Separation of cashew (Anacardium occidentale L.) nut shellliquid with supercritical carbon dioxide

R.L. Smith Jr. a,*, R.M. Malaluan b, W.B. Setianto a, H. Inomata a, K. Arai a

a Department of Chemical Engineering, Research Center of Supercritical Fluid Technology, Tohoku University, Aoba-ku,

Aramaki Aza, Aoba-04, Sendai 980-8579, Japanb Department of Chemical Engineering Technology, Mindanao State University––Iligan Institute of Technology (MSU-IIT),

Andres Bonifacio Avenue, Iligan City 9200, Philippines

Received 7 December 2001; received in revised form 24 October 2002; accepted 28 October 2002

Abstract

Cashew nut shell liquid (CNSL) represents the largest readily available bioresource of alkenyl phenolic compounds. In this work,

separation of CNSL from the pericarp of the cashew nut with supercritical carbon dioxide was studied. In the initial extractions with

CO2 at 40–60 �C and at pressures from 14.7 to 29.4 MPa, low yields were obtained. However, when the extractions were performed

with one or more intermediate depressurization steps, the yield of CNSL increased to as high as 94%. Most of the oil did not

separate from the shell during the depressurization step, but was obtained during the subsequent repressurization. The CNSL

extract had a clear light brownish pink color and exhibited no evidence of polymerization or degradation. The pressure profile

extraction method proposed in this work increases the possible CNSL extraction yields and greatly reduces the amount of CO2

required for CNSL separation.

� 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Supercritical fluid extraction; Cashew; Carbon dioxide; Pressure profile

1. Introduction

The ‘‘acajou’’ or cashew nut tree (Anacardium occi-

dentale L.) is a branchy evergreen tree that traces its

origins to the Tupi Indians of northeastern Brazil

(Ohler, 1979). The fruit of the tree consists of an outer

shell (epicarp), a tight fitting inner shell (endocarp), a

strongly vesicant cashew nut shell liquid (CNSL), testaand a kernel that is highly regarded in edible nut mar-

kets. The CNSL is contained between the inner and

outer shell (pericarp) in a honeycomb matrix.

Besides the valuable cashew nut, the cashew nut tree

is the source of many useful by-products including the

peduncle of the nut or pseudofruit (cashew apple) that is

used to make juices and wines (Da Silva et al., 2000), the

pseudofruit waste that has been proposed as a feedstockfor protein enriched animal feed or as a high-fructose

source (Azevedo and Rodrigues, 2000), the tree gum

that has been proposed as an aqueous two phase ex-

tractant substitute for fractionated dextran (Sarrubo

et al., 2000), the tree bark and leaves that have been used

as an ancient remedy for toothache and malaria, and the

CNSL that is used industrially in phenol/formaldehyde

resins, brake fluids, and coatings (Tyman, 1996).

World production of cashew nut kernels was 907,000

metric tons/year in 1998 (FAO, 1998). On the average,the shell makes up about 50% of the weight of the

nut-in-shell (NIS) while the CNSL makes up about 15–

30% of the NIS weight (Behrens, 1996), which means

that a potential 544,000 metric tons CNSL/year is avail-

able. According to available statistics, only a small

amount of CNSL enters the world market most likely

due to difficulties in removing the oil from the shell and

CNSL processing. In our research, separation of CNSLfrom the pericarp without harsh chemical or thermal

treatment is of interest since this could allow for CNSL

to be used in pharmaceutical and speciality polymer

formulations.

CNSL consists of 80–90% anacardic acids and 10–

20% cardols depending upon the source (Behrens, 1996).

The anacardic acids have high pharmacological activity

Bioresource Technology 88 (2003) 1–7

*Corresponding author. Tel.: +81-22-217-7247; fax: +81-22-217-

7293.

E-mail address: smith@scf.che.tohoku.ac.jp (R.L. Smith Jr.).

0960-8524/03/$ - see front matter � 2002 Elsevier Science Ltd. All rights reserved.

