Tải bản đầy đủ - 0 (trang)
7 Supercritical Carbon Dioxide (SC-CO 2) Extraction and Deacidification of Rice Bran Oil

7 Supercritical Carbon Dioxide (SC-CO 2) Extraction and Deacidification of Rice Bran Oil

Tải bản đầy đủ - 0trang

2



Green Fluids Extraction and Purification of Bioactive Compounds…



105



12-1

13

10-1

7



2



12-2

14



3



11-3

6



11-2

10-2

16



8

9



15

11-1

1



4



5



1. CO2 cylinder



10-1. Extraction vessel



2. CO2 cleanup column



10-2. Reboiler



3. Cold liquid circulator



11-1~11-3. Metering valve



4. Temperature controller 12-1~12-2. Back pressure regulator

5. High pressure pump



13. Needle valve



6. Pressure gauge



14. Separator



7. Hot liquid circulator



15. Wet gas meter



8. Preheater



16. Thermocouple



9. Check valve

Fig. 2.20 Schematic flow diagram of SC-CO2 extraction of rice bran oil (Reprinted from Ref.

[55]. With kind permission of Wiley-VCH Verlag GmbH & Co)



was packed into the two ends of the extractor to prevent the rice bran powder

escaping from the extractor. Liquid CO2 from a cylinder (1) into which was inserted

a siphon tube passed through a cooling bath (3) at 277 K was compressed to the

desired working pressure using a syringe pump (100DX, ISCO, USA) (5) and was

heated to supercritical conditions using a double-pipe heat exchanger (8) and a

reboiler (10–2). This carbon dioxide, maintained at a flow rate of 5 L/min (STP),

flowed into the extractor (10–1), came into contact with the rice bran powder, and

was used to extract the oil. A heating element equipped with a PID temperature



C.-R. Chen et al.



106



controller (4) was thermostatically maintained at a constant temperature; two

back-pressure regulators (12–1, 12–2) located at the outlet were manually adjusted

to maintain constant extraction pressure. Following the extraction, the oil-laden CO2

was driven into a 130-mL separator (14) by a drop in pressure and expanded through

a spiral-type nozzle at 50 bar and 303 K. The amount of low-pressure CO2 was

measured using a wet gas meter (W-NK-Da-1B, Shinagawa, Japan) (15) and thus

returned to the ambient conditions. At the end of each experiment, the extracted

solution was collected, and the solvent was evaporated using a vacuum rotary evaporator. The residue was weighed and stored in 273 K before use. The total yield, the

extraction efficiency, and the concentration factor of g-oryzanols, free fatty acids,

and triglycerides in the extracts were then calculated.

Table 2.14 presents experimental data on the RSM-designed SC-CO2 extractions

of rice bran oil at temperatures from 313 to 333 K and pressures from 250 to 350 bar.

The effects of these two factors on the extraction efficiencies and the concentration

factors seem to be of the same order of magnitude. Figure 2.21a–c show that the

total oil yield, extraction efficiency of g-oryzanols (Rory), and triglycerides (RTG)

reached to maxim value as 19.6%, 94.4%, and 94.5%, respectively, at 350 bar and

333 K (datum#9 in Table 2.14) and increased dramatically with pressure. However,

the effect of temperature was not significant. Figure 2.21d shows that the extraction

efficiency of free fatty acids is reduced as the pressure increased. The low concentration of free fatty acids at high-pressure extraction may be explained by the high

yield of other components in the extracted oil. Figure 2.22 plots the concentration

factors of g-oryzanols and triglycerides (bory and bTG) from where it is evident that

concentration factors (bory and bTG) are increased with the increasing pressure

(Fig. 2.22a, b), but the concentration factor of free fatty acids (bFFA) decreased as

shown in Fig. 2.22c.



