Qualities of lemongrass
Chemical properties
The chemical properties of lemon grass essential oil
viz. saponification value, iodine value, acid values
Where C = Concentration of sodium, V1 = Volume
were analyzed using the standard methods (AOAC,
of sodium thiosulphate used for blank, V2 = Volume
1998)
of sodium thiosulphate used for determination, M =
Mass of the sample.
Saponification value
Acid value
2 g of the oil sample was added to a flask with 30cm 3
of ethanolic KOH attached to a condenser for 30
100 ml of neutral ethyl alcohol was heated with 10
minutes to ensure the sample was fully dissolved.
g of oil sample in a 250cm 3 beaker until the mixture
After cooling the sample, 1cm 3 of phenolphthalein
began to boil. The heat was removed and was
was added and titrated with 0.5M HCl until a pink
titrated with N/10 KOH solution, using two drops of
endpoint has reached.
phenolphthalein as indicator with consistent shaking
for which a permanent pink colour was obtained at
Saponification value (SV) was calculated from the
the end point.
equation (mg KOH/g)
The Acid value was calculated using the expression
(mg KOH/g); A.V = 0.56 x No. of ml. N/10 KOH used.
Where S = sample titre value, B = Blank titre value,
Statistical analysis
M = Molarity of the HCl, 56.1 = Molecular weight of
The collected data are statistically analysed by using
KOH
OPSTAT developed by CCS Haryana Agricultural
University, Hisar, India.
Iodine value
Iodine value was estimated following the procedure
Results and Discussion
suggested by Akpan et al . (2006). In this method,
The Cymbopogon species produce essential oils rich in
0.4gm of the oil was weighed into a conical flask and
monoterpenes such as citral, citronellal, citronellol,
20 ml of carbon tetra chloride was added. Then 25 ml
linalool, elemol, 1,8-cineole, limonene, geraniol,
of Dam’s reagent was added to the flask and mixture
β-carophyllene, methyl heptenone, geranyl acetate
was swirled vigorously after inserting a stopper on
and geranyl formate. Pale yellow colour lemongrass
the flask. The flask was then kept in the dark for 2
oil extracted from fresh lemongrass plant with a
hours 30 minutes. After that, 20 ml of 10% aqueous
yield of 0.76% on fresh weight basis. This result
potassium iodide and 125 ml distilled water were
agrees with some workers who reported that oil
added by using a measuring cylinder. The content of
content should average 0.25-0.5% but with good
the flask was titrated with 0.1M sodium thiosulphate
management and selected strain could yielded up to
solution until the yellow colours almost disappear.
0.66-0.90% (Hanaa et al ., 2012).
Further, few drops of 1% starch indicator was
added and the titration was continued by adding
The method of drying had a significant effect on
thiosulphatedropwise,untilbluecolourdisappeared
the essential oil content of Lemongrass (Table 1).
after vigorous shaking. The same procedure was also
Lemongrass leaves dried in an oven at 45°C for 7
followed for blank test.
hr. had the highest essential content (3.06%) on dry
weight basis. While, lemongrass leaves dried in
The iodine value (IV) is given by the expression
sunshine and shade, contains the essential oil 2.50%
(gI 2 /100g)
and 2.65% respectively. The maximum oil yield was
recorded in oven drying samples followed by shade
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