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W.J. van Zeist1
M. Marinussen1
R. Broekema1
E. Groen1
A. Kool1
M. Dolman2
H. Blonk1
1 Blonk Consultants
2 Wageningen University and Research Centre
November, 2012
LCI data for the calculation
tool Feedprint for greenhouse
gas emissions of feed
production and utilization
Wet Milling Industry
Blonk Consultants
Gravin Beatrixstraat 34
2805 PJ Gouda
the Netherlands
Telephone: 0031 (0)182 579970
Email: info@blonkconsultants.nl
Internet: www.blonkconsultants.nl
Blonk Consultants helps companies, governments and civil society organisations put sustainability into practice. Our team of dedicated
consultants works closely with our clients to deliver clear and practical advice based on sound, independent research. To ensure optimal
outcomes we take an integrated approach that encompasses the whole production chain.
LCI data for the calculation
tool Feedprint for greenhouse
gas emissions of feed
production and utilization
Wet Milling Industry
W.J. van Zeist1
M. Marinussen1
R. Broekema1
E. Groen1
A. Kool1
M. Dolman2
H. Blonk1
1 Blonk Consultants
2 Wageningen University and Research Centre
November, 2012
Table of contents
2.1 Introduction 1
2.1.1 Context of this document & reading guide 1
2.1.2 Overview of products and allocation principles 1
2.1.3 Structure of data 1
2.1.4 Glossary of terms 2
2.1.5 References 2
2.2 By-products from the wet milling of maize 3
2.2.1 By-products from wet milling of maize 3
2.2.2 Note on allocation 3
2.2.3 Sourcing 3
2.2.4 Flowcharts 4
2.2.5 Inputs 6
2.2.6 Production of maize germ oil 10
2.2.7 Maize germ oil: Mass balance 11
2.2.8 Maize germ oil: Inputs 12
2.2.9 Maize germ oil: Allocation 12
2.2.10 References 13
2.3 Wet milling of sorghum 14
2.3.1 Introduction 14
2.3.2 References 14
2.4 Wet milling of starch potatoes 15
2.4.1 Note on allocation 15
2.4.2 By-products from potato starch production 15
2.4.3 Sourcing 15
2.4.4 Flowcharts 16
2.4.5 Mass balance 16
2.4.6 Inputs 17
2.4.7 Allocation 17
2.4.8 Energy use and allocation for heat treated and dried products 18
2.4.9 References 18
2.5 Wet milling of wheat 19
2.5.1 By-products from wet milling of wheat 19
2.5.2 Note on allocation 19
2.5.3 Sourcing 19
2.5.4 Flowcharts 20
2.5.5 Mass balance 20
2.5.6 Inputs 23
2.5.7 Allocation 23
2.5.8 References 23
FeedPrint background data report on processing, version 2012, part 3/7: Wet milling
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2.1 Introduction
2.1.1 Context of this document & reading guide
This document is part of the background documentation for the FeedPrint program and database.
Background information of this project, underlying methodology and justification thereof, can be found
in the FeedPrint methodology document. These chapters focus only on the processing step of crops into
the feed materials. Information on origin of crops is given, but details on cultivation and transportation
(to and from the processing facility) are described in separate documents: the cultivation of each crop is
described in the cultivation background reports similar to this one (Marinussen et al, 2012), whereas
transportation is described in the Feedprint methodology report (Vellinga et al, 2012).
Each chapter can be read and interpreted as a standalone set of LCI data, which covers the country of
crop cultivation, the country of processing, mass balances, energy inputs (and outputs, if applicable), as
well as data needed for the allocation of the by-products. In some cases, multiple processes can follow
one another with multiple allocation steps. In these cases, the data is entered into the database by
following these specific processing steps consecutively. Usually (but not restrictively) the data entered are
relative to an input of 1000 kg of crop product.
2.1.2 Overview of products and allocation principles
Each chapter in this document describes a different animal feed material production process within the
wet milling industry. Unless noted otherwise, the processes described in this document are treated as a
single unit process with multiple valuable output products, where allocation approach 1 is applied (see
5.3, Vellinga et al, 2012) in which all products are treated as valuable by-products to which upstream
emissions will be allocated according to economic, energy, or mass allocation.
2.1.3 Structure of data
This document contains tables that reflect those data applied in the FeedPrint program. Additionally,
tables with background data are supplied, which are often inventories of encountered literature. Only the
tables that are used as data for the FeedPrint database and calculations are given a table number (see for
an example Table 2.1.1). Other tables that are not used in the FeedPrint database are not numbered and
have a simpler layout, see the example below.
Table 2.1.1 Example default inputs table for FeedPrint database. Output Values Unit
Best estimate Error (g2)
Electricity 88 1.4 MJ/ton
Natural gas 245 1.4 MJ/ton
Example of background data not directly used in FeedPrint database
Source Data found Remarks
Reference 1 80 MJ/ton Older data from 1 processing facility.
Reference 2 90 MJ/ton Newer data from multiple facilities.
There are a number of recurring types of tables, usually in the following order:
1) Definition of feed materials related to the process;
2) Estimation of countries of origin of the crop and countries of processing;
3) Mass balances for the process;
4) Energy or material inputs needed for the process;
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5) Allocation factors for the outputs from the process.
Unless explained otherwise in a specific chapter, these five tables are present for each process. Additional
sections or figures can give information on, for example, the definition of the process represented with a
flowchart. Each section also contains the references for cited sources. The usual structure of a section is
that first the default inputs for the FeedPrint database are presented, with the rest of the section
explaining in detail which data sources were used and why.
There are a number of different types of error ranges that can be given for each data point, and these are
applied for the energy and auxiliary inputs. More background information can be found in the overall
methodology document (Vellinga et al. 2012), which also explains the decision process followed to arrive
at the error ranges.
2.1.4 Glossary of terms
Below is a list of terms with definitions as applied in this document.
DMC Dry matter content in g/kg. GE Gross Energy content in MJ/kg.
