Comparison of different extraction methods for the extraction of major bioactive flavonoid compounds from spearmint (Mentha spicata L

food and bioproducts processing 8 9 ( 2 0 1 1 ) 67–72 Contents lists available at ScienceDirect Food and Bioproducts Processing journal homepage: ww...
Author: Helen Townsend
11 downloads 0 Views 251KB Size
food and bioproducts processing 8 9 ( 2 0 1 1 ) 67–72

Contents lists available at ScienceDirect

Food and Bioproducts Processing journal homepage: www.elsevier.com/locate/fbp

Comparison of different extraction methods for the extraction of major bioactive flavonoid compounds from spearmint (Mentha spicata L.) leaves Mandana Bimakr a,∗ , Russly Abdul Rahman a,b , Farah Saleena Taip a , Ali Ganjloo b , Liza Md Salleh a,d , Jinap Selamat c , Azizah Hamid c , I.S.M. Zaidul c a

Department of Process and Food Engineering, Faculty of Engineering, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia Department of Food Technology, Faculty of Food Science and Technology, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia c Department of Food Science, Faculty of Food Science and Technology, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia d Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia b

a b s t r a c t Different bioactive flavonoid compounds including catechin, epicatechin, rutin, myricetin, luteolin, apigenin and naringenin were obtained from spearmint (Mentha spicata L.) leaves by using conventional soxhlet extraction (CSE) and supercritical carbon dioxide (SC-CO2 ) extraction at different extraction schemes and parameters. The effect of different parameters such as temperature (40, 50 and 60 ◦ C), pressure (100, 200 and 300 bar) and dynamic extraction time (30, 60 and 90 min) on the supercritical carbon dioxide (SC-CO2 ) extraction of spearmint flavonoids was investigated using full factorial arrangement in a completely randomized design (CRD). The extracts of spearmint leaves obtained by CSE and optimal SC-CO2 extraction conditions were further analyzed by high performance liquid chromatography (HPLC) to identify and quantify major bioactive flavonoid compounds profile. Comparable results were obtained by optimum SC-CO2 extraction condition (60 ◦ C, 200 bar, 60 min) and 70% ethanol soxhlet extraction. As revealed by the results, soxhlet extraction had a higher crude extract yield (257.67 mg/g) comparing to the SCCO2 extraction (60.57 mg/g). Supercritical carbon dioxide extract (optimum condition) was found to have more main flavonoid compounds (seven bioactive flavonoids) with high concentration comparing to the 70% ethanol soxhlet extraction (five bioactive flavonoids). Therefore, SC-CO2 extraction is considered as an alternative process compared to the CSE for obtaining the bioactive flavonoid compounds with high concentration from spearmint leaves. © 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Keywords: Spearmint (Mentha spicata L.); Bioactive flavonoid; Supercritical carbon dioxide (SC-CO2 ) extraction; Conventional soxhlet extraction (CSE); High performance liquid chromatography (HPLC)

1.

Introduction

Spearmint belongs to the genus Mentha in the family Labiateae (Lamiaceae) (Sweetie et al., 2007). A number of studies have found that herbs of the Lamiaceae family are a potential source of natural antioxidants (Choudhury et al., 2006). Rosemary (Rosmarinus officinalis L.), sage (Salvia officinalis L.), thyme (Thymus vulgaris L.) and lavender (Lavendula angustifolia Mill.) are native to the Mediterranean region; balm (Melissa officinalis L.) and spearmint (Mentha spicata L.) are common plants



in Britain and other European countries (Wang et al., 2004; Paranjpe, 2001). Different surveys have shown that herb extracts are useful as stabilizers of edible oils. Most studies on antioxidant compounds in the Lamiaceae family are directed to phenolic diterpenes, flavonoids and phenolic acids (Kivilompolo and Hyotylainen, 2007). Flavonoids which are widely distributed in the leaves, seeds, bark and flowers of plants are a broad class of low molecular weight compounds. Flavonoids are a kind of highly effective antioxidant and less toxic than syn-

Corresponding author. Tel.: +60 142679858; fax: +60 3 89423552. E-mail addresses: [email protected] (M. Bimakr), [email protected] (R.A. Rahman). Received 23 December 2008; Received in revised form 2 March 2010; Accepted 3 March 2010 0960-3085/$ – see front matter © 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.fbp.2010.03.002

