Traditional wet distillers grains plus solubles, modified distillers grains, Dakota Bran Cake, and distillers solubles were sampled and replicates tested using oven drying (n = 8) at 105°C and 60°C, vacuum oven drying (n = 3) and toluene distillation process (n = 8). Two replicates were evaluated using Karl Fischer titration. Oven drying was compared to toluene distillation as the standard. Oven drying at 60°C for 24 hours resulted in the same DM (P \u3e 0.10) as toluene distillation for wet byproducts

Benton, Joshua R.

Buckner, Crystal D.

Erickson, Galen E.

Gibson, Matt

Karges, Kip

Klopfenstein, Terry J.

Wilken, Mallorie F.

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Nebraska Beef Cattle Reports Animal Science Department January 2008 Evaluation of Methods for Dry Matter Determination of Ethanol Byproducts Mallorie F. Wilken University of Nebraska-Lincoln Galen E. Erickson University of Nebraska-Lincoln, gerickson4@unl.edu Joshua R. Benton University of Nebraska-Lincoln, jbenton2@unl.edu Crystal D. Buckner University of Nebraska-Lincoln, cbuckner2@unl.edu Terry J. Klopfenstein University of Nebraska-Lincoln, tklopfenstein1@unl.edu See next page for additional authors Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr  Part of the Animal Sciences Commons Wilken, Mallorie F.; Erickson, Galen E.; Benton, Joshua R.; Buckner, Crystal D.; Klopfenstein, Terry J.; Karges, Kip; and Gibson, Matt, "Evaluation of Methods for Dry Matter Determination of Ethanol Byproducts" (2008). Nebraska Beef Cattle Reports. 49. https://digitalcommons.unl.edu/animalscinbcr/49 This Article is brought to you for free and open access by the Animal Science Department at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Nebraska Beef Cattle Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors Mallorie F. Wilken, Galen E. Erickson, Joshua R. Benton, Crystal D. Buckner, Terry J. Klopfenstein, Kip Karges, and Matt Gibson This article is available at DigitalCommons@University of Nebraska - Lincoln: https://digitalcommons.unl.edu/animalscinbcr/49 Page 128 — 2008 Nebraska Beef Report  © The Board of Regents of the University of Nebraska.  All rights reserved.Evaluation of Methods for Dry Matter Determination of Ethanol ByproductsMallorie F. WilkenGalen E. EricksonJoshua R. BentonCrystal D. BucknerTerry J. KlopfensteinKip KargesMatt Gibson1SummaryTraditional wet distillers grains plus solubles, modified distillers grains, Dakota Bran Cake, and distillers solu-bles were sampled and replicates tested using oven drying (n = 8) at 105oC and 60oC, vacuum oven drying (n = 3) and toluene distillation process (n = 8). Two replicates were evaluated using Karl Fischer titration. Oven drying was com-pared to toluene distillation as the stan-dard. Oven drying at 60oC for 24 hours resulted in the same DM (P > 0.10) as toluene distillation for wet byproducts.IntroductionWith the growing availability of wet ethanol byproducts, accurate determination of the DM content of these wet byproducts is important. Many different methods are avail-able for determining DM, but the most common are oven drying proce-dures because of their cost effective-ness. Our objective was to compare different methods of DM determina-tion to obtain the most consistent and accurate DM procedure for an ethanol plant or producer using wet byproducts.ProcedureSamplesSamples of wet distillers grains plus solubles (WDGS), modified wet distillers grains (MWDGS), Dakota Bran Cake (Dbran), and distillers solubles (solubles) were obtained.  For the least variability possible, large 5 lb byproduct samples were taken and used for each method. Traditional wet distillers grains plus solubles (WDGS) has a DM of 1%-5% and is used widely in feedlot diets. Modi-fied wet distillers grains (MWDGS) is partially dried to about 42%-48% DM. Dakota Bran Cake (Dbran), mar-keted by Poet Nutrition, has a DM of 50%-54% and is a bran and distillers solubles mix. Distillers solubles (e.g. solubles), is generally 25%-5% DM and is added back to wet grains, fed as a separate ingredient, or used in liquid supplements.Oven Drying MethodsThe 105oC and 60oC oven drying methods were conducted by weighing out 8 replications of each of the four products (5g wet weight). Weights were recorded at three different dry-ing times of , 8, and 24 hours for the 105oC oven. The samples in the 60oC oven were weighed back at 24 and 48 hours.Vacuum Oven AnalysisVacuum oven analysis was con-ducted using the AOAC Official Method 94.01. Each product was replicated three times using approxi-mately 5 g of wet byproduct. The sam-ples were dried using a temperature of < 70oC and pressure of < 50 mm Hg. Toluene Distillation ProcessThe toluene distillation procedure was based on AOAC Official Method 925.04,. The 90-minute procedure required 12-15 mL of moisture, there-fore approximately 25 g (as-is) sample was used.  