fatty acids that is myristic, lauric and palmitic acids. However, the antimicrobial activities
were in agreement with antimicrobial effects of ginger reported by Akoachere et al.,
(2002). In conclusion, the
results of the assessment on ginger rhizome oil revealed that the yield of
7.05% was low; this suggests that the rhizome may not be a good source of
oil. The result also revealed that the oil can supply essential fatty acid to
the body. Finally, the oil has inhibitory characteristics over bacteria. References Abitogun,
A. S. and Olumayede, O. (2008). Extraction and
characterization of Luffa cylindrical oil. Nig. Jour. of Applied Sc. 26, 112-115. Akoachere
J.F., Ndip R,N. and Chenw.
E.B. (2002). Antimicrobial effect of Zingier
officinale and
Garcinia kola on respiratory tract parthogens. East.
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A. (2003). Ginger is effective inhibitor of HCT 116 human colorectal
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and Grundy (1988). Effect of dietary stearic acid
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W.F. and McCance, M. E. (1979). Laboratory Methods in Food and Dairy Microbiology, 2nd Edn. Academic
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96, 207-210. Table
1: Physicochemical parameters of Ginger Oil. Parameters Results Specific
gravity
0.91 Refractive
index
1.47 Moisture
Content (%) 0.52
± 0.20 Fire
points (0C) 330
± 2.00 Flash
point (0 C) 240
± 1.50 Smoke
point (0 C) 185
± 2.50 Turbidity
(jtu) 20
±2.00 Melt
point (0 C) -18.00
±0.10 Colour
(units) 38.00
±0.00 Acid
value (% Oleic Acid)
4.74 ±0.34 Free
Fatty Acid (% Oleic Acid)
2.37 ± 0.57 Saponification
value (Mg KOH/g oil) 213.18±3.20 Iodine
value 87.82±1.32 Peroxide
value (Meq Peroxide/kg) 82.00±2.12 Yield
(%) 7.05 ±2.70 Mean± Standard deviation of
triplicate Table 2: Fatty Acid Composition
of Ginger Oil. Fatty
Acid Methyl Ester Fatty Acid Carbon Number Result (%) Capritate Capric 10:0 4.14 Lauritate Lauric 12:0 8.93 Myristate Myristics 14:0 3.75 Palmitate Palmitic 16:0 20.96 Stearate Stearic 18:0 3.50 Arachidonate Arachidonic
20:0 0.19 Lignocerate Lignoceric
24:0 2.28 Oleate Oleic
18:1 22.09 Linoleate Linoleic 18:2 23.91 Linolenate Linolenic 18.3 5.64 Table 3: Antimicrobial activities
of Ginger Oil. Test
Organisms Zone
of inhibition (mm) Klebsiella pneumonia 10
±2.2 Staphylococcus
aureus (BT 331) 15 ±1.6 Pseudomonas
aeruginosa (BT 334) 10 ±1.2 Escherichia
colu (BT 333) 8 ±1.5 |