ArticlePDF Available

Mathematical Modeling of Supercritical Carbon Dioxide Extraction Kinetics of Bioactive Compounds from Mango Ginger (Curcuma amada Roxb)

Authors:

Abstract and Figures

The main goal of this work was to study the extraction kinetics aspects of the Supercritical carbon dioxide(SC-CO 2) extraction by modeling the extraction curves. Extraction of mango ginger was performed at the different level of the pressure (100-350 bar) and temperature (40-60 º C) to evaluate the effect of process parameters on the extraction kinetics. The mass transfer models used to describe the extraction curves were simple exponential model and Ficks's diffusion model. Based on the experimental data, extraction rate constant and diffusion coefficients were estimated. Results showed good agreement between calculated and experimental data with higher values of coefficient of determination (R 2). The extraction rate and diffusivity increased with increase in pressure and decreased with increase in temperature. But at higher pressure and temperature the yield increased significantly due to vapor pressure effect.
Content may be subject to copyright.
Sciknow Publications Ltd. OJOC 2014, 2(3):36-40
Open Journal of Organic Chemistry DOI: 10.12966/ojoc.07.01.2014
©Attribution 3.0 Unported (CC BY 3.0)
Mathematical Modeling of Supercritical Carbon Dioxide
Extraction Kinetics of Bioactive Compounds from Mango Ginger
(Curcuma amadaRoxb)
Thirupathihalli Pandurangappa Krishna Murthy1,* and Balaraman Manohar2
1Department of Biotechnology, Sapthagiri College of Engineering, Bangalore-560057, India
2Department of Food Engineering, CSIR-Central Food Technological Research Institute, Mysore- 570020. India
*Corresponding author (Email: crishna@live.in)
Abstract - The main goal of this work was to study the extraction kinetics aspects of the Supercritical carbon dioxide(SC-CO2)
extraction by modeling the extraction curves. Extraction of mango ginger was performed at the different level of the pressure
(100-350 bar) and temperature (40-60 ºC) to evaluate the effect of process parameters on the extraction kinetics. The mass
transfer models used to describe the extraction curves were simple exponential model and Ficks’s diffusion model. Based on the
experimental data, extraction rate constant and diffusion coefficients were estimated. Results showed good agreement between
calculated and experimental data with higher values of coefficient of determination (R2). The extraction rate and diffusivity
increased with increase in pressure and decreased with increase in temperature. But at higher pressure and temperature the yield
increased significantly due to vapor pressure effect.
Keywords - Supercritical Carbon Dioxide, Mango Ginger, Bioactive Components, Fick’s Diffusion Model, Exponential Model
1. Introduction
Curcuma amadaRoxb commonly known as mango ginger
belongs to the family Zingiberaceae. The plant is widely
cultivated in India apart from Malaysia, China, Bangladesh,
Myanmar, Thailand, Japan and Australia[1]. It is a unique
spice morphologically similar to ginger but, imparts mango
flavor and because of its exotic aroma they are extensively
used in the preparation of culinary items especially pickles,
sauces etc in Indian subcontinent. The essential oil and
nonvolatile components of rhizome exhibited antimicrobial,
antifungal and antihelmintic activity against tape worms.
Mango ginger is also an unconventional source of starch [2].
A pure component is considered to be in a supercritical
state if its temperature and pressure are higher than the critical
values [3]. In a supercritical state, liquid like densities are
approached, while viscosity is near that of normal gases and
diffusivity is about two orders of magnitude higher than in
typical liquid. Compared with the conventional solvent
extraction supercritical fluid extraction offers advantages due
to its relatively low environmental impact. [4]. The extraction
can be selective by controlling the density of the medium and
the extracted material is effortlessly recovered by simply
depressurizing, allowing the Supercritical fluid to return to the
gas phase and evaporatesleaving little or even no solvent
residue [5]. Carbon dioxide, nitrous oxide, ethane, propane,
n-pentane and water are widely used as supercritical fluids.