2.1.5 References
CVB-table: see appendix 1 in Vellinga et al. (2012)
European Commission. (2011). COMMISSION REGULATION ( EU ) No 575 / 2011 of 16 June 2011
on the Catalogue of feed materials. Official Journal of the European Union, (L 159), 2565.
Marinussen et al (2012) Background data documents on cultivation. Blonk Consultants. Gouda, the
Netherlands
Vellinga, T.V., Blonk, H., Marinussen, M., van Zeist, W.J., de Boer, I.J.M. (2012) Methodology used in
feedprint: a tool quantifying greenhouse gas emissions of feed production and utilization
Wageningen UR Livestock Research and Blonk Consultants. Lelystad/Gouda, the Netherlands.
FeedPrint background data report on processing, version 2012, part 3/7: Wet milling
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2.2 By-products from the wet milling of maize
2.2.1 By-products from wet milling of maize
Maize, also named corn, is a cereal grain1 and is known for being a high-yielding variety of cereal grains.
There are multiple types of maize which are used for various purposes like grain, cattle, seed, or cobs for
consumption. In this section, only the wet milling of the industrially processed dent corn is described.
Dent corn, getting its name from the dent in the crown of the seed, is grown more than any other type of
corn. Millions of tons of grain are produced from dent corn, and is used for human and industrial use,
and for livestock feed. The starch reaches the summit of the seed, and the sides are also starchy. The
denting is caused by the drying and shrinking of the starch. The dent corn grown in the Corn Belt came
from a mix of New England flints and gourseed (an old variety of corn grown by the Indians in
southeaster North America).
By-products from the wet milling process can come from North America as well as Europe, but since
there is no specific regional data the choice has been made to focus on reporting one general mass
balance. Feed materials derived from wet milling of maize are described below. The products from the oil
production process originate from oil extraction from dried maize germ, a by-product of wet milling.
Table 2.2.1 By-products from maize wet milling in the CVB list are: name CVB Process DMC
(g/kg) Starch (g/kg)
Maize germ meal extruded Oil production 887 299
Maize germ meal feed expeller Oil production 897 336
Maize germ meal feed extruded Oil production 875 326
Maize gluten meal Wet milling 901 177
Maize glutenfeed Crude Protein 200-230 Wet milling 893 127
Maize glutenfeed Crude Protein230 Wet milling 890 102
Maize glutenfeed fresh+sillage Wet milling 418 283
Maize solubles Wet milling 480 7.5
Maize starch Wet milling 876 836
Maize bran Wet milling 873 280
2.2.2 Note on allocation
For the wet milling of maize it was decided to apply detailed sub-process allocation (approach 2 for
allocation, see 5.3, Vellinga et al, 2012). The specific energy use for by-products is fully allocated to those
products (e.g. drying). The prices and composition data of intermediate products are derived form end
products on the basis of a deduced dry matter value of the different end-products
2.2.3 Sourcing
An inventory of the origin of feed materials for the Dutch feed industry indicated that four countries
supply the major part of this material. We assumed a division amongst these countries according to the
shares listed in Table 2.2.2. This means for example that 25% of the maize wet milling feed material is
sourced from Dutch wet milling factories which sources the maize for 34% of the USA, 33% of Germany
and 33% of France. Both the origin of wet milling feed materials form industry and the input of maize in
that industry fluctuates over the years.
1 Maize is known as corn in countries such as the United States, the English-speaking provinces of Canada, Australia and New Zealand.
FeedPrint background data report on processing, version 2012, part 3/7: Wet milling
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Table 2.2.2 Estimated countries of origins of the feed materials. Processing in: the Netherlands USA Germany France
percentage 25% 35% 20% 20%
Crop-country
the Netherlands
USA 34% 100% 25%
Germany 33% 50%
France 33% 25% 100%
2.2.4 Flowcharts
Corn
1.Receving and
Steeping
2. Degermination
3. Grinding and
Screening
4. Starch-Gluten
Separation
Corn Oil
Production
Drying
Dry germ
Starch
Steepwater/
steep liquor
Corn oil
Fiber/Bran
Gluten meal
Starch
Fiber/Bran
Gluten
Process
Main products
Input product
1 kg
Germ meal
Gluten feed
meal
Dewatering
Dewatering
Drying
5. Mixing
and drying
Figure 2.2.1 Flowchart of wet milling of maize. For each main product, a drying or dewatering step is included.
The main feed products of the wet milling of maize are corn oil, fiber, gluten, and starch. Depending on
the prices of these products though, the manufacturer can decide to alter processing routes, resulting in a
different mix of alternative products such as corn steep liquor, dry germ and ethanol (not shown in the
figure). Yields of the different by-products vary through the years so yields from processing found in
literature should be qualified as typical yields.
Gluten feed is composed by mixing bran/fiber and steep liquor. Depending on many factors steep liquor,
germ and bran/fiber can also be final products, but typically they are processed as described above
Corn oil is often included as a main product in maize wet milling studies. However, it is usually not
processed on the same site, and additional animal feed by-products (maize germ meal and expeller) arise
FeedPrint background data report on processing, version 2012, part 3/7: Wet milling
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from this next step. It is therefore treated here as a separate industry, with the maize germ as described in
the first part as an input2.
Since the data from Galatisky is detailed enough to perform a step-by-step allocation at each sub-process,
it was opted to apply the mass balance from this source. The elaboration of this is found in the next
section, while below a number of the mass balances are presented, in order to show that the mass balance
by Galitsky is reasonable in general3.
Table 2.2.3 Mass balance maize wet milling (excluding corn oil production) Input DMC (g/kg) Mass, as is Mass, dm
Corn 850 1000 1000
output
Maize germ 920 70 75
Maize gluten feed bran/fibre steep liquor
900 950 480
175 105 115
185 120 65
Maize gluten meal 900 55 56
Maize starch 920 630 680
The mass balances are expressed on a dry matter basis, since often an undisclosed amount of water is
used at a number of different points during the process.
