Comparison of Modified Dry‐Grind Corn Processes for Fermentation Characteristics and DDGS Composition

Three different modified dry‐grind corn processes, quick germ (QG), quick germ and quick fiber (QGQF), and enzymatic milling (E‐Mill) were compared with the conventional dry‐grind corn process for fermentation characteristics and distillers dried grains with solubles (DDGS) composition. Significant effects were observed on fermentation characteristics and DDGS composition with these modified dry‐grind processes. The QG, QGQF, and E‐Mill processes increased ethanol concentration by 8–27% relative to the conventional dry‐grind process. These process modifications reduced the fiber content of DDGS from 11 to 2% and increased the protein content of DDGS from 28 to 58%.     

Carotenoid Value Addition of Cereal Products by Monoculture and Mixed‐Culture Fermentation of Phaffia rhodozyma and Sporobolomyces roseus

Carotenoid value addition of corn whole stillage by red yeast fermentation has yielded astaxanthin‐ and β‐carotene‐enriched distillers dried grains with solubles (DDGS) for animal feed. In this study, commonly used animal feeds (rice bran, wheat bran, milo whole stillage, and soybean products) were subjected to carotenoid value addition. Phaffia rhodozyma and Sporobolomyces roseus monoculture and mixed‐culture submerged fermentation of these substrates supplemented with 5% glycerol were analyzed for astaxanthin, β‐carotene, and residual glycerol. Among all the substrates, full‐fat rice bran and full‐fat soy flour resulted in the highest astaxanthin (80 μg/g by P. rhodozyma) and β‐carotene yields (836 μg/g by S. roseus). P. rhodozyma produced the highest astaxanthin yield on each substrate, whereas depending on the substrate, either the mixed culture or S. roseus monoculture produced the highest β‐carotene yield. Soy hull was a poor substrate for carotenoid value addition. Both yeasts used glycerol as a carbon source for carotenoid production. This study shows that substrates influence the carotenoid yield. However, it is impossible to dissect the effect of specific nutrients on carotenoid production in complex biological substrates. Carotenoid value addition of these substrates provides as much as or more than the required daily dosage of carotenoids in animal feed.     

Physical and Chemical Characterization of Fuel Ethanol Coproducts Relevant to Value‐Added Uses

One of the fastest growing industries in the United States is the fuel ethanol industry. In terms of ethanol production capability, the industry has grown by more than 600% since the year 2000. The major coproducts from corn‐based ethanol include distillers dried grains with solubles (DDGS) and carbon dioxide. DDGS is used as a livestock feed because it contains high quantities of protein, fiber, amino acids, and other nutrients. The goal of this study was to quantify various chemical and physical properties of DDGS, distillers wet grains (DWG), and distillers dried grain (DDG) from several plants in South Dakota. Chemical properties of the DDGS included crude ash (5.0–21.93%), neutral detergent fiber (NDF) (26.32–43.50%), acid detergent fiber (ADF) (10.82–20.05%), crude fiber (CF) (8.14–12.82%), crude protein (27.4–31.7%), crude fat (7.4–11.6%), and total starch (9.19–14.04%). Physical properties of the DDGS included moisture content (3.54–8.21%), A_w (0.42–0.53), bulk density (467.7–509.38 kg/m³), thermal conductivity (0.05–0.07 W/m·°C), thermal diffusivity (0.1–0.17 mm²/sec), color L* (36.56–50.17), a* (5.2–10.79), b* (12.53–23.36), and angle of repose (25.7–47.04°). These properties were also determined for DWG and DDG. We also conducted image analysis and size determination of the DDGS particles. Carbon group characterization in the DDGS and DDG samples were determined using NMR spectroscopy; O‐alkyl comprised >50% of all DDGS samples. Results from this study showed several possibilities for using DDGS in applications other than animal feed. Possibilities include harvesting residual sugars, producing additional ethanol, producing value‐added compounds, using as food‐grade additives, or even using as inert fillers for biocomposites.     