Carbon dioxide is commonly used in food and bioprocess
industries as it is inexpensive, nontoxic, nonflammable, easily
removed from extracts and has high interpenetration in solid
matrices [6-7].
The effectiveness of supercritical fluid extraction process
may affected by many variables such as pressure, temperature,
time, particle size, solvent flow rate, density etc.
[8].Mathematical modeling may be helpful for better
understanding the experimental results obtained and then
developing design scaling up procedures. These models are
based on mass transfer mechanisms and equilibrium
relationships. Some of the process parameters like solvent
flow rate, equipment dimensions, particle size etc. need to be
determined for process design by simulation of extraction
curves [9-10].
The objective of this investigation was to study the effect
of process parameters such as pressure, temperature on the
extraction rate and mass transfer during the supercritical
carbon di oxide extraction of bioactive compounds from
mango ginger.
2. Materials and Methods
2.1. Preparation of Plant Material
Fresh and matured mango ginger rhizomes were procured
from local market, Mysore, Karnataka, India. Toluene
Open Journal of Organic Chemistry (2014) 36-40 37
distillation method was used to estimate moisture content of
fresh rhizome and found to be 90±0.5 % (wet basis). The
rhizomes were washed and sliced using a slicing machine
(M/s Robot coupe, USA, Model: CL 50 Gourmet). The slices
were dried at 45±2 oC in Low temperature Low humidity
(LTLH) dryer. The dried material was powdered in hammer
mill (M/s Apex, USA) and the mean particle diameter was
480±40 µm as measured by Particle size analyzer (Model:
CIS-100, M/s Galai production, Israel). Food grade CO2
(99.99 % pure) was used as solvent for extraction supplied by
Ms.Kiran Corporation, Mysore, Karnataka, India.
2.2. Supercritical Carbon dioxide Extraction
For all the extraction experiments, high-pressure SCF
extractor(NOVA Swiss WERKE AG, EX 1000-1.4-1.2 type,
Switzerland) designed to working pressures of up to 1000 bar
and temperature up to 100°C was used. The mango ginger
powder was loaded into the extraction vessel which is of 1.1
lit in capacity. Set of experiments were conducted at different
pressures (100-350 bar) and temperatures (40-60 oC). After
attaining the desired temperature, the CO2 which had been
compressed to the set pressure was allowed into the extractor.
A fraction has been collected from the separator at definite
time intervals and the weight of the extract would be noted.
The average flow rate was maintained around 1.8-2.0 kg/hr.
2.3. Mathematical Modeling
2.3.1. Exponential function
The mathematical relationship between the yield and
extraction time gives better insight into the kinetics of the
process. Exponential function is the simple mathematical
function to describe the extraction kinetics. The amount of the
extracted yield at time from exponential model is given below
Eq.1
where Y is the extraction yield in weight percent, Yh is the
highest yield, and kEis extraction rate constant [11].
2.3.2. Diffusion Model
During the migration of solute from the solid matrix to the
bulk of the fluid there are several mass transfer steps involved
[12]. The Fick’s second law is widely used to describe the
mass transferis given below:
Eq. 2
Where C is the concentration of the solute, t is the
extraction time, De is the effective diffusivity, r is the radius of
diffusion. The extraction process parameters strongly affect
the effective diffusivity under which the extraction process is
carried out. The extraction from food materials is generally
controlled by internal diffusion [13]. Solutions of Fick’s
second law are therefore used to determine De assuming that
De is constant with the concentration. YD is defined as the
ratio between extract concentration at time, t and the initial
extract concentration of the matrix. The following boundary
conditions will be employed for solving above equation:
YD = 0, r ± R, t ≥ 0; YD = 1, 0 < r < R, t = 0.
The solution to eq. (1) is given by:
Eq. 3
For extraction from plant matrix where external resistance
is negligible, it is generally assumed that the first term of the
series solution can usually be used with little error [14].
Therefore, when the logarithm of YD is plotted against time, a
straight line must be obtained and the diffusivity can be
calculated from its slope.