The mass balance described by Kim and Dale (2002) (see table A) was difficult to interpret. Adding up
and comparing the dry matter going in and dry matter coming out of the process described by Kim and
Dale leads to the observation that the mass balance is not complete, because more dry matter goes into
the process than seems to come out.Ethanol is produced by fermentation of starch. The chemical
equation of this fermentation process is:
2 C6H10O5 + 2 H2O 4 C2H5OH + 4 CO2
Table 2.2.4 :Mass balance according to Kim and Dale (2002) (A = original, B = deduced to input of starch used for ethanol) A B
The amount of dry matter of starch corresponding with 0,295 kg of ethanol is 0,508 kg (see equation of
fermentation process). Replacing ethanol by starch in the mass balance of table B above almost completes
the dry matter coming out of the process. The minor difference might be explained by rounding errors.
2 Other sources (e.g, http://www.ag.ndsu.edu/pubs/ansci/dairy/as1127.pdf) also describe germ meal as a separate
product from the feed by-products directly from wet milling. 3 Galitsky (2003) presents typical yields of corn components. The mass balance is on a dry matter basis, but no
information is given on exact dry matter contents and these have been deduced from other sources.
IN kg dry matter
corn 0,85
OUT
ethanol 0,295
corn oil 0,038
corn gluten meal 0,047
corn gluten feed 0,201
IN kg dry matter
corn 0,794
OUT
starch 0,508
corn oil 0,038
corn gluten meal 0,047
corn gluten feed 0,201
FeedPrint background data report on processing, version 2012, part 3/7: Wet milling
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Ramirez (2009) has also published a mass balance for the wet milling of maize. The two values are derived
from conventional and enzymatic wet milling. Ramirez has quite detailed information on the processes
involved and the evolution of dry matter contents of the intermediate products. Although unfortunately
no direct information on energy usage during the process steps is presented. The data were used in
constructing the intermediate mass balances (especially dry matter contents) for the process allocation
steps.
Mass balance according to Ramirez (2009), from 1 tonne corn, dry matter basis Product DM% Value (mass, dm) Unit
Min Max
Maize germ 92 77 80 Kg
Maize gluten feed 90 194 185 Kg
Maize gluten meal 90 62 64 Kg
Maize starch 92 667 671 Kg
Balance arises after taking into account loses of 2.4% in the prehandling of corn.
2.2.5 Inputs
Galitsky (2003) reports a rather detailed table on energy consumption of the wet milling of maize. Here,
we will follow the allocation of subprocess and intermediate product prices. The energy data by Galtisky
gives us enough information to do this. What follows will be a step-by-step breakdown of the production,
including allocation steps. Additional energy usage such as drying steps will be included as well, but not
treated as an allocation step. In this final breakdown, the mass balance from Galitsky is used, which seems
prudent as energy usage originates from the same source. The dry mater contents of (intermediate)
products have been taken from Galitsky, Ramirez and the CVB list. According to Ramirez, corn enters at
85% dry matter. Protein contents and GE (all on dry matter basis) have been calculated from the CVB
list.
Prices for allocation are derived from Faostat and Eurostat prices on bran/fiber, germ, starch and gluten
feed/meal. These were recalculated based on dry matter content and applied in the intermediate process
steps. Often the intermediate product can be directly related to a final product (such as wet germ resulting
in the final dried germ) and the price of the final product is applied (on a dry matter basis). Some
intermediate corn products arise and the price components are derived from the final product. For
example, in processing step 4, the intermediate corn product from step 3 named intermediate wet corn
(step 3) enters and the process produces starch and gluten. From the mass balance we know that 680 kg
starch (at 0.39/kg) and 56 kg gluten (at 0.18/kg) is produced from this intermediate product. From
these proportions the price of the intermediate product is calculated at 0.37/kg (resulting from
56*0.18+680*0.39)/740). The prices (and composition data) are all derived in this way.
Table 2.2.5 Product category Price (euro/kg) DMC (g/kg) Price on DM basis
Bran or fiber 0.181 875 0.21
Germ 0.570 900 0.63
Starch 0.345 875 0.39
Gluten feed/meal 0.162 900 0.18
The tables below show all the steps involved in corn wet milling, including energy usage. As the moisture
content of intermediate products vary significantly during processing and is highly uncertain, the mass
balance is based on the dry matter content.
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Step 1: Corn receiving, steeping and steepwater evaporation
Step 1a: Corn receiving and steeping
Parameter Value Unit
Inputs Mass (dm) DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Corn 1000 850 17.7
Energy inputs Error (g2)
natural gas 192 1.3 MJ/tonne corn
electricity from the grid 31 1.3 Mj/tonne corn
Outputs Mass (dm) DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Steepwater (wet) 65 10% 100 0.18 14.1
Intermediate wet corn (step 1) 935 10% 450 0.37 17.9
Step 1b: Steepwater dewatering
Parameter Value Unit
Inputs Mass (dm) DMC (g/kg)
Steepwater (wet) 65 100
Energy inputs Error (g2)
natural gas 1192 1.3 MJ/tonne corn
electricity from the grid 25.5 1.3 MJ/tonne corn
Outputs (CVB Name) Mass (dm) DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Maize Solubles 65 10% 480 0.18* 14.1
* [Editors note: This price should be double-checked; specific price for maize solubles).]
Step 2: Degermination (Germ recovery) and germ drying
Step 2a: Degermination
Step 2b: Germ drying
Parameter Value Unit
Inputs Mass (dm) DMC (g/kg)
Germ (wet) 75 500
Energy inputs Error
(g2)
natural gas 167 1.3 MJ/tonne corn
Diesel 164 1.3 MJ/tonne corn
electricity from the grid 22 1.3 MJ/tonne corn
Parameter Value Unit
Inputs Mass (dm) DM (g/kg) Price (/kg) GE (MJ/kg)
Intermediate wet corn (step 1)
935 450 0.37 17.9
Energy inputs Error (g2)
electricity from the grid 51 1.3 MJ/tonne corn
Outputs Mass (dm) DMC (g/kg)
Price (/kg) GE (MJ/kg)
Germ (wet) 75 10% 500 0.63 20
Intermediate wet corn (step 2)
860 10% 240 0.35 17.7
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Outputs Mass (dm) DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Germ (dried)* 75 920 0.63 20
* Dried germ are used as input for the oil crushing process described later in this document.
