PROGRESS REPORT
PROJECT TITLE: Food Grade DDG for Human Consumption - Value Enhancement of a Corn Co
Product
PROJECT NUMBER:
REPORTING PERIOD: 2015
PRINCIPAL INVESTIGATOR: Padu Krishnan
ORGANIZATION: South Dakota State University
PHONE NUMBER: 574-440-9215
EMAIL: Padmanaban.krishnan@sdstate.edu
1) PROJECT ACTIVITIES COMPLETED DURING THE REPORTING PERIOD. (Describe project
progress specific to goals, objectives, and deliverables identified in the project workplan.)
Progress was achieved in several areas described in the work plan.
These will be bulleted to outline the efforts and the outcomes. Further descriptions will be provided
as abstracts or tables.
Consultative agreements and Non Disclosure Agreements were signed for collaborative work
between the PI and participants in the ethanol industry. Some will be identified in this report.
However several companies have expressed the need for confidentiality.
A pilot scale DDG production facility has been identified through discussions with National
Corn to Ethanol Research Center (NCERC), Southern Illinois University to provide real world
DDG fractions for monitoring of aflatoxins, antibiotic residues, heavy metals, etc). Both Dry
Mill and Wet Mill ethanol production capability exists in this institution for large scale testing of
processing techniques. Dr. Sabrina Trupia and Post Graduate Fellow Parisa Fallahi have agreed
to collaborate on food applications of DDG. Dr. Parisa Fallahi is a graduate of SDSU.
Oil fractions from the DDG refinement are being evaluated for efficacy in food applications.
While DDG is a principle focus of this study, valuable DDG constituents such as phytonutrients,
oils and pigments extracted from it hold promise for value addition.
A high-protein, reduced-fiber DDG fraction of DDG from front-end fractionation of corn is being
explored as a food ingredient as a collaborative project with the National Corn to Ethanol
Research Center (NCERC), Edwardsville, IL.
A bench scale production process was developed for lab scale production of a food grade DDG
(10 Kilogram batches). This set up is also being used to an economic analysis of the FDDG
production process. A flow diagram is presented in this report. Students in the North American
Marketing Association (SDSU Chapter) will compete at the national level using Food Grade
DDG as a competition project.
A C Cell Instrument was acquired with funding leveraged with the SD Wheat Commission. The
C Cell provides vital information relating to the internal structure of leavened food products. The
inclusion of bran and DDG in dough systems undermines dough cell structure and its ability to
trap gas for expansion. The C-Cell output provides cell dimension that can be used in
determining statistical parameters on bread internal quality (See Appendix A).
A Provisional Patent was filed at SDSU covering processing conditions developed for Food
Grade DDG.
1.
Food Grade Distillers Grains for use in Food Applications, 9/8/2014, numbered
62/045.057.
Three journal articles were published in 2013 and 2014 relating to the use of DDG in food
applications from work done in our lab. These scientific journal articles pertain to effects of
processing treatments on DDG and the use of DDG in food applications (Tortilla, Persian bread,
and Multi Cereal blends).
1. S. Pourafshar, K.A. Rosentrater and P.G. Krishnan. 2014. Changes in chemical and
physical properties of Latin American wheat flour based tortillas substituted with
different levels of distillers dried grains with solubles (DDGS). J. Food Science and
Technology. DOI 10.1007/s13197-014-1566-5. Published on line September 23,
2014.Springer Publishing. http://link.springer.com/article/10.1007/s13197-0141566-5
2. S. Pourafshar, K.A. Rosentrater and P.G. Krishnan. 2014. Use of alternative flours
as partial replacement of Barbari bread formulation (traditional Iranian Bread.
Journal of Food Science and Technology DOI 10.1007/s13197-014-1640-z.
Published on-line, November 14, 2014, Springer Publishing.
http://link.springer.com/article/10.1007/s13197-014-1640-z
3. J. A. Saunders, Kurt A. Rosentrater and P. G. Krishnan. 2013, Removal of
Color Pigments From Corn Distillers Dried Grains With Solubles (DDGS) to
Produce an Upgraded Food Ingredient. Journal of Food Research. Vol 2
(5):111-123. http://www.ccsenet.org/journal/index.php/jfr/article/view/29483
The research presented in the publications above were conducted in my labs by my
Graduate Students, Shirin Pourafshar and Jessica Saunders in collaboration with ARS
scientist Kurt Rosentrater.
A cookie production line was developed for mass production of DDG Cookies for use in public
events. These will demonstrate to the public the efficacy of DDG as a food ingredient (figure 1)..