Eq. 4
3. Results and Discussion
3.1. Effect of Pressure and temperature on extraction rate
Experimental yield values of supercritical carbon dioxide
extract of mango ginger were regressed against the time
according to the exponential equation (Eq.1) by nonlinear
least square method using the SOLVER tool based on the
Generalized Reduced Gradient (GRG) method of iteration
available in Microsoft Excel (Microsoft Office 2010, USA).
Coefficient of determination (R2) was used as a criterion to
check the fitness of experimental value with the model
predicted values. The kinetic rate constant kE values along
with the R2 values are presented in Table .1 and graphically
shown in Fig .1 (a), (b) and (c) shows the plot of extraction
yield vs extraction time at different extraction conditions. At
constant temperature, as pressure increases density of CO2
increases and at constant pressure as temperature increases
density of CO2 decrease. In the present investigation kE values
increased with increase in pressure at constant temperature
and decrease with increase in temperature at constant pressure.
Solubility of the mango ginger extract mainly effected by the
density of CO2. But higher pressure and higher temperature
there is sudden increase in yield due to the higher solute vapor
pressure at higher temperatureeven though density of CO2 is
less. Extraction rate also increase with increase in pressure in
the SCF extraction and decreases with increase in temperature
[15-16].
38 Open Journal of Organic Chemistry (2014) 36-40
0
0.4
0.8
1.2
1.6
0 3 6 9 12 15 18
Yield, %
Tme, hr
0
1
2
3
0 3 6 9 12 15 18
Yield, %
Time, hr
0
1
2
3
4
0 3 6 9 12 15 18
Yield, %
Time, hr
Fig. 1. Yield vs time at different temperature (-40oC
-50oC-60oC---- Model predicted) and Pressure(a) 100 bar
(b) 225 bar (c) 350 bar
0.055
0.105
0.155
0.205
0.055 0.105 0.155 0.205
Predicted k, s-1
Experimental k, s-1
Fig. 2. Regression Model predicted extraction rate constant vs
exponential model extraction rate constant values.
Table 1. Extraction rate constant (kE) at different temperature
and pressure
Exponential Model
P
T
kE
R2
kE
Relative
error
100
40
0.1705
0.993
0.1699
0.31
100
50
0.1226
0.980
0.1325
8.11
100
60
0.0943
0.918
0.0848
9.99
225
40
0.1218
0.987
0.1116
8.35
225
50
0.1163
0.965
0.1188
2.20
225
60
0.1082
0.983
0.1158
7.02
350
40
0.0900
0.928
0.1007
11.8
350
50
0.1651
0.992
0.1526
7.58
350
60
0.1923
0.970
0.1942
0.94
*P-Pressure, T-Temperature, kE-extraction rate constant,
R2-Coefficient of Determination.
Table 2. Statistical analysis of the selected quadratic model
for extraction rate constant (kE)
Regression Statistics
Multiple R
0.969
R Square
0.939
Adjusted R
Square
0.838
Standard Error
0.0145
Observations
9
ANOVA
df
SS
MS
F
Significance F
Regression
5
0.0098
0.0020
9.297
0.048
Residual
3
0.0006
0.00022
Total
8
0.0104
Coefficients
Standard
Error
t Stat
P-value
A0
0.4401
0.2612
1.685
0.1905
A1
-0.0023
0.00041
-5.73
0.0105
A2
-0.0026
0.01035
-0.25
0.8130
A3
1.52E-6
6.6E-07
2.313
0.1036
A4
-5.16E-5
0.000102
-0.50
0.6498
A5
3.60E-5
5.8E-06
6.155
0.0086
To study the dependency of kE on Temperature (T) and
pressure (P), the values of kE values obtained from
exponential equation was regressed according to response
equation (Eq.5)
Eq. 5
The kE values fitted best to the model equation with R2
value of 0.969. The ANOVA for the selected model have
significance value. From the p-value, pressure is having
significant effect on the extraction rate and interaction
between the temperature and pressure is also significantly
effected the extraction process. The developed regression
model for dependent variable (kE) and independent variable
(Pressure and Temperature) is given in Eq. 6
Eq. 6
(a)
(b)
(c)
(d)
Open Journal of Organic Chemistry (2014) 36-40 39
The regression statistics and ANOVA is presented in
Table 2. The regression model predicted values along with the
relative error are shown in Table 1. In Fig 2, exponential
model predicted values were plotted against the regression
equation predicted values shows the good correlation between
values. The interaction effect of pressure and temperature on
the extraction rate constant was given in Fig.3.
