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Food Science and Technology

Print version ISSN 0101-2061On-line version ISSN 1678-457X

Ciênc. Tecnol. Aliment. vol. 17 n. 4 Campinas Dec. 1997

https://doi.org/10.1590/S0101-20611997000400013 

COMPARISON OF GINGER (Zingiber officiale Roscoe) OLEORESIN OBTAINED WITH ETHANOL AND ISOPROPANOL WITH THAT OBTAINED WITH PRESSURIZED CO21

 

Lia P. NOBREGA2, Alcilene R MONTEIRO2, M. Angela A. MEIRELES2,*, Marcia O. M MARQUES3

 

 


SUMMARY

Ginger (Zingiber officinale Roscoe) belongs to the Zingiberacea family. It is a spice of great commercial importance. In this work ginger oleoresin was obtained with ethanol, isopropanol and liquid carbon dioxide. The chemical compositions of the extract were compared with each other. All oleoresin samples had monoterpenes and sesquiterpenes. Carboxylic acids were found in organic solvent extracts for an extraction time of 2 hours. The component responsible the for pungent characteristic of the oleoresin, gingerois, were detected in samples obtained with organic solvent for extraction times of 6 hours and in samples obtained with CO2 liquid for extraction times of 2 hours.

Keywords: Essential oil, oleoresin, ginger, solvent extraction, supercritical extraction 


RESUMO

COMPARAÇÃO DA OLEORESINA DE GENGIBRE (Zingiber officiale roscoe) COM ETANOL E ISOPROPANOL E A OBTIDA COM CO2. O gengibre (Zingiber officinale Roscoe) pertence à família Zingiberacea. É uma especiaria de grande importância comercial.

Neste trabalho realizou-se extrações da oleoresina de gengibre com etanol, isopropanol e dióxido de carbono líquido e comparou-se a composição química de cada um dos extratos. A oleoresina obtida tem componentes das classes dos monoterpenos e sesquiterpenos em todas as amostras. Ácidos carboxílicos foram encontrados nos extratos obtidos com solvente orgânico, quando o tempo de extração foi de 2 horas. Os componentes que dão a característica pungente à oleoresina, os gingerois, foram detectados nas amostras obtidas com solvente orgânico, quando o tempo de extração foi de 6 horas e, nas amostras obtidas com CO2 líquido, com 2 horas de extração.

Palavras chave: Óleo essencial, oleoresina, gengibre, extração com solvente, extração supercrítica


 

 

1 — INTRODUCTION

The use of the essential oils of spices and condiments in the food industry, instead of the spices and condiments themselves, is increasing, due partly to uniformity of flavor and lack of contamination by microorganisms; some of these essential oils are also used in the perfumery, medicinal and fine chemicals industries, as well as in agricultural activities, especially those directed towards combating insects, plagues, fungi, etc. [18].

Ginger oleoresin used in food industry is, generally, obtained by extraction with organic solvent, acetone and ethanol being the most commonly used [12, 18]. However, the solvent extraction process has to overcome great difficulties to remove organic solvent from oleoresin without ruining the product, since oleoresin components are thermolabile substances. As a possible alternative to this problem, several studies have been conducted using CO2, near its critical point, as a solvent, for the oleoresin extraction of several natural products, since this solvent is easily removed when system pressure and temperature diminish [3, 11, 19, 20].

The composition of volatile oils present in ginger (mainly the ones obtained from the Asian and African species) has been widely studied [13, 21, 21] and more than one hundred compounds were detected in essential oil. However, these compounds contribute only partially to the "flavor impact" since fresh ginger is characterized by its aroma, as well as by its pungency.

Oleoresin obtained by ethanol or acetone extraction has the pungency found in ginger. Substances responsible for this characteristic are well-known compounds such as gingerois and shogaols [8, 9], with 6-gingerol being the compound that contributes the most to this characteristic [10].

The objective of the present work was to study the chemical composition of ginger oleoresin obtained by extraction with ethanol, isopropanol, and liquid carbon dioxide. Special attention was devoted to identifying in CO2 extracts the substances responsible for ginger oleoresin’s pungency.