The sample was weighed into a 250 mL Pyrex flask and toluene added to cover the byproduct sample. Toluene was then rinsed down the sides of the condenser into the collec-tion trap and the trap was filled until it was slightly running over into the flask. Heat was applied so the tolu-ene boiled at approximately 7 to 10 minutes. Measurements were taken at 0, 45, 60, 75, and 90 minutes. The condenser was rinsed after measuring at 45, 60, 75, and 90 minutes. After allowing time to cool, the condenser tube was rinsed to take a final read-ing. An aliquot of the distilled mois-ture was collected via syringe and analyzed for any volatiles using gas chromatography (GC). Four of 8 distillation replications were analyzed with the GC by preparing 2.0 mL  of moisture collected with 0.5 mL  2-Ethylbutyrate.The toluene heated faster than the solubles forcing the solubles to stick to the glassware. Therefore, to solve this challenge, dried bran (105oC for 24 hours) was added to the distill-ers solubles in a 1: ratio of bran to solubles. This allowed the solubles to remain within the toluene for the duration of the procedure. Amounts were then back-calculated to account for the bran.Karl Fischer TitrationKarl Fischer titration, AOAC method 2001.12, was conducted in duplicate on all products.ResultsFor WDGS, the DM determined from toluene distillation was .2%, which was not different (P > 0.10) from DM measured using 60oC oven for either 24 hours or 48 hours (Table 1). Also, no difference (P > 0.10) was observed between the 60oC oven for 48 hours and 105oC oven for  hours. It was determined that samples in the 105oC oven decreased in DM over time. The vacuum oven results were higher in DM content than all other methods for WDGS. The MWDGS toluene distillation DM was 4.% and was not different (P > 0.10) from the 105oC oven for  hours. The 60oC oven for 24 hours and 48 hours were not different  © The Board of Regents of the University of Nebraska.  All rights reserved. 2008 Nebraska Beef Report  — Page 129 variation from Karl Fisher to other methods. No statistical comparisons were made due to less runs using Karl Fisher. However, the values are consis-tently greater than all other methods and for all byproducts except for vac-uum oven. Interestingly, the solubles DM were consistent across all meth-ods except for the 105oC oven method suggesting that the solubles can be measured using multiple methods.Conclusions and ImplicationsToluene distillation DM values were similar to 60oC oven for 24 hours. The 60oC oven is more cost effective and more easily completed than toluene distillation. With the decrease in DM over time in the 105oC oven, it could be implied that volatiles are lost due to more intense heat. However, loss of volatiles with the forced-air 60oC oven method was not observed given the close agree-ment with toluene distillations. Karl Fischer titration provides similar DM values to the vacuum oven method, and result in higher DM calculations than oven drying and toluene distilla-tion. It is recommended that the 60oC for 24 hours be used as the standard for DM determination of wet by-products because it is less tedious and costly than toluene distillation. 1Mallorie F. Wilken, graduate student; Galen E. Erickson, associate professor; Josh R. Benton, research technician; Crystal D. Buckner, research technician; Terry J. Klopfenstein, pro-fessor, Animal Science, Lincoln. Kip Karges and Matt Gibson, Poet Nutrition, Sioux Falls, S.D.Table 1. Average DM percentages and CV between replicates of four different ethanol byproducts evaluated by different methods.Sample 60oC 105oC Toluene Vacuum 24 h 48 h  h 8 h 24 hWDGS .2a .0ab 2.7b 2.2c 1.6d .2a 5.2eCV% 1.5 1.57 0.99 1.09 1.14 1.6 0.49MWDGS 44.1a 4.7a 42.9b 42.2c 41.d 4.b 45.0eCV% 0.22 0.42 0.59 0.78 0.51 0.47 0.4Dbran 54.0a 5.7a 52.8b 52.1c 51.d 5.7a 55.4eCV% 0.56 0.42 0.54 0.57 0.6 0.46 0.4Solubles 5.6a 4.9b .5c 2.2d 1.1e 5.9a 5.8aCV% 1.5 1.96 .1 .87 .28 2.00 0.26a,b,c,d,eMeans with different superscripts differ (P < 0.10).(P > 0.10) from each other. A reduc-tion in DM was observed with drying MWDGS in the 105oC oven over time. The vacuum oven DM was 45.0%, which was greater than other methods discussed. Dry matter was not different  (P > 0.10) between the toluene distil-lation and 60oC oven (24 hours or 48 hours) for Dbran. The DM for Dbran was 5.7% for toluene distillation. Drying at 105oC decreased DM  (P < 0.10) compared to toluene distil-lation or 60oC oven drying for Dbran, which is similar to what was observed with WDGS and MWDGS. Dry mat-ter determined from the vacuum oven was also greater than oven drying at 60oC or toluene distillation. Distillers solubles DM was 5.9% for toluene distillation (Table 1). No differences (P > 0.10) between toluene distillation, 60oC oven, and vacuum oven were observed. The only byprod-uct with the vacuum oven method being similar (P > 0.10) to toluene distillation was distillers solubles. The same decreases in DM occurred with the 105oC oven over time. This sample, averaged across methods, had the highest calculated coefficient of variation (CV). The vacuum oven offered the most consistent CV as a method across all samples followed by the 60oC oven for 24 hours and toluene distillation. The 105oC oven was the least consistent especially with distillers solubles. Less than 0.0% volatiles were present for water distilled from the 4 replications of toluene distillation suggesting the distillation removed only moisture For this reason, only 4 of the 8 replications for toluene distil-lation were completed.Results from the Karl Fischer analysis were a DM of 7.% for WDGS, 45.6% for MWDGS, 54.8% for Dbran, and 5.7% for distillers solubles. Coefficients of variation were 2.85%, 0.1%, 0.77%, and 2.8%, respectively. Because only 2 replicates were evaluated using Karl Fisher, the reader is cautioned to not compare the 