蛋白原料及其混合粉料理化性质对颗粒饲料加工质量的影响

该研究旨在探究豆粕、棉粕、菜粕、酒糟蛋白（Distillers Dried Grains with Solubles,DDGS）、乙醇梭菌蛋白5种蛋白原料及其混合粉料的营养指标和理化性质的差异,确定影响颗粒饲料质量和制粒能耗的关键指标,对5种蛋白原料的制粒效果进行综合评价。以豆粕为对照组,仅改变蛋白原料,采用相同的加工参数制备颗粒饲料,比较不同蛋白原料的制粒效果,进行主成分分析及偏最小二乘回归分析（Partial Least Squares Regression,PLS）。结果表明：在原料营养指标和理化特性方面,乙醇梭菌蛋白具有高蛋白含量、高蛋白溶解度、低脂肪、低纤维的特点,棉粕具有高纤维的特点,菜粕具有高纤维和低蛋白溶解度的特点,DDGS具有低蛋白和高脂肪的特点。蛋白原料吸水性强弱排列顺序为乙醇梭菌蛋白、豆粕、棉粕、菜粕、DDGS,水溶性与之相反。乙醇梭菌蛋白组和棉粕组的制粒能耗较高,豆粕组的制粒能耗最低;棉粕组和乙醇梭菌蛋白组的修正耐久性（Modified Pellet Durability Index,MPDI）较高分别为92.72%和90.57%,菜粕组的MPDI最低为79.68%;乙醇梭菌蛋白组的硬度最高为130.95 N,DDGS组的硬度最低为74.26 N;乙醇梭菌蛋白组的糊化度最高为45.56%,DDGS组的糊化度最低为31.36%。通过偏最小二乘回归模型得到,蛋白含量、蛋白溶解度和吸水性的增加会提高颗粒饲料硬度、PDI和MPDI;粗纤维含量、蛋白溶解度和吸水性的增加会增加制粒能耗。综合分析5种蛋白原料制粒特性,由高到低排序为乙醇梭菌蛋白、棉粕、豆粕、菜粕、DDGS。研究结果为实际生产颗粒饲料时蛋白原料的选择提供参考依据。     

Economics of Fiber Separation from Distillers Dried Grains with Solubles (DDGS) Using Sieving and Elutriation

Separation of fiber from distillers dried grains with solubles (DDGS) provides two valuable coproducts: 1) enhanced DDGS with reduced fiber, increased fat and increased protein contents and 2) fiber. Recently, the elusieve process, a combination of sieving and elutriation was found to be effective in separating fiber from two commercial samples of DDGS (DDGS‐1 and DDGS‐2). Separation of fiber decreased the quantity of DDGS, but increased the value of DDGS by increasing protein content and produced a new coproduct with higher fiber content. Economic analysis was conducted to determine the payback period, net present value (NPV), and internal rate of return (IRR) of the elusieve process. The dependence of animal foodstuff prices on their protein content was determined. Equipment prices were obtained from industrial manufacturers. Relative to crude protein content of original DDGS, crude protein content of enhanced DDGS was higher by 8.0% for DDGS‐1 and by 6.3% for DDGS‐2. For a dry‐grind plant processing corn at the rate of 2,030 metric tonnes/day (80,000 bushels/day), increase in revenue due to the elusieve process would be $0.4 to 0.7M/year. Total capital investment for the elusieve process would be $1.4M and operating cost would be $0.1M/year. Payback period was estimated to be 2.5–4.6 years, NPV was $1.2–3.4M, and IRR was 20.5–39.5%.     

Substrates Influence Stimulatory Effect of Mevalonic Acid on Carotenoid Production in Red Yeasts

Stimulation of carotenogenesis in carotenoid producing red yeasts, algae, or bacteria for enhanced carotenoid production has been achieved by mevalonic acid addition. Recently, carotenoid‐enriched feed was produced by Phaffia rhodozyma fermentation of inexpensive animal feeds. Because mevalonate improves carotenoid yield in P. rhodozyma in synthetic medium, this study tested whether a similar enhancement was possible in biobased substrates. Four concentrations, 0, 0.02, 0.04, and 0.1% of mevalonate as a precursor of P. rhodozyma production of astaxanthin and β‐carotene were evaluated in five substrates: defatted rice bran, full fat rice bran, wheat bran, corn whole stillage, and synthetic media. Additionally, four concentrations, 0, 0.05, 0.1, and 0.5% of apple pomace and tomato pomace were also evaluated as precursors of carotenogenesis in P. rhodozyma fermentation of corn whole stillage and rice bran. Mevalonic acid, tomato pomace, and apple pomace enhanced carotenoid yields in all substrates in that order. However, the optimal concentration of precursor and the percent increase of carotenoid yield in each substrate were variable, potentially indicating substrate influence on carotenoid stimulation. Among animal feed substrates, mevalonic acid in corn whole stillage resulted in the best astaxanthin yield of 220 μg/g and β‐carotene of 904 μg/g. Tomato pomace resulted in 29% astaxanthin and β‐carotene enhancement in corn whole stillage, and apple pomace increased β‐carotene production by 26% in whole stillage. The use of expensive mevalonate is offset by the inexpensive process of producing carotenoid‐enriched DDGS. Optimization of tomato or apple pomace addition may further enhance the carotenoid yields.     

