Facilitatory effect of dissolved carbon dioxide in subcritical water for pectin hydrolysis Akiko Takahashi1), Takuya Suetsugu1), Masahiro Tanaka2), Munehiro Hoshino3), Mitsuru Sasaki1), Motonobu Goto4) 1)
Graduate School of Science and Technology, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555 JAPAN
2)
Maruboshi Vinegar Co. Ltd., 2342 Tabara, Kawasaki-mati Tagawagun, Fukuoka, 827-0004, JAPAN 3)
4)
ASCII, Co Ltd, 2425 Tabara, Kawasaki-mati Tagawagun, Fukuoka, 827-0004, JAPAN
Bioelectorics Research Center, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555 JAPAN
*Corresponding author, Phone: +81-96-342-3664, Fax: +81-96-342-3665, Email:
[email protected]
ABSTRACT Pectin is composed of an acidic polysaccharide and several types of neutral sugars. The main chain consists of -1,4-linked D-galacturonic acid, which is partly methyl esterified. Most of pectin products are used for the production of jelly and jam because of having high viscosity, low-solubility, and gel forming properties. Recently, many properties of decomposed pectin products have been revealed. The hydrolysis of pectin and decomposition of galacturonic acid proceeds simultaneously at relatively moderate subcritical region of 140-180 oC due to easily hydrated structures. Water in contact with carbon dioxide becomes acidic due to the formation and dissociation of carbonic acid. Citrus pectin solution was used as a starting material. Pectin hydrolysis was carried out in the vessel type reactor under the hydrothermal condition with carbon dioxide below 150 oC. Under the adding of CO2 conditions, the degradation of pectin molecule proceeded slightly with increasing pressure. It was suggested that the CO2 dissolution in water exerted the catalytic effect. ATR-FTIR spectroscopy was used as an analytical tool to qualitatively determine the chemical change in the material. The ratio of methyl group in the pectin molecule was hardly changed.
Keywords: citrus pectin, galacturonic acid, ATR-FTIR
Facilitatory effect of dissolved carbon dioxide in subcritical water for pectin hydrolysis Akiko Takahashi1), Takuya Suetsugu1), Masahiro Tanaka2), Munehiro Hoshino3), Mitsuru Sasaki1), Motonobu Goto4) 1) Graduate School of Science and Technology, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555 JAPAN 2) Maruboshi Vinegar Co. Ltd., 2342 Tabara, Kawasaki-mati Tagawagun, Fukuoka, 827-0004, JAPAN 3) ASCII, Co Ltd, 2425 Tabara, Kawasaki-mati Tagawagun, Fukuoka, 827-0004, JAPAN 4) Bioelectorics Research Center, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555 JAPAN
Aug. 28. 2011 Kumamoto University
Contents Introduction Background Purpose of this work Experiment 1 Batch type reaction Result Experiment 2 Vessel type reaction Result Summary
Introduction -What is pectinPectin
COOH COOCH3 Ca2+ COO
COOCOO- -OOC Ca2+
Su P
COO- COOMg Ca2+ COO2+COO-
- OOC
Su
P
Ca2+ COO
P
COOH
COOH
P
Acid extraction
COOH COOCH
COOCH P
Cell walls
Commercial pectin product
Cellulose
P Phosphate group Pectin Su Neutral sugar Hydrogen bond
Industrially, pectin has been extracted from citrus peel and apple pomace using mild acid to separate from cellulose.
Introduction Relationship between Molecular Size and Use of Pectin High molecular weight pectin
Gelling agent Emulsifier Mw 200000~50000 Anti cancer effect
Enzyme
Low molecular weight pectin Mw 20000~5000
Hypolipidemic action
Enzyme
High value
Easy soluble dietary fiber
Pectic oligosaccharide 20mer~monomer Antiallergenic effect
Plant growth effect
Source of nutrient for bifidus
Pectic hydrolysis products have many properties and wide availabilities suited for various molecular sizes.
Background –Property of subcritical water※Ion product of water under ambient condition Kw= [H+][OH-]= 10-14 mol2 / L2 -5 -5 Kw=10-11 mol2 / L2
log KKWw log
-10 -10 100MPa 90MPa 80MPa 70MPa 60MPa
-15 -15
50MPa
-20 -20
40MPa 30MPa 22.1MPa 20MPa
-25 -25
15MPa 10MPa
-30 -30 0 0
100 100
200 200
300 300
400 400 [oC]
Temperature o Temperature [ C]
500 500
600 600
Figure 1 Ion product for water Subcritical water have been used as a reaction medium for hydrolysis of polysaccharide. Its reaction selectivity is given by changing the operation condition.
Purpose of this work Citrus pectin (raw material)
Subcritical water
Batch type reactor and Vessel type reactor
Subcritical water ＋ Carbon dioxide
Pectic oligosaccharide Hydrolysis of high molecular weight pectin to smaller size using subcritical water and carbon dioxide.