Step 3: Grinding and screening (Fibre recovery) and fibre dewatering
Step 3a: Grinding and screening
Parameter Value Unit
Inputs Mass (dm)
DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Intermediate wet corn (step 2) 860 240 0.35 17.7
Energy inputs Error (g2)
electricity from the grid 105 1.3 Mj/tonne corn
Outputs Mass (dm)
DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Fibre/Bran (wet) 120 250 0.21 16.7
Intermediate wet corn (step 3) 740 270 0.37 17.8
Step 3b: Fibre dewatering
Parameter Value Unit
Inputs Mass (dm) DM (g/kg)
Fibre/Bran (wet) 120 250
Energy inputs Error (g2)
electricity from the grid 18 1.3 MJ/tonne corn
Outputs Mass (dm) DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Fibre/Bran (dewatered) 120 400 0.21 16.7
Step 4: Starch gluten separation (Gluten recovery), gluten drying and starch drying
Step 4a: Gluten recovery
Parameter Value Unit
Inputs Mass (dm) DM (g/kg)
Price (/kg)
GE (MJ/kg)
Intermediate wet corn (step 3) 740 270 0.37 17.8
Energy inputs Error (g2)
electricity from the grid 49 1.3 MJ/tonne corn
Outputs Mass (dm) DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Gluten (wet) 56 340 0.18 17.9
Starch (wet) 680 250 0.39 17.1
Loss 4 Loss in overall process.
Step 4b: Gluten drying
Parameter Value Unit
Inputs Mass (dm) DM (g/kg)
Gluten (wet) 56 340
Energy inputs Error (g2)
Diesel 174 1.3 MJ/tonne corn
electricity from the grid 25 1.3 MJ/tonne corn
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Outputs (CVB Name) Mass (dm) DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Maize gluten meal 56 900 0.18 17.9
Step 4c: Starch drying
Parameter Value Unit
Inputs Mass (dm) DM (g/kg)
Starch (wet) 680 250
Energy inputs Error (g2)
Diesel 1319 1.3 MJ/tonne corn
electricity from the grid 154 1.3 MJ/tonne corn
Outputs (CVB Name) Mass (dm) DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Maize Starch 680 920 0.39 17.1
Step 5. Mixing fiber with steep liquor for gluten feed.
Step 5a: Maize glutenfeed production (no drying)
Parameter Value Unit
Inputs Mass (dm)
DMC (g/kg)
Fibre/bran (dewatered) 120 400
Steep liquor (concentrated, Maize Solubles) 65 480
Output (CVB Names) DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Maize glutenfeed fresh+sillage 185 420 0.18 16.2
Step 5b: Maize glutenfeed production (with drying)
Parameter Value Unit
Inputs Mass (dm) DMC (g/kg)
Fibre/bran (dewatered) 120 400
Steep liquor (concentrated, Maize Solubles) 65 480
Energy inputs for drying step Error (g2)
Diesel 1096 1.3 MJ/tonne corn
electricity from the grid 47.5 1.3 MJ/tonne corn
Outputs (CVB Names) Mass (dm) DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Maize glutenfeed crude protein 230
185 185 185
900 0.18 16
Step 5c: Maize dried bran production (with drying)
Parameter Value Unit
Inputs Mass (dm) DMC (g/kg)
Fibre/bran (dewatered) 120 400
Energy inputs for drying step Energy input
Error (g2)
Diesel 711 1.3 MJ/tonne corn
electricity from the grid 31 1.3 MJ/tonne corn
Outputs (CVB Names) Mass (dm) DMC (g/kg)
Price (/kg)
GE (MJ/kg)
Maize bran 120 900 0.21 16.8
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Maize bran is the dried gluten feed without steep liquor (maize solubles) added. It is listed here as
comparable as maize glutenfeed as the same drying step applies, but with reduced energy usage as the
total amount dried has changed.
Detailed input and output data for end products.
Data below on composition is used in the detailed breakdown of the process in the section above. Also
included are the overall energy usage without the process breakdown. The European Commission (EC)
has published a reference document on best available techniques in the Food, Drink and Milk Industries
(2006) which indicates an energy use for the wet milling of maize comparable to the energy use reported
by Galitsky. The EC reports a variation in energy use between a minimum and a maximum. These values
have also been used to get an insight on the error margin of the values by Galitsky, which we have chosen
to be 30%.
Table 2.2.6 Input data inventory Product Parameter Value Unit Data quality Ref
Mean Min Max Rel Com TRC GSp TeC
Energy use: fuels diesel 33,2 kg/kg 1 1 3 3 2 a
natural gas 1360 950 2215 MJ/kg 1 4
1 5
3 3
3 2
2 2
a (mean) b (min-max)
Energy use: electricity electricity from the grid 113,8 100 200 kWh/kg 1 4
1 5
3 3
3 2
2 2
a (mean) b (min-max)
a) Galistky C., Worrel E., Ruth M., 2003, Energy Efficiency Improvement and Cost Saving Opportunities for the Corn
Wet Milling Industry, University of California, USA.
b) European Commission, 2006, Reference document on best available techniques in the food, drink and milk industries.
2.2.6 Production of maize germ oil
The germ that originates (in dried form) from the wet milling process, is further processed to extract the
oil content, which is particularly high in this part of maize. This produces, as a by-product, germ meal or
expeller.
The processing of germ to germ (corn) oil and germ meal is a fairly straightforward process where the oil
is extracted via a solvent extraction process with hexane (usually preceded by a light mechanical pressing
step), or via a mechanical pressing method.