2.7.2



Pilot-Scale Supercritical Carbon Dioxide

(SC-CO2) Extraction



Figure 2.23 displays a schematic flow diagram of pilot-scale SC-CO2 extraction of

rice bran oil from powdered rice bran. A mass of rice bran powder varying from 0.6

to 1 kg was individually packed inside a 5-L stainless steel tubular extractor. Liquid

CO2 from a cylinder (1) was passed through a chiller (3) at 277 K and was compressed to the desired working pressure using a high-pressure pump (2) and heated

to supercritical conditions using a preheater (6–1). This carbon dioxide flowed into

the extractor (7), came into contact with the rice bran powder, and was used to

extract the oil. A heating circulator (9–1) was maintained at a constant temperature;

a metering valve (12–5) located at the outlet was manually adjusted to maintain

constant extraction pressure. A drop in the pressure drove the oil-laden CO2 into a

1-L separator (8) at 50 bar and 308 K following the extraction. The amount of lowpressure CO2 was measured using a wet gas meter (10) and thus returned to the



250

250

250

250

250

250

300

300

300

300

300

300

350

350

350

350

350

350



313

313

323

323

333

333

313

313

323

323

333

333

313

313

323

323

333

333



5.618

5.582

5.568

5.626

5.350

5.378

6.138

6.162

6.312

6.358

6.557

6.603

6.437

6.373

6.602

6.594

6.844

6.876



16.1

15.9

15.9

16.1

15.3

15.4

17.5

17.6

18.0

18.2

18.7

18.9

18.4

18.2

18.9

18.8

19.6

19.6



4.29

4.49

4.17

4.27

4.01

4.17

15.2

15.3

14.9

15.0

14.4

14.6

13.6

13.7

14.0

14.2

14.7

14.5



0.69

0.72

0.66

0.69

0.61

0.64

2.66

2.70

2.68

2.72

2.70

2.75

2.50

2.50

2.65

2.68

2.87

2.85



22.7

23.6

21.9

22.7

20.2

21.1

87.9

89.0

88.4

89.7

89.0

90.8

82.5

82.4

87.4

88.5

94.7

94.1



1.42

1.48

1.38

1.41

1.32

1.38

5.01

5.06

4.90

4.94

4.75

4.81

4.49

4.52

4.63

4.70

4.84

4.79



118

118

118

117

120

120

106

105

104

103

101

101

97.0

96.5

99.7

99.4

97.0

96.8



19.0

18.8

18.7

18.9

18.3

18.4

18.6

18.5

18.7

18.8

19.0

19.0

17.8

17.6

18.8

18.7

19.0

19.0



99.8

99.1

98.4

99.3

96.5

96.8

97.6

97.5

98.4

98.8

99.7

100

93.8

92.4

98.9

98.6

99.8

100



6.22

6.21

6.19

6.18

6.31

6.30

5.56

5.54

5.46

5.44

5.32

5.30

5.10

5.07

5.24

5.23

5.10

5.09



825

826

834

834

835

835

831

830

819

819

811

812

777

776

766

767

771

771



132

132

133

134

128

128

146

146

148

149

152

153

143

141

145

144

151

151



82.8

82.3

82.9

83.8

79.8

80.2

91.1

91.4

92.3

93.0

95.0

95.7

89.3

88.3

90.4

90.3

94.3

94.6



5.16

5.16

5.21

5.21

5.22

5.22

5.19

5.19

5.12

5.12

5.07

5.07

4.85

4.85

4.79

4.79

4.82

4.82



56

56

48

48

44

44

61

62

75

75

85

85

124

125

131

131

129

130



Woil weight of the extracted, TY total oil yield = (Woil/WRB) × 100%, WRB weight of rice bran, WOry weight of oryzanols, W*Ory yield of oryzanols, WFFA weight of free

fatty acids, W*FFA yield of free fatty acids, WTG weight of triglycerides, W*TG yield of triglycerides, ROry oryzanol extraction efficiency = (W*Ory/W*Ory,Soxhlet) × 100%,

RFFA free fatty acids extraction efficiency = (W*FFA/W*FFA,Soxhlet) × 100%, RTG triglycerides extraction efficiency = (W*TG/W*TG,Soxhlet) × 100%, bOry concentration factor of

oryzanols = ROry/TY, bFFA concentration factor of free fatty acids = RFFA/TY, bTG concentration factor of triglycerides = RTG/TY, Others weight of waxes, glycolipids, and

phospholipids.