Samples will be distributed at public events in the summer of 2015. A calendar of events is
planned for 2015 for dissemination of literature and DDG food samples.
Super Critical Carbon Dioxide Extraction of DDG was studied for pigment removal. SFE (or
SCO2) was explored for use in conjunction with solvent extraction with Ethanol, Hexanes,
Petroleum Ether and Water. While several of these solvents do not qualify as food grade
solvents, comparisons were made to demonstrate their potential for pigment removal (please see
figures 2,3 and 4).
Particle size distribution of FDDG relative to All Purpose Flour, and several extraction
treatments were studied to determine the nature of the ingredients and their role in dough
formation (table 1).
The effects of Food-grade DDG in steamed breads were investigated. Bread dough is steamed in
many parts of Asia. The internal structure of such breads is similar to baked bread. Fiber
inclusion in steamed bread dough will likely interfere with air cell formation during mixing and
dough expansion during fermentation. A flour replacement of 20% (with DDG) was found to
yield satisfactory color and textures in the products. Sensory evaluation of these products will be
conducted to determine product acceptability and preference.
A study on effects of 100% whole-wheat products fortified with DDG on Glycemic Index of
human subjects is reported in this progress report (figure 7). DDG and DDG in conjunction with
pulses (chickpea flour) showed reductions in the blood glucose in test subjects when the test meal
(Pita bread) was fortified at the 20% and 10% flour replacement levels. A 100% whole wheat Pita
served as the control. Such products hold good promise for diabetic diets.
Extrusion processing of pulse/DDG blends were explored fro the production of DDG snacks.
Chickpea and Chick pea/DDG blends were extruded in a single screw extruder to determine
puffing characteri of starch and fiber.
A Graduate Research Assistant, Ashley Adamski, was hired to implement laboratory
investigations (12 months, half-time).
2) IDENTIFY ANY SIGNIFICANT FINDINGS AND RESULTS OF THE PROJECT TO DATE.
Figure 1. News Food Product Development Team operating cookie machine for mass production
of DDG extruded cookies. Effects of DDG on batter viscosity on cookie spread and redness are
also noticeable.
Supercritical Carbon Dioxide Processing of Corn Distillers Dried Grain with Solubles
(DDGS)
Supercritical carbon dioxide (SCO2) is an ideal alternate solvent that can be used to upgrade
DDGS to food-grade flour. Its high diffusion coefficients and dissolving power makes it suitable
for the selective extraction of fatty acids and carotenoids. Carotenoids impart color while fatty
acids produce an off-odor and off-flavor and their removal from DDGS will improve the baking
functionality and customer acceptability. Ethanol washing of DDGS has been shown to improve
the color but the use of SCO2 gave similar or superior results with less processing time.
Figure 2. Food-grade DDGS (far right, FDDGS) produced via ethanol washing was
compared to Carbon Dioxide Processed DDGS, FDDG. and Raw DDGS (a) Raw DDGS, (b) SCO2 processed DDGS, (c) Ethanol Processed FDDGS, (d) SCO2Ethanol processed FDDG
Figure 3. From left:
1-Raw DDGS
2,3- SCO2 processed DDGS
4-FDDG
5,6-SCO2 processed FDDG
NOTE: Particle sizes are slightly different for DDGS and FGDDG but visual differences in
terms of appearance are observable.
SCO2 processed DDGS was much lighter in color than both FGDDGS and SCO2 processed
FDDGS. The removal of pigments was highly improved when using SCO2 as the yellowness and
redness coloration were much lower than those of FDDGS. Besides, SCO2 was capable of
reducing the yellowness/redness of the FGDDGS that had already been washed with ethanol.
DDG is light in color as compared to ddgs but the major difference is the low levels of coloration
as determined from yellowness/redness measurements. Processing DDG with SCO2 showed
minimal change in both lightness and yellowness/redness values and this might be attributable to
the lack of solubles addition.
SCO2 shows superior results when compared to the ethanol washing method. It’s ability to
extract more pigments from FGDDGS shows its ideal nature as an alternate solvent. There seems
to be a difference in the mechanism by which SCO2 and ethanol washing process DDGS. Ethanol
is polar while carbon dioxide is non-polar and this will confer difference in selectivity for
solutes. Qualitative and quantitative analysis of fatty acids and carotenoids is underway and this
will help in identifying their difference in mechanism of action. GC-MS will be used for fatty
acid profiling while LC-MS/MS will be used to quantify the carotenoids.
