www.elsevier.com/locate/jfoodeng

Journal of Food Engineering 74 (2006) 516–522

Sunflower oil miscella degumming with polyethersulfone membranesEffect of process conditions and MWCO on fluxes and rejections

Ana Garcıa a, Silvia Alvarez b, Francisco Riera a, Ricardo Alvarez a,*, Jose Coca a

a Department of Chemical Engineering and Environmental Technology, University of Oviedo, C/Julian Claverıa 8, 33071 Oviedo, Spainb Department of Chemical and Nuclear Engineering, Polytechnic University of Valencia, ETSII, C/Camino de Vera s/n, 46022 Valencia, Spain

Received 15 July 2004; accepted 7 March 2005

Available online 26 May 2005

Abstract

The aim of this work was to study the removal of phospholipids from sunflower oil miscella by membrane filtration using a cross-

flow UF pilot-plant. Two tubular polyethersulfone membranes with different MWCO (4000 and 9000 Da) were compared. A sun-

flower oil miscella with an oil content of about 30% w/w was used as feed and the following operating conditions were employed:

40 �C, 5 m/s, and 0.4–1.2 MPa. Both membranes presented approximately the same rejection of phospholipids (95–97%), although

the 9000 Da membrane showed higher miscella permeate flux, lower oil rejection and higher free fatty acids rejection. The influence

of operating parameters, i.e. temperature, feed flow rate, and applied pressure, on fluxes and rejections was studied with the 9000 Da

membrane. The results were then evaluated in order to choose the best operating conditions to concentrate a sunflower oil miscella

using this membrane up to a VCR of 3.2.

� 2005 Elsevier Ltd. All rights reserved.

Keywords: Sunflower oil; Polyethersulfone; Ultrafiltration; Degumming; Bleaching

1. Introduction

The sources of commercial edible oils and fats in-

clude oilseeds, fruit pulps, animals and fish, oilseeds

being the major source. The most widely used method

to obtain the oil from oilseeds is pressing followed by

solid-liquid extraction. The main solvent used in the

extraction is commercial hexane, which is a mixture

of aliphatic and cyclic hydrocarbons. The extraction

step results in an oil/solvent mixture (miscella) withabout 25–30% (w/w) oil content. The solvent is subse-

quently removed by evaporation until the hexane con-

tent in the oil is lower than 1%. Besides the oil, the

solvent also extracts certain undesirable compounds,

0260-8774/$ - see front matter � 2005 Elsevier Ltd. All rights reserved.

doi:10.1016/j.jfoodeng.2005.03.038

* Corresponding author. Tel.: +34 985 10 34 38; fax: +34 985 10 34

34.

E-mail address: ralvarez@uniovi.es (R. Alvarez).

such as phospholipids, free fatty acids (FFA), pig-

ments, sterols, carbohydrates, proteins and theirrespective degradation products. These are substances

that may impart an undesirable flavour and colour

and shorten the shelf life of the oil (Lin, Rhee, &

Koseoglu, 1997; Pagliero, Ochoa, Marchese, & Mattea,

2004). Crude vegetable oils therefore undergo complex

refining processes to achieve the desired quality,

namely degumming, neutralisation, bleaching and

deodorization. The process has remained unchangedin recent decades even though it presents numerous

drawbacks, such as high energy requirements, loss of

neutral oil, the need for large amounts of water and

chemicals, loss of nutrients and disposal of highly pol-

luted effluents (Subramanian et al., 2001, 2001a,

2001b).

The removal of phospholipids (degumming) is the

first step in the refining process, in which water, salt

FT PT

TT

PTTT

criostato

N2

P PT

cryostat

Fig. 1. Experimental set-up. PT: pressure transducer, TT: temperature

transducer; FT: flow transducer.