68

food and bioproducts processing 8 9 ( 2 0 1 1 ) 67–72

thetic antioxidants such as BHA and BHT. Therefore, these secondary plant phenolics have received the greatest attention and have been studied extensively (Heim et al., 2002; Naczk, 2004; Syed and Sharma, 2001). Effective separation of antioxidants (high extraction yield and concentration of bioactive compounds) from a complex plant matrix is a difficult procedure due to co-extraction of other various compounds, which are undesirable in antioxidant extract. Different extraction techniques such as percolation, soxhlet and supercritical fluid extraction have been used to isolate antioxidants from plants. Conventional soxhlet extraction (CSE) is a standard technique which has been used for a long time. The main disadvantages of conventional soxhlet extraction are long extraction time and consumption of large amounts of used solvents. This extraction method is also not suitable for the extraction of thermo-sensitive compounds due to the possibility of thermal decomposition of target compounds as extraction usually occurs at the boiling point of used solvent for a long time. However, conventional soxhlet extraction comparing to supercritical fluid extraction (SFE) is still widely used due to its simplicity (Grigonis et al., 2005). Supercritical fluid extraction with CO2 is an attractive method for food industry applications due to its unique properties (Lin et al., 1999). The unique characteristic of this system is application of gases above their critical points to extract selective soluble components from a raw material (Cavero et al., 2006). However, CO2 is not a suitable solvent for the extraction of polar compounds because it behaves as non-polar fluid for certain conditions of temperature and pressure. Therefore, this is the main limiting step in its use for the separation of polar phenolic compounds. But, in order to increase the polarity of extraction solvent some food grade modifiers like ethanol can be used (Qingyong Lang, 2001). The objectives of the present work were to investigate the effect of different parameters, such as pressure, temperature and dynamic extraction time on the supercritical fluid extraction of spearmint leaves flavonoids and to compare the extraction yield and concentration of flavonoids in the extracts obtained under conventional soxhlet and supercritical fluid extraction. To the best of our knowledge, no report has been yet appeared on the supercritical fluid extraction (SFE) of Malaysian spearmint leaves flavonoid compounds.

2.

Materials and methods

2.1.

Materials

The leaves of spearmint (M. spicata L.) were obtained from Cameron Highland in Pahang, Malaysia. After harvesting, the leaves were separated and washed under tap water. Leaves were dried at 40 ◦ C in a ventilated drying oven (1350FX, USA) for 24 h and then stored at ambient temperature (22 ◦ C) in the dark. The samples were ground in grinding mill (MX-335, Panasonic, Malaysia) for 10 s to produce a powder with an approximate size of 0.525 mm.

2.2.

Reagents

Carbon dioxide (CO2 , SFE grade), contained in a diptube cylinder, was purchased from MOX Company in Malaysia. Methanol (MeOH, analytical grade), ethanol (EtOH, 99.5%, analytical grade) and petroleum ether (analytical grade) were purchased from Scharlau chemical, European Union. Methanol (MeOH, HPLC grade) was purchased from Fisher scientific chemical, USA. TFA (trifluoroacetic acid, ≥98%) was obtained from Sigma–Aldrich, Germany. All flavonoid standards including (+)-catechin, (−)-epicatechin, apigenin, rutin, luteolin, myricetin and naringenin were purchased from Sigma–Aldrich, Germany.

2.3.

Conventional soxhlet extraction (CSE)

Three grams (3 g) of dried and ground spearmint leaves were placed in a soxhlet apparatus. Extraction was performed with 150 ml of an appropriate solvent for 6 h. After extraction, a rotary vacuum evaporator (Eyela, A-1000S, Japan) at 40 ◦ C was used in order to remove solvent. In this experiment four solvents were used: pure ethanol, methanol, petroleum ether and 70% ethanol. All extractions were performed in duplicate.

2.4.

Supercritical carbon dioxide (SC-CO2 ) extraction

Supercritical CO2 (SC-CO2 ) extraction was performed on a supercritical fluid extractor (ABRP200, Pittsburgh, PA, USA) with the extractor volume 500 ml (Fig. 1). The flow rate of CO2 , the extraction temperature and pressure were adjusted by the

Fig. 1 – Schematic diagram of supercritical fluid extractor.