Evaluation of Methods for Dry Matter Determination of Ethanol Byproducts

UNL | Libraries

University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Nebraska Beef Cattle Reports Animal Science Department 
January 2008 
Evaluation of Methods for Dry Matter Determination of Ethanol 
Byproducts 
Mallorie F. Wilken 
University of Nebraska-Lincoln 
Galen E. Erickson 
University of Nebraska-Lincoln, gerickson4@unl.edu 
Joshua R. Benton 
University of Nebraska-Lincoln, jbenton2@unl.edu 
Crystal D. Buckner 
University of Nebraska-Lincoln, cbuckner2@unl.edu 
Terry J. Klopfenstein 
University of Nebraska-Lincoln, tklopfenstein1@unl.edu 
See next page for additional authors 
Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr 
 Part of the Animal Sciences Commons 
Wilken, Mallorie F.; Erickson, Galen E.; Benton, Joshua R.; Buckner, Crystal D.; Klopfenstein, Terry J.; 
Karges, Kip; and Gibson, Matt, "Evaluation of Methods for Dry Matter Determination of Ethanol 
Byproducts" (2008). Nebraska Beef Cattle Reports. 49. 
https://digitalcommons.unl.edu/animalscinbcr/49 
This Article is brought to you for free and open access by the Animal Science Department at 
DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Nebraska Beef Cattle 
Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 
Authors 
Mallorie F. Wilken, Galen E. Erickson, Joshua R. Benton, Crystal D. Buckner, Terry J. Klopfenstein, Kip 
Karges, and Matt Gibson 
This article is available at DigitalCommons@University of Nebraska - Lincoln: https://digitalcommons.unl.edu/
animalscinbcr/49 
Page 128 — 2008 Nebraska Beef Report  © The Board of Regents of the University of Nebraska.  All rights reserved.
Evaluation of Methods for Dry Matter Determination 
of Ethanol Byproducts
Mallorie F. Wilken
Galen E. Erickson
Joshua R. Benton
Crystal D. Buckner
Terry J. Klopfenstein
Kip Karges
Matt Gibson1
Summary
Traditional wet distillers grains 
plus solubles, modified distillers grains, 
Dakota Bran Cake, and distillers solu-
bles were sampled and replicates tested 
using oven drying (n = 8) at 105oC and 
60oC, vacuum oven drying (n = 3) and 
toluene distillation process (n = 8). Two 
replicates were evaluated using Karl 
Fischer titration. Oven drying was com-
pared to toluene distillation as the stan-
dard. Oven drying at 60oC for 24 hours 
resulted in the same DM (P > 0.10) as 
toluene distillation for wet byproducts.
Introduction
With the growing availability of 
wet ethanol byproducts, accurate 
determination of the DM content of 
these wet byproducts is important. 
Many different methods are avail-
able for determining DM, but the 
most common are oven drying proce-
dures because of their cost effective-
ness. Our objective was to compare 
different methods of DM determina-
tion to obtain the most consistent 
and accurate DM procedure for an 
ethanol plant or producer using wet 
byproducts.
Procedure
Samples
Samples of wet distillers grains 
plus solubles (WDGS), modified wet 
distillers grains (MWDGS), Dakota 
Bran Cake (Dbran), and distillers 
solubles (solubles) were obtained.  
For the least variability possible, large 
5 lb byproduct samples were taken 
and used for each method. Traditional 
wet distillers grains plus solubles 
(WDGS) has a DM of 1%-5% and 
is used widely in feedlot diets. Modi-
fied wet distillers grains (MWDGS) 
is partially dried to about 42%-48% 
DM. Dakota Bran Cake (Dbran), mar-
keted by Poet Nutrition, has a DM of 
50%-54% and is a bran and distillers 
solubles mix. Distillers solubles (e.g. 
