Effect of Decorticating Sorghum on Ethanol Production and Composition of Ddgs

7/27/2019 Effect of Decorticating Sorghum on Ethanol Production and Composition of Ddgs

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EFFECT OF DECORTICATING SORGHUM ON ETHANOL PRODUCTION

AND COMPOSITION OF DDGS

D.Y. Corredor, Graduate Student

Department of Biological and Agricultural Engineering, Kansas State University, Manhattan, KS66506.

ABSTRACT

The use of a renewable biomass that contains considerable amounts of starch and

cellulose could provide a sugar platform for the production of numerous bioproducts.

Pretreatment technologies have been developed to increase the bioconversion rate for

both starch and cellulosic-based biomass. This study investigated the effect of

decortication as a pretreatment method on ethanol production from sorghum as well as its

impact on quality of distillers dry grains with solubles (DDGS). Eight sorghum hybrids

with 0, 10, and 20% of their outer layers removed were used as raw materials for ethanol

production. The decorticated samples were fermented to ethanol using Saccharomyces

cerevisiae. Removal of germ and fiber prior to fermentation allowed for a higher starch

loading for ethanol fermentation and resulted in increased ethanol production. Ethanol

yields increased as the percentage of decortication increased. The decortication process

resulted in DDGS with higher protein content and lower fiber content, which may

improve the feed quality.

Keywords:Ethanol, fermentation, sorghum, decortication process, DDGS.

INTRODUCTION

During the last twenty years, many industries and manufacturers have been

seeking to replace petroleum-based feedstocks with renewable materials. The use of


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renewable biomass, which contains significant amounts of starch or cellulose, could

provide a sugar platform for numerous bio-products. Ethanol demand is growing as a

clean substitute for direct use as fuel, which can ease both natural resource limitation

and environmental pollution (Roehr, 2001). The U.S ethanol production capacity is

projected to increase from its current 3.1 billion gallons to 6.0 billion gallons per year by

2006 (MacDonald et al., 2003).

Starch-rich grains such as maize and sorghum are viable renewable resources for

ethanol production (Turhollow and Heady, 1986; Christakopoulos et al., 1993; Lezinou et

al., 1995; Dien et al., 2002a). Grain sorghum (Sorghum bicolor[L] Moench) is one of the

most important crops in the United States, and its production ranks third among cereal

crops. Sorghum contains 55 - 75% starch by kernel weight (Serna-Saldivar and Rooney,

1995). Sorghum is a tropical grass grown primarily in semiarid and dry parts of the

world, especially in areas too dry for maize. The diversity of climate that sorghum can

grow in, as well as the fact that it is heat and drought tolerant, makes it an important

cereal crop, especially in arid areas of the world. Currently about 90% of U.S. sorghum

production is used for animal feed and only about 10% for ethanol production.

Pretreatment technologies have been developed to increase the conversion rate of

biomass, including mechanical methods such as size deduction through milling,

decortication, and the extrusion process; physical methods such as steaming, radiation,

and sonication; chemical methods such as alkaline and acid hydrolysis; biological

methods such as microbial and enzyme degradation; and a combination of these methods.

Decortication is the removal of the bran or outer layers of the grain. Abrasive

decortication operates on the principle of progressively rubbing off the outer layers of the


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kernel (Beta et al., 2000). MacLean et al. (1983) studied the effect of decortication on the

apparent protein quality and digestibility of sorghum. They suggested that the use of

decortication can markedly improve the apparent protein quality and digestibility of

sorghum. Higiro et al. (2003) compared the quality and yield of starch between the

sorghum grits from milling techniques using roller mills and the grits from a decorticator-

degerminator. The grits obtained from the decorticator-degerminator had a higher starch

recovery (61-70 %) than the grits from roller milling (51-68%). Beta et al. (2000) also

demonstrated that abrasive decortication and roller milling reduced the levels of

polyphenols from high-tannin sorghum. Tannin is the primary nutrient-limiting

component in sorghum lines with a pigmented testa. High levels of tannin may have a

negative effect on the fermentation process since starch and protein digestibility reduce

10% (Leeson and Summers, 1997). For the above reasons, decortication may increase

the bioconversion rate of sorghum in sorghum lines containing tannins (i.e. those with a

pigmented testa). Decortication may also reduce other fermentation inhibitors such as

phenolic acid, color compounds, etc.