 

2 — MATERIAL AND METHODS

Ginger from the 1996 crop was purchased at Tapiraí (Juquiá, São Paulo, Brazil). Raw material was cleaned, selected and packed in plastic bags (10kg) and kept in a domestic freezer (-5oC, Brastemp, Brazil ). The humidity of the ginger rhizomes was 83.8± 0.01 % (water mass/total solid mass), as determined by the method described by Jacob [16].

2. 1 – Preparation of raw material

Frozen ginger was cut and ground in a domestic food processor (Wallita Master) for 15 seconds. Soon after, ginger pieces were dried in a heat-pump tray dryer (with inlet air at a dry bulb temperature of 25oC, a wet bulb temperature of 16oC, and a relative humidity of 41%). Fifty grams of ginger were placed in each tray, the dryer temperature was 25 or 30oC and the drying time was 80 or 60 minutes, respectively. Dried ginger was vacuum packed in plastics bags and stored in a domestic refrigerator (Brastemp, Frostfree, Brazil) at 5oC. The humidity of the dried material was 14.00± 0.01%, as determined by the method described by Jacob [16]. Particle size distribution of the dried ginger was determined in a sieve shaker (Art-Lab, BERTEL, Brazil) fitted with sieves of the following Tyler series sizes: 6, 8, 10, 12, 14, 16, 24, 35 and 48 mesh. Mean solid size distribution was: 38.00% mesh 6, 32.00% mesh 8, 14.05% mesh 10, 8.35% mesh 16, 4.60% mesh 35, and 3.00% mesh 48.

2.4 – Oleoresin extraction with organic solvent

Ethanol (P.A., 99.8% purity, Merck) and isopropanol (P.A., 99.5% purity, Merck) were used. The extraction equipment was composed of a 500ml jacketed glass beaker and a 250ml plastic beaker with a porous base where ground ginger was placed (fresh or dried). Water circulated in the jacketed glass beaker to maintain the ginger and solvent mixture at a constant temperature.

A preliminary set of experiments using 10 g of dried ginger and different amounts of solvent was performed. The amount of the two solvents used was varied from 10 ml up to 100ml, by 5 ml intervals. Oleoresin extraction time varied from 2 to 6 hours. Based on the results it was decided to use 10 g of solid material and 75 g of solvent. Solvent and dried ginger were placed in the glass beaker and in the plastic beaker, respectively. The later one was then placed inside the glass beaker so that the ginger rhizomes entered into contact with the solvent. The system was maintained under constant agitation (magnetic stirrer: Cole Parmer, Hot Plate-Solid State, Model 4817, USA) during the whole experiment to improve solid and solvent contact (Figure 1). After the preselected extraction time was reached, the small beaker containing the refined or leached phase (ginger plus retained solvent) was weighed (Analytical Balance, Sartorius, Germany). The extract or clear phase (soluble material and solvent) contained in the glass beaker was also weighed and kept in glass flasks for analysis. Extractions were performed in duplicate for both solvent and for the following times: 60, 90, 120, and 360 minutes. An extraction of a 240 minute duration was also done for ethanol. Extracts from the above experiments will be referred to as EtOH-Ext and IC3-Ext. A factorial design was employed.

 

FIGURE 1. Flow sheet of apparatus employed for organic solvent extractions

 