3.2. Effect of Pressure and temperature on mass transfer
The diffusivity was calculate from the slope of ln(YD) vs t
(Eq.4). The average particle size of the mango ginger was 480
µm. The experimental data shows the linearity with high
coefficient of determination.
Fig. 3. Effect of Temperature and pressure on extraction rate
(s-1)
Table 3. Diffusivity values (De, m2/s) at different temperature
and pressure
Pressure
(bar)
Temperature
(oC)
Diffusivity, x10-12
(m2/sec)
100
40
0.799
100
50
0.717
100
60
0.546
225
40
2.550
225
50
1.650
225
60
0.669
350
40
1.690
350
50
3.560
350
60
18.50
The diffusivity values for the experimental conditions are
tabulated in Table 3. At the lower pressures the diffusivity is
low due to the less density of carbon dioxide. As the
temperature increases the diffusivity also decreased. But at
350 bar pressure trend has changed. Diffusivity is higher
athigher pressure. Also it has increased with increase in
temperature. Although the solubility of the carbon dioxide is
less at higher temperature, the vapor pressure played a
significant role here. The estimated diffusivity values were in
the range of 0.5 -19 x 10-12m2/sec.
4. Conclusion
The extraction kinetics of mango ginger extract in
supercritical carbon dioxide was explored experimentally at
different extraction conditions, and the results were checked
by using two models. The experimental data correlated well
with the model predicted values of the selected models. The
extraction rate constant obtained from the exponential model
shows there is significant effect of pressure and interaction
between temperature and pressure. Effective diffusivity
calculated using Fick’s law of diffusion increased with
increase in pressure. At higher temperature and pressure both
extraction rate and diffusivity values are very high. This
shows the vapor pressure effect dominates solvent density.
The values of mass transfer coefficients determined could
provide good information especially on design or sizing of
actual extractor and provides the information during industrial
operation to evaluate the extraction time required for given
yield at different pressure and temperature.
References
[1] Sasikumar, B. (2005). Genetic resources of Curcuma: diversity,
characterization and utilization. Plant Gen. Res., 3, 230251.
[2] Policegoudra, R .S., Aradhya, S. M., Singh, L. (2011). Mango ginger
(Curcuma amadaRoxb.) A promising spice for phytochemicals and
biological activities. J. Biosci., 36, 739748.
[3] Brunner, G. (2005). Supercritical fluids: technology and application to
food processing. J. Food Eng., 67(1), 21-33.
[4] Williams, J. R., Clifford, A. A., Al-Saidi, S. H. (2002). Supercritical
fluids and their applications in biotechnology and related areas. Mol.
Biotech, 22(3), 263-286.
[5] Jia, D., Li, S., Xiao, L. (2009). Supercritical CO2 extraction of
Plumulanelumbinis oil: Experiments and modeling. J. Supercritic.
Fluid., 50 (3), 229-234.
[6] Ixtaina, V. Y., Vega, A., Nolasco, S. M., Tomás, M. C., Gimeno, M.,
rzana, E., Tecante, A. (2010). Supercritical carbon dioxide
extraction of oil from Mexican chia seed (Salvia hispanica L.):
Characterization and process optimization. J. Supercritic. Fluid.,
55(1), 192-199.
[7] Zougagh, M., Valcárcel, M., Rıos, A. (2004). Supercritical fluid
extraction: a critical review of its analytical usefulness. Trend. Anal.
Chem., 23(5), 399-405.
