LOW TEMPERATURE EXTRACTION OF BULGARIAN ESSENTIAL OIL BEARING
PLANTS FROM LAMIACEAE BY LIQUEFIED GASES.
20. Oregano (Origanum heracleoticum L.)
Mihaela Ivanova, Nenko Nenov, Maria Doushkova, Radka Vlaseva, Albena Stoyanova
University of Food Technologies, Plovdiv, Bulgaria
Abstract: The chemical composition of extract from the Bulgarian essential oil bearing plants
from Lamiaceae family - oregano (Origanum heracleoticum L.) by extraction with C2H2F4
(1,1,1,2-tetrafluorethane) was analyzed using GC and GC/MS. The main compounds
(concentration higher than 3 %) of extract was as follows: carvacrol (70.05 %), p-cymene
(11.83 %) and para-cymene-2,5-dione (3.78 %).
Kew Words: Origanum heracleoticum, extract, 1,1,2-tetrafluorethane, chemical composition.
Bulgaria has been renowned as one of the two major global supplier of rose oil (Rosa
damascena Mill.) and, also, as a source of many other essential oils and aromatic products,
including lavender (Lavandula vera D.C.), zdravetz (Geranium macrorrhizum L.),
peppermint (Mentha piperita L.), tobacco (Nicotiana tabacum L.) etc. [2, 8, 9, 10].
Many essential oil bearing plants, belonging to various genera, are industrially cultivated and
processed in Bulgaria, but the major part belongs to the genera Lamiaceae. The plants of
oregano (O. heracleoticum L.) cultivated in Europe and Asia have been classified into five
major chemotypes based on the main components of their volatile oils : carvacrol
chemotype – carvacrol (above 80 %); tymol chemotype – tymol (above 70 %);
tymol/carvacrol chemotype – tymol (25 - 55 %) and carvacrol (15 - 65 %); mixed carvacrol
chemotype – carvacrol (above 60 %), р-cymene (to 15 %) and -teroinene (to 15 %); mixed
tymol chemotype – tymol (to 55 %), р-cymene (to 12 %) and -terpinene (tо 17 %).
In Bulgaria mainly local population of oregano is grown as garden plant, nevertheless those
cultivars “Hebros 43”, “Hebrosс 55” and “Hebros 64” were selected and introduced as
industrial culture [3, 5]. The major compounds of Bulgarian oregano essential oil were:
carvacrol (65.7 %), р-cymene (12.8 %) and -terpinene (12,4 %) [4, 11], and the oil have
higher antimicrobial activity .
Currently in many countries essential oil bearing plants are processed by extraction with
liquefied gases (СО2, air, freon and other). The produced extracts are harmless that’s why
they can be widely used in food and flavour industry. The usage of liquefied gases overcomes
the drawbacks of installations working with volatile polar and apolar solvents [6, 7]. The
installations for extraction with liquefied gases characterized with high working pressure (0.6
MPa when butane is used, 1.5 MPa when propane is used and 4-7 MPa when СО2 is used)
and increased capital investments are needed. There are only three extracting installations
working with liquefied gases in Bulgaria. Two of them, one laboratory and one industrial,
working with liquefied СО2 are situated in Dimitrovgrad and one laboratory installation,
working with liquefied 1,1,1,2-tetrafluorethane is situated in University of Food Technologies
The aim of present study is producing of new plant extracts from oregano, growing in
Bulgaria, by using liquefied 1,1,1,2-tetrafluorethane in laboratory installation and
determination of their chemical composition for possible application in food products.
Material and methods
Obtaining of extract:
The air-plant was ground separately in an attrition mill to a size of 0.15 – 0.25 mm and the
extract obtained by a 1 dm3 volume C2H2F4 (1,1,1,2-tetrafluoroethane) laboratory-extractor
under following conditions: temperature 20 – 25 ОC, pressure 5,7 - 6,5 bar, time 150 min.
Determination of chemical composition.
GC analysis was performed using an Agilent 7890A gas chromatograph equipped with FID
detector and HP-INNOWax Polyethylene Glycol column (60 m x 0,25 mm; film thickness
0,25 m); temperature: 70 О - 10 min, 70 - 240 ОC - 5 ОC/min, 240 ОC – 5 min; 240 - 250 ОC -
10 ОC/min, 250 ОC – 15 min; carrier gas helium, 1 ml/min constant flow; injector split, 250
ОC, split ratio 50:1.
Gas Chromatography-Mass Spectrometry Analysis: GC/MS analysis was carried out on an
Agilent 5975C gas chromatograph, carrier gas helium, column and temperature as for GC
analysis, FID, 280 ОC, MSD, 280 ОC, transfer line.
Results and discussion
The produced extract is dark brown liquid with characteristic odour. The yield extract was
2,3-2,4 % (v/w).
Chemical compositions of the extract are listed in Table 1. As seen 23 components
representing 94.92 % of the total content were identified. Five of them were in concentrations
over 1 % and the rest 20 constituents were in concentrations under 1 %. As seen the major
constituents (up 3 %) of the extract is as follows: carvacrol (70.05 %), p-cymene (11.83 %)
and para-cymene-2,5-dione (3.78 % %). According to quantitative content of the major
constituents the produced extract is equal to the essential oil from mixed carvacrol
chemotypes: carvacrol (above 60 %), р-cymene (to 15 %) и - terpinene (to 15 %) [1, 4].
Table 1. Chemical composition of extracts from peppermint.
Distribution of major groups of aroma substances in the extract is shown in Figure 1. Phenyl
propanoids are the dominant group in the extract 91.25 %, followed by sesquiterpene
hydrocarbons 2.78 %.
Figure 1. Group of components in the extract, %.
1- monoterpene hydrocarbons (0.87 %), 2 – oxygen monoterpenes (0.85 %),
3 – sesquiterpene hydrocarbons (2.78 %), 4 - oxygen sesquiterpenes (1.58 %),
5 – phenyl propanoids (91.25 %), 6 – others (2.67 %).
For the first time in Bulgaria new extract from oregano (Origanum heracleoticum L.), was
produced by extraction with liquefied tetrafluoroethane. The optimal conditions for extraction
procedure were determined. The produced extract was almost equal with essential oil from the
same essential oil bearing plant, according to its chemical composition. The extract is
prospective for possible application in different food products, but of course additional
investigations are a must.
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