9(A)



8(F)



7(A)



6(F)



5(C)



4(F)



3(A)



2(F)



1(A)



Table 2.14 SC-CO2 extractions of rice bran oil designed using response surface methodology (Reprinted from Ref. [55]. With kind permission of Wiley-VCH Verlag

GmbH & Co)

WOry

W*Ory

WFFA

W*FFA

WTG

W*TG

Others

RSM # P (bar) T (K) Woil (g) TY (%) (mg/goil) (mg/gRB) ROry (%) bOry (mg/goil) (mg/gRB) RFFA (%) bFFA (mg/goil) (mg/gRB) RTG (%) bTG (mg/goil)



2

Green Fluids Extraction and Purification of Bioactive Compounds…

107



C.-R. Chen et al.



108



333

350



328



325



323



Temperature

(K)



300

318



275

313 250



Pressure

(bar)



Concentration of TG (%)



c



100

80

60

40

20



333



350



328



325



323



Temperature

(K)



300

318



275

313 250



Pressure

(bar)



d

96.0

92.2

88.5

84.8

81.1



333



350



328

323



325



Concentration of FFA (%)



Total of Oil (%)



19.7

18.7

17.6

16.6

15.5



Concentration of Ory (%)



b



a



11.8

11.3

10.7

10.2

9.7



333



300



Temperature 318

275

Pressure

313 250

(K)

(bar)



350



328



Temperature

(K)



325



323



300



318



275

313 250



Pressure

(bar)



Fig. 2.21 Effects of pressure and temperature on SC-CO2 extractions of rice bran oil (a) total oil

yield, (b) extraction efficiency of oryzanols, (c) extraction efficiency of triglycerides, and (d)

extraction efficiency of free fatty acids (F-testing: R(a)2 = 0.9808, S.D.(a) = 0.34; R(b)2 = 0.9996,

S.D.(b) = 1.12; R(c)2 = 0.9731, S.D.(c) = 1.48; R(d)2 = 0.9163, S.D.(d) = 0.98) (Reprinted from Ref. [55].

With kind permission of Wiley-VCH Verlag GmbH & Co)



ambient conditions. At the end of each experiment, the extracted oil was collected

through a metering valve (13–3).

Table 2.15 presents experimental data on the SC-CO2 extraction of rice bran oil

from 0.6 to 1.03 kg of powder. The total oil yield exceeded 15% upon extraction at

300 bar and 313 K using a constant solvent-to-feed ratio of 20. The concentrations

of g-oryzanols, free fatty acids, and triglycerides remain unchanged. The oil

extracted in Exp. #4 was used for following SC-CO2 deacidifications.



2



Green Fluids Extraction and Purification of Bioactive Compounds…



b

Concentration Factor of FFA (%)



Concentration Factor of Ory (%)



a



109



5.3

4.3

3.3

2.3

1.3



333



350



328



325



323



Temperature

(K)



300

318



275

313 250



6.3

6.0

5.7

5.4

5.1



333



350



328

300

318



Temperature

(K)



Pressure

(bar)



325



323

275

313 250



Pressure

(bar)



Concentration Factor of TG (%)



c



5.2

5.1

5.0

4.9

4.8



333



350



328



Temperature

(K)



325



323



300

318



275

313 250



Pressure

(bar)



Fig. 2.22 Effects of concentration factors on SC-CO2 extractions of rice bran oil (a) concentration

factor of oryzanols, (b) concentration factor of free fatty acids, and (c) concentration factor of triglycerides (F-testing: R(a)2 = 0.9981, S.D.(a) = 0.12; R(b)2 = 0.9751, S.D.(b) = 0.13; R(c)2 = 0.9703,

S.D.(c) = 0.05) (Reprinted from Ref. [55]. With kind permission of Wiley-VCH Verlag GmbH & Co)



2.7.3



Experimentally Designed Supercritical Carbon Dioxide

(SC-CO2) Deacidification



Figure 2.24 presents a schematic flow diagram of the SC-CO2 deacidification of rice

bran oil. Thirteen grams of the SC-CO2 oil obtained by extraction at 300 bar and

313 K and the q type of packed materials were vertically loaded into the bottom of

the deacidified column (8) in succession. Liquid CO2 from a cylinder (1) was passed

through a cooling bath (3) at 277 K, preheated by a hot plate (6) through an oil bath

(7), and was compressed using a syringe pump (4). This carbon dioxide, maintained

at a flow rate of 10 g/min, flowed into the deacidification column whose pressure



C.-R. Chen et al.



