Received: 30 April 2016
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Revised: 12 November 2016
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Accepted: 25 November 2016
DOI: 10.1111/jfpp.13286
ORIGINAL ARTICLE
The effect of drying methods on the concentration of compounds in sage and thyme Urszula Sadowska1 | Aneta Kopeć2 | Lenka Kourimska3 | Lena Zarubova3 | Pavel Kloucek3 1 Institute of Machinery Exploitation, Ergonomics and Production Processes, Faculty of Production and Power Engineering, University of Agriculture in w, Łupaszki 6, Krakow 30-198, Poland Krako 2
Department of Human Nutrition, Faculty of Food Technology, University of Agriculture in Krakow, Balicka 122, Krakow 30-149, Poland 3
Abstract The aim of the study was to evaluate effects of three drying methods of thyme and sage. Collected herbs were dried: under natural conditions, at temperature of 35 8C/40 8C, and freezedried. The material was tested on the essential oil content using Clevenger apparatus; chemical composition was determined using gas chromatography coupled to mass spectrometry (GC-MS). Antioxidant activity was analyzed by determining the ability to neutralize the free radical 2,20 azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) with simultaneous measurement of
Department of Quality of Agricultural Products, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamycka 129, 165 21 Praha 6 – Suchdol, Czech Republic
phenolic compounds content. Most oils were isolated from herbs dried at 35 8C, but the largest
Correspondence Urszula Sadowska, Institute of Machinery Exploitation, Ergonomics and Production Processes, Faculty of Production and Power Engineering, University of w, Łupaszki 6, Krakow, Agriculture in Krako 30-198, Poland. Email:
[email protected]
Practical applications
Funding information Ministry of Science and Higher Education in Poland (statutory funds No. DS-3111/ WRE/2014 and DS3700/WTZ/2014, Institute of Plant Production, University of Agriculture in Krakow, and Department of Human Nutrition, Faculty of Food Technology, University of Agriculture in Krakow) and by the Ministry of Agriculture of the Czech republic (project NAZV QJ1310226)
which are helpful in the prevention of civilizational diseases. Nowadays thyme and sage are widely
amount of thymol in thyme and thujone in sage leaves was determined at 40 8C. The highest content of polyphenols for thyme was found at 35 8C and for sage in lyophilized leaves. The lyophilized material was characterized by the largest ability of free radical (ABTS) elimination.
Drying as a method of preservation of herbal plants, like food preservation, is a necessary process of maintenance, especially in temperate climates. The way in which thyme and sage leaves are dried, has a significant influence on their chemical composition, and thereby the properties of the received raw material. Therefore, there is a possibility of programming their composition according to the needs. Owing to appropriate technological treatment it is possible to obtain the substances used. The presented research results are useful not only in the process of obtaining dried leaves from thyme and sage but also in isolating the essential oil with the desirable chemical composition, for further use and development of functional food.
1 | INTRODUCTION
eties, for example, thyme oil exhibits cytotoxic action against cancer cells (Ait M’Barek et al., 2007; Berdowska et al., 2013; Berrington &
Because of their aromatic properties thyme (Thymus vulgaris L.) and
Lall, 2012; Sertel, Eichhorn, Plinkert, & Efferth, 2011 (Bommer, Klein, &
sage (Salvia officinalis L.) are popular herbal and spice plants of the mint
Suter, 2011) and strong antimicrobal properties (Esmaeili, Mobarez, &
family. They have been also commonly applied in traditional medicine
Tohidpour, 2012; Loizzo et al., 2008; Tohidpour, Sattari, Omidbaigi,
(Fecka & Turek, 2008; Topçu, 2006). Thyme is recommended for treat-
Yadegar, & Nazemi, 2010). Sage exhibits strong antioxidant activity.
ing upper respiratory congestion and digestive disorders (Hajimehdi-
These properties are connected with other healthy properties including
poor, Shekarchi, Khanavi, Adib, & Amri, 2010), whereas sage has an
antidiabetic and anticancer activities (Eidi & Eidi, 2009; Grzegorczyk,
anti-inflammatory properties (Baricevic et al., 2001).
ska, 2007; Russo et al., 2013). Matkowski, & Wysokin
In vitro studies conducted in recent years reported their various
Food and pharmaceutical industry commonly uses herbs due to
new applications in treatment of diseases which affect modern soci-
the presence of bioactive compounds. However, fresh plant raw
J Food Process Preserv. 2017;e13286. https://doi.org/10.1111/jfpp.13286
wileyonlinelibrary.com/journal/jfpp
C 2017 Wiley Periodicals, Inc. V
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material undergoes adverse changes quickly, thus there is the need
pounds profile in the future. So far, there is lack of such comprehensive
for its preservation. Moreover, for the maintaining continuity of
study on the effect of drying regarding thyme and sage.
production as well as for better handling, the industry prefers to use dried material.