69

food and bioproducts processing 8 9 ( 2 0 1 1 ) 67–72

ICE software, and the extraction time was measured by the stopwatch. Liquid CO2 was supplied from a gas cylinder. Before liquid CO2 passed into the extraction vessel, filled with the samples, by the means of a pump (P-50, Thar designs, Inc. Pittsburg, PA, USA), it was pressurized to the desired pressure and heated to the specified temperature in order to reach the supercritical state. Absolute ethanol (EtOH) acted as the cosolvent and the flow rate was maintained at 3 g/min. In this study, extractions were performed at three different temperatures (40, 50 and 60 ◦ C), three different pressure levels (100, 200 and 300 bar) and three different dynamic extraction time (30, 60 and 90 min). The supercritical CO2 flow rate was maintained at 15 g/min and the duration of static extraction time was fixed to 30 min. The powdered plant material (30 g) was mixed with 90 g glass beads (2.0 mm in diameter), placed into the extractor vessel. The extractions were performed in duplicate. In this study, the SC-CO2 extraction of spearmint leaves was planned according to the full factorial with complete randomized design (CRD) for the highest crude extract yield.

2.4.1.

Further processes

After extraction, the extract was collected and the co-solvent (ethanol) was removed with vacuum rotary evaporator (Eyela, A-1000 S, Japan) under reduced pressure at 40 ◦ C (water-bath temperature). Then a gravimetric measurement was used to obtain the amount of total crude extract weight. Afterward, to destruct glycosides bounds each sample was acid hydrolysed as follows: 0.05 g sample + 16 ml H2 O + 24 ml pure methanol + 5 ml HCl (6 M) (Perva-Uzunalic et al., 2006). After 2 min manual homogenizing in order to complete the effect of acid hydrolysis the sample was refluxed at 90 ◦ C for 2 h and finally cooled at room temperature. Then, the sample was filtered through filter paper 541, 70 mm. By using filter syringe set, sample was filtered through 0.45-␮m nylon membrane filter. At the end, 20 ␮l of extract obtained using SFE was quantitatively analyzed by HPLC for the flavonoid compounds detection. The extractions were performed in duplicate.

2.5. High performance liquid chromatography (HPLC) analysis The extracts obtained from optimum supercritical CO2 (SCCO2 ) extraction condition and conventional soxhlet extraction (CSE) were analyzed using a HPLC which was composed of a Water 600 pump Controller, 9486 tuneable absorbance UV detector and equipped with an Eclipes XDR-C18 reversedphase column (25 cm × 4.6 mm × 5 ␮m, Supelco, USA). The volume of the injection loop was 20 ␮l. Classic Millenium 2010 software was used for the manipulation of data processing. The mobile phase used for analysis was solvent A: TFA (trifluoroacetic acid) 2.5 pH in deionized water and solvent B consists of methanol 100% (HPLC grade). MeOH 70% was also required for washing the system. The flavonoids were detected at 280 nm. The temperature was set to room temperature and flow rate was set at 1.0 ml/min. All of the main flavonoid compounds were identified by matching their retention time against those of standard compounds. Quantity calculations were made according to the linear calibration curves of standards.

2.6.

Statistical analysis

The optimization of the method can be carried out step by step or by using an experimental design. In the present study the

process of extraction was optimized with complete randomized design (CRD) full factorial for a higher extraction yield from spearmint (M. spicata L.) leaves. Independent variables for SC-CO2 extraction were temperature (40, 50 and 60 ◦ C), pressure (100, 200 and 300 bar) and dynamic extraction time (30, 60 and 90 min). Data were subjected to analyses of variance (ANOVA) and multiple comparison tests were performed using LSD’s test at the 95% of confidence level. All the analyses were carried out using the statistical software, Minitab v.14. A probability value of p < 0.05 was considered significant. The factors and levels investigated are reported in Table 1.

3.

Results and discussion

3.1.