110

11-1



11-2



11-3



11-4



12-2

12-5

12-4

12-6



12-1

3

7

5



3



4-1



4-2

3



1



6-1



8



6-2



2

13-1



3

2



12-3

9-1



13-2



9-2



13-3



1



10



1. CO2 cylinder



2. Pump



3. Chiller



4-1~2. CO2 cleaner



5. Mixer



6-1~2. Pre-heater



7. Extractor



8. Separator



9-1~2. Circulator



10. Wet gas meter 11-1~4. Gauge



12-1~6. Metering valve



13-1~3. Vent valve

Fig. 2.23 Schematic flow diagram of pilot-scale SC-CO2 extraction of rice bran oil (Reprinted

from Ref. [57]. With kind permission of © Elsevier)



was maintained by a back-pressure regulator (9–1). A heating element, equipped

with a PID temperature controller (16), was thermostatically maintained at a constant temperature. Following SC-CO2 deacidification, a drop in pressure drove the

acid-laden CO2 into a separator (12), and the gas was then expanded through a spiral-type nozzle at 50 bar. The amount of low-pressure CO2 was measured using a

wet gas meter (14) before the gas was returned to the ambient conditions. Following

this process, the deacidified oil was collected in a flask (13) by opening the metering

valve (11–3) after depressurization and was then ready for analysis and calculation.

In addition, the free fatty acid–enriched extracted oil was also gathered by opening

the metering valve (11–2).

Table 2.16 displays experimental data on the RSM-designed SC-CO2 deacidification. In these experiments, the amount of remaining triglycerides and the removal

efficiencies of free fatty acids are two major variables of interest. The free fatty acid

content, 0.13%, in the deacidified oil was obtained at 250 bar, 353 K, and 2,700 g of

CO2 extraction. This experiment demonstrated that the retention efficiency of oil

and the removal efficiency of free fatty acids were 82.2 and 97.8%, respectively.

The product of these two responses reached 80.4, which is the highest value among

all 15 RSM experiments. Further examination of these data revealed that the concentration factors of g-oryzanols and triglycerides increased, but the concentration

factors of free fatty acids decreased to zero (datum # 9), implying that active compounds in the deacidified oil were concentrated and the free fatty acid content in the



2



0.60

12.1

1.03 ± 0.01 20.5 ± 0.2



90.7

15.1

6.0

52.0

3.44

35.4

82.3

5.45

864

157 ± 5 15.7 ± 0.5 6.3 ± 0.1 56.3 ± 2.4 3.58 ± 0.04 37.5 ± 0.8 90.7 ± 4.5 5.76 ± 0.13 866 ± 7



89.0

5.89

94.6

93.4 ± 3.7 5.93 ± 0.05 89.9 ± 7.2



WRB weight of rice bran, WCO weight of carbon dioxide, Woil weight of extracted oil, TY total oil yield = (Woil/WRB) × 100%, WOry concentration of oryzanols, WFFA concentration

2

of free fatty acids, WTG concentration of triglycerides, Wothers concentration of waxes, glycolipids, and phospholipids, ROry oryzanol extraction efficiency = [(WOry × TY)/

(WOry,Soxhlet × TYSoxhlet)] × 100%, RFFA free fatty acids extraction efficiency = [(WFFA × TY)/(WFFA,Soxhlet × TYSoxhlet)] × 100%, RTG triglycerides extraction efficiency = [(WTG × TY)/

(WTG,Soxhlet × TYSoxhlet)] × 100%, bOry oryzanol concentration factor = ROry/TY, bFFA free fatty acids concentration factor = RFFA/TY, bTG triglycerides concentration factor = RTG/TY



3

4



Table 2.15 Experimental data on SC-CO2 extractions of rice bran oil from 0.6- to 1.03-kg powder at 300 bar and 313 K (Reprinted from Ref. [57]. With kind permission

of © Elsevier)

WOry

WFFA

WTG

Wothers

Exp # WRB (kg)

WCO (kg) Woil (g) TY (%) (mg/goil) ROry (%) bOry

(mg/goil) RFFA (%) bFFA

(mg/goil) RTG (%) bTG

(mg/goil)



C.-R. Chen et al.