In this work, we evaluated the results of three drying methods of thyme and sage in relation to active compounds content. Therefore: (I)
Nowadays, lyophilization is considered to be one of the most suit-
we determined the effect of drying method on the amount of essential
able methods of preservation of various plant products. Generally, its
oil content and change of their compound composition; (II) we analyzed
outcome is products of high quality (Ratti, 2001). Conversely, drying is
and compared antioxidant properties of thyme herb and sage leaves
one of the oldest methods of food preservation (Akpinar, 2006). Drying
dried under various conditions, with the simultaneous measurement of
slows down the development of microorganisms and prevents some of
phenolic compounds content; and also (III) we assessed the best drying
rez-Coello, the unfavorable biochemical reactions (Díaz-Maroto, Pe
method in relation to desired parameters of raw material.
Gonzalez Vinas, & Cabezudo, 2003; Sellami et al., 2012). Although new drying technologies appeared in recent years, convection drying is still
2 | MATERIALS AND METHODS
the most popular and very cheap method of preservation of plant raw rrez-Ortíz, & Carbonell-Barrachina, material (Szumny, Figiel, Gutie 2010). The basis of thyme and sage qualification in pharmacy is minimal essential oil content (Ph. Eur. 6). The amount and chemical composition of essential oils depends not only on the genotype used but also on geographical location, climate, growing and harvest conditions, and method of preservation (Raut & Karuppayi, 2014). Demand for high quality dried products grows worldwide, and drying method can have significant effect on the chemical composition of the obtained material and its properties. Venskutonis (1997) indicates that volatile compound losses depend primarily on drying parameters and biological properties of plants. The existing data on the effect of drying method on oil content are not unequivocal (Rahimmalek & Goli, 2013; Sarosi et al., 2013). Value of herb raw material does not always have to be linked to the presence of major biologically active compounds (Diplock et al., 1998). The Lamiaceae are considered to be one of the most potent antioxidants (Zheng & Wang, 2001). Also, Hossain, Brunton, Barry-
2.1 | Plant material For the study two species of herbs of the Lamiaceae family were used, thyme (Thymus vulgaris L.)—cultivar Słoneczko and sage (Salvia officinalis L.)—cultivar Bona. They originated from plantation located in northeastern part of Krakow (50.0608N, 19.9598E). Plantation was performed on soil with granulometric composition of heavy loamy sand. Plants were grown on soil mats. No pesticides were used during cultivation. Study was carried out in 2014, during the fourth year of sage growth and second year of thyme growth. Thyme was collected in full bloom, whereas sage was collected when first inflorescences appeared. Both harvests were conducted at the end of May, before noon, in sunny and dry weather conditions. Approximately 21 bushes were harvested from each species, and before subsequent experiments all branches of each species were mixed together to avoid interindividual variations.
2.2 | Methods
Ryan, Martin-Diana, and Wilkinson (2008) and Shan, Cai, Sun, and
2.2.1 | Chemical composition
Corke (2005) reported high antioxidant compound content in this fam-
Fresh samples of thyme were divided in leaves with flowers or used
ily. Nickavar and Esbati (2012) found antioxidant activity of various
whole for selected analyses. Fresh leaves of sage were separated from
Thymus species. Furthermore, the results of study by Roby, Sarhan,
stalk or also used with stalk for selected analyses. In fresh herbs, con-
Selima, and Khalel (2013) point out to high antioxidant potential of
tent of the dry matter was measured. In, thus, prepared samples the
sage, thyme, and marjoram.
basic chemical composition was measured, that is, total proteins (pro-
Compounds of plant origin with the highest biological activity apart from essential oils include polyphenols. Plant polyphenols exhibit
cedure no. 950.36), raw fat, (procedure no 935.38), and ash (procedure no 930.05) according to the AOAC (2006) methods.
antioxidant, antiatherosclerotic, antiallergic, antiswelling, and antimutagenic effects (Ellis et al., 2011). Phenolic compounds in plants provide
2.2.2 | Drying conditions
an array of natural sources of antioxidants for use in foods and nutra-
For the harvested plants various drying conditions were employed.
ceuticals (Shahidi, 2000).
Natural drying was conducted in a dry and shaded room (20 6 0.6 8C),
In literature, there is only a small amount of information about the
convection drying in laboratory driers at temperature of drying factor
changes of phenolic compounds and antioxidant potential in herbs in
of 35 8C and 40 8C. Convective drying with parallel movement of dry-
the context of drying together with variability of essential oils and their
ing factor was conducted separately for thyme and sage. The height of
composition. Both sage (Salvia officinalis L.) and thyme (Thymus vulgaris
deposit of material on shelves amounted 40 mm and the distance
L.) are species with a long tradition of food and medicinal use but also
between shelves amounted 160 mm. Lyophilization was conducted in
with huge potential to be used in treatment and prevention of diseases
vacuum freeze drier (Christ Alpha 1-4, Gefriertrocknungsanlangen, Ger-
of modern societies. Understanding at what level different drying tech-
many). For the 24 hr the following parameters of freeze drying were
niques may influence the content of compounds with proven effect on
kept pressure 1.030 mbar temp. 220 8C. After this time the pressure
human organism may lead to postharvest management of these com-
was decreased for 0.100 mbar and temperature was lower than 20 8C.