PII: S0960-8524 (02 )00271-7

including antitumor, inhibitory, properties, antifungal

properties, hepatitis B inhibitory activity, and antivec-

torial activities (Toyomizu et al., 2000; Laurens et al.,

1997). However, CNSL is difficult to remove from the

shell with high yields due to the hard outer shell,

the intricate honeycombed features of the pericarp and

the thermally sensitive nature of the CNSL.

Methods for removing CNSL from the shell includethe artisanal method of roasting, hot-oil bath method,

steam processing at 270 �C, quick roasting at 300 �C,cold methods, and solvent extraction (Behrens, 1996).

In the hot-oil method used industrially, raw humidified

cashew nuts are placed on a slow moving conveyor belt

and submerged in a hot bath of CNSL at 180–190 �C(Tyman, 1996) for about 90 s. The heat causes the shell

to become embrittled and the CNSL to seep out of theshell. According to Tyman (1996), the yield of CNSL

with the hot-oil process is about 10% of the total NIS

weight (40% maximum theoretical) but it invariably

causes some of the CNSL to undergo polymerization

due to the temperatures used. Thermal methods gener-

ally cause decarboxylation of the anacardic acids as

shown in Fig. 1.

Tyman et al. (1989) evaluated liquid extraction of theshell material with carbon tetrachloride, light petroleum,

or diethyl ether and found that these solvents could give

15–30% of the total NIS weight. When this is combined

with catalytic decarboxylation to prevent polymeriza-

tion, near theoretical yields of technical grade CNSL can

be obtained. However, long extraction times (22–336 h),

large amounts of solvent, harsh mechanical pretreat-

ment, and low yield of whole kernels make this processunattractive. Furthermore, solvent extraction of CNSL

tends to extract undesirable colored compounds from

the shell material (Tyman, 1996). Methods based on

ammoniated solutions and mixed organic solvents have

been proposed that can recover virtually all of the

CNSL (Paramashivappa et al., 2001), but these can be

expected to have substantial environmental consider-

ations due to solvent recovery and recycle.Supercritical fluids have been suggested as attractive

alternative solvents for many organic solvents by Saito

(1995), who reviewed research activity. For example,

CO2 has been suggested as a replacement for n-hexaneor toluene in desolventation of polymer solutions by

Inomata et al. (1999). In their supercritical states, CO2

and water can be used in many extractions and reactions

and have been recognized as earth compatible solvents

(Arai and Adschiri, 1999). CO2 has been proposed for

use in a process for improving the digestion properties

of cellulosic material by Kim and Hong (2001). Fur-

thermore, CO2 in its supercritical state has been used for

fractionating thermally sensitive natural oils (Suzuki

et al., 1997) and has the potential for refining the ex-tracts reported in this study.

Previous research exists on extraction of CNSL with

supercritical carbon dioxide (SC–CO2). Shobha and

Ravindranath (1991) studied extraction of CNSL with

SC–CO2 and found that 18.7% yields (�75% maximum

theoretical yield) could be obtained. Those authors

suggested that raw undecarboxylated CNSL could be

used. Arai et al. (1993) considered supercritical carbondioxide with isopropanol cosolvent to concentrate

cardanol in the critical phase and cardol in the residue.

However, neither of these works examined the extrac-

tion yields in detail. Further, the results reported in

those works showed that large quantities of CO2 solvent

were required in the extractions. In this research, our

objective was to evaluate supercritical carbon dioxide as

a solvent for separating CNSL from the raw cashew nutshells and to examine methods to improve the extraction

yields.

2. Methods

Unshelled cashew nuts were obtained from Indonesia

(Sumbawa Island) through courtesy of BPP Teknologi

(Jakarta). Unshelled nuts from the Philippines (Cagayande Oro) were used in some of the runs. Carbon dioxide

(99.99%) was supplied from Nippon Sanso and used as-

received. Cashew nut shells were prepared by cutting in

half with a micro-saw removing the kernel and testa. No

crushing or other pretreatment was performed. The ca-

shew nut shells (CNS) thus prepared were weighed and

placed on a fine screen that was elevated within the ex-

tractor. The average shell-only weight was 64% of thetotal nut-in-shell (NIS) weight and within a range of 61–

66%.