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Figure 2.2.2 Flowchart of germ processing
2.2.7 Maize germ oil: Mass balance
Typical oil contents for maize germ (dried) is up to 50% (http://www.westfalia-
separator.com/applications/renewable-resources/maize-germ-oil.html) while typical values lie around
45% (http://www.aaccnet.org/cerealchemistry/backissues/1989/66_273.pdf)
If the dry matter and oil contents of the oilseed are known, the mass balances can be deduced for both
the mechanical cold pressing (which leaves more oil in the residue, typically 75% of the oil is extracted)
and oil extraction with an organic solvent (which leaves very little oil, typically 98% of the oil is extracted).
The numbers in Table 2.2.7 and Table 2.2.8 are based on these extraction rates (while also taking into
account de deshelling), while allowing for a loss of around 1.5% (see Schmidt (2007)). Oil content data is
found in a range from around 40 (Johston, 2005) to 48 (Ramirez, 2009) procent. A 44% oil content is
used as a basis for the mass balance below.
The dry matter contents of dried germ are calculated backwards based on the germ meal and expeller
production and moister content from the CVB. The moisture content is within the expected range for
dried germ (see for example http://www.satake.co.uk/cereal_milling/maize_products.htm)
Table 2.2.7 Default mass balance of germ processing (cold pressing, from 1 tonne of germ).
Input DMC (g/kg) Mass (kg)
Germ (dried) 920 1000
Output
Germ expeller 900 655
Germ oil 1000 330
Loss (mostly water) 0 15
*Germ originating from corn wet milling process as described in 6.2.5.
Table 2.2.8 Default mass balance of germ processing (solvent extraction, from 1 tonne of germ).
Input DMC (g/kg) Mass (kg)
Germ 920 1000
Dried maize germ
Solvent extraction
Crude oil Meal
Mechanical pressing
Crude oil Expeller
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Output
Germ meal 880 555
Germ oil 1000 430
Loss (mostly water) 0 15
*Error margin determined by pedigree matrix, see generic oilseed processing.
2.2.8 Maize germ oil: Inputs
Rapeseed processing is used as a basis of comparison to obtain general oilseed figures on energy
requirements for processing of germ. Thus, values obtained for the CFPAN project for rape seeds are
used (see chapter Generic oilseed production in the background data report on the crushing industry
(Part 1/7). These can then be recalculated based on the energy required for the extraction of a unit of oil.
Table 2.2.9 and Table 2.2.10 show the inputs needed for processing 1 tonne of germ, calculated in this
manner.
Table 2.2.9 Default inputs for oilseed processing (pressing, for 1 tonne of germ, based on rapeseed) for the production germ expeller.
Input Values Unit
Best estimate Error (g2)
Electricity (pressing) 212 1.3 MJ/ton
Based on values from Croezen (2005) and Hamelinck (2008), recalculated relative to oil production.
* Error margin to be calculated based on pedigree matrix.
Table 2.2.10 Default inputs for oilseed processing (solvent extraction, for 1 tonne of germ, based on rapeseed) for the production germ meal.
Input Values Unit Ref
Best estimate Error (g2)
Electricity (extraction) 148 1.3 MJ/ton b
Natural gas (extraction) 760 1.3 MJ/ton b
Hexane 1.0 1.3 kg/ton c
b: Based on values from Croezen (2005), Schmidt (2007), and Hamelinck (2008), recalculated relative to oil production.; c:
Schmidt (2007)
2.2.9 Maize germ oil: Allocation
All items on the CVB list, except for the unprocessed germ, are represented in the mass balances and
allocation data tables below. Maize germ meal prices derived from Faostat (Cake of Maize) average prices
from 2005 2009 (prices not available for 2007 and 2008). Germ oil prices are from Eurostat (Corn oil).
Table 2.2.11
Pressing Name CVB Mass DMC (g/kg) Price
(euro/ton) GE (MJ/kg)
Germ expeller Maize germ meal feed expeller (13600) 655 900 0.11 15.1
Germ oil NA 330 1000 0.91 37.0
Extraction
Germ meal Maize germ meal extruded (13500) Maize germ meal feed extruded (13700)
555 880
0.11 14.1
Germ oil NA 430 1000 0.91 37.0
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2.2.10 References
Croezen, H. en B. Kampman 2005. Op (de) weg met pure plantenolie? De technische, milieuhyginische en
kostengerelateerde aspecten van plantenolie als voertuigbrandstof. Report 2GAVE-05.05. CE Delft.
CVB-table: see appendix 1 in Vellinga et al. (2012)
European Commission, 2006, Reference document on best available techniques in the food, drink and
milk industries.
Galistky C., Worrel E., Ruth M., 2003, Energy Efficiency Improvement and Cost Saving Opportunities
for the Corn Wet Milling Industry, University of California, USA.
Hamelinck, C., K. Koop, H. Croezen, M. Koper, B. Kampman, G. Bergsma 2008. Technical specification:
Greenhouse gas calculator for biofuels. Version 2.1b. Ecofys CE Delft.
Johnston, David B, Mcaloon, Andrew J, Moreau, Robert A, Hicks, Kevin B. Composition and Economic
Comparison of Germ Fractions from Modified Corn Processing Technologies. JAOCS, Vol. 82, no. 8
(2005).
Kim S., Dale B.E., 2002, Allocation Procedure in Ethanol Production System from Corn Grain, Michigan
State University, USA.
National Academy of Sciences,1971, Atlas of nutritional data of United States and Canadian feeds
Ramirez (2009), Enzymatic corn wet milling: engineering process and cost model, Biotechnology for
biofuels, january 2009.
Singh, VijaySchmidt, J. H. 2007. Life cycle assessment of rapeseed oil and Ph.D. thesis, Part 3: Life cycle inventory
of rapeseed oil and palm oil. Department of Development and Planning, Aalborg University, Aalborg.