Figure 4. One Liter extraction flask for large scale Supercritical CO2 treatment and color
measurement scale for determining pigment removal in processing streams (L=brightness,
a=red versus green, and b=yellow versus blue)
Extrusion of DDG with Pulses
Influence of the Extrusion Processing Parameters on the Physico-Chemical and Sensory
Characteristics of Garbanzo Flour and Distillers Grain Based Expanded Snacks
Extrusion of starch-based ingredients is an important technology used in the manufacturing of
processed foods. While many of the starch-based ingredients are highly functional, there is need
for ingredients that can deliver nutrients, fiber and health promoting food constituents. Pulse
flours, when combined with distillers grains, represent a novel blend as they are gluten-free and
high in protein and fiber content.
In this study we investigated the effect of food grade distillers dried grains developed at
South Dakota State University (FDDG: 1 to 10%) and extrusion process variables including barrel
temperature (80-140oC), screw speeds (80-140 rpm) and feed moisture content (14-20%) on the
physicochemical properties (density, expansion, water absorption index-WAI, water solubility
index-WSI) and sensory characteristics (hardness and crispness) of the garbanzo flour-based
extruded snacks.
In this study, high-protein puffed snacks were produced with unique blends of garbanzo
flour (protein 22.42%, fiber 19%) and food grade distiller’s dried grains (FDDG; protein 36.8%,
fiber 10.5%). An optimal design with three factor interactions was developed. Blends were
extruded in a single-screw extruder. Incorporation of DDGS into garbanzo flour decreased torque
and product expansion, but increased bulk density and hardness. The barrel temperature had a
significant effect (p<0.05) on these parameters. Optimum extrusion conditions resulting in
minimum bulk density and maximum expansion ratio were estimated. The expanded products have
good cell structure with varying cell sizes when viewed under a microscope. Expanded products
with FDDG content 4-8%, 16% feed moisture extruded at barrel temperature 100-120oC and screw
speed of 80-100 rpm were chosen for sensory evaluation. Expanded snacks made with 5% FDDG
were well accepted by taste panel. Sensory assessment of the extruded samples before and after
frying in oil indicated that extrusion of garbanzo flour-DDGS blends can produce acceptable
snacks. These products may be used as tasty snacks having significantly improved protein and
dietary fiber content. Combining pulses with distiller’s grains also shows promise for the Gluten-free
market.
Figure 5. Extrusion of Garbanzo flour (Chickpea) with 5% FDDG for production of
“Cheetos-like”snack foods. Puffed products are generally fried or baked and then
flavored.
Particle Size Determination
Table 1. Particle size distribution of all purpose flour (APF) and FDDG
washed with different solvents. Aqueous treatment contributed to
particle swelling and a shift in size distribution.
Mesh Size
APF
(%)
DDG:
Original
(%)
DDG:
Aqueous/
alcohol
Tmt
(%)
Above 40
0.00
1.95
2.08
2.00
0.96
4.96
44.65
64.09
63.67
8.09
41.40
51.12
28.88
31.21
24.47
39.86
0.90
2.75
2.28
43.27
5.68
0.18
0.41
0.40
14.14
5.78
0.04
0.15
0.24
6.63
40
400μm
0.0165”
60
250μm
0.0098”
80
180μm
0.007”
100
150μm
0.0059”
200
75μm
0.0029”
DDG:
Aqueous/
DDG: Ethanol
alcolhol
Wash only
Tmt
(%)
Effect of corn distillers dried grains on dough properties and qualities of Chinese steamed
bread
Abstract: Corn distillers dried grains (DDG) is a co-product of the corn alcohol production. DDG
is rich in protein and fiber. Adding DDG to the Chinese staple food-steamed bread can increase
the nutritional value of steamed bread. The effect of DDG added to all purpose flours at the
replacement levels of 0, 10, 15, 20 and 25 g per 100 g flours on the properties of dough and
Chinese steamed bread was investigated. The rheological behavior of the blend dough was
determined by Mixolab and the texture analysis (TA) of the blend dough and streamed bread
were performed in a texture analyzer. The quality scoring system was set up according to China
standard GB/T 17320-2013 to test the qualities of the steamed bread with DDG. The results
showed that the addition of DDG can lead to changes in dough properties and textural properties
of dough and steamed bread. With the increasing amount of DDG, the water absorption rate of
dough increased, the extensibility of dough decreased; the volume of steamed bread with DDG
decreased; and the hardness of dough and steamed bread increased. The steamed bread with 20g
DDG per 100 g flours was acceptable.