2.1. Experimental apparatus

The apparatus used for contacting the CNS with SC–

CO2 is shown in Fig. 2. The extractor had a volume of

500 cm3 that was rated for working pressures of 40 MPa

at 100 �C. The CO2 supply pressure to the extractor was

controlled with a backpressure regulator. Two methods

were used for extraction: (i) typical extraction method

and (ii) pressure profile extraction method. Only theweights of CNSL extracted and general CNSL charac-

teristics are reported here. CNSL component analysis by

HPLC will be reported in a future work.Fig. 1. Heating CNSL results in decarboxylation of anacardic acids

and formation of cardanol or polymerization products.

2 R.L. Smith Jr. et al. / Bioresource Technology 88 (2003) 1–7

2.2. Typical extraction method

In the typical extraction method, CNS was loaded

and the extractor was sealed and brought to extraction

temperature. Then, CO2 was compressed to the desired

pressure and allowed to flow into the extractor. After

the pressurization, the metering valve was controlled to

achieve a CO2 flowrate of 0.5–5 L/min measured atstandard temperature and pressure. Extract was col-

lected in the trap periodically at intervals of about 1 h.

Details of the apparatus are given in Fig. 2.

2.3. Pressure profile extraction method

In the pressure profile extraction method, extractions

were performed as a series of typical extraction methodsbut with one or more intermediate depressurization

steps to 0.1 MPa. During the time at atmospheric con-

ditions, the extractor and trap were isolated from the

surroundings.

2.4. Pressurization and depressurization

Times required for pressurization were approximately5, 10, and 20 min for operating pressures of 10, 20 and

30 MPa, respectively. After the end of a given extraction

period, the CO2 feed supply was closed off and the

metering valve was opened further to achieve the desired

depressurization rate. This generally required about 15

min for depressurizations from pressures of 10 MPa and

30 min for depressurizations from pressures of 20 or 30

MPa. Extraction periods for all runs reported in the

tables do not include the pressurization and depressur-

ization times. However, the mass of CO2 reported in the

tables and figures includes the amount of CO2 required

to pressurize the extraction vessel at the given conditionsassuming a total extractor volume of 500 cm3.

3. Results

3.1. Typical extraction method

Weights of CNSL extracted for the typical extractionmethod are shown in Table 1 for various pressures,

temperatures, flowrates, extraction time and loadings.

From the data in Table 1, it was clear that supercritical

carbon dioxide could extract CNSL from the cut shells.

Color of the extracted CNSL was clear with a light

brown/reddish tint. Cooling of the liquid to 4 �C gave

fine needle-like crystals indicating that the extract con-

tained high purity components.According to the amount of CNS loaded, the theo-

retical amount of CNSL available for extraction can be

estimated to be 16.5, 2, 6.7, 12.7 g, for runs 0, 1, 2, 3,

respectively. However, the amounts of CNSL obtained

Fig. 2. Supercritical fluid extraction apparatus.

Table 1

Experimental conditions and data for extraction of cashew nut shells with the typical extraction method

Run no.a P (MPa) T (�C) Flowrate

CO2@STP

(L/min)

Extraction time

(h)

CO2 used

(kg)

WCNS loaded

(g)

WCNSL extracted

(g)

0 30.0 60 3.0 2 0.20 50.0 2.00

1 14.7 40 3.0 1 0.10 6.001 0.07

2 29.4 60 0.5 3 0.31 20.123 0.50

3 29.4 60 5.0 4 0.41 37.974 1.30

CNS: cashew nut shells; CNSL: cashew nut shell liquid.