A. Garcıa et al. / Journal of Food Engineering 74 (2006) 516–522 517

solutions or dilute acid are added to the oil in order to

convert phospholipids into hydratable gums, which are

insoluble in oil. These gums are then separated from

the oil by filtering, settling or centrifugal action (Pagli-

ero, Ochoa, Marchese, & Mattea, 2001). The main

drawbacks of these processes are considerable oillosses, large amounts of wastewater and high energy

consumption (Ochoa, Pagliero, Marchese, & Mattea,

2001). Membrane technology may provide an alterna-

tive to the traditional degumming step. As triglycerides

and phospholipids have similar molecular weights

(about 900 and 700 Da, respectively), this could hinder

their separation by membrane technology. However, in

non-polar media like hexane or crude oil, phospholip-ids tend to form reverse micelles with an average molec-

ular weight of 20 kDa or more (Lin et al., 1997; Ochoa

et al., 2001; Pagliero et al., 2001). Phospholipids may

hence be separated from triglycerides using appropriate

ultrafiltration membranes (Kim, Kim, Lee, & Tak,

2002). The major limitations of oil degumming using

membranes are the poor stability of some organic mem-

branes in organic solvents and the low permeate fluxes(Pagliero et al., 2001). Solvent-resistant membranes

with pore sizes ranging from dense membranes to

microfiltration have been tested by several research

groups with the main goal of achieving both membrane

degumming and bleaching in only one step (Kim et al.,

2002; Koike, Subramanian, Nabetani, & Nakajima,

2002; Ochoa et al., 2001; Pagliero et al., 2001, 2004;

Reddy, Subramanian, Kawakatsu, & Nakajima, 2001;Subramanian et al., 2001, 2001a, 2001b; Subramanian

et al., 2003).

The use of a pre-treatment on some polymeric mem-

branes has been reported in the literature (Jirjis, 2000;

Jirjis, 2001; Koseoglu, 1991; Koseoglu, Lawhon, &

Lusas, 1990; Ochoa et al., 2001) to prevent the collapse

of pores that occurs when some membranes are in con-

tact with a mixture of hydrocarbons, as is the case understudy. This pre-treatment consists in soaking the mem-

branes in mixtures of solvents of decreasing polarity,

such as 50% water/isopropanol for 24 h, 50% isopropa-

nol/hexane for 24 h and finally, 100% hexane for 24 h.

This pre-treatment has been shown to be very effective

on polyethersulfone membranes.

The aim of the present work is to evaluate the effi-

ciency of membrane technology under different operat-ing conditions in the degumming of crude sunflower

oil miscella using polyethersulfone membranes in a

cross-flow arrangement. Two polyethersulfone mem-

branes with different MWCO were used and their per-

formance was compared in terms of permeate flux,

retention of oil, phospholipids and free fatty acids

and reduction of colour. Furthermore, the effect of ap-

plied pressure, flow velocity and temperature on fluxesand rejections was evaluated with the PES209 mem-

brane.

2. Experimental

2.1. Membranes

Polyethersulfone ultrafiltration membranes, with

molecular weight cut-offs (MWCO) of 4000 (ES404)and 9000 (ES209) Da were used (PCI Membrane Sys-

tems�, Laverstoke Mill, UK). Both of these were

tubular membranes, with a channel diameter of

7 mm, a length of 1120 mm and a filtration area of

0.044 m2.

2.2. Experimental equipment

Experiments were performed in a cross-flow UF

pilot-plant consisting of a closed stainless-steel tank of

50 L volume, a six-stage centrifugal pump with a maxi-

mum power rating of 5.5 kW (Lowara, Italy), pressure

and temperature transducers, and a feed flowmeter

(Endress-Hauser, Germany). As the maximum pressure

that this pump can supply is 0.4 MPa, higher pressures

were achieved by adding industrial nitrogen gas to thefeed tank. The device did not require external heating.

However, external cooling was needed to compensate

the increase in feed temperature caused by friction.

The temperature was controlled by circulating cold

water from a cryostat (Haake, Germany) through an

internal coil in the tank. Fig. 1 shows a scheme of the

experimental set-up. The equipment was placed under

an extractor hood in order to remove hexane vapors.Tubing, valves and accessories were made of stainless

steel and the gaskets were made of a material stable in

hexane, such as Teflon or Viton.