112

16

17

5

17

16

5

9-1 5

10



15



11-1



8



9-2



2

11-4



5



12

11-2

17



11-3



14



¢

J



7



1



3



4



13



6



1. CO2 cylinder



10. Micro-metering valve



2. CO2 cleanup column



11-1~4. Metering valve



3. Constant temperature circulator



12. Separator



4. High-pressure pump



13. Collection flask



5. Pressure gauge



14. Wet gas meter



6. Hot plate



15. Temperature display



7. Oil bath



16. Temperature controller



8. Extraction vessel



17. Thermocouple



9-1~2. Back-pressure regulator

Fig. 2.24 Schematic flow diagram of SC-CO2 deacidification of rice bran oil (Reprinted from Ref.

[57]. With kind permission of © Elsevier)



WCO2 (g)

89.7

85.7

86.7

83.5

79.7

84.0

86.3

84.5

85.5

81.0

74.6

70.1

84.6

85.1

90.6



45.9

7.8

18.4

59.1

20.4

6.3

37.7

8.6

2.9

9.3

15.5

0.1

4.0

15.7

0.9



96.4

92.7

93.9

96.0

93.6

86.2

96.4

92.1

90.2

90.8

76.2

54.6

76.6

88.2

76.1



1.02

1.02

1.00

0.94

0.92

1.06

0.98

0.98

1.03

0.97

1.05

1.40

1.19

1.05

1.29



0.52

0.09

0.21

0.67

0.24

0.08

0.43

0.10

0.03

0.11

0.22

0.003

0.06

0.20

0.01



bFFA

1.10

1.11

1.09

1.09

1.09

1.10

1.11

1.08

1.10

1.09

1.08

1.10

1.09

1.09

1.09



bTG

63.8

93.7

85.3

55.4

83.9

95.5

70.5

93.4

97.8

92.7

90.2

99.9

97.2

88.5

99.3



55.9

78.6

73.2

48.8

72.0

74.6

61.3

79.3

80.4

77.0

63.9

49.7

68.9

71.6

69.6



RRFFA (%) Roil × RRFFA



WCO2 weight of carbon dioxide, Woil weight of extracted oil, Roil oil retention = Woil/Woil,feed × 100%, Ory oryzanol concentration = (WOry/Woil) × 100%, FFA free fatty

acids concentration = (WFFA/Woil) × 100%, TG triglycerides concentration = (WTG/Woil) × 100%, ROry oryzanol recovery = (WOry/WOry,feed) × 100%, RFFA free fatty acids

recovery = (WFFA/WFFA,feed) × 100%, RTG triglycerides recovery = (WTG/WTG,feed) × 100%, bOry oryzanol concentration factor = Ory/Oryfeed, bFFA free fatty acids concentration factor = FFA/FFAfeed, bTG triglycerides concentration factor = TG/TGfeed, RRFFA free fatty acids removal = (WFFA,feed − WFFA)/WFFA,feed × 100%



95.2

95.8

94.4

93.9

94.2

95.2

95.8

93.5

94.9

94.6

93.3

94.9

93.9

94.6

94.2



P (bar) T (K) Woil (g) Roil (%) Ory (%) FFA (%) TG (%) ROry (%) RFFA (%) RTG (%) bOry



Oil contained 0.63% Ory, 3.75% FFA, 86.6% TG before deacidification

1(F)

900

200

343

11.4

87.6

0.64

1.96

2(F)

2,700

200

343

10.9

83.9

0.64

0.35

3(A)

1,800

200

353

11.2

85.8

0.63

0.80

4(F)

900

200

363

11.5

88.1

0.59

2.50

5(F)

2,700

200

363

11.2

85.8

0.58

0.89

6(A)

1,800

250

343

10.2

78.1

0.67

0.30

7(A)

900

250

353

11.3

86.9

0.62

1.62

8(C)

1,800

250

353

11.1

84.9

0.62

0.38

9(A)

2,700

250

353

10.7

82.2

0.65

0.13

10(A)

1,800

250

363

10.8

83.1

0.61

0.42

11(F)

900

300

343

9.2

70.8

0.66

0.82

12(F)

2,700

300

343

6.5

49.7

0.88

0.01

13(A)

1,800

300

353

9.2

70.9

0.75

0.21

14(F)

900

300

363

10.5

80.9

0.66

0.73

15(F)

2,700

300

363

9.1

70.1

0.81

0.05



RSM #



Table 2.16 Experimentally designed SC-CO2 deacidifications of rice bran oil obtained by SC-CO2 extraction at 300 bar and 313 K (Reprinted from Ref. [57].