Ponnanpalam et al. (2004) studied the effect of germ and fiber removal on ethanol

production from maize. They reported that the integration of germ and fiber removal in

the dry-grind ethanol industry could increase fermentation capacity and add value to co-

products, resulting in increased productivity and profits. Decortication not only increases

the starch loading for fermentation, but also changes the chemical composition of

distillers dried grains with solubles (DDGS). This is a stable, free-flowing granular

product that is yellow/tan to brown in color with a bulk density of 30-40 pounds per cubic

foot (Distillers Grains Technology Council, 2005). A light-colored DDG is an indication


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of high amino acid digestibility and provides an excellent energy and available

phosphorous source (Rai et al., 2004). However, product color may vary, but several

animal studies have shown that color is not an indicator of nutritional quality (Distillers

Grains Technology Council, 2005). Increased demand for ethanol (EtOH) has resulted in

rapid growth of the dry-grind (DG) EtOH industry.

In the past, DDGS were viewed as more of a by-product than a co-product;

however, as more ethanol processing plants are built in response to demand for fuel

ethanol, there will be an increasing supply of DDGS. Currently, dry-mill ethanol plants

produce more than 5.5 million metric tons of DDGS annually. Industry experts predict

that the volume of DDGS produced will increase to more than 7.5 million metric tons by

the end of 2005 (Kansas Sorghum Commission). For each 1,000 bushels of grain, eight to

nine tons of distillers dried grains with solubles (DDGS) are produced (Distillers Grains

Technology Council, 2005). By finding more uses for DDGS, ethanol plants can

potentially maintain or improve their profitability even as competition increases (Davis,

2001). Historically, more than 85% of DDGS have been fed to dairy and beef cattle as a

high-quality, economical feed ingredient. With continuing research, DDGS use in swine

and poultry diets is expanding also. The export market represents an opportunity for new

market growth as DDGS production expands along with ethanol production. Today, the

U.S exports approximately one million metric tons of DDGS, with the largest importers

being Ireland, the United Kingdom, Europe, Mexico, and Canada. In DG processing,

marketing of DDGS is critical to the economic stability of DG plants (Renewable Fuels

Association, 2005). One factor that affects market value is variation. The composition of


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DDGS can vary substantially (Belyea et al., 1989); this reduces quality of DDGS and

negatively impacts market value ( Belyea et al., 2004).

Belyea et al (2004) studied DDGS and composition from dry-grind ethanol

processing. They reported that DDGS are composed mainly of protein, fat, crude fiber,

and starch. Protein is the most important nutrient in animal feed; protein variation in

feeds can cause mis-formulation and can affect animal productivity. Fat is also an

important nutrient, because it increases available energy concentrations. They concluded

that variation in the composition of DDGS was not related to variation in corn

composition and probably was due to variation in processing streams or processing

techniques. They showed that the protein content of DDGS from maize can range from

27 to 35%. The fat content of DDGS from maize can range from 8-12% (Rai et al.,

2004). Both fat and protein affect market value; DDGS with high fat (> 12%) and high

protein (>30%) is worth about $5 - $20 per ton more from a nutrient content basis than

DDGS with lower fat (< 11%) and lower protein (


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fermentation efficiency; therefore, the objective of this research was to study the effect of

the decortication process as a pretreatment method for ethanol production and DDGS

quality.

MATERIALS AND METHODS

Decortication Process

Eight sorghum hybrids were decorticated by using a tangential abrasive dehulling

device (TADD) equipped with an 80-grit abrasive pad (Venebles Machine Works,

Canada). The abrasive pad was shimmed to minimum distance from the upper plate.

Bran removed during decortication was collected for analysis, and decorticated grains

were removed for fermentation. The decorticated samples were milled (Cyclone Sample

Mill, UDY Corp. Fort Collins, CO) into powder with a particle size of less than 2 mm

and were used as substrate for ethanol fermentation. Moisture content of these samples

was determined by using AACC standard methods (Approved Methods 44-15A, AACC

2000).

