Sorghum Starch for BiofuelsSorghum Starch for Biofuels
Donghai WangBiological and Agricultural Engineering
Kansas State University
International Conference on Sorghum for BiofuelHouston, Texas
August 19-22, 2008
01000200030004000500060007000
Mill
ions
of G
allo
ns
'00 '01 '02 '03 '04 '05 '06 '07
Production Import
OtherBarley, wheat, cheese whey,potato waste, brewery waste
Sorghum~3.5% total
2.3 Billion bu
~85 Million bu
Raw materials for ethanol productionRaw materials for ethanol production
Current capacity is ~9 B gallons and will be ~14 B gal by 2009Driven by corn grain production, with sorghum contributions
Current capacity is ~9 B gallons and will be ~14 B gal by 2009Driven by corn grain production, with sorghum contributions
Data source: DOE-EIA
Domestic productionDomestic production
MM galMM gal Import
Composition Sorghum CornStarch (%) 71.8 73.4Protein (%) 12.3 9.1Fat (%) 3.6 4.4Ash (%) 1.6 1.4
Compositions of corn & sorghum
Corn ~96%
Relative low digestibility compared with cornNo enough scientific information about fermentation quality of sorghum to support bio-industry and breeding research. Less investment for grain research.
Relative low digestibility compared with cornNo enough scientific information about fermentation quality of sorghum to support bio-industry and breeding research.Less investment for grain research.
The main focus is to understand the key factors (genetic, composition, chemical structure, and physical properties) affecting bioconversion efficiency of grain sorghum for biofuel production.
The main focus is to understand the key factors (genetic, composition, chemical structure, and physical properties) affecting bioconversion efficiency of grain sorghum for biofuel production.
Sorghum Samples:Seventy sorghum samples with broad range of genetic backgrounds, chemical and physical features were selected from over 1200 sorghum lines and hybrids.
Variation = 9.1%Low 86.0% High 93.8%
Conversion Efficiencies (%)
Variation = 22.1%Low 12.2% High 14.8%
Ethanol Yields (%, V/V)
Starch content and type of starch
Protein content and protein quality
Protein starch interaction
Mash viscosity
Formation of amylose-lipid complex
Phenol compounds
Combined interactions
Major factors affecting sorghum bioconversion
68.5 - 72.0%
13.5%
14.5%
7.4%
Starch content vs. Ethanol yield
65.0
70.0
75.0
80.0
85.0
90.0
95.0
36 42 48 54 60 66 72
Fermentation Hours
Effic
ienc
y(%
)
Waxy Normal
Tannin
82.2%
93.8%
86%
93.1%
87.5%
Fermentation efficiency of grain sorghums
93.8%93.8%
60-85 C
68 - 132 C
Amylose content
<5%
25%
50%
70% Ferm
enta
tion
effic
ienc
y
@ 95 ºC
Inso
lubl
e pa
rtic
les
93%
70%
Low
High
Effect of amylose content on starch gelatinization, insoluble, and efficiency
Starch gelatinization during cooking – Normal starchStarch gelatinization during cooking – Normal starch
Starch gelatinization during cooking – Waxy starchStarch gelatinization during cooking – Waxy starch
40.040 60 80 100 120 140 160
Temperature (°C)
Hea
t Flo
w
Solid residues after enzymatic hydrolysis
Before enzymatic hydrolysis
After enzymatic hydrolysis
Before enzymatic hydrolysis
Amylose-lipids complex
Formation of amylose-lipids complex
8%
Effect of protein content on ethanol yield and fermentation efficiency
Ethanol fermentation efficiency vs. protein digestibility
Area/mg proteins extracted by sonication and separated by SE-HPLC
Ethanol fermentation efficiency vs. extractable proteins from mashed samples
After enzymatic hydrolysis
Starch and protein interactionStarch and protein interaction
Protein body Starch granules
The range of sorghum starch granules is from 2 to 30 m
Before steeping
After steeping with SO2
2.5%
Starch and protein interactions
Ethano
l ferm
entatio
n effic
iency
(%)
Viscosity at 95 ºC and with amylase
Viscosity is one of the key factors affecting sorghum bioconversion efficiency
-1000
3000
7000
11000
15000
0.00 2.00 4.00 6.00 8.00 10.00
Time (min)
Vis
cosi
ty (c
P)
0
20
40
60
80
100
120
Tem
pera
ture
(°C
)
Normal amylase10 times of amylase20 times of amylaseDecorticated
Effect of phonolic compounds on mash viscosityand fermentation efficiency
Sorghum Efficiency (%)
Chemical Composition (%) Protein Digestibility
(%)Starch Protein Fiber Fat Ash
High (5) 93.3 72.1 9.33 1.63 2.69 1.59 65.7
Low (5) 86.8 68.8 12.10 2.10 3.50 1.90 50.8
Difference -7.0 -3.63 13.1 15.0 2.94 11.8 -22.8(%)
Comparison of high vs. how fermentation efficiency sorghums
ELCAM: Average “base case”…ELCAM: Average “base case”…
0
10
20
30
40
50
60
70
80
90
100
Component
K Btu/gal EtOHK Btu/gal EtOH
plant
cultivate
fertilizerchemicals
Irrigateharvest
transport
Grind/cook
Other
Net energy gain= 25,500 Btu/galNet energy gain
= 25,500 Btu/galDDGS
EtOH
Sorghum, regional average, yield = 70 bu/ac
Used as the comparativebase case for analyses
Used as the comparativebase case for analyses
Ferment
DistillDehydrate
Delivery
Dr. Jim McLaren
0
3
6
9
12
15
50 70 90 110 130 150
NEV (Ref base)NEV (Ref base)
Yield bu/ac
NEV 104 Btu/gal EtOHNEV 104 Btu/gal EtOH
NEV 106 Btu/acreNEV 106 Btu/acre
Net energy value (NEV) for different levels of grain yield per acre
Sorghum can make a great contribution…Sorghum can make a great contribution…
Data Source: USDA
Main Corn Belt
The research to-date shows thatsorghum is a viable renewable
resource for biofuel production.
The research to-date shows thatsorghum is a viable renewable
resource for biofuel production.
Future research on sorghum bioconversion:
Develop new or modified sorghum hybrids for biofuel production with high fermentation efficiency and low energy input.
Increase starch content and grain yield per acre.
Develop advanced bioprocessing technology to increase sorghum fermentation efficiency.
Acknowledgement
Research Associates and Graduate students in Wang’s research group,
Drs. Bean, McLaren, Seib, Tuinstra, Shi, Hays, Madl, Mr. Lenz,
Company: Monsanto Company, Novozymes, Inc.,
KansasSorghum
Commission
KansasSorghum
Commission
Thanks