University of Missouri Exntention, april 2011, Feed prices of by-products sorted by product:
http://agebb.missouri.edu/dairy/byprod/AllProducts.asp
USDA: http://www.nal.usda.gov/fnic/foodcomp/search/
Vellinga, T.V., Blonk, H., Marinussen, M., van Zeist, W.J., de Boer, I.J.M. (2012) Methodology used in
feedprint: a tool quantifying greenhouse gas emissions of feed production and utilization
Wageningen UR Livestock Research and Blonk Consultants. Lelystad/Gouda, the Netherlands.
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2.3 Wet milling of sorghum
2.3.1 Introduction
Sorghum gluten meal is included as a number of sources indicate that the wet milling of sorghum is quite
comparable to that of maize. This is valid for the processes involved as well as the resulting products.
Since only one, relatively unimportant, feed ingredient is derived from sorghum, it is included here as a
similar product to those arising from corn wet milling. See:
- C. Wayne Smith,Richard A. Frederiksen. 2001. Sorghum: origin, history, technology, and
production.
- Ping Yang and Paula Seib. 1995, Low-Input Wet-Milling of Grain Sorghum for Readily
Accessible Starch and Animal Feed. Cereal Chem. 72(5):498-503
Therefore, sorghum gluten meal can be considered a substitute of maize gluten meal, which is discussed
in the chapter on maize wet milling. Obviously upstream emissions from sorghum cultivation can be
applied instead of maize cultivation.
Table 2.3.1 By-products from sorghum wet milling in the CVB list are: name CVB Process DMC (g/kg) Starch (g/kg)
Sorghum gluten meal Wet milling 900 245
Thus, for the process description, inputs and outputs, and allocation, the chapter on maize wet milling
applies, specifically the by-product Maize gluten meal which is the maize version of Sorghum gluten
meal.
2.3.2 References
C. Wayne Smith,Richard A. Frederiksen. 2001. Sorghum: origin, history, technology, and production.
Ping Yang and Paula Seib. 1995, Low-Input Wet-Milling of Grain Sorghum for Readily Accessible Starch
and Animal Feed. Cereal Chem. 72(5):498-503
Vellinga, T.V., Blonk, H., Marinussen, M., van Zeist, W.J., de Boer, I.J.M. (2012) Methodology used in
feedprint: a tool quantifying greenhouse gas emissions of feed production and utilization
Wageningen UR Livestock Research and Blonk Consultants. Lelystad/Gouda, the Netherlands.
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2.4 Wet milling of starch potatoes
2.4.1 Note on allocation
Unlike for the wet milling of maize, not enough detailed information was uncovered to allocate according
to subprocesses in the wet milling of potatoes.4 Thus, the wet milling is described as a single unit process.
It should be noted that the European starch industry has informed us that, in the beginning of 2012, a
detailed report on energy usage in the industry will be publicly released. It is our intention to update the
default values in this document when this report becomes available.
2.4.2 By-products from potato starch production
Feed materials derived from the potato starch production are:
name CVB DMC (g/kg)
Starch (g/kg)
Potato protein Crude ASH 10 905 54
Potato starch dried 800 800
Potato pulp pressed 165 165
Potato juice concentrated 577 697
Potato pulp Crude Protein95 881 246
Potato starch heat treated and dried 875 745
According to Roelof de Weerd potato pulp crude protein, which is mentioned in the CVB-table, is hardly produced
any more by this industry. Roquette in France is to his knowledge the only producer of potato pulp crude protein
in Europe. Potato starch heat treated is produced in another process than is being done in this industry. For sake of
completeness, however, these products will be included, with an estimate on the amount of energy needed for drying
the products to the listed moisture content.
2.4.3 Sourcing
It is assumed that the Dutch feed industry sources the feed materials in the countries that are listed in
Table 2.4.1.
Table 2.4.1 Estimated countries of origins of the feed materials
Processing in: the Netherlands
percentage 100%
Crop-country
Germany 30%
the Netherlands 70%
4 Although and older source (Blonk, 1997), does mention an estimation of energy use in a number of processes. However, as the source is somewhat outdated, it was decided not to incorporate these data
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2.4.4 Flowcharts
Figure 2.4.1 Flowchart of potato starch production (as is).
The first stage in potato processing is a cleaning stage in which the tare is removed from the potatoes.
Then the potatoes are grinded and the fibers are extracted. From the remaining substance the starch and
fruit juice are separated. The fruit juice can be a final product from processing but can also be further
processed producing a protein meal and protamylase (also called concentrated fruit juice). Protamylase is a
thick fluid substance, which can be used as a fertilizer.
2.4.5 Mass balance
Various mass balances have been found in literature, providing information on varying output products
(Blonk 1997, Rosenau 1979, Karup Kartoffelmehl Fabrik (2002-2003)). However, most literature was
found to be outdated, and superior information was retrieved from an industry expert of AVEBE, which
represents a large part of the feed rawe materials being consumed in the Dutch sector. The figures
endorsed by the industry expert are generally in agreement with average figures from the older sources
and are considered broadly applicable. They are presented below in the default mass balance. This mass
balance will be applied to the Netherlands with an error of 10%, and for Germany and Belgium with an
error of 20%.
Table 2.4.2 Default mass balance per tonne of potatoes. Input DMC (g/kg) (kg/tonne)
Potatoes 260 1000
Output DMC (g/kg) Best estimate (kg/tonne)
Starch potatoes
Cleaning of
potatoes
Grinding of
potatoes
Tare
Extraction of fibers
Fibers
Starch
Fruit juice
Separation
process
Starch refinery
Protein
Protamylase
Starch
Additional products
Process
Input product
Main products
1 kg
0,238 kg
0,140 kg
0,016 kg
0,054 kg
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Potato Starch 800 238
Potato fibers/ pulp 165 140
Potato protein 900 16
Protamylasse/ concentrated fruit juice 560 54
2.4.6 Inputs
Table 2.4.3 gives the default values for energy usage in potato starch processing. These values will be
underpinned in the remainder of the text.