Effect of Decorticating Sorghum on Ethanol Production and Composition of DDGS

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 investigating 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 before fermentation allowed for greater 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.     

Influence of different dietary doses of n-3- or n-6-rich vegetable fats and alpha-tocopheryl acetate supplementation on raw and cooked rabbit meat composition and oxidative stability

This study evaluates the effects of replacing beef tallow added to rabbit feeds (3% w/w) by different doses (0%, 1.5% and 3% w/w) of n-6- or n-3-rich vegetable fat sources (sunflower and linseed oil, respectively) and alpha-tocopheryl acetate supplementation (0 and 100 mg/kg) on the fatty acid composition, alpha-tocopherol content, and oxidation levels [assessed by analyzing thiobarbituric acid (TBA) and lipid hydroperoxide values] in rabbit meat. We also measured these parameters after cooking and refrigerated storage of cooked rabbit meat. Both dietary alpha-tocopheryl acetate supplementation and the dose and source of fat added to feeds influenced meat fatty acid composition, modifying the n-6/n-3 ratio, which was more nutritionally favorable when linseed oil was used. Furthermore, the addition of linseed oil and the supplementation with alpha-tocopheryl acetate enhanced long-chain PUFA biosynthesis. However, the addition of 3% linseed oil increased meat oxidation, and although it was reduced by dietary supplementation with alpha-tocopheryl acetate in raw meat, this reduction was not as effective after cooking. Therefore, dietary supplementation with 1.5% linseed oil plus 1.5% beef tallow and with alpha-tocopheryl acetate would be recommended to improve the nutritional quality of rabbit meat.     

Mycotoxins in ethanol co-products: modeling economic impacts on the livestock industry and management strategies

The rapidly expanding U.S. ethanol industry is generating a growing supply of co-products, mostly in the form of dried distillers' grain and solubles (DDGS) or wet distillers' grains (WDG). In the United States, 90% of the co-products of maize-based ethanol are fed to livestock. An unintended consequence is that animals are likely to be fed higher levels of mycotoxins, which are concentrated up to three times in DDGS compared to grain. The model developed in this study estimates current losses to the swine industry from weight gain reduction due to fumonisins in added DDGS at $9 million ($2-18 million) annually. If there is complete market penetration of DDGS in swine feed with 20% DDGS inclusion in swine feed and fumonisins are not controlled, losses may increase to $147 million ($29-293 million) annually. These values represent only those losses attributable to one mycotoxin on one adverse outcome on one species. The total loss due to mycotoxins in DDGS could be significantly higher due to additive or multiplicative effects of multiple mycotoxins on animal health. If mycotoxin surveillance is implemented by ethanol producers, losses are shifted among multiple stakeholders. Solutions to this problem include methods to reduce mycotoxin contamination in both pre- and postharvest maize.     

Effect of Fractionation of Distillers Dried Grains With Solubles (DDGS) on Pelleting Characteristics of Broiler Diets

Recently, the Elusieve process, a combination of elutriation (air classification) and sieving (screening) was developed to separate fiber from distillers dried grains with solubles (DDGS) to increase DDGS utilization in nonruminant (poultry and swine) diets. Elusieve process produces three products: 1) Pan DDGS, with 5% higher protein content than conventional DDGS, which would be used at higher inclusion levels in broiler diets because of low fiber content; 2) Big DDGS, with nearly the same protein content as conventional DDGS, which would be used at same inclusion levels as conventional DDGS; and 3) Fiber product. The objective of this study was to determine and compare pellet‐mill throughput, power consumption, and pellet quality for broiler diets incorporating different levels (0, 10, and 20%) of conventional DDGS and DDGS products from Elusieve process. Poultry oil contents were lower (1.5–1.6%) in diets comprising Pan DDGS and diets without DDGS than in the other diets (2.2–3.1%). The feed throughput was not affected by inclusion levels or type of DDGS. Pellet quality (pellet durability index [PDI]) for diets comprising Pan DDGS (both 10 and 20% inclusion levels) was significantly better than PDI for diets comprising conventional DDGS, Big DDGS, and the diet without DDGS. Better pellet quality of diets comprising Pan DDGS could be due to lower quantity of poultry oil used as well as compositional characteristics such as low fiber and high protein. Diets with Big DDGS had similar pelleting characteristics to those with conventional DDGS. Pellet quality deteriorated at higher inclusion levels of conventional DDGS, Big DDGS, and Enhanced DDGS. Considering that Pan DDGS would be included at higher inclusion levels in broiler diets, superior pellet quality of diets comprising Pan DDGS is beneficial.     