Figure 6. Steamed breads as a carrier of Food Grade DDG. Steams breads are yeast
leavened and have the same internal structure as baked breads. The dough cell structure is
sensitive to bran and DDG inclusion.
Glycemic Index
Glycemic Index testing procedure: The glycemic index ranks foods according to their effect on blood
glucose and it is an indication of the rate of absorption of carbohydrate in the food. To determine the GI
of foods, a portion of the test food containing 25g or 50g available carbohydrate is fed to 10 or more
healthy people and blood glucose levels are then measured over two hours. This procedure is repeated
using a control food containing the same amount of carbohydrate. The areas under blood glucose curves
are calculated. A GI value for the test food is then calculated for each person by dividing their glucose
AUC for the test food by their glucose AUC for the reference food. The final GI value for the test food is
the average GI value for the 10 people. As the GI measure reflects the rate of carbohydrate absorbed, only
foods containing carbohydrate can be tested for their GI.
Glycemic response results from feeding trials employing DDG and pulses:
The objective of this section of the study was to compare the glycemic response to consumption
of all five different types pita bread made varying ratios of wheat, Corn DDG and Pulses
(W/D/G). Pita bread is traditionally made with white flour (All Purpose Flour, APF) from
wheat. Treatments were therefore Pita breads made with the following formula:
Control - 100% APF
Treatment 80% wheat, 20% garbanzo
Treatment 80% wheat, 20% DDG
Treatment 70% wheat, 20% Garbanzo, 10% DDG
Treatment 70% wheat, 10% garbanzo, 20 DDG
Only preliminary results from selected treatments (in red) are reported in this document. More
complete data will be available for March 11.
Measurement of Glycemic index of pita bread
The glycemic response of pita bread final products and control was measured in twelve
healthy participants. Subjects were in the age group of 18-30 years and having fasting blood
glucose level between 70-100 mg/dL were selected for the test. The height and weight of the
participants was recorded prior to test to calculate BMI (Body Mass Index). Patients having
similar BMI were included in the test. Participants were required to fast for 12 hours and limit
their physical activity for 48 hours prior to testing.
Following fasting, each participant was given 50 g of available carbohydrates of the pita
bread final product or control to ingest in a random order. After ingestion, blood samples were
collected from each participant using the simple finger-prick test to measures the individual's
glucose levels at 0, 30, 60, 90, and 120 minutes. Available carbohydrates is defined as the
fraction of carbohydrates that human enzymes can digest. It can be calculated either by the
difference or analyzed directly. To calculate available carbohydrate by difference, the formula
is:100 - (weight in grams [protein + fat + water + ash + alcohol + dietary fiber] in 100 g of food)
Available carbohydrate was calculated for all different types of pita breads that were tested for
glycemic response test. Each type of pita bread had a different weight when it was given to
participants on the test day.
Table 2 below provides the average for blood glucose concentrations for all 12 participants.
The graph shows the curves for the glycemic response for 3 different types pita breads.
Time(min)
AP
70w-20d-10g
80w- 20d
0
82.58
83.83
85
30
104.33
78.67
81.5
60
98.75
77.42
79.42
90
93.33
80.75
81
120
90.92
84.33
83.08
Table 2.
Glycemic
Response for select treatments. Numbers reflect blood glucose values in 12 subjects.
120
100
80
AP
60
70w-20d-10g
80w-20d
40
20
0
-50
0
50
100
150
Figure 7. Glycemic Index response of test subjects fed wheat Pita bread (Control), Pita
bread with 20% Garbanzo and 10% FDDG and Pita Bread made with 20 FDDG. Y
Axis=Blood Glucose (mg/DL) and X Axis is time in Minutes.
Legend:
APF=Pita bread made with All Purpose Flour
d=Pita bread made with DDGS
g=Pita bread made with Garbanzo Flour(chickpea)
blue line=100% All Purpose Flour
red line =70%APF + 20% DDG + 10% Garbanzo Flour
Figure 8. Production Flow Chart of a Potential Production Process for Economic Analysis.
Prepared by Dr. Scott Fausti, Department of Economics, SDSU (personal communication).
Step 1: Blending process of combining food grade ethanol with wet
DDGs to create a slurry.
Step 2: Slurry flows into pressure cooker/press (soy
cow)
Heated to 151 degrees at 15psi.
Internal press compaction mechanism presses cooked
DDG into solid form and thus removes all liquid (slurryA) that is collected at bottom of pressure cooking device.