[8] Bimakr, M., Rahman, R. A., Ganjloo, A., Taip, F. S., Salleh, L. M.,
Sarker, M. Z. I. (2012). Optimization of supercritical carbon dioxide
extraction of bioactive flavonoid compounds from spearmint
(Menthaspicata L.) leaves by using response surface methodology.
Food Bioprocess Tech., 5(3), 912-920.
[9] Machmudah, S., Sulaswatty, A., Sasaki, M., Goto, M., & Hirose, T.
(2006). Supercritical CO2 extraction of nutmeg oil: Experiments and
modeling. J Ssupercritic. Fluid, 39(1), 30-39.
[10] Döker, O., Salgin, U., Yildiz, N., Aydoğmuş, M., &Çalimli, A. (2010).
Extraction of sesame seed oil using supercritical CO2 and
mathematical modeling. J. Food Eng., 97(3), 360-366.
[11] Manohar, B., Udayshankar(2012). Extraction Modelling and
Characterization of Bioactive Components from Psoraleacorylifolia L.
Obtained by Supercritical Carbon Dioxide. J. Food Process. Tech., 3,
144-149.
[12] Treybal RE (1986) Mass Transfer Operations, (3rd Edn.), McGraw Hill,
New York, USA.
40 Open Journal of Organic Chemistry (2014) 36-40
[13] Dibert, K., Cros, E., Andrieu, J. (1989). Solvent extraction of oil and
chlorogenic acid from green coffee. Part II: Kinetic data. J. Food. Eng.,
10(3), 199-214.
[14] Schwartzberg, H. G., Chao, R. Y. (1982). Solute diffusivities in
leaching processes. Food Tech., 36(2), 73-86.
[15] Krishna Murthy, T. P., Manohar, B. (2014). Optimization of
Supercritical Carbon Dioxide Extraction of Phenolic Compounds from
Mango Ginger Rhizome (Curcuma AmadaRoxb.) Using Response
Surface Methodology. Biomed. Biotech., 2 (1) ,14-19.
[16] Zarena, A. S., Manohar, B., Sankar, K. U. (2012). Optimization of
supercritical carbon dioxide extraction of xanthones from mangosteen
pericarp by response surface methodology. Food Bioprocess
Tech., 5(4), 1181-1188.
... To evaluate the mass transfer process, two simple models, i.e., the exponential and Langmuir model have been repeatedly used by researchers (Manohar and Kadimi, 2012;Murthy and Manohar, 2014). The Langmuir model is one of the well-known models used to explain the extraction kinetics. ...
... These extracts when subjected to HPLC showed a major peak of caffeine; more than 85% (w/w) of the caffeine was extracted with very little amount of chlorophyll (not quantified). The effective diffusivity of mango ginger (Curcuma amada Roxb.) extract varied from 0.669×10 -12 to 18.50×10 -12 m 2 /s with extraction pressure (10 to 35 MPa) and temperature (313 to 333 K) in supercritical CO 2 (Murthy and Manohar, 2014). The effective diffusivity (De) in the present study was found to be about 9 times greater than De for certain seeds like coffee beans and guaraná seeds reported in the literature (Table3). ...
Article
Full-text available
Abstract Supercritical carbon dioxide extraction was employed to extract solids from fresh tea leaves (Camellia sinensis L.) at various pressures(15 to 35 MPa) and temperatures (313 to 333K) with addition of ethanol as a polarity modifier. The diffusion model and Langmuir model fit well to experimental data and the correlation coefficients were greater than 0.94. Caffeine solubility was determined in supercritical CO2 and the Gordillo model was employed to correlate the experimental solubility values. The Gordillo model fit well to the experimental values with a correlation coefficient 0.91 and 8.91% average absolute relative deviation. Total phenol content of spent materials varied from 57 to 85.2 mg of gallic acid equivalent per g spent material, total flavonoid content varied from 50.4 to 58.2 mg of rutin equivalent per g spent material and the IC50 value (antioxidant content) varied from 27.20 to 38.11 µg of extract per mL. There was significant reduction in polyphenol, flavonoid and antioxidant content in the extract when supercritical CO2 extraction was carried out at a higher pressure of 35 MPa.