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Both for thyme and sage drying was conducted until achieving 10% of
2.2.7 | GC-MS analysis
humidity of drying material. Whole leaves and flowers, which consti-
Samples were analyzed by GC/MS using Agilent 7890A GC coupled to
tute pharmaceutical raw material, were separated from dried thyme
Agilent 5975C single-quadrupole mass detector with a HP-5MS col-
herb, whereas only leaves were separated from sage herb (Ph. Eur. 6).
umn (30 m 3 0.25 mm, 0.25 mm film) from Agilent (Santa Clara, CA). Samples of thyme and sage essential oils (5 mL) were dissolved in 1,000
2.2.3 | Methanolic extracts preparation
mL of n-hexane for GC analysis. The sample volume of 1 mL was
The five grams of fresh material or 0.200 g of dried herbs was homoge-
injected in split mode (1:12), the injector temperature was 250 8C and
nized with 80 mL of 70% methanol with laboratory homogenizer (CAT
the electron ionization energy set at 70 eV. The oven temperature
type X 120). The lower amount of dry samples was used to omit the
started at 60 8C for 3 min. and was programmed to 250 8C at a rate of
dilution process during the analysis of total polyphenolic compounds
3 8C/min, and then kept constant for 10 min. The flow rate was 1 mL/
and antioxidant activity. In each case, plant materials were extracted by
min and helium was used as carrier gas. The identification of constitu-
shaking (Elpan, water bath shaker type 357, Poland) at room tempera-
ents was based on the comparison of their mass spectra and relative
ture for 2 hr. Obtained solution was centrifuged (Centrifuge type
retention indices with the National Institute of Standards and Technol-
MPW-340, Warszawa, Poland) and filtered. Thus, prepared extracts
ogy Library (NIST 10) as well as authentic standards and literature
were stored at 222 8C (Pellegrini, Del Rio, Colombi, Bianchi, & Brigh-
(Adams, 2007). Following standards were used (Sigma-Aldrich, CZ):
enti, 2003).
a-thujene, a-pinene, camphene, b-pinene, myrcene, d-3-carene, paracymene, limonene, 1,8-cineole, g-terpinene, camphor, terpinen-4-ol,
2.2.4 | Total phenolic compounds concentration
thymol, carvacrol, b-caryophyllene.
Methanolic extracts were used to measure the total polyphenolic compounds content, with the Folin–Ciocalteu reagent (Sigma St. Luis Missouri). The level of total polyphenolic compounds in the herbs extracts was determined spectrophotometrically according to the Folin–Ciocalteu procedure (Poli-Swain & Hillis, 1959). Results were calculated as chlorogenic acid equivalents (CGA) in milligrams per 100 g of fresh or dry weight of samples.
2.2.5 | The antioxidant activity
2.3 | Statistical analysis For each sample the chemical analyses were performed in three replicates. The arithmetic mean as well as standard deviations (SD) were calculated. All calculations were made by using Statistica 10.0. package (Stat Soft, Inc., Tulsa, Oklahoma). One-way analysis of variance was used. The significance of differences was evaluated with Duncan test at the significance level a 5.05 and results were significant below the level p < .05).
Methanol extracts were also used to measure antioxidant activity of herbs, by identifying the ability to extinguish an ABTS·1 (2,20 -azinobis-
3 | RESULTS
(3-ethylbenzothiazoline-6-sulfonic acid) free radical (Re et al., 1999). Values obtained for each sample were compared to the concentration–
3.1 | Drying
response curve of the standard Trolox solution and expressed as micromoles of Trolox equivalent per gram of fresh or dry weight (mmol TEAC/1 g).
The most time consuming was drying of the studied raw material under natural conditions until pharmaceutically required moisture was obtained. Thyme was dried for 264 hr and sage for 288 hr. Conversely,
2.2.6 | Hydrodistillation Determination of essential oil content from dried material of both species was conducted using Clevenger apparatus. The raw material in the form of herb of thyme and leaves of sage had been milled using a lab
drying in laboratory driers at 35 8C was carried out for 85 hr, and at temperature of 40 8C for 77 hr.
3.2 | Chemical composition
grinder into minor powder before a hydrodestilation. Dried and then
The chemical composition of the studied plants is presented in Table 1.
powdered thyme and sage leaves were weighed precisely with accu-
The highest dry mass content was exhibited by entire thyme plants,
racy of .001 g. For the study, 30 g of thyme and 20 g of sage were
more hydrated were leaves and flowers. Similafindings were in case of
used. Then, the study material was placed in 1,000 mL round-bottom
initial moisture of fresh samples (Table 1). A reverse dependency was
flask and 400 mL of distilled water was added. Flask containing thyme
observed in sage. More dry mass as well as initial moisture were found
was heated for 2 hr, adjusting intensity of heating to the desired distil-
in leaves compared to whole plants. Sage had more protein and fat
lation rate (Ph. Eur. 6), whereas flask containing sage for 3 hr. Distilla-
than thyme. In 100 g f.m., sage had on average 2.4 g of protein, almost
tion rate was at 2–3 mL/min. After the distillation was finished, heating
4 times more than leaves, and 7 g of fat, 1.73 g more than in leaves. A
was closed, and after 10 min oil volume was measured on the calibra-
very large amount of ash compounds were found, both in sage herb as
tion tube. Three tests for each drying condition were conducted.
well as in leaves. Conversely, thyme was characterized by considerably
Thereafter, the obtained essential oil samples were stored in glass vials
higher carbohydrate content and low content of mineral compounds
at 4 8C until analysis.