R.L. Smith Jr. et al. / Bioresource Technology 88 (2003) 1–7 3

with the typical extraction method were far below the

theoretical amounts. Shobha and Ravindranath (1991)

reported on a single experimental trial for extraction of

CNSL with supercritical CO2 at 40 �C and 25 MPa. In

their work, approximately 80 kg CO2 was used over a

17.5 h extraction period to obtain 56.1 g CNSL from

broken CNS from 300 g NIS. From their work, 0.7 g

CNSL was obtained for every kilogram of CO2. Fromthe data in Table 1, it became clear that greater amounts

of CNSL could be obtained for given amounts of CO2

solvent. This could be due to a number of factors such as

CNS loading amount and placement in the extractor,

mass transfer or the extraction conditions used.

The extractor was opened at the end of each of these

runs and it was found that liquid was on the outer

portion of the shell. Just after removal of the shells fromthe extractor, a curious bubbling was observed, which

indicated that the CO2 had high solubility in the CNSL

and possibly caused the liquid phase to expand. Fol-

lowing up on this observation, Setianto et al. (2001)

examined changing the pressure during the extraction.

This led to our study of the pressure profile extraction

method as described next.

3.2. Pressure profile extraction method

At the completion of run 3, the apparatus was de-

pressurized and left overnight. Then, the apparatuswas repressurized and extraction was continued for 4 h

at the same conditions. This is run 4 in Table 2. Un-

expectedly, additional CNSL extract was obtained as

shown in Table 2. Data obtained from several other

experimental runs made with a depressurization step

are also shown. Pressure profile extraction methods for

these runs and others are summarized in Fig. 3. As

shown in Table 2, the amount of CNSL obtained with

an intermediate depressurization step was very con-

sistent for three different loadings (runs 4–6). In run 7,

the first extraction period was shortened to 1 h and the

later extraction segment was lengthened to 5 h. A de-crease in the weight of CNSL obtained was observed,

which can be attributed to the equilibration times as

explained below. It should be pointed out that the

amount of CO2 required to extract a given amount of

CNSL in Table 2 was much less than that reported by

Shobha and Ravindranath (1991). Those authors used

more than 80 kg CO2 to obtain comparable amounts of

CNSL.Table 3 and Fig. 3 summarize the additional studies

performed with various pressure profiles. A large

amount of CNSL could be obtained with the various

pressure profiles. It should be emphasized that the

pressurization steps, although as rapid as possible for

the given equipment, were relatively slow and gentle

towards the natural materials. Slower depressurization

rates (�1 L CO2/min at STP) were performed butwithout significant differences in the extraction yields.

Rapid depressurization rates could not be considered

with the present experimental setup.

From the longest run made (run 12), the shells were

clearly dry. Examination of shells cut in sections with a

low power microscope did not reveal any free oils.

However, some dried CNSL-like solids were observed.

Some of the shells exhibited cracks along the internalwall of the endocarp but no common structural defects

Fig. 3. Pressure profile extraction methods for runs 4–12; run 4 includes run 3; run 12 includes run 11.

Table 2

Data for extraction of cashew nut shells with a single intermediate depressurization step to 0.1 MPa

Run no. Extraction time (h) CO2 used (kg) WNIS (g) WCNS loaded (g) WCNSL extracted (g)

4a 4þ 4 4.5 58.4 37.974 5.989

5 4þ 4 4.5 56.2 36.986 6.212

6 4þ 4 4.5 63.2 41.309 6.134

7 1þ 5 3.5 52.4 33.239 4.961

CNS: cashew nut shells; CNSL: cashew nut shell liquid; NIS: nut-in-shell.a Run 4 NIS calculated from CNS/0.65. Extraction conditions: 60 �C, 29.4 MPa, CO2 flowrate of 5 L/min@STP. Symbol: ‘‘þ’’: reduction of

pressure to 0.1 MPa, then repressurization to extraction conditions.