Microorganisms

Saccharomyces cerevisiae (S. cerevisiae, ATCC 24860) was used for ethanol

fermentation. Yeast cells were maintained on a YPD medium with 20 g yeast extract, 5 g

peptone, 5 g dextrose, and 20 g agar (per L). Yeast cells were cultured in a rotatory

shaker with a shaker speed of 200 rpm at 30 C for 48 h in a pre-culture media ( 2%

glucose, 0.5 % peptone, 0.3 % yeast extract, 0.1% KH2PO4, and 0.05 % MgSO4 . 7H2O at

pH 5.5).


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Ethanol Fermentation

Termanyl 120 L (0.01 ml -amylase / g dry starch) (Novozymes North America

Inc. Franklinton, NC) was used for starch liquefaction. Erlenmeyer flasks (250 mL) with

a 100-mL medium containing (per liter): 200 g starch substrate, 3 g peptone, 1 g KH2PO4,

and 1 g (NH4)2SO4 at pH 5.8 were placed in the temperature-controlled water bath shaker

at 95C with agitation speed of 140 rpm (Model Giramax 939 XL). After lower the

temperature to 80C, the second Termanyl 120 L (0.01 ml -amylase / g dry starch) was

added and the liquefaction was continued for 30 min with continuous agitation at 140

rpm. Amyloglucosidase solution (3000U/ml) was used for starch saccharification based

on 150 U/g dry starch at 60C with continuous agitation in the water bath shaker for 30

min at 140 rpm.

After saccharification, the fermentation medium was adjusted to pH 3.85. The

medium was then inoculated with 6% yeast suspension (1 x106 cells/ml) and incubated in

a rotatory shaker (200 rpm) at 30C for 72 h. All experiments were duplicated and the

average values were reported.

After completion of the distillation, the whole broth was dried at 49 C until the

moisture content was less than 15% (w.b.). A coffee grinder was used to homogenize the

dried samples. These represented the distillers dried grains with solubles (DDGS).

Analysis Methods

Starch content was determined using commercially available kits from Megazyme

(Bray, Ireland) following AACC Approved Method 76-13 (AACC, 2000). Protein was


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determined via nitrogen combustion using a LECO FP-528 Nitrogen Determinator (St.

Joseph, MI) according to the AACC 46-30 crude protein-combustion method (AACC,

2000). Nitrogen values were converted to protein content by multiplying by 6.25. Crude

fiber, fat, and ash were determined using AOAC standard methods (AOAC, 1995). Free

sugar was measured as glucose before and after fermentation using the Lane and Enyon

volumetric method (Plews, 1970). Calcium and phosphorous were determined using the

AOAC #968.08 standard method (AOAC,1995). Ethanol was obtained by distillation of

the fermentation broth, and the ethanol concentration was determined according to the

specific-gravity method (AOAC-942.06, 1995). All experiments were duplicated and the

average values were reported.

Kernel color (HunterL, a and b values) of the undecorticated and decorticated

sorghum were obtained by using a Hunter Color Quest 45/0. In L-a-b color space, L

varies from 0 (black) to 100 (perfect white); a measures green when negative and red

when positive; and b is a measure of blue when negative and yellow when positive.

Analysis of variance (ANOVA) and least significant difference (LSD) was done

by using the Statistical Analysis System (SAS Institute, Cary, NC).

RESULTS AND DISCUSSION


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Effect of Decortication on Chemical Composition and Kernel Color of

Sorghum

The initial chemical composition of sorghum samples ranged from 69.3 to 76.6%

for starch, 9.7 to 11.1% for protein, 3.0 to 4.1% for crude fat, and 1.3 to 1.8% for crude

fiber. Decortication had a significant effect on the chemical composition of sorghum.

Starch content increased significantly as the degree of decortication increased, while

crude fiber and crude fat contents decreased significantly as the degree of decortication

increased (Table 1). This can be explained due to the fact that the decortication process

removed the outer layer of the kernels, including pericarp and germ, which are higher in

fiber and fat and lower in starch compared with endosperm.