(Table 1).
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T A B LE 1
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ET AL.
Chemical composition of thyme and sage (g/100 g fresh weight)
Ingredient
Thyme all plant
Thyme Flowers and leaves
Sage all plant
Sage leaves
Dry mass
30.72 6 0.83c
26.46 6 0.88a
24.41 6 0.64b
26.62 6 0.20a
Initial moisture
69.28 6 0.83c
73.54 6 0.88a
75.59 6 0.64c
73.38 6 0.20a
protein
1.99 6 .03b
0.59 6 .01a
2.40 6 .07c
0.62 6 .01a
Crude fat
1.39 6 0.14a
1.06 6 0.12a
7.00 6 1.10c
5.27 6 0.33b
24.88 6 0.85a
22.30 6 0.69a
13.16 6 1.64b
18.45 6 0.39c
2.46 6 0.19a
2.55 6 0.14a
1.86 6 .03b
2.37 6 .07a
Total carbohydrates Ash
Values with different letters (a, b, c) are significantly different, p < .05.
3.3 | Polyphenols content and antioxidant activity of sage and thyme
tions no statistically significant differences occurred. Average essential oil content for sage ranged from 1.8 to 2.05 mL/100 g, whereas for thyme 1.9–2.06 mL/100 g of dried material. In all drying conditions,
In the fresh herbs, the highest content of polyphenolic compounds was found in whole fresh thyme as compared to the fresh leaves with flow-
essential oil content within pharmaceutical standards was obtained.
ers (Table 2). In case of sage the highest level of polyphenols was measured in leaves of fresh sage. Additionally the leaves of fresh sage
3.5 | Chemical composition of essential oil
had the highest concentration of polyphenolic compounds compared
3.5.1 | Thyme
to the rest of the samples. The ability to scavenge free radicals did not differ in experimental samples.
Table 4 summarizes results of essential oils composition isolated from thyme herb dried in various conditions. In summary, 51 compounds
In the dried herbs, the highest concentration of polyphenolic compounds was measured in thyme samples dried at 35 C compared to the other thyme samples (Table 3). In sage, the concentration of polyphenolic compounds was significantly highest in freeze-dried samples as compared to the other samples of sage and thyme. The lowest level of these compounds was measured in sage dried at 35 C. The highest antioxidant activity was found in samples of freezedried and dried in 35 C thyme compared to the other thyme samples. In sage, the highest antioxidant activity was measured in freeze-dried samples comparing to the other sage samples (Table 3).
were detected and identified. Quantitatively dominant were thymol, pcymene, and g-terpinene. In each condition, the major compound of the essential oil obtained from thyme herb was thymol (51.6%–55.4%). The lowest proportion of thymol was observed after freeze drying, whereas the largest amount was found after drying at 40 8C. Carvacrol, structural isomer of thymol, exhibited opposite results. The highest amount was found in freeze dried material (5.56%), lowest in natural dried (3.86%). Because of similar biological activities of these two compounds, sum of their content could be taken as a marker for the medicinal properties of the herb. In this regard, 40 8C was the most favorable drying method (60.44%), showing more than 3% difference when compared to the freeze drying (57.16%). Conversely, there are two precur-
3.4 | Essential oils content
sors of these compounds, p-cymene and g-terpinene. Both of them
As shown in Table 3 both for thyme herb as well as sage leaves, the
had the highest content in thyme herb dried naturally and freeze-dried.
greatest amount of essential oil was obtained from convection drying
Particularly freeze-dried material was rich in p-cymene (15.57%) in
of raw material at temperature 35 8C. Among the rest of drying condi-
comparison to the other methods (12.24%–12.34%).
T A B LE 2
Total phenolic, essential oil content, and antioxidant activity of fresh thyme and sage
Treatment
Polyphenolic compoundsa
ABTS mmol Trolox/1 gb
Essential oil (mL/100 g d.m.)
Fresh Thyme All plant Flower and leaves
1,236.40 6 1.2b 1,063.17 6 3.6a
147.46 6 38a 147.49 6 36a
– 2.03 6 .06 b
Fresh Sage All plant Leaves
1,333.63 6 6.0c 1,773.20 6 7.2d
155.91 6 6.8a 153.11 6 7.4a
– 1.11 6 0.1 a
Values in column with different letters (a, b, c) are significantly different, p < .05. mg/100 fresh weight—chlorogenic acid equivalent. b mmol Trolox/1 g fresh weight. a
SADOWSKA
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Total phenolic and essential oils content and antioxidant activity of thyme and sage dried by various methods
Treatment
Polyphenolic compounds (mg/100 d.m.)
ABTS mmol Trolox/1 g (d.m.)
Essential oils (mL/100 g d.m.)