... The Langmuir model [25,26] is the common one sorption explanation for wellknown reacting column packed explaining sequential diffused and concentrated adsorbed matter and kinetics. Although the linear concentration sequentially followed, sequential adsorption packed bed column was usually experimented by various researchers for the sorption diffusion process of fuel carbon materials, and it can also be used for the sorption over leafy composites. ...
Chapter
Full-text available
Considerable research on emission control of coal combustion with popped borax and salted pumice has been conducted in this study. However, the packed bed column adsorption results are widely dispersed because of the complex chemistry of coal. Time-related hazardous emission, stack gas coal-mixing with slurries washing in microwave-heated packed bed column sorption units and cycling sorption modeling assumed basically first-order kinetic equations, or less sensitive for microwave heating rate. The other reactivity distributed on activation model was dependent on the microwave heating rate. The more advanced models for microwave radiation progressed sorption need three and four constants, respectively, which basically depend on the coal properties but also cover, to some extent, the effect of porosity and gas to salt mass transfer phenomena. That was the reactivity reason for the different conditions of sorbents values on the activation energy and pre-exponential factor. The same situation exists in the other sorbent case of coal-lead and CS, COS gas. The sorption reaction rate of popped borax and bed effected of the salt reaction of pumice and the specific surface area of pumice, which changed the sorption reaction cycle with the development of internal pores type.
Article
Full-text available
Mangosteen fruit pericarp is one of the important sources of bioactive compound xanthone. Supercritical carbon dioxide (SC-CO2) extraction was employed to extract xanthones from mangosteen fruit pericarp at three different levels of pressure (200–300 bar), temperature (40– 60 °C) and solvent to material ratio (100–300 kg/kg). The optimal conditions for the total xanthone yield and the influence of parameters were determined by response surface methodology (RSM) using Box–Behnken design. In our study, the increase in total xanthone yield in SC-CO2 fluid extraction depends more on the solute’s vapor effect. From response surface plots, pressure, temperature and solvent to material ratio exhibited independent and interactive effects on the extraction of xanthones. A regression equation for predicting the total xanthone yield was derived by statistical analysis, and a model with predictive ability of 0.99 was obtained. Maximum xanthone yield of 8.01% was predicted by RSM at 60 °C, 300 bar and a solvent to material ratio of 300 kg/kg while experimentally a yield of 7.56% was achieved. HPLC analysis was carried out for the optimum conditions for the identification and quantification of the xanthones. The antioxidant activities of the extracts were investigated by ferric reducing antioxidant power (FRAP) and the results showed that the extracts were enriched with antioxidant compound
Article
Full-text available
Relying on modern methods of separation, strict quality control, advanced technology and optimal manufacturing process, supercritical carbon dioxide (SC-CO2) is considered to offer an opportunity to efficiently and economically improve recovery and reproducibility of natural product in its pure form. Three-level Box–Behnken factorial design (BBD) from response surface methodology (RSM) was applied to optimize the main extraction conditions including pressure, temperature and extraction time. The three different levels of Pressure, temperature and time are between 100-250 bar, 40-60°C and 5-15 hrs respectively. The optimum conditions were found to be 350 bar, 60°C and 15 hrs. Under the optimum conditions, total phenolic content obtained was 152 mg GAE/total extract, which well agreed with the predicted yield. HPLC analysis was carried out for the optimum conditions for the identification and quantification of the phenolic compounds.