Solid-state fermentation of soybean and corn processing coproducts for potential feed improvement

Two agro-industrial coproducts, soybean cotyledon fiber and distiller's dried grains with solubles (DDGS), were used as substrates to evaluate the effect of coculturing three different fungi, Aspergillus oryzae , Trichoderma reesei , and Phanerochaete chrysosporium , on enzyme production by solid-state fermentation (SSF). When soybean fiber was used as the substrate, a maximum xylanase activity of 757.4 IU/g and a cellulase activity of 3.2 IU/g were achieved with the inoculation and incubation of T. reesei and P. chrysosporium for 36 h, followed by A. oryzae for an additional 108 h. This inoculation scheme also resulted in the highest xylanase activity of 399.2 IU/g compared to other fungi combinations in the SSF of DDGS. A large-scale SSF by this fungus combination produced fermented products that had xylanase and cellulase activities of 35.9-57.0 and 0.4-1.2 IU/g, respectively. These products also had 3.5-15.1% lower fiber and 1.3-4.2% higher protein contents, suggesting a potential feed quality improvement.     

调控饲料营养减少畜禽排泄物对环境的污染

阐述了饲料营养研究、新型饲料添加剂研制、日粮营养平衡技术、饲料加工工艺改进、饲养体系的改善等多种调控措施对降低动物排泄物污染环境的作用,并指出生态型饲料应用前景。     

Chemical composition of natural and polyphenol-free apple pomace and the effect of this dietary ingredient on intestinal fermentation and serum lipid parameters in rats

Unprocessed pomace containing 61% of dietary fiber (DF) and 0.23% of polyphenols (PP) and ethanol- or ethanol/acetone-extracted pomaces containing 66% DF and 0.10% PP and 67% DF and 0.01% PP, respectively, were subjected to a 4 week study in rats. The aim of the study was assessing the advantages of dietary supplementation with the above pomaces. To measure the animal response to dietary treatments, parameters describing cecal fermentation and lipoprotein profile were assessed. The dietary use of 5% unprocessed pomace caused an increase in cecal short-chain fatty acid (SCFA) production and a decrease in blood triacylglycerols, leading to a drop in serum atherogenic index. Ethanol-extracted pomace increased the glycolytic activity of cecal microbiota and decreased cecal branched-chain fatty acid production, whereas acetone extraction led to lower cecal ammonia concentration, decreased colonic pH value, and higher HDL/total cholesterol ratio. The variations in the atherogenic index indicate flavonoids as the key pomace component in relation to blood lipid profile benefits.     

Separation of Fiber from Distillers Dried Grains with Solubles (DDGS) Using Sieving and Elutriation

A process was developed to separate fiber from distillers dried grains with solubles (DDGS) in a dry‐grind corn process. Separation of fiber from DDGS would provide two valuable coproducts: 1) DDGS with reduced fiber, increased fat, and increased protein contents; and 2) fiber. The process, called elusieve process, used two separation methods, sieving and elutriation, to separate the fiber. Material carried by air to the top of the elutriation column was called the lighter fraction and material that settled to the bottom of the column was called the heavier fraction. We evaluated the compositions of fractions produced from sieving and elutriation. Two commercial samples of DDGS were obtained from two dry‐grind corn plants. Sieving over four screens (869, 582, 447, and 234 μm openings) created five size categories. The two smallest size categories contained >40% (w/w) of the original DDGS and had reduced fiber and increased protein and fat contents relative to the original DDGS. Elutriation of the remaining three size categories increased protein and fat contents and reduced fiber contents in the heavier fractions. Elutriation at air velocities of 1.59–5.24 m/sec increased the protein content of the heavier fraction by 13–41% and increased the fat content of the heavier fraction by 4–127% compared with the bulk fractions of each size category. This process was effective in separating fiber from both DDGS samples evaluated. Elusieve process does not require changes in the existing dry‐grind process and can be implemented at the end of the dry‐grind process.     