Table 2.4.3 Default values for energy inputs unit process I Product Parameter Value Unit
Best estimate
Min Max
Energy use: fuels natural gas 0.79* 0.32 1.27 MJ/kg
Energy use: electricity electricity from the grid
0.00* 0.04 0.08 kWh/kg
* Best estimate energy usage is Dutch industry data based on a facility with a CHP, hence no electricity is
listed as input. This input translates to 0.08 kWh and 0.51 MJ natural gas per kg.
The tables below give background information on composition and references for the energy usage
included. For potato starch wet milling, reference values are found in the EC (2006) BREF document,
which give a range of values for energy inputs. The best estimate is information for the Dutch industry
obtained from AVEBE.
Table 2.4.4 Inventory data potato starch processeing Energy use: fuels diesel 0,0016 kg/kg 2 1 3 1 2 a
natural gas 0,079 0,32 1,27 MJ/kg 2 4
1 1
3 5
1 5
2 2
c (mean) b (min-max)
Energy use: electricity electricity 0,00 0,04 0,08 kWh/kg 2 4
1 1
3 5
1 5
2 2
c (mean) b (min-max)
C-contents are based on reference h.
a) Blonk et al.., 1997.
b) European Commission (2006)
c) AVEBE (2011)
2.4.7 Allocation
Table 2.4.5 Data for allocation By-product Name CVB Mass DMC
(g/kg) Economic Fraction*
GE (MJ/kg)
Potato protein Potato protein Ruw ASH 10 (34920)
16 900 2 20,930
Potato starch Potato starch dried (34700) 238 800 1 13,592 Potato fibers/ pulp Potato pulp pressed (53600) 140 165 0.035 2,917 Protamylasse/ concentrated fruit juice
Potato juice concentrated (35000) 54 560 0.05 7,989
* Economic fraction are relative prices provided by AVEBE.
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2.4.8 Energy use and allocation for heat treated and dried products
The input table below concerns the potato starch production by-products that are not specifically listed
but are dried varieties of potato pulp (potato pulp crude protein and Potato starch heat treated). There
is no specific information available on how much of this is produced. It is, however, possible to estimate
the energy needed to dry these products from approximately 20% dry matter content in the pulp or wet
starch, which can be subsequently added separately as an input for this specific category. Based on (Roe,
2003) the energy use for drying ranges from 3 6 MJ per kg water evaporated. For drying potatoes from
the 60% dry matter to 88% (up until 60% usually happens via significantly more efficient mechanical
process), this amounts to 920 to 1920 MJ of heat (assumed to be produced with natural gas) per tonne
potatoes.
Table 2.4.6 Default input/output of for drying by-product. Product Parameter Value Unit
Input: Wet potato by-product Amount 1000 kg
DMC 165 g/kg
Natural gas for heat 0.92 (min) 1.92 (max) MJ/kg
Output: DMC (g/kg) Amount (kg)
Potato pulp Crude Protein95 (34820) Potato starch heat treated and dried (79800)
880 186
A: (Nemecek & Kgi, 2007),
As these products likely arise form wet low value by-products, we treat these within the scope of
allocation approach 3 (see 5.3, Vellinga et al, 2012) and no upstream allocation takes place towards these
residual by-products prior to drying. Thus, only the energy use for drying and subsequent transportation
will be taken to be taken into account. No further information on allocation is therefore required.
2.4.9 References
AVEBE (2011), personal communication with Roelof de Weerd.
Blonk H., Lafleur M., van Zuijts H., 1997, Screening LCA on potato starch, IVAM Environmental
Research, Amsterdam.
CVB-table: see appendix 1 in Vellinga et al. (2012)
European Commission, 2006, Reference document on best available techniques in the food, drink and
milk industries.
Eurostat: http://epp.eurostat.ec.europa.eu/newxtweb/submitdimselect.do
Karup Kartoffelmehl Fabrik (2002-2003):
http://www.lcafood.dk/processes/industry/potatoflourproduction.htm
Rosenau J.R., Whitney F., 1979, Low wastewater potato starch/protein production process, Industrial
Environmental Research Laboratory, Cincinnati, Ohio.
USDA: http://www.nal.usda.gov/fnic/foodcomp/search/
Vellinga, T.V., Blonk, H., Marinussen, M., van Zeist, W.J., de Boer, I.J.M. (2012) Methodology used in
feedprint: a tool quantifying greenhouse gas emissions of feed production and utilization
Wageningen UR Livestock Research and Blonk Consultants. Lelystad/Gouda, the Netherlands.
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2.5 Wet milling of wheat
2.5.1 By-products from wet milling of wheat
Feed materials derived from wet milling of wheat are:
name CVB DMC (g/kg)
Starch (g/kg)
Wheat gluten meal 930 63
Wheat gluten feed 906 205
Wheat bran 883 146
Wheat starch tot 300 275 301
Wheat starch tot 400 256 262
Wheat starch tot 600 224 49
2.5.2 Note on allocation
Unlike for the wet milling of maize, not enough detailed information was uncovered to allocate according
to subprocesses in the wet milling of wheat. The manner of allocation is thus chosen to be approach 1 as
described in the methodology document (see 5.3, Vellinga et al, 2012). Thus, only input/output data
covering the overall process is included.
It should be noted that the European starch industry has informed us that, in the beginning of 2012, a
detailed report on energy usage in the industry will be publicly released. It is our intention to update the
default values in this document when this report becomes available.
2.5.3 Sourcing
The Dutch feed industry source the feed materials in the countries that are listed in Table 2.5.1.
Table 2.5.1 Estimated countries of origins of the feed materials.
Processing in: the Netherlands Belgium Germany
percentage 80% 10% 10%
Crop-country
France 25%
Germany 35% 100%
Denmark 10%
UK 25%
Belgium 100%
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2.5.4 Flowcharts
Figure 2.5.1 Flowchart of wet milling of wheat
The main products of the wet milling of wheat are bran, vital gluten, wheat gluten feed and starch slurry.