2.3 – Extraction with liquid carbon dioxide

Extractions were conducted using a fixed-bed extractor (with a length of 60.5 cm and an inside diameter of 2.16 cm). Experiments were performed in the equipment described by Monteiro et al [17] which is a semi-continuous apparatus. Solid material was put into the extractor, the system was allowed to reach steady state in terms of pressure and temperature, and then the apparatus was filled with CO2 (White Martins do Brazil, 99%). After this, no CO2 flow was allowed for a period of one hour. Then CO2 flow was started and continued for up to 3 hours. The fixed bed was formed with 121.7± 0.5 g of dried ginger. Particle size distribution was the same as that for solvent extractions. Fixed-bed characteristics were a true density of 1.200± 0.001g/ml, as measured by the helium picnometry technique [11]; an apparent density of 0.51 ± 0.01 g/ml; an average particle size diameter of 1.27± 0.01 mm; and a porosity of 0.57. The temperature was 16 ± 0.5oC, the pressure was 70.0 ± 0.5 bar, and the solvent flow rate was 5.3± 0.1 gCO2/min. The experimental procedure was the same as that used by Monteiro et al [17]. Extracts samples were collected at three stages during the experimental runs: i) The first sample was collected for the first 30 minutes of extraction in an adapted porapak Q column at the solvent exit of the collector flask, to capture the more volatile substances that could be otherwise lost; ii) The second sample was collected in the flask for the first 30 minutes of the extraction; iii) The third sample was collected in the flask for the first 90 minutes of extraction; iv) The fourth sample was collected at the end of the experiment (extraction time of 120 minutes) during the operation of depressurization of the extraction line. These samples will be called as CO2-E1, CO2-E2, and CO2-E3, and CO2-E4, respectively.

2.4 – Extract compositions

EtOH-Ext and IC3-Ext were esterified using the method described by Maia [14]. Esterified extracts were kept in a domestic freezer for 24 hours and afterwards dried with anhydrous sodium sulfate. Extract compositions were analyzed using a GC-MS system (Shimadzu, model QP-5000) equipped with a fused silica capillary column DB-1 (25 m x 0.25 mm x 0.25mm). The electron impact technique (70 ev) was used. The carrier gas was helium (1 ml/min.) and 1mL of sample was injected. Temperature was raised from 50° C to 280° C at 4° C/min. Detector temperature was 230° C and that the for injector was 250° C. Identification of chemical constituents was based on: i) comparison of substance mass spectrums with the GC-MS system data bank (Wiley 139 Library); and ii) comparison of mass spectrums with data in literature [15].

 

3 — RESULTS AND DISCUSSION

Table 1 presents chemical substances identified in ginger oleoresin obtained with ethanol, isopropanol and liquid carbon dioxide. Extracts obtained with ethanol and isopropanol for 2 hours of extraction show the same chemical composition for all the samples, independent of solvent volume used. This was expected since the amount of solvent employed was well above the amount required to form a saturated solution. Thus, extracts were dilute solutions and no solubility limitations affecting the system. Therefore, differences in chemical compositions could be expected as a result of influences other than operational variables such as extraction temperature, extraction time, solid particle size, drying conditions for ginger rhizomes, and so on.

For samples obtained for extraction times of 4 and 6 hours using ethanol as the solvent (Table 1), the probable oleoresin chemical composition revealed the presence of monoterpenes (b-pinene, camphene, b-mircene, and a-pinene) and sesquiterpenes (a-zingiberene, farnesene, b-sesquiphellandrene, ar-curcumene). IC3-Ext with an extraction time of 6 hours also had monoterpenes and sesquiterpenes. The presence of 6-gingerol was confirmed. The percentages were 1.32% and 2.40% for extraction times of 2 and 6 hours, respectively.

Table 1 also shows that CO2-E1, CO2-E2, CO2-E3, and CO2-E4 sample compositions are different. More volatile substances, such as b-pinene (22.63%) and a-zingiberene (31.18%), were detected in the CO2-E1 sample. The CO2-E2 sample had another profile for the same retention time. b-pinene appeared in a very small amount (1.00%) and a-zingiberene in very large quantities (50.10%). Mass spectrum for both samples showed the most abundant sesquiterpenes to be a -zingiberene, a-farnesene and b-sesquiphellandrene. In the CO2-E3 sample these substances were detected, but no monoterpenes were identified. 6-gingerol, the substance responsible for ginger’s pungency, was also detected (14.07%). The mass spectrum of sample CO2-E4 suggested 6-gingerol (80.71%) as the main component. From these results we concluded that the extraction time for the organic solvent was not enough to solubilize 6-gingerol. According to solvent extraction studies conducted by Spiro et al [24] (6 hours total extraction time), the largest amount of 6-gingerol was present in the acetone extract, followed by the dicloromethane and ethanol extracts, and the smallest amount was observed when isopropanol was used. The authors also observed that the equilibrium concentration was obtained after 24 hours for isopropanol and after 6 hours for acetone and ethanol.

