Thermoplasticization of zein and kafirin
IMCB-CNR
November 2004
Processing condition for extrusion
I. Increase of viscosity due to plasticization
II. Decrease of viscosity due to the increase of T
III. Increase of viscosity due to further plasticization and/or chemical reactions
IV. Decrease of viscosity due to the increase of T and degradation0
200
400
600
800
1000
1200
40 60 80 100 120 140 160
Tq
(N
cm)
T (°C)
III
III
IV
zein-25%PEG400, 50rpmHeating rate: 10°C/5min
The second peak does not depend on rpm
Extrusion of zein
Materials and procedures
Zein/PEG 400 or zein/stearic acid were mixed before feeding
The following T profiles were utilizedT1=30°C, T2=60°C, T3=T4=65°C, 70°C, 75°C, 80°C, 85°C.
For each profile the rotational speed of the screws were: 20, 40, 80 e 120 rpm.
T1 T2 T3 T4Profile
Zein, 25%PEG400
Extrusion process
0
10
20
30
40
50
60
70
80
0 5 10 15 20 25
Tq (Nm)
rpm
T (°C)
Time (min)
0
20
40
60
80
100
0 400 800 1200 1600 2000 2400 2800 3200
TQ (Nm)
rpm
T (°C)
Time (sec)
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20
40
60
80
100
0 1000 2000 3000 4000 5000
TQ (Nm)
rpm
T (°C)
Time (sec)
0
50
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150
0 500 1000 1500 2000 2500
TQ(Nm)
R1
T4
Time (sec)
Zein vs stearic acid
Extrusion process
0
10
20
30
40
50
60
70
80
0 5 10 15 20 25
Tq (Nm)
rpm
T (°C)
Time (min)
0
20
40
60
80
100
120
140
0 4 8 12 16
Tq (Nm)
rpm
T (°C)
Time (min)
Kafirin from batch 4 does not thermoplasticize like batch 2
Different plasticizers and experimental conditions were used
Mixing process of Kafirin
0
10
20
30
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40
50
60
70
80
90
100
110
120
0 2 4 6 8 10 12
Tq (Nm) B4
Tq (Nm) B2
T (°C) B4
T (°C) B2
Time (min)
Tensile properties of extruded zein films
200
400
600
800
1000
1200
1400
0 20 40 60 80 100 120 140 160
70°C
75°C
80°C
screw speed (rpm)
0
5
10
15
20
0 20 40 60 80 100 120 140
70°C 75°C 80°C
screw speed (rpm)
Tensile properties of extruded zein films
0
0,05
0,1
0,15
0,2
0,25
0 20 40 60 80 100 120 140
70°C75°C80°C
screw speed (rpm)
Tensile properties of extruded zein films
Plasticizer R (MPa) R (mm/mm)
E (MPa)
PEG 400 8.060.48 0.110.0015 516.8445.16
Stearic acid 17.916.33 0.0230.016 130262.285
Water permeability of extruded zein films
0.00E+00
5.00E-08
1.00E-07
1.50E-07
2.00E-07
2.50E-07
3.00E-07
0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90Water activity
Wat
er P
erm
eabilit
y
Extruded 20 rpm
Extruded 40 rpm
Extruded 80 rpm
Extruded 120 rpm
Casting - PEG
Oxigen permeability of extruded zein films
0.00E+00
2.00E-07
4.00E-07
6.00E-07
8.00E-07
1.00E-06
1.20E-06
0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90
Water activity
Oxyg
en P
erm
eabilit
y
Extruded 20 rpm
Extruded 40 rpm
Extruded 80 rpm
Extruded 120 rpm
Casting - PEG
Kafirin-mechanical properties
0
1
2
3
4
5
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8
30°C38°C45°C
Strain (mm/mm)
T R (MPa) R (mm/mm
)
E (MPa)
30°C 3.310.43 0.690.12 157.7440.14
38°C 4.770.44 0.680.13 172.3313.11
45°C 2.970.56 0.720.12 107.9612.02
Kafirin-mechanical properties
0
0,5
1
1,5
2
2,5
3
3,5
4
0 0,5 1 1,5
Acido lattico
PEG 400
Strain (mm/mm)
Plasticizer type R (MPa) R (mm/mm) E (MPa)
PEG 400 2.970.56 0.720.12 107.9612.02
Lactic acid 1.480.11 1.170.25 38.546.37
Film blowing process
Film blowing process
Film blowing process
The protepack…edible??
Fiber spinning
Foams with CO2
Conclusions on zein
• Zein (from Aldrich) can be thermoplasticized directly in the extruder
• Extrusion parameters are correlated to mixing process parameters
• The mechanical properties of extruded zein varied with the extrusion conditions. The variation in oxigen and water permeability was not relevant.
• Residence time and T must be optimized to get melt with good rheological properties
• Preliminary results showed that, in certain conditions, the elongational properties of zein are suitable for film blowing and fiber spinning.
Conclusions on kafirin
• From FTIR (Peter) analysis batch 2 and batch 4 contained different amount and alfa-helix and beta-sheets.
• When compated to batch 2, the termoplasticization of batch 4 required a higher amount of plasticizer (30% instead of 25%) and lower T (45°C instead of 60°C)
• The higher amount of plasticizer required leaded to melt with poor rheological properties, not suitable for film blowing. However, the amount of kafirin available was not enough to optimize process parameters.
• We believe kafirin films can be obtained but need a lot….sorry!!!