Step 3: Slurry-A is transferred
to distillation device. Food grade
ethanol is recovered and
nutraceuticals recovered. Step 5:
Slurry-B from first round of
washing is processed the same as
Slurry-A.
Step 4: DDG solid moved to station for a two step
washing process. First round is 70% food grade
ethanol and 30% water. Again a slurry is made and
then pressed to separate liquid (Slurry-B) and solids
Step 5: DDG Solid to now mixed with 100% water
and then the slurry is pressed to separate solids and
liquid (Slurry-C).
Step 6: Slurry-C is now processed in a centrifuge to
separate nutraceuticals for collection. Water is
disposed.
Step 7: DDG solid is now food grade and
ready for drying and then shipped to miller.
Table 3. Amino acid content of pita bread fortified with food grade DDGS and Chickpeas.
Addition of DDG and Chick pea flour increased amino acids content significantly over control
100% wheat flat breads.
Sample
Arginine
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Valine
Control (wheat)
.290 e
.180 e
.290 e
.540 e
.230 e
.130 e
.370 e
.220 d
.320 d
80%w-20%g
.400 d
.220 d
.340 d
.650 d
.310 d
.150 d
.450 d
.280 c
.390 c
80%w-20%d
.420 c
.280 b
.410 b
1.01 a
.340 c
.200 a
.530 b
.370 a
.500 a
70%w-20%g-10%d
.450 b
.250 c
.390 c
.850 c
.370 b
.170 c
.500 c
.330 b
.450 b
70%w-20%d-10%g
.550 a
.290 a
.430 a
.920 b
.440 a
.180 b
.570 a
.370 a
.500 a
w: what flour
d:food grade DDGS
g:garbanzo flour (chickpea flour)
Table 4. Proximate Composition (%), Stability and Brightness of FDDG and Pita made with
Wheat:DDG:Garbanzo blends
mean
Protein
fat
Aw
L*
Pure Garbanzo (G)
23.3 b
1.97 g
0.3696 f
90.1000 b
Pure DDGS
(D)
30.2 a
10.24 a
0.0810 g
73.3233 f
Treatment 1
(100%APF)
Control
11.4 g
4.03 e
0.5720 a
90.7333 a
Treatment 2
(80%W-20%D)
15.2d
5.24 b
0.4596 d
84.2900 d
Treatment 3
(70%W-20%D10%G)
16.7 c
4.37 c
0.4140 e
83.4833 e
Treatment 4
(80%W-20%G)
11.8 f
2.58 f
0.5266 b
90.4367 ab
Treatment 5
(70%W-20%G10%D)
14.9 e
4.07d
0.4800 c
86.2033 c
3) CHALLENGES ENCOUNTERED. (Describe any challenges that you encountered related to project
progress specific to goals, objectives, and deliverables identified in the project workplan.)
Challenges center around the time and effort required to establish linkages with industrial partners
who may eventually benefit from the technologies that arise from this study. Conversations that have
occurred so far have identified key barriers (both real and perceived) that may stand in the way
commercialization. We will need adequate research data to provide the assurance that we have done
the due diligence in asking the right questions and in doing the appropriate groundwork.
4) FINANCIAL INFORMATION. (Describe any budget challenges and provide specific reasons for
deviations from the projected project spending.)
PI anticipates no budget challenges. Several contractual agreements with external labs need to be
implemented in relation to materials testing for toxicology and non-food residues. Shifting of
resources between budget categories may be needed. Pilot scale production is anticipated in 2015.
An economic production cost analysis is also anticipated that will call for contractual services.
5) EDUCATION AND OUTREACH ACTIVITIES. (Describe any conferences, workshops, field days,
etc attended and/or publications developed to disseminate project results.)
PI Krishnan attended the National Corn Utilization Conference in Kentucky in June, 2014. A
research poster was presented. DDF Cookies were provided as samples.
A color brochure of DDG Cookies was designed for use in public taste testing events anticipated in
2015.
Journal publications will be disseminated via the Internet.
Three research abstracts were submitted to the Institute of Food Technologists Conference in
Chicago, IL in June 2015. All the abstracts relate to food application of DDG and are pending
review.
Figure 9. Brochure on cookie recipes and nutritional composition of FDDG fortified cookies.
Appendix A. Crumb Structure analysis of steamed breads using a C-Cell Instrument
Figure 10. Solvent extraction of FDDGS after pin milling showing improved pigment removal
potential with fine grinding.