Depending on the current prices of these products though, de manufacturer can make the decision to
alter processing resulting in another variety of products. Altering processing can lead to other products
like pure starch or to alterations in for instance protein, starch and dry matter contents of products.
2.5.5 Mass balance
Below, the default mass balance for wet milling of wheat is shown. As explained below, it is difficult to
construct one accurate mass balance due to large varieties of components and process outputs. The upper
and lower boundaries are therefore quite uncertain.
Table 2.5.2 Default mass balance (in kg, from 1 tonne of wheat). Output DMC (g/kg) Mass
Wheat bran 900 176
Bra
n
Wheat
Dry milling Bran
Dough Making
Vital Gluten
Separation
Dewatering and
DryingVital Gluten
Starch Separation
Evaporation
Stripping
DryingWheat Gluten
Feed
Starch slurry
Main products
Process
Input product
1 kg
0,18 kg
0,10 kg
0,08 kg
0,54 kg
Additional products
Starch
Slurry 0,10 kg
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Wheat protein/ gluten 950 93
Wheat gluten feed 900 78
Wheat starch 880 540
Wheat slurry 210 419
Various mass balances have been found in literature, providing information on varying output products.
One overall mass balance is elaborated for the five main products from the wet milling of wheat. Due to
incomplete data or variations in processing and for instance dry matter content of process outputs it is
unclear what the most likely mass balance is. By combining all mass balances, including protein and starch
contents a mass balance has been constructed.
Table 2.5.3 Mass balance constructed based on Westfalia Seperator Industry and industry experts and based on protein and starch content.
The following mass balance has been found in a presentation given by dr. W. Witt, M. Seiler and B.
Schiemann by Westfalia Separator Industry.
Table 2.5.4 Mass balance according to Westfalia Separator Industry
In the process described by Westfalia Separator Industry the first step is the dry milling of wheat in order
to produce wheat flour. This step is not described in this presentation. A more detailed mass balance is
given below. First the dough is prepared using wheat flower and water. The dough enters a 3 phase
decanter/ 2 gear drive adding more water and separating b-starch, gluten, pentosanes and a rest product
which is added to the starch slurry. The pentosanes are also added to the starch slurry. The b-starch and
gluten are treated in the gluten screen system separating the gluten from the starch. The b-starch is
combined with the rest of the starch slurry. The gluten is treated in a gluten finisher. A rest product from
the gluten finisher is transported back to the gluten screen system.
Table 2.5.5 Detailed mass balance according to Westfalia Separator Industry
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Personal communication with an industry expert in 2009 resulted in the following mass balance:
Table 2.5.6 Mass balance according to industry experts (2009)
This process includes dry milling of wheat in which the bran is separated from the wheat flower (82%).
The wheat flower enters the next process which results in a protein rich gluten fraction, a starch fraction
and starch slurry.
According to another industry expert (2004) the mass balance of the wet milling of wheat looks like this:
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Table 2.5.7 Mass balance according to industry experts
2.5.6 Inputs
Below the default energy inputs for the wet milling wheat are listed. The energy values are from European
Commission (2006), which should give a reliable range of energy uses for the European industry.
Table 2.5.8 Eergy inputs for wet milling of wheat. Product Parameter Value
Mean Min Max
Energy use: fuels natural gas 3,78 2,88 4,68 MJ/kg
Energy use: electricity electricity from the grid 1,26 0,72 1,80 MJ/kg
2.5.7 Allocation
It is likely that the in order to process various types of starch the process and the mass balance will also
slightly vary. We expect that the allocation factor might be different for the three types of wheat starch.
The price per type of wheat starch will probably also be different per type. For now there is not enough
data available to make a well based differentiation between these products.
Table 2.5.9 Allocation data By-product CVB Name Mass (kg) DMC (g/kg) Price
(euro/kg)a GE (MJ/kg)
Wheat bran Wheat bran (20700) 176 900 0.116 9.04
Wheat protein/gluten Wheat gluten meal (21100) 93 950 0.775 15.48
Wheat gluten feed Wheat gluten feed (21200) 78 900 0.85 17.6
Wheat starch NA 540 880 0.25 16.9
Wheat starch slurry Wheat starch tot 300 (80210) Wheat starch tot 400 (80010) Wheat starch tot 600 (59500)
419 210 0.02 2
a. Industry experts, 2004, personal communication, Blonk Milieu Advies database.
2.5.8 References
CVB-table: see appendix 1 in Vellinga et al. (2012)
European Commission, 2006, Reference document on best available techniques in the food, drink and
milk industries.
Industry experts, 2004, personal communication, Blonk Milieu Advies database.
Industry experts, 2009 personal communication, Blonk Milieu Advies database.
National Academy of Sciences,1971, Atlas of nutritional data of United States and Canadian feeds
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Ponsioen T., van der Flier S., Blonk H., 2009, Broeikasgasemissies voedergrondstoffen Nutreco, Blonk
Milieu Advies, Gouda.
Punter G., et. al., 2004, Well to Wheel evaluation for production of ethanol from wheat, Low carbon
vehicle partnership
University of Missouri Exntention, april 2011, Feed prices of by-products sorted by product:
http://agebb.missouri.edu/dairy/byprod/AllProducts.asp
USDA: http://www.nal.usda.gov/fnic/foodcomp/search/
Vellinga, T.V., Blonk, H., Marinussen, M., van Zeist, W.J., de Boer, I.J.M. (2012) Methodology used in
feedprint: a tool quantifying greenhouse gas emissions of feed production and utilization
Wageningen UR Livestock Research and Blonk Consultants. Lelystad/Gouda, the Netherlands.
Westfalia Separator Industry, Presentation: Comparison of wet milling and dry milling by Dr. E. Witt, M.
Seiler and B. Schiemann.
Recommended