Optimization of the experimental conditions

Optimization of the experimental conditions is a critical step in the development of SC-CO2 extraction method due to the effect of various parameters on the extraction yield. Generally, extraction pressure, temperature and dynamic time are considered as important factors. The extraction yields obtained under studied conditions were 30.12–60.57 mg/g. In general, a full evaluation of the effect of three selected factors from three levels and duplicate experiments on the extraction yield needed 54 (33 × 2) experiments. The mean values of the extraction yields for the corresponding parameters at each level were calculated according to the assignment of the experiment. The mean values of the three levels of each parameter show how the extraction yield changes when the level of that parameter is changed. All the three studied parameters had significant effect on the extraction yield (p < 0.05). In Table 2 the average response of each level about extraction yield was presented. Also, R-value which is mentioned in Table 2 means range between three average responses of each level about extraction yield. From the R-value it can be concluded that temperature (R = 10.58) had a dominant effect on the extraction yield followed by the pressure (R = 10.38) and dynamic time (R = 8.12).

3.1.1.

Effect of temperature

Fig. 2 shows the effect of temperature on the extraction yield of spearmint (M. spicata L.) leaves in SC-CO2 extraction at three temperature levels of 40, 50 and 60 ◦ C. The density of CO2 at constant pressure is reduced with increasing temperature and leading to reduce the solvent power of supercritical CO2 . The effect of temperature on solute solubility is different at pressures in the critical range. Near the system critical pressure, the fluid density is very sensitive to temperature. This might be the reason that flavonoid yield was changed significantly when temperature was changed over the range of 40–60 ◦ C. A moderate increase in temperature can lead to a large decrease in fluid density, with a consequent reduction in solute solubility (Roop et al., 1989). However, the increase in temperature will also accelerate mass transfer and improve the extracTable 1 – Experimental levels of the factors used in complete randomized design (CRD) full factorial. Factors

Pressure (bar) Temperature (◦ C) Dynamic time (min)

Levels 1

2

3

100 40 30

200 50 60

300 60 90

70

food and bioproducts processing 8 9 ( 2 0 1 1 ) 67–72

Table 2 – Results obtained at the experimental condition using complete randomized design (CRD) full factorial. Parameter

Yielda (mg/g) L1c

Yielda (mg/g) L2c

Yielda (mg/g) L3c

Pressure Temperature Time

40.69 ± 4.43 40.48 ± 5.32 40.28 ± 3.45

51.07 ± 3.21 45.36 ± 5.61 48.21 ± 4.43

45.13 ± 4.72 51.06 ± 5.43 48.40 ± 6.3

a b c

Rb 10.38 10.58 8.12

Values are mean ± SD of duplicate runs. R-value means range between three average responses of each level about extraction yield. Average responses of each level about extraction yield.

Fig. 2 – Effect of temperature on the extraction yield of crude extract at the constant pressure. tion yield (Wang et al., 2008). The increase of temperature can increase the vapour pressure of the extractable compounds. Thus, the tendency of the compounds to be extracted is increased to pass in the supercritical fluid phase (Reverchon and De Marco, 2006). For a volatile solute, there is competition between its solubility in supercritical carbon dioxide and its volatility (Pourmortazavi and Hajimirsadeghi, 2007). Therefore, it is difficult to predict the effect of temperature. In the present study, the extraction yield increased with temperature and the highest extraction yield (60.57 mg/g) was obtained at 60 ◦ C. In this manner, the solute vapour pressure played a key role leading to increase in the extraction yield.

3.1.2.

Effect of pressure

Fig. 3 presents the effect of pressure on the extraction yield of spearmint (M. spicata L.) leaves in SC-CO2 using three pressure levels of 100, 200 and 300 bar. According to the obtained

Fig. 4 – Effect of dynamic extraction time on the extraction yield of crude extract at the constant pressure. results, the extraction yield increased with pressure from 100 to 200 bar, which was due to increase of SC-CO2 density at higher pressures. However, an increase in the pressure level above 200 bar led to an unexpected reduction in the extraction yield. This unexpected result can probably be related to the reduced diffusion rates of the extracted compounds from the plant matrix to the supercritical fluid medium (Rezaei and Temelli, 2000). An increase of pressure can result in an increase in the fluid density, which alters solute solubility. Gomes et al. (2007) have indicated that a higher recovery of volatile fractions and a lower recovery of non-volatile fractions are obtained at high pressure. Therefore, it is interesting to control the composition of the extract using pressure. In this study, the flavonoid yield increased with increasing pressure to a certain value. Over this range of pressure, increasing fluid density is presumably the main mechanism leading to a higher flavonoid yield. Above this range of pressure, a decreasing flavonoid yield with increasing pressure was observed. The volatility and polarity of extracted analytes might be responsible for the result (Gomes et al., 2007; Wang et al., 2008).