518 A. Garcıa et al. / Journal of Food Engineering 74 (2006) 516–522

2.3. Degumming experiments

First, the membranes were cleaned and the water flux

was measured. The membranes were then pre-treated

according to the aforementioned procedure (Jirjis,

2000, 2001; Koseoglu, 1991; Koseoglu et al., 1990;Ochoa et al., 2001) and the hexane permeate flux was

subsequently measured as a function of the applied pres-

sure (from 0.2 to 1.2 MPa) at room temperature (about

20 �C) and 3 m/s. The degumming experiments were car-

ried out with a sunflower oil miscella supplied by the

Spanish manufacturer KOIPE, S.A. (Jaen, Spain). The

miscella used for the experiments with the ES404 mem-

brane had a sunflower oil content of around 30%, some1.20 g phospholipids/100 g oil, and a free fatty acids

content of about 2.80 g oleic acid/100 g oil. The miscella

used with the ES209 membrane had the same sunflower

oil content, some 1.50 g phospholipids/100 g oil, and a

free fatty acids content of about 1.20 g oleic acid/100 g

oil.

The experimental conditions chosen were 40 �C, feedflow of 5 m/s, increasing the pressure within the range of0.4–1.2 MPa. Phospholipids and free fatty acids reten-

tions were expressed in oil basis terms, according to

the following equation:

Ri ð%Þ ¼ 1� Ci;p

Ci;f

� �� 100 ð1Þ

where Ri is the rejection coefficient for component i, and

Ci,f and Ci,p are the concentrations of this component in

the feed and permeate, respectively (in grams per 100 gof oil).

The influence of temperature, feed flow rate and ap-

plied pressure on permeate flux and retention was then

analysed using the ES209 membrane. After each run,

the membrane was cleaned with hexane until the original

pure hexane permeate flux was restored. The best oper-

ating conditions obtained from these runs were then

used to perform a miscella concentration experimentwith this membrane. A batch operating mode was con-

sidered for the concentration tests.

2.4. Analytical methods

Oil, phospholipids and free fatty acids content were

analysed in feed, permeate and retentate streams using

the following procedures:

• To determine the oil content, hexane was evaporated

from the mixture under vacuum. The oil content was

calculated from the weight difference of the sample

before and after evaporation of the solvent (method

supplied by KOIPE, Spain).

• Phospholipids content was determined by adding ace-

tone to a weighed amount of oil (having previouslyevaporated the hexane). A precipitate constituted by

the phospholipids was thus obtained. This was sepa-

rated from the sample by vacuum filtration and was

subsequently weighed (UNE 55-115).

• The amount of free fatty acids (FFA) in the oil was

determined after evaporating the solvent by titration

with KOH (in ethanol solution). The percentage ofFFA was expressed as oleic acid content (UNE 55-

102).

• The colour of the samples (without dilution in any

solvent) was spectrophotometrically estimated.

Absorption was measured in the wavelength range

of 400–750 nm with a Helios a spectrophotometer

(Thermo Electron Corporation, United States), using

cyclohexane as blank.

3. Results and discussion

3.1. Water and hexane permeate fluxes

Water permeability for the ES404 (4000 Da) and

ES209 (9000 Da) membranes was 141 and 476 L/

h m2 MPa (at 25 �C), respectively, while hexane perme-

ability was 97 and 170 L/h m2 MPa (at 20 �C), respec-tively. As expected, water and hexane permeate fluxes

were higher for the ES209 membrane, due to its higher

MWCO. Moreover, water permeability was greater than

hexane permeability for both membranes.

3.2. Degumming experiments

The aim of the degumming process is to remove as

many phospholipids as possible from the crude oil, thus

obtaining an almost phospholipid-free edible oil. Low

triglyceride losses are also required during this opera-

tion. After degumming, the oil is submitted to the subse-quent refining operations, i.e. neutralization (removal of

free fatty acids), bleaching (removal of pigments) and

deodorization. These refining steps could be improved

if free fatty acids and/or pigments were removed to-

gether with the phospholipids. When membranes are

used for edible oil degumming, high permeate fluxes

are desirable in order to achieve high yields. To date,

the authors who have studied the applicability of mem-brane technology to edible oil processing have used both

miscella and crude oil as feed. If miscella is used as feed,

viscosity is lower, which improves permeate fluxes.

When using miscella, however, the hexane could damage

the membrane structure if this is not solvent resistant. In

this study, it was observed that pre-treated polyether-

sulfone membranes were hexane-resistant. Therefore,

the miscella was used as feed in order to obtain higherpermeate fluxes. Apart from a high permeate flux, the

operating conditions should be chosen to obtain high

phospholipids, free fatty acids and pigments retention,

and low oil retention.