Survey of mycotoxins in U.S. distiller's dried grains with solubles from 2009 to 2011

Distiller's dried grains with solubles (DDGS) is a major coproduct of the fuel-ethanol industry and is becoming a popular low-cost ingredient for animal feed. Uncertainties regarding the risk factors in DDGS, such as level of mycotoxins, could limit its application in the animal feed industry. To provide a scientifically sound assessment of the prevalence and levels of mycotoxins in U.S. DDGS, we measured aflatoxins, deoxynivalenol, fumonisins, T-2 toxin, and zearalenone in 67 DDGS samples collected from 8 ethanol plants in the midwestern United States from 2009 to 2011. Among the five mycotoxins, deoxynivalenol was the main focus of the study because the crop year of 2009 was favorable for deoxynivalenol occurrence in corn. We learned that no more than 12% of the samples contained deoxynivalenol levels higher than the minimum advisory level for use in animal feed provided by the U.S. FDA, and the deoxynivalenol levels in all DDGS collected in 2011 were <2 mg/kg. Besides, intensive study showed that the enrichment of deoxynivalenol from contaminated corn to DDGS was about 3.5 times. With regard to the other mycotoxins in DDGS, the study suggested that (1) almost none of the DDGS samples produced in 2010 contained detectable aflatoxins and the highest level of aflatoxins in DDGS was 5.7 μg/kg; (2) no more than 6% of the samples contained fumonisin levels higher than the guidance level for feeding equids and rabbits provided by the U.S. FDA; (3) none of the samples contained T-2 higher than the detection limit; (4) most samples contained zearalenone levels between 100 and 300 μg/kg. This study was based on representative DDGS samples from the U.S. ethanol industry, and the data were collected using state-of-the-art analytical methodology. This study provided a comprehensive and scientifically sound assessment of the occurrence and levels of mycotoxins in DDGS produced from 2009 to early 2011 by the U.S. ethanol industry.     

Comparison of Enzymatic (E‐Mill) and Conventional Dry‐Grind Corn Processes Using a Granular Starch Hydrolyzing Enzyme

A new low temperature liquefaction and saccharification enzyme STARGEN 001 (Genencor International, Palo Alto, CA) with high granular starch hydrolyzing activity was used in enzymatic dry‐grind corn process to improve recovery of germ and pericarp fiber before fermentation. Enzymatic dry‐grind corn process was compared with conventional dry‐grind corn process using STARGEN 001 with same process parameters of dry solid content, pH, temperature, enzyme and yeast usage, and time. Sugar, ethanol, glycerol and organic acid profiles, fermentation rate, ethanol and coproducts yields were investigated. Final ethanol concentration of enzymatic dry‐grind corn process was 15.5 ± 0.2% (v/v), which was 9.2% higher than conventional process. Fermentation rate was also higher for enzymatic dry‐grind corn process. Ethanol yields of enzymatic and conventional dry‐grind corn processes were 0.395 ± 0.006 and 0.417 ± 0.002 L/kg (2.65 ± 0.04 and 2.80 ± 0.01 gal/bu), respectively. Three additional coproducts, germ 8.0 ± 0.4% (db), pericarp fiber 7.7 ± 0.4% (db), and endosperm fiber 5.2 ± 0.6% (db) were produced in addition to DDGS with enzymatic dry‐grind corn process. DDGS generated from enzymatic dry‐grind corn process was 66% less than conventional process.     