Thyme Naturally dry Freeze dry flowers and leaves Flowers and leaves 35 8C Flowers and leaves 40 8C
5,550.97 6 104a 5,572.73 6 108a 6,759.82 6 108c 5,185.31 6 103a
1,937.53 6 18.0a 2,631.27 6 169b 2,358.49 6 49b 1,736.55 6 32a
1.90 6 .03 1.90 6 .00 2.06 6 .05 1.90 6 .06
a a b a
Sage Naturally dry Freeze dry leaves Leaves 35 8C Leaves 40 8C
7,288.26 6 16d 14,402.91 6 469e 6,351.17 6 31b 7,953.58 6 16d
1,807.68 6 102a 3,201.20 6 419b 1,963.01 6 7.0a 1,779.69 6 8.0a
1.88 6 .03 1.80 6 .09 2.05 6 .00 1.82 6 .06
b b c b
Values in column with different letters (a, b, c) are significantly different, p < .05.
3.5.2 | Sage
not react with Folin–Ciocalteu reagent (Harvert-Hernandez, García,
Table 5 summarizes results of composition of oils obtained from
~ i, 2011; Kolniak, 2008). It can be suggested that in temRosado, & Gon
sage leaves in various conditions. They point out to the fact that the main components of the essential oil are 1,8-cineol, a-thujone, a-humulene, b-caryophyllene, and viridiflorol. 1,8-cineole was the most abundant in oil from naturally dried raw material (19.42%) and the least after freeze drying (18.12%). Reverse dependency was observed for a-caryophyllene. The largest amount of a-thujone was found in sage leaves dried at 40 8C (16.71%), whereas the lowest amount in sage leaves after freeze drying (15.18%) and leaves dried at 30 8C (15.27%). Similar behavior was observed for the second bicyclic monoterpene—camphor—in the range from 5.57% for the 40 8C to 4.73% when freeze-dried. Higher boiling compounds like a-humulene, b-caryophyllene, and viridiflorol were found in highest proportions in freeze dried samples, while they were least abundant in leaves dried at 35 8C. In general freeze drying seems to protect higher boiling compounds, while for the therapeutically most important component—1,8-cineol the natural drying is the best option. Sum of the controversial compounds—a- and b-thujone—was lowest in freeze and naturally dried leaves.
perature of 40 C these binds may be destroyed and it caused highest concentration of phenolic compounds in leaves dried at this temperature. This was not the case of thyme where the highest content of polyphenolic compounds was measured in samples dried at 35 C. Thyme flowers contains anthocyanins, these bioactive compounds may be destroyed at temperature about 37 C (Díaz-García et al., 2015; Rababah, Banat, Rababah, Ereifej, & Yang, 2010; Wilska-Jeszka, 2002). Probably it was the reason that higher content of phenolic compound was measured at 35 C. Antioxidant activity of thyme and sage was also affected by various drying methods. It was found that thyme which was freeze-dried or dried at 35 C and freeze-dried sage had the highest antioxidant activity (Table 3). Similar data, concerning the content of polyphenolic compound and antioxidant activity in fresh thyme and sage reported Hossain, Barry-Ryan, Martin-Diana, and Brunton (2010).These authors reported the lowest content of polyphenolic compounds and antioxidant activity found in fresh thyme and sage as compared to various drying methods. However, these authors reported that the highest content of polyphenolic compounds and antioxidant activity was measured in samples of thyme and sage which were air dried compared to the freeze dried
4 | DISCUSSION
~o, Benedito, & Bon (2013) reported that the samples. Rodríguez, Ortun optimization of the antioxidant capacity depends on the drying
The highest concentration of polyphenolic compound was found in
methods.
leaves of sage as compared to the rest of the samples. There were not
In our study, in each drying condition pharmaceutically required
differences in antioxidant activity of analyzed parts of thyme or sage
essential oil content was obtained. However, the largest amount of
(Table 2). In literature, there are mainly the information concerning the
essential oils was acquired from sage leaves and thyme herb that were
content of phenolic compounds and antioxidant activity of dry thyme
convection-dried at 35 8C, while no statistically significant difference of
or sage. However, a lot of people use fresh herbs for preparation of
the essential oils content isolated from naturally dried material, dried in
various types of meals. These fresh herbs may be a source of antioxi-
40 8C and freeze-dried samples was noticed.
dant compounds including polyphenols. The methods of drying
A decrease of the amount of essential oils in prolonged natural dry-
affected the level of phenolic compounds content in analyzed herbs.
ing seems to be obvious due to the losses of volatile compounds. Drying
Generally the highest concentration of polyphenols was found in sage
at 40 8C and freeze-drying probably resulted in damaging oil glands.
especially in freeze dried leaves. Additionally the leaves of sage dried at
Available empirical literature data on the effect of preservation method
40 C had higher concentration of these compounds compared to the
on essential oil content are not unequivocal. The study of Sarosi et al.
samples dried at 35 C. It has been already published that some pheno-
(2013) indicate lower essential oil content in material obtained by lyophi-
lic compounds in plants may be a part of bigger molecules which do
lization and at high temperatures (50 8C). In the cited experiment, thyme
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T A B LE 4
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Chemical composition of Thymus vulgaris depending on the drying conditions Pct Total
R.I.