A. Garcıa et al. / Journal of Food Engineering 74 (2006) 516–522 519

In order to select the best membrane to carry out the

degumming of sunflower oil miscella, ES404 and ES209

membranes were compared in terms of permeate fluxes

and rejections at 40 �C, 5 m/s and increasing pressure

from 0.4 to 1.2 MPa. As expected, miscella permeate

fluxes were higher for the membrane with the higherMWCO (Fig. 2). Furthermore, miscella permeate fluxes

increased when the operating pressure was increased

within this range. However, miscella permeate flux with

the ES404 membrane at 1.2 MPa was slightly lower than

that corresponding to a linear increase. According to the

literature, the permeation process is pressure-controlled

when low pressures are employed. However, when high

pressures are used, it is mass transfer-controlled(Pagliero et al., 2001). Within the chosen operating pres-

sure range, the miscella permeate flux with the ES209

membrane lay within the pressure controlled region,

though both regions could be observed when using the

ES404 membrane.

As can be seen in Table 1, phospholipids rejection

was more or less the same for both membranes (95–

97%). Oil rejection was slightly lower for the ES209membrane. As already mentioned, low oil retention is

desirable for the degumming process. Free fatty acids

rejection was lower with the ES404 membrane. This

contradicts the expected trend, as the theoretical

MWCO of this membrane is lower than that of the

0

20

40

60

80

100

120

140

160

0 0.4 0.8 1.2 1.6P (MPa)

J (L

/h m

2 )

ES209ES404

Fig. 2. Effect of operating pressure on miscella permeate flux at 40 �Cand 5 m/s flow rate during the filtration of 30% (w/w) sunflower oil

miscella with ES404 and ES209 polyethersulfone membranes.

Table 1

Effect of operating pressure on oil, phospholipids and free fatty acids rejec

sunflower oil miscella with ES404 and ES209 polyethersulfone membranes

P (MPa) Oil retention (%) Phosphol

ES404 ES209 ES404

0.4 25.2 21.6 96.2

0.8 35.6 32.6 94.6

1.2 42.1 38.2 95.9

ES209 membrane. However, the free fatty acids content

in the miscella used as feed was not the same for the

experiments carried out with both membranes, being

higher for those runs performed with the ES404 mem-

brane. This fact could be the reason for the different

rejections observed. Some authors (Subramanian et al.,2003) have reported that a higher concentration of

FFA in the feed reduced viscosity and increased the

FFA permeation rate, thus decreasing their rejection.

Moreover, the free fatty acids retentions obtained with

the ES404 membrane were negative, which means a

higher FFA concentration in the permeate than in the

feed. This result may be explained by the preferential

permeation of these constituents when compared to tri-glycerides due to selective sorption (Subramanian et al.,

2001, 2001a, 2001b, 2003; Snape & Nakajima, 1996).

The increase in applied pressure had no significant

influence on phospholipids rejection for any of the mem-

branes tested. However, free fatty acids rejection de-

creased for both of the membranes with increasing

pressure. These results were similar to those reported

by other authors (Subramanian et al., 2001, 2001a,2001b), who also obtained negative FFA rejections.

On the other hand, oil content in the permeate decreased

with increasing operating pressure for both membranes.

Fig. 3 shows the absorbance spectra of the following

streams: the crude oil used as feed for the ES404 and

tion at 40 �C and 5 m/s flow rate during the filtration of 30% (w/w)

ipids retention (%) Free fatty acids retention (%)

ES209 ES404 ES209

96.8 �18.4 12.7

96.5 �33.8 7.6

97.2 �48.5 4.2

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

400 450 500 550 600 650 700 750

λ (nm)

Abso

rban

ce

Crude oil. ES404Crude oil. ES209ES404. 1.2 MPaES209. 1.2 MPaRefined oil

Fig. 3. Absorbance spectra of crude and refined sunflower oil, and of

permeates obtained through ES404 and ES209 membranes at 1.2 MPa,

40 �C and 5 m/s.

520 A. Garcıa et al. / Journal of Food Engineering 74 (2006) 516–522

ES209 membranes, the conventionally refined oil, and

permeates obtained at 1.2 MPa with both membranes.