With kind permission of © Elsevier)



2

Green Fluids Extraction and Purification of Bioactive Compounds…

113



C.-R. Chen et al.



114



b

FFA Removing (%)



FFA Removing (%)



a

105

93

80

68

55



2700



300

275

2250



1350



WCO2 (g)



225

900 200



363



300



358



250

1800



105

98

90

83

75



Pressure

(bar)



275



353



Temperature

(K)



250



348



225

343 200



Pressure

(bar)



FFA Removing (%)



c

105

93

80

68

55



363



2700



358



2250



353



1800



348



1350



WCO2 (g)



900 343



Temperature

(K)



Fig. 2.25 Three-dimensional responded experimental data on removal efficiency of free fatty

acids using SC-CO2 deacidification (a) temperature: 363 K, (b) WCO2 : 1,800 g, and (c) pressure:

250 bar, datum #10 in Table 2.16 (F-testing: R2 = 0.9788, S.D. = 3.30) (Reprinted from Ref. [57].

With kind permission of © Elsevier)



oil was substantially decreased. Figure 2.25 shows that effects of pressure and the

amount of consumed CO2 are important to the removal efficiency of free fatty acids.

Figure 2.26 reveals that the effect of pressure is more significant than that of CO2

consumption. The effect of temperature is insignificant because the operative region

is close to the crossover pressure and the solubility of triglycerides in supercritical

carbon dioxide increases as the fluid density increases with pressure. Figure 2.27

plots the effects of the pressure and CO2 consumption associated with a multiple

response of the retention of oil and the removal efficiency of free fatty acids. The

value of this response is optimal at 260 bar, 363 K, and with 2,160 g of CO2

consumed.



2



Green Fluids Extraction and Purification of Bioactive Compounds…



115



b



a



Oil Remaining (%)



Oil Remaining (%)



95

83

70

58

45



2700

300

2250

275

1800

250

225

WCO2 (g) 1350

Pressure

900 200



(bar)



90

81

73

64

55



363

300



358



275



353



Temperature

(K)



250

348



225

343 200



Pressure

(bar)



c

Oil Remaining (%)



90

81

73

64

55



2700

2250

1800

WCO2 (g) 1350



363

358

353

348

900 343



Temperature

(K)



Fig. 2.26 Three-dimensional responded experimental data on retention efficiency of oil using

SC-CO2 deacidification (a) temperature: 353 K, (b) WCO2 : 1,800 g, (c) pressure: 250 bar, datum

# 8 in Table 2.16 (F-testing: R2 = 0.9798, S.D. = 2.44) (Reprinted from Ref. [57]. With kind permission of © Elsevier)



2.8



Conclusions



For SC-CO2 extraction of the DHCA from Brazilian propolis, the addition of ethyl

acetate significantly affects the recovery and purity of DHCA. The purity of DHCA

extracted by SC-CO2 extraction is superior to that obtained by Soxhlet ethyl acetate

extraction. Furthermore, SC-CO2 extraction has been recognized as an environmentally benign method to produce natural healthy materials. The purest DHCA could

be obtained by further purification of the SC-CO2 extracts using a normal-phase

column adsorption chromatography without solvent pretreatment. Therefore, the

SC-CO2 is a green solvent to avoid several organic solvent partitions in obtaining

the purest DHCA in the product. For SC-CO2 antisolvent precipitation of Brazilian



Tài liệu bạn tìm kiếm đã sẵn sàng tải về

7 Supercritical Carbon Dioxide (SC-CO 2) Extraction and Deacidification of Rice Bran Oil

Tải bản đầy đủ ngay(0 tr)

×