Experiment 1 - Batch type reaction-
Mixing heater
Reactor 5.5mL
Experimental Conditions Material ： 3 mL of 1wt % of citrus pectin solution Reaction time ： 3, 15, 30, 60 min Reaction temperature ：120, 140, 160, 180, 200oC
Result -Analysis of decomposition productsRI response
Pectin molecule Pectic oligosaccharide Galacturonic acid
160 oC, 60min
Neutral sugars Decomposition products Dyhydroxy acetone
Column: Sugar SH1011 Detector：RI, UV-Vis 430nm
Abs. 430 nm
Pectin molecule Galacturonic acid Lactic acid Formic acid Acetic acid
Void volume 0
10
20
30
40
50
60
Retention time [min]
Figure 2 HPLC chromatograms of SH1011 column obtained from 60 min of batch
reaction at 160 oC.
Result -Decomposition behavior of pectinPectin (Mw >1000) 140oC
160oC
Galacturonic acid (monomer)
180oC
200oC
100 90 80 70 60 50 40 30 20 10 0
120oC
140oC
160oC
180oC
200oC
5
Yield [%]
Residual [%]
120oC
4 3 2
1 0 0
10
20
30
40
50
60
70
0
10
Reaction time [min]
20
30
40
50
60
70
Reaction time [min]
Figure 3 Effect of reaction temperature and time on residual pectin molecule for a batch reactor
Figure 4 Effect of reaction temperature and time on yield of galacturonic acid for a batch reactor
Result -Further decomposition productsFormic acid 120 oC
140 oC
160 oC
2-furfral
180 oC
120
200 oC
3.5
oC
140
oC
160 oC
180 oC
200 oC
4
3 3 Yield [%]
Yield [%]
2.5 2 1.5 1
2
1
0.5
0
0
10
20
30
40
50
60
70
Reaction time [min]
Figure 5 Effect of reaction temperature and time on yield of formic acid for a batch reactor
0
0
10
20 30 40 50 60 Reaction time [min]
70
Figure 6 Effect of reaction temperature and time on yield of 2-furfural for a batch reactor
Result -Oligomerization behavior of pectinBatch reaction at 160 oC Pectin molecule (>Mw 10000) DP=8
Control 3 min 15 min 30 min 60 min
Galacturonic acid
RI response
DP=7 DP=6 DP=5
Column: Sugar SH1821 Detector：RI
DP=4 DP=3 DP=2
3
4
5
6
7
8
9
10
11
12
Retention time [min]
Figure 7 Oligosaccharide distribution chromatogram of hydrothermal reactive solutions at 160 oC using batch reactor.
Result Citrus pectin Hydrolysis ~120 oC
Pectic oligosaccharides Hydrolysis ~120 oC
Hydrolysis and further decomposition proceed simultaneously with ・Progress of reaction time and ・Rise of reaction temperature
Galacturonic acid Dehydration ~160 oC
2-furfural
Decomposition ~120 oC
Organic acids
Shorter reaction time and Lower reaction temperature
Experiment 2 -Vessel type reactorBPR
P Gas meter
Feed pump Chiller
1% Pectin solution T
CO2 pump Heater
Metering valve
Sample
Stirrer
N2
CO2
Vessel:30mL
Experimental Conditions Feed material： 25 mL of 1wt % of citrus pectin solution Reaction time ： 30 min Reaction pressure：30 MPa Reaction temperature ：100, 120, 140, 150 oC
Result -Effect of adding CO2Add CO2
N2
[MPa]
30
10
20
Pectin molecule
Acetic acid
30
(b) UV
(a) RI 100 oC
120
oC
Intensity
CO2 10MPa CO2 10MPa
CO2 20MPa
CO2 20MPa CO2 30MPa
CO2 30MPa N2 30MPa
140 oC 4
5
6
7
8
9
10 11 4
Retention time [min]
Figure 8 Appearance of samples
N2 30MPa
5
6
7
8
9
10 11
Retention time [min]
Figure 9 Effect of adding CO2 on the HPLC chromatograms of reaction solutions
Conclusions Pectic oligosaccharide was obtained under hydrothermal condition without using catalyst. Hydrolysis and further decomposition of pectic substances proceed simultaneously with progress of reaction time and rise of reaction temperature. Slight catalysis effect has been confirmed by adding carbon dioxide in pectin hydrolysis.
ACKNOWLEDGEMENT This research was supported by Kumamoto University Global COE Program “Global Initiative Center for Pulsed Power Engineering”.
Thank you very much for your kind attention!
-Complex structure of pectin moleculeH H
Homogalacturonan
O
COOH
OH
O OH
H
H O COOCH3
H
H
O H
H
OH H
O
H
H
OH
OH
H
COOH O
H
H
O COOCH3
OH
H
O H
OH
H
H
OH
O n
a-1,4-linked D-galacturonic acid
Rhamnogalacturonan I
Rhamnogalacturonan II Glucronic acid
Glacturonic acid
Arabinose Xylose
Galactose Fucose
Apiose
4-O-cetyl-2-O-methylfucose
Aceric acid
Rhamunose
2-methylxylose
Kdo
M Methyl group
Dha
Figure 1 The canonical primary structure of pectin
-Solubility of carbon dioxide in subcritical water0.045
Solubility of CO2 (mol fraction)
60MPa Wiebe et.al, (1939) Wiebe et.al, (1940) A. N. Sabirzyanov, (2003)
0.04 0.035
40MPa
0.03 0.025
30MPa
0.02
15MPa
30MPa 15MPa
7.5MPa
0.015
20MPa
10MPa
10MPa
7.5MPa
0.01 0.005 0
0
20
40
60
80
100
Temperature [oC]
120
140
160