Article
Full-text available
The bioactive flavonoid compounds of spearmint (Mentha spicata L.) leaves were obtained by using supercritical carbon dioxide (SC-CO2) extraction. Extraction was carried out according to face-centred central composite design, and independent variables were pressure (100, 200 and 300 bar), temperature (40, 50 and 60 °C) and co-solvent amount (3, 6 and 9 g/min). The extraction process was optimized by using response surface methodology for the highest crude extraction yield of bioactive flavonoid compounds. The optimal conditions were identified as 209.39 bar pressure, 50.00 °C temperature and 7.39 g/min co-solvent amount. The obtained extract under optimum SC-CO2 condition was analysed by high-performance liquid chromatography. Seven bioactive flavonoids including catechin, epicatechin, rutin, luteolin, myricetin, apigenin and naringenin were identified as major compounds. The results of quantification showed that spearmint leaves are potential source of antioxidant compounds.
Article
The rapid development of nutraceuticals and functional foods which are more often prepared from the phytochemicals / plant extracts has created a new trend in food processing industries. Among the various plant materials available for extraction of bioactives, the present work focuses on Psoralea corylifolia L., known commonly as bakuchi. It is widely used in Chinese medicine to treat a variety of diseases and possesses antitumor, antibacterial, cytotoxic and antihelmenthic properties. Thermally sensitive bakuchiol, psoralen and isosporalen, the major components present in the seed possess high biotechnological values. The extraction of bioactives from Psoralea corylifolia seeds was carried out using the high pressure supercritical carbon dioxide (SCCO 2 ) system at pressures 22, 26 and 30 MPa and at temperature of 313 K. Even though yield of extraction by SCCO 2 extraction process was slightly less than the yield by hexane extraction method, bakuchiol concentration in the extract was much higher than the hexane extraction. Experimental extraction data regressed well with diffusion model. LC-MS chromatogram of the extract identified presence of nine primary compounds. The results indicated that the extract having bakuchiol concentration of 51% was possible with SCCO 2 extraction.
Article
Solid-liquid extraction kinetic data for green coffee oil and chlorogenic acid were obtained using respectively hexane and methanol-water as solvents. The influence of the various extraction variables, i.e. the green coffee particle diameter, the mass ratio of ground coffee to solvent and the temperature, was studied.The mass transport is entirely controlled by the internal resistance of the solid. The kinetic results for the chlorogenic acid were interpreted by the diffusional model (Fick's second law) with apparent diffusivity values independent of concentration and slightly influenced by the temperature (Ea ≈ 9·74 kJ/mol). For the coffee oil extraction kinetics, the same model can be used only for long times (t > 30 min). The experimental values for short times (t < 10 min) are much longer than those predicted by the model; this could be due to leaching phenomena.
Article
Supercritical CO2 extraction of Plumula nelumbinis oil was investigated at temperatures of 308–338K and pressures of 15–45MPa. The yield of the extracted oil was 0.128g/g material at optimal conditions, in which gamma-sitosterol, unsaturated fatty acids and gamma-tocopherol had higher relative concentrations as determined by GC–MS. The broken and intact cell (BIC) model, with reduced adjustable parameters, was utilized to simulate the SFE process. The values of average absolute relative deviation (AARD) were in the range 2.34–10.9%, indicating that the improved method had a similar effect to the BIC model when three parameters were adjusted. The parameters obtained during the modeling had clear physical meanings and were used to gain an in-depth understanding of the SFE process theoretically.
Article
Nutmeg oil was extracted from nutmeg seed at pressures of 15–20MPa and temperatures of 313–323K with supercritical CO2. The effects of separation parameters such as temperature, pressure, CO2 flow rate and particle size on the extraction rate of nutmeg oil were observed. Broken and intact cells (BIC) model combined with discontinuous phase equilibrium between fluid phase and solid phase, and shrinking core model were selected to describe the extraction process. For BIC model, the initial fraction solute in broken cell to total solute in the ground particle f, dimensionless transition concentration Xc and partition coefficient K were used as fitting parameters. For shrinking core model, two effective diffusivities De were used as fitting parameters. The best fitting of De1 was from 4.33×10−9 to 7.69×10−8m2/s and De2 was from 1.90×10−9 to 3.20×10−8m2/s. From comparison of experimental data and models calculation, the shrinking core model could describe the experimental data well for all extraction conditions, while the BIC model could only describe the data at lower extraction yields well.