solubles), is generally 25%-5% DM 
and is added back to wet grains, fed as 
a separate ingredient, or used in liquid 
supplements.
Oven Drying Methods
The 105oC and 60oC oven drying 
methods were conducted by weighing 
out 8 replications of each of the four 
products (5g wet weight). Weights 
were recorded at three different dry-
ing times of , 8, and 24 hours for the 
105oC oven. The samples in the 60oC 
oven were weighed back at 24 and 48 
hours.
Vacuum Oven Analysis
Vacuum oven analysis was con-
ducted using the AOAC Official 
Method 94.01. Each product was 
replicated three times using approxi-
mately 5 g of wet byproduct. The sam-
ples were dried using a temperature of 
< 70oC and pressure of < 50 mm Hg. 
Toluene Distillation Process
The toluene distillation procedure 
was based on AOAC Official Method 
925.04,. The 90-minute procedure 
required 12-15 mL of moisture, there-
fore approximately 25 g (as-is) sample 
was used.  The sample was weighed 
into a 250 mL Pyrex flask and toluene 
added to cover the byproduct sample. 
Toluene was then rinsed down the 
sides of the condenser into the collec-
tion trap and the trap was filled until 
it was slightly running over into the 
flask. Heat was applied so the tolu-
ene boiled at approximately 7 to 10 
minutes. Measurements were taken 
at 0, 45, 60, 75, and 90 minutes. The 
condenser was rinsed after measuring 
at 45, 60, 75, and 90 minutes. After 
allowing time to cool, the condenser 
tube was rinsed to take a final read-
ing. An aliquot of the distilled mois-
ture was collected via syringe and 
analyzed for any volatiles using gas 
chromatography (GC). Four of 8 
distillation replications were analyzed 
with the GC by preparing 2.0 mL  
of moisture collected with 0.5 mL  
2-Ethylbutyrate.
The toluene heated faster than the 
solubles forcing the solubles to stick 
to the glassware. Therefore, to solve 
this challenge, dried bran (105oC for 
24 hours) was added to the distill-
ers solubles in a 1: ratio of bran to 
solubles. This allowed the solubles 
to remain within the toluene for the 
duration of the procedure. Amounts 
were then back-calculated to account 
for the bran.
Karl Fischer Titration
Karl Fischer titration, AOAC 
method 2001.12, was conducted in 
duplicate on all products.
Results
For WDGS, the DM determined 
from toluene distillation was .2%, 
which was not different (P > 0.10) 
from DM measured using 60oC oven 
for either 24 hours or 48 hours (Table 
1). Also, no difference (P > 0.10) was 
observed between the 60oC oven for 
48 hours and 105oC oven for  hours. 
It was determined that samples in the 
105oC oven decreased in DM over 
time. The vacuum oven results were 
higher in DM content than all other 
methods for WDGS. 
The MWDGS toluene distillation 
DM was 4.% and was not different 
(P > 0.10) from the 105oC oven for  
hours. The 60oC oven for 24 hours 
and 48 hours were not different  
© The Board of Regents of the University of Nebraska.  All rights reserved. 2008 Nebraska Beef Report  — Page 129 
variation from Karl Fisher to other 
methods. No statistical comparisons 
were made due to less runs using Karl 
Fisher. However, the values are consis-
tently greater than all other methods 
and for all byproducts except for vac-
uum oven. Interestingly, the solubles 
DM were consistent across all meth-
ods except for the 105oC oven method 
suggesting that the solubles can be 
measured using multiple methods.
Conclusions and Implications
Toluene distillation DM values 
were similar to 60oC oven for 24 