4 R.L. Smith Jr. et al. / Bioresource Technology 88 (2003) 1–7

were observed. Therefore, we concluded that most of the

CNSL had been extracted from the NIS and that the

ultimate amount of CNSL available was close to 15% of

the NIS weight based on the lower of the average values

summarized by Behrens (1996). It should be noted that

the precise value of the ultimate amount of CNSL used

in Eq. (1) does not change the general conclusions of thiswork. In the analysis of the results, it is convenient to

define a yield of the CNSL extracted, defined as:

Yield ð%Þ ¼ CNSL extracted ðgÞNIS ðgÞ � 0:15

� 100% ð1Þ

Fig. 4 shows results for runs 6–8 and 10, which used

simple pressure profiles (Fig. 3). At a flowrate of 5 L/min

at STP, roughly 0.5 kg/h of CO2 were consumed. Values

in the figure include the CO2 needed to pressurize the

extractor as explained previously. The effect of the de-

pressurization on the extraction yield for each run can

be clearly seen. As explained in detail next, the effect ofthe depressurization on each run could be clearly ob-

served.

In runs 6–8, extraction pressures were held constant

at 29.4 MPa. In run 6, yields began to greatly increase

after the first (4 h) extraction period (�2 kg CO2 used)

and depressurization. In run 7, the extraction yield be-

gan to increase earlier due to the shorter initial (1 h)

extraction period and depressurization. In run 8, two

short (5 min) extraction periods were used, however, the

extraction yield did not greatly increase after the initial

(5 min) extraction as expected. From these results, it

appeared that some contact time was necessary before

depressurization was initiated.

In run 10, we examined the effect of reducing the

initial extraction pressure compared with that used inrun 7. As shown in Table 3 and Fig. 3, the initial ex-

traction pressure for run 10 was 9.8 MPa for a period of

1 h and that for run 7 was 29.4 MPa. Even for the dif-

ferent initial extraction pressures, the trends of the ex-

traction yields were similar for the two runs as shown in

Fig. 4.

These results may be understood as follows. Gener-

ally, only small changes in the CNSL can be expectedaccording to the pressure–volume–temperature behavior

of pure oils unless there is a phase change of some of the

solid components (Acosta et al., 1996). It would seem,

therefore, that it is unlikely that solid–liquid phase

transitions occurred as a result of the hydrostatic pres-

sure. Such a phase transition would cause the extraction

yield curves for runs 7 and 10 to be significantly differ-

ent. Further, if the available CNSL changed accordingto the hydrostatic pressure on the shell, then, one would

expect the two curves (runs 7 and 10) to be significantly

different. Since the two curves were similar, the effects of

the hydrostatic pressure on the shell can be said to be

similar. On the other hand, if the CO2 penetrated into

the interstices of the shell matrix and dissolved into the

CNSL, then for both cases there would be considerable

swelling of the liquid phase, which would result in aviscosity reduction of the CNSL and a tendency for the

liquid to flow. A swelling phenomenon has been re-

ported by Smith et al. (1998), who found that the vol-

ume expansion of oils in contact with supercritical CO2

could be as high as 200% for n-decane or close to 50%for fish oil methyl esters. The possibility of CNSL

swelling was confirmed to some extent by examination

of the CNS after a single depressurization. The CNSLshowed a frothy appearance in which slow evolution of

CO2 was apparent. The CNSL swelling would increase

the available surface area of the CNSL to the bulk CO2

phase and would account for some of the higher ex-

traction yields observed and for the similarity in ex-

traction yield curves for runs 7 and 10.Fig. 4. Extraction yields versus CO2 used for runs 6, 7, 8, and 10. Basis

for yields: 15% of NIS being CNSL.