The major pigments present in edible oils are carote-

noids and chlorophyll, with absorbance maximums at

about 450 and 670 nm, respectively. As can be seen in

Fig. 3, the ES404 membrane retained both carotenoidsand chlorophyll, although the colour in the permeate

was stronger than that in a conventionally refined oil.

However, the ES209 membrane showed negative pig-

ment rejection. Previous studies (Koseoglu, 1991; Lin

et al., 1997; Pagliero et al., 2001, 2004) suggested that

pigment rejection was due to the entrapment of these

compounds in phospholipid micelles. Thus, two mem-

branes with similar phospholipid rejection should showsimilar pigment rejection. However, other authors have

reported that the mechanism of pigment retention is

more complex. Subramanian et al. (2001, 2001a,

2001b) concluded that some carotenoids do not have

affinity for the phospholipid reverse micelles, and the ex-

tent of rejection depends on the actual composition of

the different carotenoid pigments present in the oil and

their relative polarity. On the other hand, chlorophyllrejection seems to depend on the MWCO of the mem-

branes (Reddy et al., 2001). Therefore, the different

composition of both types of miscellas may be the rea-

son for the differences observed in pigment retention.

As miscella permeate fluxes were higher with the

ES209 membrane, phospholipid rejection being similar,

FFA rejection higher and oil rejection lower than with

the ES404, the former was selected for the followingset of experiments, which analysed the effect of the oper-

ating parameters on permeate flux and retention. Pig-

ment retention was not taken into account in this part

of the study.

Fig. 4 shows the effect of operating pressure (0.4–

1.2 MPa), temperature (25–40 �C) and feed flow rate

0

20

40

60

80

100

120

140

160

0 0.4 0.8 1.2 1.6

P (MPa)

J (L

/h m

2 )

3 m/s, 25ºC3 m/s, 40ºC5 m/s, 25ºC5 m/s, 40ºC7 m/s, 40ºC

Fig. 4. Effect of operating pressure, temperature and feed flow rate on

permeate flux during the filtration of 30% (w/w) sunflower oil miscella

with ES209 polyethersulfone membranes.

(3–7 m/s) on miscella permeate flux. As expected, when

the operating pressure was increased, the permeation

rate of miscella increased. The operating temperature

also affected the miscella permeation rate: increasing

the temperature lowers viscosity and increases diffusiv-

ity. Both effects result in a higher miscella permeate fluxthrough the membrane (Kim et al., 2002; Lin et al.,

1997; Pagliero et al., 2004). Furthermore, the miscella

permeate flux increased when the feed flow rate was in-

creased from 3 to 5 m/s, although a further increase to

7 m/s had no effect on permeate flux. Therefore, the feed

flow rate of 7 m/s was disregarded due to not having any

positive influence on permeate flux, while the energy

consumption required for the separation would be muchhigher.

Table 2 shows the effect of operating conditions on

oil, phospholipid and free fatty acid rejection. An in-

crease in operating pressure had no noticeable effect

on phospholipid rejection, but caused a slight increase

in oil rejection and a decrease in FFA rejection regard-

less of the operating temperature and feed flow rate. An

increase in the operating temperature had no apprecia-ble effect on phospholipid rejection, but caused a slight

decrease in oil rejection. The effect of temperature on

FFA rejection is not clear from the experimental results.

The effect of the feed flow rate was not significant and

did not follow a clear trend either.

The best conditions for carrying out a degumming

process with this polyethersulfone membrane would

be those that lead to a permeate with as high an oilcontent as possible (low oil rejection) together with a

low phospholipid and free fatty acid content (high

rejections for both components). Furthermore, a high

permeate flux is desirable. As a result of the aforemen-

tioned experiments, the best conditions chosen for a

degumming process with the PES209 polyethersulfone

Table 2

Effect of operating pressure, temperature and feed flow rate on oil,

phospholipids and free fatty acids rejection during the filtration of 30%

(w/w) sunflower oil miscella with ES209 polyethersulfone membranes

Temperature

(�C)Feed flow

rate (m/s)

Pressure

(MPa)

Roil (%) Rphospholipids

(%)

RFFA

(%)

25 3 0.4 26.8 100.0 13.9

0.8 38.5 98.0 6.1

1.2 44.8 98.0 �1.7

25 5 0.4 26.6 96.5 16.8

0.8 39.2 96.5 11.8

1.2 46.2 98.6 �1.7

40 3 0.4 24.1 98.7 20.2

0.8 35.4 97.4 14.0

1.2 41.2 97.4 6.1

40 5 0.4 21.6 96.8 12.7

0.8 32.6 96.5 7.6

1.2 38.2 97.2 4.2

A. Garcıa et al. / Journal of Food Engineering 74 (2006) 516–522 521

membrane were the following: operating pressure,

1.2 MPa; operating temperature, 40 �C; feed flow rate,

5 m/s.