In general, protein content decreased significantly as the degree of decortication

increased, except for samples KS11 and KS15. This may have been due to differences in

thickness of the pericarp in those samples or in the distribution of the protein within the

endosperm. Starch content was increased by 4.9 7.1 % and by 8.6 15.6 % for

sorghums with 10% and 20% decortications, respectively; crude fat content was

decreased by 9.8 to 20.5% and by 28.9 to 38.6% for sorghums with 10% and 20%

decortication, respectively; and crude fiber content was decreased by 49.2 to 63.4% and

by 74.4 to 85.6% for sorghums with 10% and 20% decortications, respectively (Table 2).

Crude protein content was decreased by 1.4 to 3.4% and by 6.6 to 11.5% for 10% and

20% decortications, respectively, except KS11 and KS15. These changes in composition

allow for higher starch loading during fermentation, which benefits the fermentation

process by increasing fermentable substrate and fermentation yields. For example, with


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the same substrate concentration, starch loading would increase 5 to 12% when the

decorticated sorghum was used.

Decortication has a significant effect on grain color. The percentage of luminance

increased as the degree of decortication increased. Thus, the L-values of the grains

increased significantly as the degree of decortication increased, which was expected

(Table 3). This indicates that whiteness of the grain increased as percentage of

decortication increased. On the other hand, a-values decreased as the degree of

decortication increased. The b-values also decreased as the degree of decortication

increased, indicating the sorghum samples are less yellow after decortication. The same

tendency was not presented by sample KS-3, whose a-values varied only a little. These

changes suggest that DDGS color would change with decorticated sorghum. Lighter

colored DDGS may avoid the problem of the DDGS appearing burnt during the drying

process, which is often mistaken for lower quality DDGS.

Ethanol Production

Ethanol yields increased significantly as the degree of decortication increased.

Removal of hull and outer-layer pericarp prior to fermentation optimized starch digestion

and increased ethanol production. As mentioned above, decortication resulted in samples

with higher starch levels and increased the amount of fermentable substrate, in turn

resulting in higher fermentation yields. Decortication may have other benefits for

fermentation including removal of fermentation inhibitors such as phenolic acids,

polyphenols (when present), and color compounds present in the bran. Decortication

may also increase access of the endosperm to the enzymes used during the fermentation

process by removing bran that could be attached to endosperm particles during milling.


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Research is in progress to determine if decortication increases the rate of ethanol

fermentation for this reason.

Ethanol yields were in the range of 8.2 9.1% for undecorticated samples, 9.0

9.7 % for sorghums with 10% decortication, and 9.3 10.2 % for sorghums with 20%

decortication, respectively (Table4). Ethanol yields increased 3.3 to 11.1% for sorghums

with 10% decortication and increased 7.6 to 18.1% for sorghums with 20% decortication.

The samples with the maximum increase in the percentage of starch due to the

decortication were KS1, KS2 and KS15 with 20% decortication (Table 4). The highest

increase in starch resulted in the highest ethanol yields. The percentage increases in

ethanol yields for these samples were 15.9% for KS1, 18.1% for KS2, and 11.6 % for

KS15, respectively (Table 4).

The results indicated that starch loading is the major factor affecting ethanol

yield. To further study the effect of substrate concentration on ethanol fermentation and

quality of DDGS, KS1 and KS2 were selected and substrate concentrations of 20, 25, 30,

and 35% were used. In general, ethanol yields increased as substrate concentration and

degree of decortication increased (Table 5). The percentage of ethanol increment

increased as the degree of decortication increased; however, it decreased as the substrate

concentration increased. This may be because the ethanol concentration achieved

inhibited ethanol fermentation by yeast. Ethanol level is one of three major factors

(temperature, acidity, and ethanol level) affecting ethanol yield; the rising concentration

of ethanol, due to the increase in the substrate concentration and higher initial starch

loads due to decortication, tended to have an inhibitory effect on the fermentation

process. This effect is partially due to feedback inhibition, whereby accumulation of the


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end products of a process tends to slow the process itself. With 10% decortication, the

percentage of ethanol increment increased by 9.0 to 11.1% for KS1 and by 9.2 to 10.9%

for KS2, respectively. With 20% decortication, the ethanol increased by 11.6 to 15.9 %

for KS1 and by 12.5 to 18.1% for KS2, respectively.