 

TABLE 1. Chemical Composition of Ginger Oleoresin Obtained With Organic Solvent and Liquid CO2

Extract Samples

 

EtOH-Ext
2 hs

EtOH-Ext
4 hs

EtOH-Ext
6 hs

IC3-Ext
2 hs

IC3-Ext
6 hs

CO2 - E1

CO2- E2

CO2- E3

CO2- E4

Substance

        %

2-heptanol

-

-

-

-

-

0.40

-

-

-

a-Pinene

-

0.78

1.11

-

1.14

0.85

-

-

-

camphene

-

2.74

2.97

-

4.02

2.78

-

-

-

b-myrcene

0.81

1.26

-

2.10

3.12

-

-

-

b-pinene

-

4.60

4.72

-

4.99

22.63

1.00

-

-

m-diethylbenzene

-

-

-

-

-

1.38

-

-

-

o-diethylbenzene

-

-

-

-

-

0.75

-

-

-

p-cymene

3.19

-

-

4.52

-

-

-

-

-

nonanal

-

1.23

0.97

-

0.97

-

-

0.54

4.07

citronellal

-

-

-

-

-

1.23

-

-

-

neral

-

2.80

1.13

-

1.97

3.00

2.53

0.76

-

geranial

-

3.42

2.54

-

5.16

2.17

5.10

2.66

-

2-undecanone

-

-

-

-

-

0.87

tr

tr

-

ar-curcumene

tr

3.30

3.05

tr

2.99

4.29

5.36

3.49

tr

a -Zingibirene

7.57

44.42

37.53

15.53

35.10

31.18

50.1

39.17

6.91

farnesene

14.74

18.01

18.74

15.82

14.43

12.47

20.8

17.47

2.01

b-sesquiphellandrene

2.44

13.22

12.86

13.79

11.25

8.83

15.08

12.99

2.68

methyl 14-methyl- pentadecanoate

24.30

-

-

15.20

-

-

-

-

-

methyl 4,6, 10, 14-tetrametyl petadecanoate

4.01

-

-

4.99

-

-

-

-

-

methyl linolelaidate

18.93

-

-

6.62

-

-

-

-

--

methyl 11-octadecenoate

12.71

-

-

5.98

-

-

-

-

-

6-gingerol

-

1.32

3.81

-

1.29

-

tr

14.07

80.71

not identified

11.88

3.35

9.31

17.55

18.88

3.36

-

8.85

3.62

tr = traces (< 0.5%)

 

The variation in oleoresin composition obtained with liquid CO2 agrees with results found in the literature [11, 20]. This may have been influenced by the solvent flow rate. During the extraction process the solvent flow rate varied. This phenomena was more pronounced for the first 30 minutes of extraction and during depressurization. The larger the solvent flow rate, the larger are the chances of losing volatile substances. This probably explains the fact that the porapak-Q column had collected the most volatile substances that would otherwise have flown out of the collector flask (CO2-E1 sample). During depressurization, the flow rate of the remaining solvent increased due to the pressure difference, which allowed suction of the retained material in the equipment tubing. This vacuum pressure effect could also promote the extraction of gingerois. According to the literature [25], these substances are located near the particle center. The vacuum effect observed could have promoted cell rupturing, which facilitated gingerois extraction.

 

4 — CONCLUSIONS

Ginger oleoresin extracted with ethanol or isopropanol for 2 hours revealed the presence of monoterpenes, sesquiterpenes and fatty acids. The absence of gingerois may be a result of the short extraction time employed. Another possibility is that gingerois were present in the samples, but at such a low concentration that was impossible to detect them by the analytical method used.

Monoterpenes, sesquiterpenes and gingerois were identified in oleoresin samples obtained for both organic solvents (6 hour extraction time). In the ethanol extract (4 hours of extraction) only monoterpenes, sesquiterpenes and small amounts of gingerois were detected.