hours. The 60oC oven is more cost 
effective and more easily completed 
than toluene distillation. With the 
decrease in DM over time in the 
105oC oven, it could be implied that 
volatiles are lost due to more intense 
heat. However, loss of volatiles with 
the forced-air 60oC oven method was 
not observed given the close agree-
ment with toluene distillations. Karl 
Fischer titration provides similar DM 
values to the vacuum oven method, 
and result in higher DM calculations 
than oven drying and toluene distilla-
tion. It is recommended that the 60oC 
for 24 hours be used as the standard 
for DM determination of wet by-
products because it is less tedious and 
costly than toluene distillation. 
1Mallorie F. Wilken, graduate student; 
Galen E. Erickson, associate professor; Josh R. 
Benton, research technician; Crystal D. Buckner, 
research technician; Terry J. Klopfenstein, pro-
fessor, Animal Science, Lincoln. Kip Karges and 
Matt Gibson, Poet Nutrition, Sioux Falls, S.D.
Table 1. Average DM percentages and CV between replicates of four different ethanol byproducts 
evaluated by different methods.
Sample 60oC 105oC Toluene Vacuum
 24 h 48 h  h 8 h 24 h
WDGS .2a .0ab 2.7b 2.2c 1.6d .2a 5.2e
CV% 1.5 1.57 0.99 1.09 1.14 1.6 0.49
MWDGS 44.1a 4.7a 42.9b 42.2c 41.d 4.b 45.0e
CV% 0.22 0.42 0.59 0.78 0.51 0.47 0.4
Dbran 54.0a 5.7a 52.8b 52.1c 51.d 5.7a 55.4e
CV% 0.56 0.42 0.54 0.57 0.6 0.46 0.4
Solubles 5.6a 4.9b .5c 2.2d 1.1e 5.9a 5.8a
CV% 1.5 1.96 .1 .87 .28 2.00 0.26
a,b,c,d,eMeans with different superscripts differ (P < 0.10).
(P > 0.10) from each other. A reduc-
tion in DM was observed with drying 
MWDGS in the 105oC oven over time. 
The vacuum oven DM was 45.0%, 
which was greater than other methods 
discussed. 
Dry matter was not different  
(P > 0.10) between the toluene distil-
lation and 60oC oven (24 hours or 48 
hours) for Dbran. The DM for Dbran 
was 5.7% for toluene distillation. 
Drying at 105oC decreased DM  
(P < 0.10) compared to toluene distil-
lation or 60oC oven drying for Dbran, 
which is similar to what was observed 
with WDGS and MWDGS. Dry mat-
ter determined from the vacuum oven 
was also greater than oven drying at 
60oC or toluene distillation. 
Distillers solubles DM was 5.9% 
for toluene distillation (Table 1). No 
differences (P > 0.10) between toluene 
distillation, 60oC oven, and vacuum 
oven were observed. The only byprod-
uct with the vacuum oven method 
being similar (P > 0.10) to toluene 
distillation was distillers solubles. 
The same decreases in DM occurred 
with the 105oC oven over time. This 
sample, averaged across methods, had 
the highest calculated coefficient of 
variation (CV). 
The vacuum oven offered the most 
consistent CV as a method across all 
samples followed by the 60oC oven for 
24 hours and toluene distillation. The 
105oC oven was the least consistent 
especially with distillers solubles. 
Less than 0.0% volatiles were 
present for water distilled from the 
4 replications of toluene distillation 
suggesting the distillation removed 
only moisture For this reason, only 4 
of the 8 replications for toluene distil-
lation were completed.
Results from the Karl Fischer 
analysis were a DM of 7.% for 
WDGS, 45.6% for MWDGS, 54.8% 
for Dbran, and 5.7% for distillers 
solubles. Coefficients of variation 
were 2.85%, 0.1%, 0.77%, and 2.8%, 
respectively. Because only 2 replicates 
were evaluated using Karl Fisher, the 
reader is cautioned to not compare the 


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