Chemical composition of distillers dry grains with solubles (DDGS)

Protein content is the most important quality factor for marketing and end-use

quality of DDGS (Belyea et al., 2004). DDGS contains much higher protein than the

original sorghum. Protein content of DDGS increased significantly as the degree of

decortication increased (Table 6). Protein content of the DDGS ranged from 40 to 45.3%

for undecorticated sorghums, 46.6 to 53.1% for sorghums with 10% decortication, and

51.6 to 57% for sorghums with 20% decortication. The percentage increase of protein

content in DDGS ranged from 11.1 to 25.6% for sorghums with 10% decortication and

20.8 to 38.9% for sorghums with 20% decortication, respectively. The increase of

protein content may increase the market value of the DDGS and have an impact on its

feed quality. The increase in protein content of DDGS could be caused by two main

sources yeast growth and sorghum composition. As yeast grows during fermentation,

cell mass as yeast protein increased significantly, and this contributes to the final protein

content of DDGS. Decortication only decreases 1-2% protein in the sorghums, but

increases starch up to 10%. This means that decortication can decrease the total DDGS

yield up to 12%. With a small percentage of protein decreased and a large percentage of

starch increased, protein content of DDGS must increase significantly.

Since starch in sorghum is converted to ethanol and removed, the remaining

nutrients in the grain are concentrated and often increased two or three fold in the


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resulted DDGS. Compared with the original samples, the most important changes were

five-to-six-fold increase in protein concentration, a five-to-six-fold increase in fat

content, a 12-to-14-fold increase in crude fiber content, and a 15-fold decrease in starch

when sorghums with 20% decortication were used. With the similar starch content in

DDGS and the ratio of DDGS to initial substrate decreased as the degree of decortication

increased, the amount of unfermented starch decreased as the degree of decortication

increased (Figure 1). The lower amount of starch in DDGS resulting from the

decorticated samples compared with DDGS resulting from the original grain indicates

that decortication increased starch conversion rate. The decortication process also

reduced the crude fiber, and increased starch and crude oil contents of DDGS, which

must increase the feeding value and energy level of DDGS (Table 7). While most of the

attention is given to the amount of protein in DDGS, fat and starch are also important

nutrients because they increase available energy concentrations (Belyea et al., 2004).

Phosphorous, calcium, and ash were not severely affected by degree of decortication.

This is significant as their presence is important as valuable nutrients for animal feeds.

Currently, most (~98%) of DDGS in North America come from both maize and

sorghum ethanol fermentation (Belyea, 2004). The remaining 1 to 2% of DDGS are

produced by the alcohol beverage industry. Approximately 5.5 million metric tons of

DDGS are produced annually in U.S. It would be beneficial to compare nutritional values

of DDGS from sorghum with other grains. Some published results related to chemical

composition of DDGS from different grains are summarized in Table 8. Protein contents

of DDGS from both undecorticated and decorticated sorghum (approximately 45.1% for

undecorticated sorghum, 53% for 10% decorticated sorghum, and 56% for 20%


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decorticated sorghum) were much higher than the protein in DDGS from corn and wheat

(from 23-31.3% for corn and 19.6-35.6% for wheat). While likely fermented under

different conditions, with different amounts of added yeast nutrients, etc., the

decorticated sorghum samples used in this study had much higher protein levels than the

other gains listed in Table 8. Fat content was also higher than wheat and corn. Ash,

starch, and phosphorous were well within the ranges reported by Wu et al. (1984) and the

SoueHigh Plains Corporation. The level of ash is lower than that of wheat and corn,

suggesting there was no significant effect of salt formation during pH adjustments before

fermentation.

CONCLUSIONS

Removal of the outer layer of the pericarp prior to fermentation by the

decortication process allowed higher starch loading and resulted in increased ethanol

yields. Ethanol yield increased as decortication and substrate concentration increased.