CO2-E1, CO2-E2, CO2-E3, and CO2-E4 samples had different profiles. The presence of gingerois was observed in sample CO2-E4. During depressurization, the flow rate of the remaining solvent increased due to a difference in pressure, which allowed suction of the material retained in the equipment tubing. This vacuum pressure effect could also promote the extraction of gingerois. These substances, according to the literature, are located near the particle center. The vacuum effect observed could have promoted cell rupturing which facilitate gingerois extraction.

 

5 — REFERENCES

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[11] GOVINDARAJAN, V. S. Ginger-Chemistry, Technology and Quality Evalution: Part I e II. In Critical Reviews in Food Science and Nutrition. CRC Press Inc., 1982

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[13] MAIA, E. L. Otimização da Metodologia para Caracterização dos Constituintes Lipídicos e Determinação da Composição em Ácidos Graxos e Aminoácidos de Peixe de Água Doce (Characterization of Lipids and Fatty Acids Determination in Fish]. Campinas, São Paulo, Brazil, 1992. 242pp. Ph.D. dissertation [Doctor in Food Science) - Faculdade de Engenharia de Alimentos, Universidade Estadual de Campinas (UNICAMP).

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[15] MARTINS, M. C. Obtenção e Avaliação de Curcumina a partir de Rizomas Secos de Cúrcuma (Curcuma longa L]) (Extraction of Turmeric [Curcuma longa L] Oleoresin). Campinas, São Paulo, Brazil, pp.176, 1993. Master’s thesis [Master in Food Technology] - Faculdade de Engenharia de Alimentos, Universidade Estadual de Campinas (UNICAMP).

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[17] PURSEGLOVE, J. W.; BROWN, E.G.; GREEN, G. L.; ROBBS, S. R. J. Spices. London: Logman, 420p, 1981.

[18] RIZVI, S.S.H.; DANIEL, J. A.; BENADO, A. L.; ZOLLWEG, J. A. Supercritical Fluid Extraction: Operating Principles and Food Applications. Food Technology, vol.17, no. 1, pp. 57-64, 1986.

[19] RODRIGUES, V. M.; MARQUES, M. O.; MEIRELES, M. A. A. Evaluation of the chemical composition of clove [Eugenia caryophyllus] essential oil obtained by SCFE. The 4th International Symposium on Supercritical Fluids, vol. A, pp. 215-218, 1997.

[20] SAKAMURA, F.; HAYASHI, S. Studies on Constituents of Essential Oil from Zingiber Officinale . Nihon Nogei Kogakkai-shi. vol.52, no. 5, p. 207-211, 1978.

[21] SMITH, R. H.; ROBINSON, J. M. The Essential Oil of Ginger from Figi. Phytochemistry, vol. 20, no. 2, p. 203-206, 1981.

[22] SPIRO, M.; KANDIAH, M. Extraction of ginger rhizome: Kinetic studies with acetone. International Journal of Food Science and Technology, vol. 24, no. 6, pp. 589-600, 1989.

[23] SPIRO, M.; KANDIAH, M.; PRICE, W. Extraction of Ginger Rhizome: Kinetic Studies with Dichloromethane, Ethanol, 2-propanol and an Acetone-water Mixture. International Journal of Food Science and Technology, vol. 25, no. 2, pp. 157-167, 1990.

[24] SPIRO, M.; KANDIAH, M. Extraction of Ginger Rhizome: Partition Constants and other Equilibrium Properties in Organic Solvents and in Supercritical Carbon Dioxide. International Journal of Food Science and Technology, vol., 25, no. 5, pp. 566-575, 1990.

 

6 — ACKNOWLEDGEMENTS

This work was supported by FAPESP, CNPq, and CAPES. L. P. Nóbrega received a scholarship from CNPq/PIBIC-UNICAMP. A. R. Monteiro has a Ph.D. scholarship from CAPES. The authors are grateful to Dr. Florência C. Menegalli who provided the drying equipment.

 

1 Received for publication on 5/08/97. Accepted for publication on 9/12/97

2 LASEFI-DEA, FEA-UNICAMP, Cidade Universitária "Zeferino Vaz", Cx. Postal 6121, 13083-970 Campinas, SP, Brazil; meireles@ceres.fea.unicamp.br 

* To whom correspondence should be addressed

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