3.1.3.

Fig. 3 – Effect of pressure on the extraction yield of crude extract at constant temperature.

Effect of dynamic extraction time

Fig. 4 shows the effect of dynamic time on the extraction yield of spearmint (M. spicata L.) leaves in SC-CO2 by applying three different levels of dynamic time including: 30, 60 and 90 min. At 100 bar pressure the extraction yield was increased with dynamic time until 90 min. However, at higher pressures (200 and 300 bar) the extraction yield increased with dynamic extraction time until 60 min. It can be concluded that the solvent power of supercritical CO2 density is reduced at 100 bar pressure due to the lower CO2 density and maximum yield was obtained at 90 min. However, at higher pressures (200 and 300 bar) the extraction rate is higher and as a consequence the

71

food and bioproducts processing 8 9 ( 2 0 1 1 ) 67–72

Table 3 – Identification and quantification of bioactive flavonoid compounds extracted by conventional soxhlet extraction (CSE) and supercritical carbon dioxide (SC-CO2 ) extraction. Extraction mode

Extraction yield (mg/g)a

Flavonoid content (mg/g) Catechin Epicatechin

Conventional soxhlet extraction (CSE) Methanol 267.33 Ethanol (99.5%) 218.0 Ethanol:water (70:30) 257.66 Petroleum ether 30.47 SC-CO2 extraction (60 ◦ C, 200 bar and 60 min)

± ± ± ±

Rutin

Myricetin Luteolin Apigenin Naringenin

3.12e 4.24c 3.47d 2.34a

0.144 0.081 0.117 –

0.163 0.114 0.149 –

0.161 0.109 0.140 –

0.041 0.090 – –

0.093 0.154 0.146 –

0.392 0.246 0.305 –

0.054 – – –

60.566 ± 3.14b

0.140

0.156

0.148

0.117

0.657

0.270

0.249

Values in the yield column followed by letters are significantly different (p-value < 0.05). a

Values are mean ± SD of duplicate runs.

extraction yield kept increasing but after 60 min of extraction time, the extraction yield dropped (Reverchon and De Marco, 2006). Therefore, as shown in Fig. 4, the highest extraction yield was achieved at 60 min dynamic extraction time.

3.2.

Conventional soxhlet extraction (CSE) yields

Different solvents with different polarities were used to determine which one gives the highest recoveries of bioactive flavonoid compounds. Four solvents were used: (1) methanol, (2) pure ethanol, (3) ethanol (70%) and (4) petroleum ether. The extraction yield obtained by using each solvent is presented in Table 3. Based on the obtained results, the highest extraction yield (267.3 mg/g) was found with methanol extraction and then with a little difference followed by ethanol 70% extraction (257.6 mg/g). The lowest extraction yield was obtained by using petroleumether (30.4 mg/g), suggesting that polar compounds in the plant matrix would be easier to extract with a more polar solvent while lower polarity solvents enable to obtain the extracts with higher concentration of bioactive compounds. The extracts which were obtained from methanol, pure ethanol, ethanol 70% and petroleum ether were then analyzed by HPLC to identify and quantify the major bioactive flavonoid compounds profile. With different solvent, different flavonoid compounds were extracted. The flavonoid compounds concentration in the extract obtained with petroleum ether was undetectable. Using pure ethanol five flavonoid compounds including catechin, epicatechin, rutin, luteolin and apigenin were extracted from spearmint (M. spicata L.) leaves. Apigenin had the highest concentration (0.246 mg/g) among the other flavonoids, which are obtained with pure ethanol conventional soxhlet extraction. The highest extraction yield (267.33 mg/g) was obtained with methanol solvent, which extracted seven flavonoid compounds including catechin, epicatechin, rutin, myricetin, luteolin, apigenin and naringenin. However, the concentrations of myricetin and naringenin were low (0.041 and 0.054 mg/g, respectively) and apigenin had the highest concentration (0.392 mg/g). The obtained extraction yield from ethanol 70% conventional soxhlet extraction was near to the obtained extraction yield from methanol soxhlet extraction but extracted flavonoids were same as compounds which are extracted with pure ethanol soxhlet extraction. Five flavonoid compounds catechin, epicatechin, rutin, luteolin and apigenin were extracted from spearmint leaves with pure ethanol and ethanol 70%. But higher concentrations of more bioactive flavonoid compounds were detected with ethanol 70% due to