The ethanol yields increased by 3.3-11.1% for sorghums with 10% decortication and by

7.6-18.1% for sorghums with 20% decortication, when 20% substrate content was used.

The ethanol yields increased 9.0-18.1% when the substrate concentrations were higher

than 20%. Decortication also resulted in significant changes in the chemical composition

of DDGS. Protein and fat contents of DDGS increased as the degree of decortication

increased, and crude fiber decreased as the degree of decortication increased.

Decortication had no significant effect on starch, ash, calcium, and phosphorous contents


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in DDGS. The protein content of DDGS from sorghum was higher than that reported for

maize and wheat, which may improve the feeding quality.

ACKNOWLEDGMENTS

Dr. S.R Bean, Research Chemist

USDA-ARS Grain Marketing and Production Research Center, Manhattan, KS 66502.

Dr. T. Schober. Research Associate


Dr. D. Wang, Assistant Professor



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Table 1. Chemical composition of sorghum as affected by decortication [a],[b].

Chemical

CompositionKS1 KS2 KS3 KS4 KS11 KS15 KS20 KS23

Starch(%)

0% D 73.8 a 76.6 a 76.5 a 75.6 a 74.3 a 69.3 a 73.9 a 72.5 a

10% D 79.0 b 81.4 b 80.2 b 80.8 b 78.7 a 73.5 b 79.1 b 76.9 b

20% D 82.3 c 85.6 c 83.1 c 85.8 c 81.8 c 80.1 c 83.3 c 80.9 c

Protein (%)

0% D 11.12 a 10.04 a 9.66 a 10.01 a 10.69 a 11.05 a 10.28 a 11.02 a10% D 10.06 b 9.71 b 9.36 b 9.79 b 10.80 a 11.18 a 10.14 b 10.65 b

20% D 9.72 c 9.34 c 8.61 c 8.86 c 10.18 b 10.95 a 9.60 c 9.87 c

Crude fiber (%)

0% D 1.34 a 1.42 a 1.59 a 1.32 a 1.42 a 1.61 a 1.71 a 1.80 a

10% D 0.52 b 0.52 b 0.81 b 0.49 b 0.61 b 0.71 b 0.66 b 0.76 b

20% D 0.14 c 0.27 c 0.41 c 0.21 c 0.20 c 0.29 c 0.21 c 0.29 c

Crude fat (%)

0% D 4.07 a 2.98 a 3.84 a 3.70 a 3.57 a 3.60 a 3.19 a 3.57 a

10% D 3.24 b 2.52 b 3.38 b 3.13 b 3.12 b 3.25 b 2.72 b 2.95 b

20% D 2.57 c 2.12 c 2.67 c 2.27 c 2.33 c 2.51 c 2.07 c 2.41 c[a] . Means with the same letter in the same column of the same characteristic are not

significantly different. (


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Table 2. Chemical composition change (%) of sorghum as affected by decortication.

Chemical

Composition

Percentage of chemical composition change (%)

KS1 KS2 KS3 KS4 KS11 KS15 KS20 KS23

Starch (%)0% vs 10% 7.1 6.2 4.9 6.9 5.8 6.1 7.0 6.10% vs 20% 11.5 11.7 8.6 13.5 10.1 15.6 12.8 11.5Protein (%)0% vs 10% -9 -3.3 -3.1 -2.2 1.0 1.2 -1.4 -3.40% vs 20% -12 -7.0 -10.9 -11.5 -4.8 0.9 -6.6 -10.4

Crude Fiber (%)0% vs 10% -61.3 -63.4 -49.2 -62.7 -56.8 -56.1 -61.5 -57.70% vs 20% -89.4 -81.2 -74.4 -84.5 -85.6 -81.9 -87.9 -84.0

Crude Fat (%)0% vs 10% -20.5 -15.6 -12.0 -15.6 -12.7 -9.8 -14.7 -17.50% vs 20% -37.0 -28.9 -30.4 -38.6 -34.9 -30.4 -35.2 -32.5

Table 3. Color variations of sorghum flours affected by degree of decortication [a],[b]