3.3. Miscella concentration

Miscella concentration tests were performed under

the best conditions chosen for the degumming process,

mentioned above. The results were evaluated in terms

of volume concentration ratio (VCR), defined as the

ratio of the initial feed volume to the retentate volume.

A sunflower oil miscella with an oil content of about

30% (w/w) was concentrated up to a VCR of 3.2. Fig.

5 shows the observed permeate fluxes and rejections.The miscella permeate flux decreased more noticeably

initially, suggesting that fouling of the membranes is

an important factor at the beginning of the permeation

process. Flux decline is less pronounced at longer times,

which implies that a gel layer may be affecting the mem-

brane at the final stage (Pagliero et al., 2001). Table 3

summarizes the effect of VCR on retentate composition.

As expected, with increasing VCR, the phospholipidcontent in the retentate increased from an initial value

-20

0

20

40

60

80

100

1.0 1.5 2.0 2.5 3.0 3.5VCR

R (%

)

0

20

40

60

80

100

120

140

J (L

/h m

2 )

R phospholipidsR oilR FFAJ miscella

Fig. 5. Permeate flux and rejection during the concentration of a 30%

(w/w) oil content sunflower oil miscella with the ES209 membrane

(40 �C, 1.2 MPa, 5 m/s).

Table 3

Composition of the retentate when concentrating a 30% sunflower oil

miscella with ES209 polyethersulfone membranes (40 �C, 1.2 MPa,

5 m/s)

VCR Retentate

(g)

Sunflower

oil (g)

Phospholipids

(g)

FFA

(g)

1.00 34,000 9894 158 107

1.05 32,381 9747 170 104

1.11 30,631 9465 165 99

1.25 27,200 8731 164 93

1.43 23,776 8060 152 85

1.67 20,359 7350 145 74

2.00 17,000 6545 147 71

2.50 13,600 5617 135 62

3.20 10,625 4696 128 55

of 1.60 g/100 g oil up to a value of 2.72 g/100 g oil when

the VCR was equal to 3.2 (processing time: around 7 h).

A 1.7-fold increase in concentration was achieved, which

represented a recovery of 81% of the total phospholipids

present in the feed. However, the oil content in the

retentate increased from 29.1% to 44.2%, which meantthat only 52% of the oil was recovered in the permeate

stream. The FFA content increased from 1.08 to

1.19 g/100 g oil, thus achieving 49% removal.

4. Conclusions

Polyethersulfone membranes with different MWCO(4000 and 9000 Da) were used for degumming a sun-

flower oil miscella with about 30% (w/w) oil content in

a cross-flow pilot plant equipment. Both membranes re-

jected phospholipids to the same extent (95–97% rejec-

tion), although the 9000 Da membrane was selected

for further experiments due to its higher miscella perme-

ate flux, its lower oil rejection and its higher FFA rejec-

tion. The effect of temperature, cross-flow velocity andapplied pressure on permeate flux and rejections were

studied with the ES209 membrane. Increasing the tem-

perature from 25 to 40 �C had a positive influence on

permeate flux, as did increasing the feed flow rate from

3 to 5 m/s. However, the influence of these variables on

rejection was not very important. When increasing the

pressure from 0.4 to 1.2 MPa, an increase in permeate

flux was observed, as well as an increase in oil rejectionand a decrease in free fatty acids rejection, although no

significant influence was found on phospholipids rejec-

tion. A sunflower oil miscella with about 30% (w/w)

oil content was concentrated in a batch mode up to a

VCR of 3.2 (1.2 MPa, 40 �C, 5 m/s) with the 9000 Da

membrane. About 81% of the total phospholipids pres-

ent in the oil remained in the retentate. However, only

52% of the oil was recovered in the permeate stream.A 49% reduction in FFA content was also achieved in

the process. A further increase in the MWCO of the

membrane could lead to an increase in permeate flux

and to a decrease in oil losses, while phospholipid rejec-

tion would remain high enough, thus achieving better

separation conditions for subsequent industrial imple-

mentation. Further work with higher MWCO mem-

branes is currently being carried out.