Pericarp Fiber Separation from Corn Flour Using Sieving and Air Classification

In the dry‐grind process, starch in ground corn (flour) is converted to ethanol, and the remaining corn components (protein, fat, fiber, and ash) form a coproduct called distillers dried grains with solubles (DDGS). Fiber separation from corn flour would produce fiber as an additional coproduct that could be used as combustion fuel, cattle feed, and as feedstock for producing valuable products such as “cellulosic” ethanol, corn fiber gum, oligosaccharides, phytosterols, and polyols. Fiber is not fermented in the dry‐grind corn process. Its separation before fermentation would increase ethanol productivity in the fermenter. Recently, we showed that the elusieve process, a combination of sieving and elutriation (air flow), was effective in fiber separation from DDGS. In this study, we evaluated the elusieve process for separating pericarp fiber from corn flour. Corn flour remaining after fiber separation was termed “enhanced corn flour”. Of the total weight of corn flour, 3.8% was obtained as fiber and 96.2% was obtained as enhanced corn flour. Neutral detergent fiber (NDF) of corn flour, fiber, and enhanced corn flour (dry basis) were 9.0, 61.5, and 5.7%, respectively. Starch content of corn flour, fiber, and enhanced corn flour (dry basis) were 68.8, 23.5, and 71.3%, respectively. Final ethanol concentration from enhanced corn flour (14.12% v/v) was marginally higher than corn flour (13.72% v/v). No difference in ethanol yields from corn flour and enhanced corn flour was observed. The combination of sieving and air classification can be used to separate pericarp fiber from corn flour. The economics of fiber separation from corn flour using the elusieve process would be governed by the production of valuable products from fiber and the revenues generated from the valuable products.     

Variation in the nutritional quality of rice straw and grain in response to different nitrogen levels

Abstract

Nitrogen (N) applied through urea is essential for rice crops and usually it is the most yield-limiting nutrient in irrigated rice production around the world. A field experiment was conducted to evaluate the effect of nitrogen levels (0, 90,120, and 150?kg?ha^?1) on the nutritional quality of straw and grain of rice varieties, PR 111, PR 122, and Pusa 44. In rice straw, significant interaction between nitrogen levels and all proximate components was observed. Increase in nitrogen level increased the crude protein by 69.23% (dry matter basis) whereas the neutral detergent fiber, acid detergent fiber, and cellulose content decreased by 7.82%, 11.18%, and 14.16%, respectively. In rice grain, crude protein content, starch content, and gel consistency were positively related to increase in nitrogen levels. Therefore, increase in nitrogen fertilization led to improved nutritive quality of both straw and grain for use as feed resource and human consumption, respectively.     

Verification of organic feed identity by fatty acid fingerprinting

The origin and authenticity of feed for laying hens is an important and fraud-susceptible aspect in the production of organic eggs. Chemical fingerprinting in combination with chemometric methods is increasingly used in conjunction with administrative controls to verify and safeguard the authenticity of food commodities. On the basis of fatty acid fingerprinting data of 36 organic and 60 conventional feeds, we have developed a chemometric classification model to discriminate between organic and conventional chicken feed. A two-factor partial least squares-discriminant analysis (PLS-DA) model was developed using 70% of the original data. External validation of the model with the remaining 30% of the data showed that all of the organic feeds and 90% of the conventional feeds (18 of 20) were correctly identified by the model. These results indicate that the PLS-DA model developed in this study could be routinely used to verify the identity of unknown or suspicious feed for laying hens.     

Selected Factors Affecting Crude Oil Analysis of Distillers Dried Grains with Solubles (DDGS) as Compared with Milled Corn

With increasing production of distillers dried grains with solubles (DDGS), both fuel ethanol and animal feed industries are demanding standardized protocols for characterizing quality. AOCS Approved Procedure (Am 5‐04) was used for measuring crude oil content in milled corn and resulting DDGS. Selected factors, including sample type (milled corn, DDGS), sample origin (ethanol plant 1, 2, 3), sample particle size (original matrix, <0.71 mm, <0.50 mm mesh opening; the last two materials were obtained by grinding and sieving), solvent type (petroleum ether, hexane), extraction time (30, 60 min), and postextraction drying time (30, 60 min) were investigated by a complete factorial design. For milled corn, only sample origin and extraction time had significant effects (P < 0.05) on crude oil values measured, but for DDGS, besides those two factors, sample particle size, solvent type, and drying time also had significant effects. Among them, the particle size of DDGS had the most effect. On average, measured oil content in DDGS ranged from 11.11% (original matrix) to 12.12% (<0.71 mm) and to 12.55% (<0.50 mm). For measuring the crude oil content of DDGS, particle size reduction, 60 min of extraction, and 60 min of drying are recommended. Regardless of the underlining factors, the method was very repeatable (standard errors <0.05). The observed particle size effect on crude oil analysis of DDGS suggests the need for similar confirmations using other analytical methods.