ABSTRACT
Thorough studies have been made and excellent reviews have been
written about the chemical composition of orange flower oil (neroli
oil) and of rose oil. Hundreds of compounds have been identified in
these oils.
Orange flower oils and rose oils were obtained by hydrodistillation
and by supercritical fluid carbondioxide extraction of the concretes
from the flowers. The chemical composition and olfactive properties
of orange flower oils from Morocco, Spain and Tunisia, and of rose
oils from Bulgaria and Turkey were studied.
Significant differences were found between the concentrations of some main constituents and within the olfactive qualities of the oils obtained by either hydrodistillation or by fluid carbondioxide extraction.
DISCUSSION
The composition of the carbondioxide-extracted oil from Moroccan bitter orange flower concrete is quite different from those of the before-mentioned hydrodistilled oils. The average differences are shown in the next table (Table I).
Table I
CONCENTRATIONS OF MAIN CONSTITUENTS AND DIFFERENCES BETWEEN
HYDRODISTILLED AND CARBONDIOXIDE EXTRACTED ORANGE FLOWER OIL
|
compounds |
hydrodistilled oil |
carbondioxide extract |
difference |
|
Monoterpene hydrocarbon |
38 % |
28 % |
10 % |
|
Linalyl acetate |
3-5 " |
24 " |
20 " |
|
Linalool |
38 " |
35 " |
3 " |
|
Nitrogen derivatives |
<0.5" |
2 " |
1.5" |
|
Sesquiterpene alcohols |
4 " |
<2 " |
2 " |
The sensory properties of the rose oil components have been discussed in detail by Ohloff (1a, 1b). Moreover Ohloff reviewed the odour units (= concentration of a constituent: odour threshold) of the 14 main constituents of Bulgarian rose oil. The concentrations, thresholds and odour units of the essential and characteristic constituents of Bulgarian rose are shown in Table II.
Table II
CONCENTRATIONS OF MAIN CONSTITUENTS, THRESHOLD VALUES AND ODOUR UNITS
OF BULGARIAN ROSE OILS
|
Compounds |
Concentration |
Threshold value |
Odour units |
x 10-3 |
|
|
hydrod. extr.: |
CO2-extr.: |
ppb in water |
hydrod. extr.: |
CO2-extr.: |
|
|
(-)-citronellol |
30 % |
8 % |
40 |
7500 |
2000 |
|
geraniol |
18 " |
4 " |
75 |
2400 |
530 |
|
nerol |
9 " |
2 " |
300 |
300 |
67 |
|
linalool |
2 " |
0.1 " |
6 |
3300 |
165 |
|
2-phenylethanol |
2 " |
67.5" |
750 |
25 |
900 |
|
rose oxides |
0.5" |
0.15" |
0.5 |
10000 |
3000 |
|
nerol oxide |
0.05" |
0.03" |
0.5 |
1000 |
600 |
|
eugenol |
1 " |
1 " |
30 |
330 |
330 |
|
methyl eugenol |
2 " |
0.7" |
820 |
25 |
10 |
|
farnesol |
1.5" |
0.1" |
20 |
750 |
50 |
|
beta-damascenone |
0.015" |
<0.005" |
0.01 |
15000 |
<5000 |
|
Total odour units: |
40630 |
<12652 |
CONCLUSION
The odour intensity of the CO2-extracted bitter orange oil was twice that of the hydrodistilled oil, because more odour-intense constituents are extracted with CO2 and fewer compounds decompose during the extraction than in boiling water during hydrodistillation. Just the reverse is true for the two rose oils with respect to the odour intensity, due to the fact that much (65%) of the less odour-intense 2-phenylethanol is dissolved in the distillate water and therefore is not present in the hydrodistilled oils.
1a. G. Ohloff, in: Scent and Fragrances, Rose Oil pp. 154-158.
Springer-Verlag, Berlin (1994).
1b. G. Ohloff, Importance of minor components in flavors and
fragrances. Perf. Flav., Vol. 3, Febr. March 1978, 10-22.
Reprinted by Leffingwell & Associates, 2006, with Permission