Table 3

Data for extraction of cashew nut shells with single and multiple intermediate depressurization and pressurization steps

Run no. Extraction time (h) Pressure (MPa) CO2 used (kg) WNIS (g) WCNS loaded (g) WCNSL extracted (g)

8 5 minþ 5 minþ 4 29:4þ 29:4þ 29:4 3.69 53.7 33.629 4.660

9 5 minþ 1=5þ 3:5þ 5 min 9:8þ 9:8=29:4þ 29:4þ 29:4 5.67 56.5 36.184 6.566

10 1þ 4 9:8þ 29:4 2.90 53.1 32.418 4.657

11 1þ 4 9:8þ 19:6 2.73 56.3 37.326 4.201

12a 1þ 4þ 4=4 9:8þ 19:6þ 19:6=29:4 6.72 56.3 37.326 7.951a

Extraction conditions: 60 �C; CO2 flowrate of 5 L/min at STP. CNS: cashew nut shells; CNSL: cashew nut shell liquid; NIS: nut-in-shell.a Run 12 is the continuation of run 11. Mass of CO2 used and CNSL extracted include respective masses from run 11. Symbols: ‘‘þ’’: depres-

surization to 0.1 MPa. ‘‘/’’: intermediate pressurization to given pressure.

R.L. Smith Jr. et al. / Bioresource Technology 88 (2003) 1–7 5

Next, we considered more complicated pressure pro-

files as shown in Fig. 5. In run 9, a short pressurization

period at 9.8 MPa was used followed by a two-step

pressurization. Extraction yields increased rapidly dur-

ing the pressurizations. After approximately 3 kg of CO2

was consumed, slow depressurization followed by pres-surization to 29.4 MPa gave a new clear pattern in the

yield as shown in Fig. 5. A final depressurization and

repressurization resulted in a slight increase as shown by

the last three points of run 9.

In run 12, a 1 h extraction period at 9.8 MPa was used

before depressurization. Upon repressurization, the ex-

traction yield increased as expected and seemed to reach

a plateau. In the next pressurization step at approxi-mately 4 kg CO2 used (�6 h), a two-stage pressurizationgave a considerably high extraction yield. The effect of

the pressure profiles can be clearly seen for each step.

Fig. 5 also shows the initial experimental data from

Shobha and Ravindranath (1991), who performed ex-

tractions at 40 �C and 25 MPa. Although the basis for

the extraction yields and conditions are different, the

slopes of the extraction yield curves from the data in thiswork were similar to those of the literature during the

initial extraction period before the depressurization step.

These results confirm that a large quantity of CO2 would

be required to obtain the desired extraction yields with

the typical extraction method.

3.3. CNSL characteristics and quality

The CNSL obtained in all runs was clear with a light

brownish red tint at room temperature. No signs of

polymerization or degradation of the CNSL product

were apparent from visual analysis. In some cases, theextracted CNSL was brighter in color. Most samples

became solid or exhibited a solid-like appearance when

placed in a refrigerator at 4 �C. Examination of the

solid-like samples showed the presence of needle-like

crystals that were well defined.

3.4. Further processing of extracted CNSL and shells

The pressure profile extraction methods presented in

this work gave high extraction yields and CNSL that

appeared to be of high quality. Analysis of the time

evolution of the CNSL compositions as a future work

will provide information on whether fractionation of

CNSL with supercritical CO2 solvent is feasible using theinverse temperature gradient column developed by Su-

zuki et al. (1997) or whether optimization of the sepa-

rations can be approached according to the methodology

of Yonei et al. (1995). Regarding the remaining shell

material, supercritical water has been found to be a

useful solvent for converting cellulose and biomass ma-

terials into valuable pharmaceuticals and sugar com-

pounds (Adschiri et al., 1993; Malaluan, 1995; Sasakiet al., 1998). In some preliminary experiments (Smith

et al., 2001), we have found that the cashew nut shell can

be dissolved completely into supercritical water using

techniques described in Fang et al. (1999). This means

that it is highly probable that a comprehensive process

for the bioresource cashew tree can be developed, which

uses only carbon dioxide and water as solvents.