its higher polarity than pure ethanol. For example, in ethanol soxhlet extraction apigenin with 0.246 mg/g had the highest concentration in contrast to ethanol 70% the concentration of dominant detected flavonoid, apigenin, was reached to 0.305 mg/g. By adding water to the pure ethanol up to 30% for preparing ethanol 70% the polarity of solvent was increased. Therefore, polar compounds, flavonoids, could be isolated better from herb matrix.

3.3. Comparison of SC-CO2 extraction and CSE methods Different methods of natural matter extraction have different extraction yield and efficiencies. Higher concentration of natural bioactive compounds in the extracts is an important factor in the production of natural products while a primary task in the industries is lower economic cost which can be achieved by better extraction yield (Grigonis et al., 2005). Based on the results obtained with methanol conventional soxhlet extraction the extraction yield and recovery of flavonoid compounds were better but due to its toxicity and less consumption in food industry comparison was performed between the obtained results of optimum SC-CO2 extraction condition and ethanol 70% conventional soxhlet extraction (Table 3). The composition of the extracts obtained from SC-CO2 and conventional soxhlet extraction was strongly different. According to the extraction yield results, ethanol 70% conventional soxhlet extraction (257.6 mg/g) had a higher yield comparing to the SC-CO2 extraction (60.57 mg/g). But, supercritical carbon dioxide extract (optimum condition) was found to have better quality and more main flavonoid compounds (seven flavonoids) comparing to the ethanol 70% conventional soxhlet extraction (five flavonoids). Flavonoid compounds of plants have usually been extracted by the other conventional extraction methods such as solvent extraction, steam distillation. Some of the main disadvantages of all these methods include: long extraction time, losses of volatile compounds and degradation of unsaturated compounds, resulting unfavourable off-flavour compounds due to heat (Grigonis et al., 2005). Supercritical CO2 (SC-CO2 ) extraction has different advantages over conventional soxhlet extraction (CSE) method such as low operating temperature, thus no thermal degradation of most of the labile compounds, shorter extraction duration and high selectivity in the extraction of target compounds. SC-CO2 extraction also, seems to be a cost-effective process at laboratory scale, but a precise economic evaluation will need additional experiments for establishing large-scale

72

food and bioproducts processing 8 9 ( 2 0 1 1 ) 67–72

units (Qingyong Lang, 2001). Therefore, it can be recommended as a suitable extraction method to isolate bioactive flavonoid compounds from spearmint (M. spicata L.) leaves. However, for the complete extraction of the other flavonoid compounds may be higher pressure and extraction times are needed. Further studies are in progress to quantitatively assess the extract antioxidant power and the enrichment of antioxidants at different extraction conditions.

4.

Conclusion

Generally, it may be possible to concentrate the flavonoid compounds in spearmint (M. spicata L.) extracts by manipulating extraction condition of SC-CO2 extraction. In this study the effect of the three tested parameters including temperature, pressure and dynamic extraction time were investigated and it is revealed they have significant effect on the extraction yield. The highest extraction yield achieved at 60 ◦ C, 200 bar and 60 min. The product of best condition (60 ◦ C, 200 bar and 60 min) was analyzed by HPLC to identify and quantify major bioactive flavonoid compounds. Seven flavonoid compounds including catechin, epicatechin, rutin, myrecitin, luteolin, apigenin and naringenin with different concentration were identified and quantified in mentioned extract. Based on the obtained conventional soxhlet extraction results, polar solvents show better recoveries of flavonoids and solvents with lower polarity enable to extract high concentration of flavonoids. Pure ethanol and ethanol 70% were safe solvents with lower toxicity than methanol. Also, good yield and high concentration of bioactive flavonoid compounds could be isolated with these safe solvents from plant matrix. Despite good results obtained with the conventional soxhlet extraction, supercritical CO2 extraction was tested to search for a faster and better extraction method consuming less solvent, especially those that are undesirable in food industry. Soxhlet extraction comparing to supercritical fluid extraction (SFE) possessing some disadvantages but it is still widely used due to its simplicity. Conventional soxhlet extraction (CSE) is not always acceptable for industrial applications due to long extraction time, large consumption of hazardous solvents and some other disadvantages. Therefore, supercritical CO2 (SCCO2 ) extraction could be an alternative extraction method.