Name compound
Thyme natural dry
Thyme noc. dry 35 8C
Thyme noc. dry 40 8C
Thyme freeze dry
930
a-thujene
0.75
0.70
0.65
0.75
937
a-pinene
0.43
0.40
0.39
0.42
952
camphene
0.20
0.18
0.19
0.19
979
b-pinene
0.12
0.11
0.12
.09
982
1-octen-3-ol
0.81
0.75
0.64
0.93
988
3-octanone
.05
.05
.05
.05
992
b-myrcene
0.92
0.86
0.81
0.85
997
3-octanol
0.12
0.10
0.11
0.10
1,005
b-phelandrene
0.14
0.13
0.12
0.12
1,012
d-3-carene
.07
.07
.06
.07
1,019
a-terpinene
1.07
1.03
0.94
1.04
1,028
p-cymene
12.34
12.24
12.29
15.57
1,032
D-limonene
0.36
0.35
0.35
0.38
1,034
1,8-cineol
0.17
0.17
0.19
0.20
1,042
b-cis-ocimene
.05
.05
.05
.09
1,052
b-trans-ocimene
.04
.03
.03
tr.
1,062
c-terpinene
6.40
6.21
5.56
6.30
1,070
trans-sabinene hydrate
0.76
0.73
0.71
0.66
1,083
nonen-3-ol
.03
.03
.03
.04
1,090
terpinolene
0.11
0.10
0.10
0.12
1,098
cis-sabinene hydrate
0.17
0.16
0.15
0.14
1,101
linalool
2.90
2.76
2.51
2.62
1,123
cis-p-2-menthen-1-ol
.05
.05
.05
.05
1,146
camphor
.08
.08
tr.
.08
1,168
borneol
0.55
0.56
0.66
0.52
1,179
terpinen-4-ol
0.48
0.46
0.45
0.51
1,187
p-cymene-8-ol
.06
.06
.06
.06
1,192
a-terpineol
0.11
0.11
0.11
0.12
1,197
cis-dihydrocarvone
.05
.05
.06
.06
1,238
thymol methyl ether
3.83
3.77
4.04
2.68
1,247
carvacrol methyl ether
2.16
2.15
2.39
1.53
0
geraniol
tr.
tr.
.08
.01
1,287
bornyl acetate
.05
.07
.09
.07
1,302
thymol
54.10
55.26
55.40
51.60
1,309
carvacrol
3.86
4.14
5.04
5.56
1,358
thymol acetate
.07
.07
.05
.07
1,378
a-copaene
0.11
0.10
0.10
0.11
1,386
b-bourbonene
0.11
0.10
0.10
0.11 (Continues)
SADOWSKA
T A B LE 4
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(Continued) Pct Total
R.I.
Name compound
Thyme natural dry
Thyme noc. dry 35 8C
Thyme noc. dry 40 8C
Thyme freeze dry
1,420
b-caryophyllene
3.50
3.34
3.04
3.52
1,430
b-gurjunene
0.10
0.11
0.10
0.11
1,455
a-humulene
0.11
0.10
.08
0.15
1,478
g-muurolene
0.38
0.33
0.30
0.33
1,482
germacrene D
0.21
0.19
0.16
0.27
1,495
Valencene
0.15
0.14
0.13
0.13
1,501
a-muurolene
0.10
.09
.09
.09
1,515
g-cadinene
0.35
0.31
0.26
0.28
1,525
d-cadinene
0.67
0.61
0.52
0.54
1,581
caryophyllene oxide
0.48
0.42
0.44
0.64
1,617
10-epi-g-eudesmol
0.15
0.14
0.14
0.13
1,640
epi-a-cadinol
.07
tr.
tr.
tr.
100
100
100
100
+ identified %
Characters have been bolded in order to show the most important values.
herb preserved using these methods did not meet pharmaceutical stand-
55.4%, which meant that normative pharmaceutical standards were met
ards, that is, 1.2 mL/100 g of raw material. Herb dried at 50 8C con-
in each condition (Ph. Eur. 6). The largest losses of thymol were
tained only 0.69 mL/100 g and freeze-dried 1.04 mL/100 g. In the same
observed during natural drying, similar results were obtained by Rahim-
experiment, thyme was also conventionally dried at 30 8C and 40 8C in
malek & Goli (2013) for Thymys daenensis ssp. daenensis dried under the
which 1.84 mL/100 g and 1.55 mL/100 g was obtained, respectively.
shade, and also at 50 8C. However, in the present study the largest
Therefore, the raw material met pharmaceutical standards, similarly to
amount of this compound was found after drying at 40 8C. Conversely,
naturally dried raw material, where 1.73 mL/100 g was obtained. Con-
the results of Sarosi et al. (2013) indicate the largest amount of thymol
versely, the study of Rahimmalek & Goli (2013) performed with Thymys
in the raw material preserved using lyophilization (71.19%) and conven-
daenensis ssp. daenensis indicate the highest essential oil content in
tionally dried at 40 8C and 50 8C, 67.76% and 68. 99%, respectively.