Article
Supercritical carbon dioxide (SC-CO2) was employed to extract oil rich in omega-3 fatty acids (FAs) from chia seeds, and the physicochemical properties of the oil were determined. A central composite rotatable design was used to analyze the impact of temperature (40°C, 60°C and 80°C), pressure (250bar, 350bar and 450bar) and time (60min, 150min and 240min) on oil extraction yield, and a response surface methodology (RSM) was applied. The extraction time and pressure had the greatest effects on oil. The highest oil yield was 92.8% after 300min of extraction time at 450bar. The FA composition varied depending on operating conditions but had a high content of α-linolenic acid (44.4–63.4%) and linoleic acid (19.6–35.0%). The rheological evaluation of the oils indicated a Newtonian behavior. The viscosity of the oil decreased with the increase in temperature following an Arrhenius-type relationship.
Article
The genus Curcuma (family Zingiberaceae) comprising over 80 species of rhizomatous herbs, is endowed with widespread adaptation from sea level to altitude as high as 2000 m in the Western Ghats and Himalayas. Having originated in the Indo-Malayan region, the genus is widely distributed in the tropics of Asia to Africa and Australia. Curcuma species exhibit inter-and intra-specific variation for the biologically active principles coupled with morpho-logical variation with respect to the above-ground vegetative and floral characters as well as the below-ground rhizome features besides for curcumin, oleoresin and essential oil. Curcuma is gaining importance world over as a potential source of new drug(s) to combat a variety of ailments as the species contain molecules credited with anti-inflammatory, hypocholestraemic, choleratic, antimicrobial, insect repellent, antirheumatic, antifibrotic, antivenomous, antiviral, antidiabetic, antihepatotoxic as well as anticancerous properties. Turmeric oil is also used in aromatherapy and in the perfume industry. Though the traditional Indian Ayurvedic system of medicine and Chinese medicine long ago recognized the medicinal property of turmeric in its crude form, the last few decades have witnessed extensive research interests in the bio-logical activity and pharmacological actions of Curcuma, especially the cultivated species. Tur-meric powder obtained from rhizomes of Curcuma longa or related species is extensively used as a spice, food preservative and colouring material, in religious applications as well as a household remedy for bilary and hepatic disorders, anorexia, diabetic wounds, rheumatism and sinusitis in India, China and South-East Asia and in folk medicine. Cucuminoids, the bio-logically active principles from Curcuma, promise a potential role in the control of rheuma-tism, carcinogenesis and oxidative stress-related pathogenesis. Curcuma longa L. syn. Curcuma domestica Val., common turmeric, is the most economically valuable member of the genus having over 150,000 hectares under its cultivation in India. In addition to Curcuma longa, the other economically important species of the genus are C. aromatica, used in medi-cine and toiletry articles, C. kwangsiensis, C. ochrorhiza, C. pierreana, C. zedoaria, C. caesia etc. used in folk medicines of the South-East Asian nations; C. alismatifolia, C. roscoeana etc. with floricultural importance; Curcuma amada used as medicine, and in a variety of culinary preparations, pickles and salads, and C. zedoaria, C. malabarica, C. pseudomontana, C. montana, C. decipiens, C. angustifolia, C. rubescens, C. haritha, C. caulina etc. all used in arrowroot manufacturing. Crop improvement work has been attempted mainly in C. longa and to a little extent in C. amada. At present there are about 20 improved varieties of C. longa in India and one in C. amada, evolved through germplasm/clonal selection, mutation breeding or open-pollinated progeny (true turmeric seedlings) selection. Though work on morphol-ogical characterization of Curcuma species has been attempted, its molecular characterization is in a nascent stage except for some genetic fidelity studies of micropropagated plants and isozyme-based characterization. The genus has also been examined from the biochemical pro-filing and anatomical characterization angle. This article is intended to provide an overview of biological diversity in the genus Curcuma from a utilitarian and bio-prospection viewpoint.