4. Conclusions

In this work, we have examined the separation of

CNSL with supercritical carbon dioxide. It was foundthat extractions performed with intermediate depressur-

ization steps increased the yields of CNSL obtained and

decreased the amount of CO2 required. Contact period

seemed to be an important factor in the initial pressur-

izations. Further, staged pressurizations seemed to pro-

vide increased extraction yields. A number of pressure

profile extractionmethods were used and yields as high as

94% (15% NIS basis) were obtained. In the initial ex-traction period, dissolution of CO2 into the CNSL phase

probably reduced the CNSL viscosity and caused the

liquid phase to expand. Then, perturbations made in

system conditions probably led to increased available

surface area of CNSL to the bulk CO2. Experiments are

needed regarding the phase behavior of CNSL with

supercritical CO2 to allow understanding of the funda-

mental phenomena that are occurring during the ex-traction. However, use of supercritical CO2 with the

pressure profile extraction method is an effective tech-

nique for separating CNSL from bulk cashew nut shells.

Acknowledgements

The authors wish to thank Mr. Priyo Atmaji (BPP

Teknologi, Jakarta) for supplying the raw Indonesian

Fig. 5. Extraction yields versus CO2 used for runs 9 and 12 (includes

run 11). Basis for yields: 15% of NIS being CNSL. Basis for Ref. FAO,

1998: 25% of NIS being CNSL.

6 R.L. Smith Jr. et al. / Bioresource Technology 88 (2003) 1–7

cashew nuts used in this study. The authors also wish to

thank Mikio Kikuchi for assistance with the experi-

mental apparatus and the many sample preparations.

References

Acosta, G.M., Smith Jr., R.L., Arai, K., 1996. High-pressure PVT

behavior of natural fats and oils, trilaurin, triolein, and n-tridecanefrom 303 to 353 K from atmospheric pressure to 150 MPa.

J. Chem. Eng. Data 41, 961–969.

Adschiri, T., Hirose, S., Malaluan, R., Arai, K., 1993. Noncatalytic

conversion of cellulose in supercritical and subcritical water.

J. Chem. Eng. Jpn. 26, 676–680.

Arai, K., Adschiri, T, 1999. Importance of phase equilibria for

understanding supercritical fluid environments. Fluid Phase Equi-

libria 158–160, 673–684.

Arai, K., Ajiri, T., Suzuki, S., Nishimura, M., 1993. Method for

separating and purifying cashew nutshell juice. (Japanese Patent)

JP 05-000979, August 1.

Azevedo, D.C.S., Rodrigues, A., 2000. Obtainment of high-fructose

solutions from cashew (Anacardium occidentale) apple juice by

simulated moving-bed chromatography. Sep. Sci. Technol. 35 (16),

2561–2581.

Behrens, R., 1996. Cashew as an Agroforestry Crop, Tropical

Agriculture [9]. Margraf Verlag, Weikersheim, Germany.

Da Silva, K.D.P., Collares, F.P., Finzer, J.R.D., 2000. A simple and

rapid method for estimating the content of solids in industrialized

cashew juice. Food Chem. 70, 247–250.

Fang, Z., Smith Jr., R.L., Inomata, H., Arai, K., 1999. Phase behavior

and reaction of polyethylene terephthalate–water systems at

pressures up to 173 MPa and temperatures up to 490 �C.J. Supercrit. Fluids 15, 229–243.

Food and Agriculture Organisation (FAO) Yearbook, 1998. Food

Statistics Series no. 148, 52, p. 167.

Inomata, H., Honma, Y., Imahori, M., Arai, K., 1999. Fundamental

study of de-solventing polymer solutions with supercritical CO2.

Fluid Phase Equilibria 158–160, 857–867.

Kim, K.H., Hong, J., 2001. Supercritical CO2 pretreatment of

lignocellulose enhances enzymatic cellulose hydrolysis. Biores.

Technol. 77, 139–144.

Laurens, A., Fourneau, C., Hocquemiller, R., Cave, A., Bories, C.,

Loiseau, P.M., 1997. Antivectorial activities of cashew nut shell

extracts from Anacardium occidentale L.. Phytother. Res. 11, 145–

146.