freeze-dried material (1.7%) compared to convection-dried at 50 8C
Thyme oil is well known for its antimicrobial activity, and thymol
(1.46%) and in the sun (1.42%). Differences of the amount of essential oil obtained from different drying conditions between our study and the
together with carvacrol are the main active compounds (Rota, Herrera, Martínez, Sotomayor, & Jordan, 2008). The research of Segević-Klarić,
cited studies may come not only from a different genotype used in the
Kosalec, Mastelić, Pieckova, & Pepeljnak (2007) indicates that thymol
experiment but also slightly different methodology (i.e., distillation lasting
isolated from thyme oil has approximately three times stronger effect on
for 5 hr in the cited literature). The results of the tests of essential oil
fungi of genera Aspergillus, Penicillium, Cladosporium, Trichoderma, Rhizo-
content conducted on sage by Sellami et al. (2012) indicated losses from
pus (compared with MIC value) than the oil itself. Furthermore, our
0.3% to 0.26% during convection-drying method at 45 8C compared to
results do not confirm the tendencies observed by Sarosi et al. (2013)
naturally drying at approximately 22 8C which is comparable to the val-
on p-cymene. In the obtained results its largest amount was found in
ues presented in this paper. Pirbalouti, Mahdad, and Craker (2013)
freeze-dried 15.57%. Losses were observed during all other drying con-
observed the lowest oil losses in green and red basil dried naturally in
ditions (12.24–12.34%). Conversely, studies of the cited authors indicate
the shade. This method of conservation, though the least expensive, is
the largest amount of this compound in raw material dried at 30 8C
however linked to the risk of adverse atmospheric conditions and pro-
(25.37%), the lowest in lyophilized thyme (14.81%). It should be noted
longed time of drying, during which enzymatic decomposition and devel-
that thymol is a derivative of p-cymene.
opment of unwanted microbiota may occur. Temperature of the room in
The largest amount of oil was obtained from sage leaves dried at
which natural drying was conducted for the present study was 20 6
35 8C. Results of the in vivo study conducted by Santos et al. (2004)
0.6 8C. At this condition, an average of 1.9% of oil in thyme and 1.88%
with the use of 1,8-cineole indicate its anti-inflammatory effect and
in sage leaves was obtained. In the present study, the dominant com-
the use in the prophylaxis of ulcers and digestive inflammation. This
pound of essential oil obtained from thyme herb was thymol, which is in
compound is also used for the treatment of asthma (Juergens et al.,
line with the results obtained for this species by Golmakani and Rezaei
2003). Conversely, Dob, Berramdane, Dahmane, Benabdelkader, and
(2008) and Sarosi et al. (2013). Thymol content ranged from 51.6% to
Chelghoum, (2007) obtained significantly lower amount of this
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T A B LE 5
SADOWSKA
ET AL.
Chemical composition of Salvia officinalis depending on the combination of drying conditions Pct Total
R.I.
Name compound
Salvia natural dry
Salvia noc. Dry 35 8C
Salvia noc. Dry 40 8C
Salvia freeze dry
925
tricyclene
.03
.04
.04
.03
930
a-thujene
0.17
0.14
0.13
0.16
937
a-pinene
3.78
4.23
4.01
3.53
952
camphene
1.05
1.23
1.26
1.00
979
b-pinene
3.38
3.13
2.94
3.35
981
1-octen-3-ol
.06
.05
.04
.06
992
myrcene
0.63
0.68
0.62
0.65
1,005
b-phelandrene
.05
.05
.05
.04
1,019
a-terpinene
0.23
0.23
0.21
0.20
1,027
p-cymene
tr
tr
tr
tr
1,032
D-limonene
0.69
0.73
0.67
0.59
1,034
1.8-cineol
19.42
18.65
18.17
18.12
1,042
b-cis-ocimene
0.79
0.83
0.65
0.83
1,052
b-trans-ocimene
0.17
0.17
0.14
0.22
1,062
g-terpinene
0.57
0.49
0.42
0.44
1,070
trans-sabinene hydrate
0.18
0.16
0.14
0.13
1,090
terpinolene
0.16
0.18
0.17
0.17
1,098
cis-sabinene hydrate
0.11
0.11
0.10
.08
1,101
linalool
0.25
0.22
0.15
0.28
1,106
a-thujone
16.48
15.27
16.71
15.18
1,118
b-thujone
4.69
6.78
5.42
5.70
1,123
isopulegol
tr.
tr.
.08
.05
1,146
camphor
4.88
5.35
5.57
4.73
1,163
cis-pinocamphone
0.13
0.15
0.13
0.10
1,168
borneol
1.86
2.08
1.98
1.90
1,175
trans-pinocamphone
.04
.06
.05
.05
1,179
terpinen-4-ol
0.28
0.27
0.25
0.28
1,192
a-terpineol
0.13
0.11
.09
0.13
1,197
myrtenol
.07
.07
.08
.05
1,287
bornyl acetate
0.14
0.19
0.22
0.12
1,299
thymol
tr
tr
tr
tr
1,308
carvacrol
tr
tr
tr
tr
1,377
a-copaene
0.20
0.28
0.10
.08
1,420
b-caryophyllene
12.51
11.47
11.53
12.59
1,455
a-humulene
14.12
13.15
14.25
15.30
1,462
aromadendrene
0.21
0.48
0.55
0.57
1,478
g-muurolene
0.36
0.34
0.14
0.11
1,495
viridiflorene
0.20
0.21
0.13
0.12 (Continues)
SADOWSKA
T A B LE 5
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ET AL.