Acknowledgment

The authors are grateful to the European Union for

supporting this work (Project ROSE, ‘‘Recovery of or-

ganic solvents in edible oil extraction by nanofiltration’’,

G1RD-CT-1999-00133). The sunflower oil miscella

used in this study was kindly supplied by KOIPE (Jaen,

Spain).

522 A. Garcıa et al. / Journal of Food Engineering 74 (2006) 516–522

References

Jirjis, B. (2000). Method and apparatus for processing vegetable oil

miscella. International Patent 00/42138.

Jirjis, B. (2001). Method for removing phospholipids from vegetable

oil miscellas, method for conditioning a polymeric microfiltration

membrane, and membrane. US Patent 6207209.

Kim, I.-C., Kim, J.-H., Lee, K.-H., & Tak, T.-M. (2002). Phospho-

lipids separation (degumming) from crude vegetable oil by polyi-

mide ultrafiltration membrane. Journal of Membrane Science, 205,

113–123.

Koike, S., Subramanian, R., Nabetani, H., & Nakajima, M. (2002).

Separation of oil constituents in organic solvents using polymeric

membranes. Journal of American Oil Chemists Society, 79, 937–942.

Koseoglu, S. S. (1991). Membrane technology for edible oil refining.

Oils and Fats International, 5, 16–21.

Koseoglu, S. S., Lawhon, J. T., & Lusas, E. W. (1990). Membrane

processing of crude vegetable oils: Pilot plant scale removal of

solvent from oil miscellas. Journal of American Oil Chemists

Society, 67(5), 315–322.

Lin, L., Rhee, K. C., & Koseoglu, S. S. (1997). Bench-scale membrane

degumming of crude vegetable oil: Process optimisation. Journal of

Membrane Science, 134, 101–118.

Ochoa, N., Pagliero, C., Marchese, J., & Mattea, M. (2001).

Ultrafiltration of vegetable oils. Degumming by polymeric mem-

branes. Separation and Purification Technology, 22-23, 417–422.

Pagliero, C., Ochoa, N., Marchese, J., & Mattea, M. (2001).

Degumming of crude soybean oil by ultrafiltration using polymeric

membranes. Journal of American Oil Chemists Society, 78, 793–

796.

Pagliero, C., Ochoa, N., Marchese, J., & Mattea, M. (2004). Vegetable

oil degumming with polyimide and polyvinilidenfluoride ultrafil-

tration membranes. Journal of Chemical Technology and Biotech-

nology, 79, 148–152.

Reddy, K., Subramanian, R., Kawakatsu, T., & Nakajima, M. (2001).

Decolorization of vegetable oils by membrane processing. Euro-

pean Journal of Food Research Technology, 213, 212–218.

Snape, J. B., & Nakajima, M. (1996). Processing of agricultural fats

and oils using membrane technology. Journal of Food Engineering,

30, 1–41.

Subramanian, R., Nabetani, H., Nakajima, M., Ichikawa, S., Kimura,

T., & Maekawa, T. (2001). Rejection of carotenoids in oil systems

by a nonporous polymeric composite membrane. Journal of

American Oil Chemists Society, 78, 803–807.

Subramanian, R., Raghavarao, K. S. M. S., Nabetani, H., Nakajima,

M., Kimura, T., & Maekawa, T. (2001a). Differential permeation

of oil constituents in nonporous denser polymeric membranes.

Journal of Membrane Science, 57–69.

Subramanian, R., Raghavarao, K. S. M. S., Nabetani, H., Nakajima,

M., Kimura, T., & Maekawa, T. (2001b). Differential permeation

of oil constituents in nonporous denser polymeric membranes.

Journal of Membrane Science, 57–69.

Subramanian, R., Raghavarao, K. S. M. S., Nakajima, M., Nabetani,

H., Yamaguchi, T., & Kimura, T. (2003). Application of dense

membrane theory for differential permeation of vegetable oil

constituents. Journal of Food Engineering, 60, 249–256.