Acknowledgment The authors are grateful for the financial support received from the RMC, the Universiti Putra Malaysia for this project.

References Cavero, S., Garcıa-Risco, M., Marin, F., Jaime, L., Santoyo, S., Senorans, F., Reglero, G. and Ibanez, E., 2006, Supercritical

fluid extraction of antioxidant compounds from oregano Chemical and functional characterization via LC–MS and in vitro assays. J Supercrit Fluids, 38: 62–69. Choudhury, P., Kumar, R. and Garg, A.N., 2006, Analysis of Indian mint (Mentha spicata) for essential, trace and toxic elements and its antioxidant behaviour. J Pharm Biomed Anal, 41: 825–832. Gomes, P.B., Mata, V.G. and Rodrigues, A.E., 2007, Production of rose geranium oil using supercritical fluid extraction. J Supercrit Fluids, 41: 50–60. Grigonis, D., Sivik, P.R.V., Sandahl, M. and Eskilsson, C.S., 2005, Comparison of different extraction techniques for isolation of antioxidants from sweet grass (Hierochloe odorata). J Supercrit Fluids, 33: 223–233. Heim, K., Tagliaferro, A. and Bobilya, D.J., 2002, Flavonoid antioxidants: chemistry, metabolism and structure–activity relationships. J Nutr Biochem, 13: 572–584. Kivilompolo, M. and Hyotylainen, T., 2007, Comprehensive two-dimensional liquid chromatography in analysis of Lamiaceae herbs: characterisation and quantification of antioxidant phenolic acids. J Chromatogr A, 1145: 155–164. Lin, M.C., Tsai, M.J. and Wen, K.C., 1999, Supercritical fluid extraction of flavonoids from Scutellariae Radix. J Chromatogr A, 830: 387–395. Naczk, M., 2004, Extraction and analysis of phenolics in food. J Chromatogr A, 1054: 95–111. Paranjpe, P., (2001). Indian Medicinal Plants-Forgotten Healers. (Chaukhambha Sanskrit Pratishtan, New Delhi), p. 316 Perva-Uzunalic, A., Skerget, M., Knez, Z., Weinreich, B., Otto, F. and Gruner, S., 2006, Extraction of active ingredients from green tea (Camellia sinensis): extraction efficiency of major catechins and caffeine. Food Chem, 96: 597–605. Pourmortazavi, S.M. and Hajimirsadeghi, S.S., 2007, Supercritical fluid extraction in plant essential and volatile oil analysis. J Chromatogr A, 1162: 2–24. Qingyong Lang, C.M.W., 2001, Supercritical fluid extraction in herbal and natural product studies—a practical review. Talanta, 53: 771–782. Reverchon, E. and De Marco, I., 2006, Review Supercritical fluid extraction and fractionation of natural matter. J Supercrit Fluids, 38: 146–166. Rezaei, K. and Temelli, F., 2000, Using supercritical fluid chromatography to determine the binary diffusion coefficient of lipids in supercritical CO2 . J Supercrit Fluids, 17: 35–44. Roop, R.K., Akgerman, A., Dexter, B.J. and Irvin, T.R., 1989, Extraction of phenol from water with supercritical carbon dioxide. J Supercrit Fluids, 2: 51–56. Sweetie, R.K., Chander, R. and Sharma, A., 2007, Antioxidant potential of mint (Mentha spicata L.) in radiation-processed lamb meat. Food Chem, 100: 451–458. Syed, A.A. and Sharma, S.C., (2001). Herbal Cure for Common and Chronic Diseases. (Pustak Mahal, New Delhi), p. 152 Wang, H., Provan, G. and Helliwell, K., 2004, Determination of rosmarinic acid and caffeic acid in aromatic herbs by HPLC. Food Chem, 87: 307–311. Wang, L., Yang, B., Du, X. and Yi, C., 2008, Optimisation of supercritical extraction of flavonoids from Pueraria lobata. Food Chem, 108: 737–741.

Suggest Documents