9 of 11
(Continued) Pct Total
R.I.
Name compound
Salvia natural dry
Salvia noc. Dry 35 8C
Salvia noc. Dry 40 8C
Salvia freeze dry
1,524
d-cadinene
0.48
0.63
0.22
0.21
1,581
caryophyllene oxide
0.47
0.50
0.50
0.54
1,591
viridiflorol
9.11
8.00
9.37
9.45
1,606
humulene epoxide II
0.99
1.35
1.67
1.47
99.18
98.66
98.97
98.96
+ identified %
Characters have been bolded in order to show the most important values.
compound (12.3%) from S. officinalis naturally dried in Algeria. How-
5 | CONCLUSIONS
ever, it should be expected that in the same drying temperatures its amount was higher. Furthermore, what cannot be overlooked are the
The results obtained in this study confirm the hypothesis that essential
possible differences in genotype. In naturally drying condition the larg-
oils content and their chemical composition, polyphenol content, and
est amounts of 1,8-cineole, a-pinene, and limonene were observed
the ability to eliminate the free radical (ABTS) both in thyme (Thymus
(summary content 23.89%). Therapeutically important mixture of these
vulgaris L.) as well as sage (Salvia officinalis L.), are strongly dependent
monoterpenes referred to as geromyrtol has a similar effect to com-
on drying conditions. Considering all the mentioned factors the most
monly used antibiotics and mucolytics, and it is used in the treatment
favorable drying condition for thyme was temperature of 35 8C. How-
, of acute bronchitis (Trytek, Paduch, Fiedurek, & Kandefer-Szerszen
ever, slightly higher content of thymol was obtained at the condition of
2007).
temperature of 40 8C. Even a small difference in the percentage of this
Salvia officinalis oil is known for large variations of the main mono-
compound results in a significant change that translated to the yield
terpene compounds: thujones, camphor, 1,8-cineole, and pinenes (Law-
obtained from 1 ha. Changes in the quantitative and qualitative compo-
rence, 1998). The study of Schmiderer, Torres-Londono, and Novak
sition of essential oil obtained from sage leaves dried in various condi-
(2013) conducted in Albania on the chemical composition of oil
tions were also demonstrated. The most favorable method of sage
obtained from naturally dried raw material indicate large variation of
preservation in terms of the amount of essential oil, similarly to thyme,
compounds dependent on geographical location. Northern populations
was drying at 35 8C. However, in terms of the percentage content of
contained relatively large amounts of a-thujone, approximately 20% on
the main active compounds of the oil, this drying method was not the
average, whereas southern approximately 9% on average. Conversely,
most suitable. The largest amounts of 1,8-cineole were found in natu-
camphor was least abundant in northern part of the country, 19% on
rally dried material, while a-thujone and camphor in leaves dried at
average, compared to southern, 33% on average. Such significant dif-
40 8C, whereas a-humulene, b-caryophyllene, and viridiflorol after
ferences are explained by intraspecies variability. According to Russo
lyophilization. Therefore, it seems that using various drying method we
et al. (2013), thujones and other active compounds of the sage oil, such
can modify the oil chemical composition. Generally, considerably larger
as camphor, have potentially synergistic anticancer effect. In our study,
content of polyphenols and ABTS relative to the remaining samples
considerably lower amount of camphor was obtained, which in similar
was determined in lyophilized leaves.
drying method amounted to only 5% and its maximum content was observed in the leaves dried at 40 8C but it amounted to only 5.57%. Analogous differences can be observed for the major sesquiterpenes: b-caryophyllene, a-humulene, and viridiflorol. Oil obtained from samples dried at 40 8C was characterized by the largest a-thujone content (16.71%); however, compared to raw material from Brazil dried at the same temperature (Longaray-Delamare, Moschen-Pistorello, Artico, Atti-Serafini, & Echeverrigaray, 2007) this amount was significantly lower. However, in this case certain methodo-
ACKNOWLEDGMENTS Financial support for this study was provided by the Ministry of Science and Higher Education in Poland (statutory funds No. DS-3111/ WRE/2014 and DS3700/WTZ/2014, Institute of Plant Production, University of Agriculture in Krakow, and Department of Human Nutrition, Faculty of Food Technology, University of Agriculture in Krakow) and by the Ministry of Agriculture of the Czech republic (project NAZV QJ1310226).
logical differences were noticed, which can affect the obtained results; oil was obtained using hydrodistillation that lasted only for 1 hr. The observed discrepancies between the present results and these presented in literature may have different reasons. It should be noted, that changes in the chemical composition of oil may result from environmental factors in which the plants grew as well as genetic factors (Perry et al., 1999).
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How to cite this article: Sadowska U, Kopeć A, Kourimska L, Zarubova L, Kloucek P. The effect of drying methods on the concentration of compounds in sage and thyme. J Food Process Preserv. 2017;00:e13286. https://doi.org/10.1111/jfpp.13286