Malaluan, R.M., 1995. Study on cellulose decomposition in subcritical

and supercritical water. Ph.D. Thesis, Tohoku University (in

English).

Ohler, J.G. Cashew, 1979. Communication 71, Koninklijk Institut

voor de Tropen, Amsterdam.

Paramashivappa, R., Kumar, P.P., Vithayathil, P.J., Srinivasa Rao,

A., 2001. Novel method for isolation of major phenolic constitu-

ents from cashew (Anacardium occidentale L). nut shell liquid.

J. Agric. Food. Chem. 49, 2548–2551.

Saito, S., 1995. Research activities on supercritical fluid science and

technology in Japan––a review. J. Supercrit. Fluids 8, 177–

204.

Sarrubo, L.A., Oliveira, L.A., Porto, A.L.F., Duarte, H.S., Carneiro-

Leao, A.M.A., Limo-Filho, J.L., Campos-Takaki, G.M., Tam-

bourgi, E.B., 2000. New aqueous two-phase system based on

cashew-nut tree gum and poly(ethylene glycol). J. Chromatogr. B

743, 79–84.

Sasaki, M., Kabyemela, B., Malaluan, R.M., Hirose, S., Takeda, N.,

Adschiri, T., Arai, K., 1998. Cellulose hydrolysis in subcritical and

supercritical water. J. Supercrit. Fluids 13, 261–268.

Setianto, W.B., Smith Jr., R.L., Inomata, H., 2001. Application

of supercritical CO2 to the extraction of cashew nut shell oil.

Published proceedings of the Japan Oil Chemist�s Society, 40thannual meeting, Sendai, October 4–5, paper 1E-05 (in

Japanese).

Smith Jr., R.L., Yamaguchi, T., Sato, T., Suzuki, H., Arai, K., 1998.

Volumetric behavior of ethyl acetate, ethyl octanoate, ethyl laurate,

ethyl linoleate, and fish oil ethyl esters in the presence of

supercritical CO2. J. Supercrit. Fluids 13, 29–36.

Smith Jr., R.L., Malaluan, R.M., Setianto, W.B., Inomata, H., Arai,

K., 2001. Biobased manufacture of alkenyl phenolics and polysac-

charide feedstocks from cashew nut with supercritical water and

carbon dioxide processing. Proceedings of the 5th Biomass Con-

ference of the Americas (cancelled), September 17–21, Orlando,

Florida, session 26.

Shobha, S.V., Ravindranath, B., 1991. Supercritical carbon dioxide

and solvent extraction of the phenolic lipids of cashew nut

(Anacardium occidentale) shells. J. Agric. Food Chem. 39, 2214–

2217.

Suzuki, H., Chen, J., Adschiri, T., Inomata, H., Arai, K., 1997.

Purification of EPA ethyl ester from fish oil with a supercriti-

cal CO2 temperature gradient rectification column. JOCS 46, 331–

340.

Tyman, J.H.P., Johnson, R.A., Muir, M., Rokhgar, R., 1989. The

extraction of natural cashew nut-shell liquid from the cashew nut

(Anacardium occidentale). J. Am. Oil Chem. Soc. 66, 553–557.

Tyman, J.H.P., 1996. In: Synthetic and Natural Phenols Studies in

Organic Chemistry, vol. 52. Elsevier, Amsterdam, pp. 518–521.

Toyomizu, M., Okamoto, K., Ishibashi, T., Chen, Z., Nakatsu, T.,

2000. Uncoupling effect of anacardic acids from cashew nut shell

oil on oxidative phosphorylation of rat liver mitochondria. Life Sci.

66 (3), 229–234.

Yonei, Y., Kobari, M., Yokoyama, C., Arai, K., 1995. A search for

optimum extraction conditions of flavor from tabacco leaves by

high pressure CO2. Kagaku Kogaku Rombunshu 21, 674–682 (in

Japanese).

R.L. Smith Jr. et al. / Bioresource Technology 88 (2003) 1–7 7