Color KS1 KS2 KS3 KS4 KS11 KS15 KS20 KS23

L value

0% D 61.8 a 60.8 a 61.9 a 61.6 a 60.4 a 56.9 a 70.0 a 70.9 a10% D 69.4 b 72.2 b 65.1 b 71.2 b 69.7 b 60.9 b 76.7 b 77.6 b20% D 75.7 c 76.7 c 68.6 c 76.2 c 75.2 c 68.8 c 79.7 c 81.1 ca value0% D 10.8 a 9.8 a 10.6 a 11.1 a 11.2 a 11.8 a 3.7 a 2.5 a10% D 9.4 b 5.3 b 11.1 b 7.3 b 8.4 b 10.2 b 2.5 b 1.2 b20% D 7.7 c 3.0 c 10. 6 a 5.9 c 7.5 c 7.3 c 1.7 c 0.5 cb value


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0% D 18.0 a 21.5 a 16.1 a 20.6 a 20.6 a 16.7 a 19.2 a 20.1 a10% D 15.7 b 18.6 b 15.6 b 17.9 b 16.3 b 15.4 b 16.8 b 18.5 b20% D 13.7 c 16.4 c 14.3 c 15.8 c 13.8 c 13.4 c 15.8 c 17.2 c

[a]. Means with the same letter in the same column of the same characteristic are not



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Table 5. Ethanol concentration (%) as a function of starch substrate and degree of

decortication [a]

Sample substrate (%) Ethanol yields (%,v/v) Ethanol increase (%)

0% 10% 20% 0% vs 10% 0% vs 20%

KS-1

20 8.19 a 9.10 b 9.49 c 11.11 15.87

25 10.60 a 11.71 b 12.08 c 10.47 13.96

30 13.07 a 14.34 b 14.73 c 9.71 12.70

35 15.05 a 16.41 b 16.79 c 9.03 11.56

KS-2

20 8.62 a 9.56 b 10.18 c 10.90 18.09

25 10.77 a 11.87 b 12.33 c 10.21 14.48

30 13.38 a 14.71 b 15.22 c 9.94 13.75

35 15.82 a 17.28 b 17.80 c 9.22 12.51[a]. Means with the same letter in the same row of the same variety are not significantly

different. (


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Table 6. Protein content (%) of DDGS as affected by degree of decortication [a].

Sample ID Protein (%) Protein increase (%)

0% 10% 20% 0% vs 10% 0% vs 20%

KS 145.1 a

a 53.1 b 56.8 c 17.6 25.7

KS 2 43.3 a 52.5 b 56.0 c 18.1 28.6

KS 3 41.9 a 46.6 b 51.6 c 11.1 23.0

KS 4 45. 3 a 51.6 b 54.7 c 14.0 20.8

KS 11 43.9 a 52.7 b 56.9 c 20.0 29.6

KS 15 39.9 a 48.6 b 55.4 c 21.6 38.9

KS 20 44.2 a 51.7 b 56.4 c 16.9 27.6

KS 23 41.3 a 51.9 b 56.3 c 25.6 36.2[a]

. Means with the same letter in the same row of the same characteristic are not



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Crude fiber 7.48a 5.82b 3.35c 9.20a 6.93b 4.69c

Crude fat 11.98a 13.02b 14.20c 10.77a 11.43b 11.80c

Phosphorous 0.85a 0.86a 0.79b 0.81a 0.85a 0.81b

Calcium 0.03a 0.03a 0.03a 0.04a 0.03b 0.03b

Ash 3.77a 3.97a 3.91a 3.65a 3.63a 3.88a[a]. Means with the same letter in the same row are not significantly different. (


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Sources: [a]. Rasco et al., (1987); [b]. Belyea et al., (2004); [c]. Wu et al., (1984); [d].

Mohawk Canada,Ltd. SoueHigh Plains Corporation, Colwich, KS.


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Percentage of decortication (%)

0% 10% 20%

RatioofD

DGStoinitalsubstrates(%)

16

18

20

22

24

26

28

30

Figure 1. Effect of decortication on the ratio of DDGS to initial substrate.


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LITERATURE CITED

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Documents

Effect of Decorticating Sorghum on Ethanol Production and Composition of Ddgs