Extruded Corn Meal Research Articles

Soluble corn arabinoxylan has desirable material properties for high incorporation in expanded cereal extrudates

Incorporation of soluble dietary fiber to cereal extrudates is a practical approach to improve its nutrition values, but it can be technically challenging as a reduction in extrudate quality commonly occurs at a high incorporation level. In the present study, we incorporated soluble corn arabinoxylan (CAX) into cornmeal at a high level (25% w/w) and produced expanded extrudates with a comparable microstructure to cornmeal without added fibers. For a comparison, wheat arabinoxylan (WAX)- and long chain inulin-incorporated cornmeal extrudates had low degrees of expansion and high bulk density. CAX-incorporated cornmeal had comparable melt viscosities as the cornmeal control at shear rates higher than 100 s −1 and an endothermic transition occurring at the same temperature range (130–170 °C), both similar to cornmeal alone. On the other hand, WAX-incorporated cornmeal instead had an exothermic transition at 130–170 °C, and a substantially higher melt viscosity than cornmeal. Long chain inulin-incorporated cornmeal had two overlapped endothermic transitions at 130–170 °C and a markedly lower melt viscosity than cornmeal. The superior functionality of CAX in corn extrudates was attributed to its highly branched xylan backbone extensively substituted by complex sidechains and charged structure. CAX had a hypothesized ellipsoid-shaped conformation that presumably would not engage in intermolecular entanglements, resulting in a low viscous near-Newtonian flow behavior. In summary, addition of CAX to cornmeal did not cause major changes in melt viscosity and endothermic transition of the pre-extrusion material, nor to the quality of resulting extrudates. • Corn arabinoxylan (CAX)-incorporated (25%) cornmeal extrudates had good expansion. • CAX performed better in extrusion than wheat arabinoxylan or long-chain inulin. • CAX-incorporated cornmeal had desirable thermal and rheological properties. • Branched structure of CAX appeared to contribute to its functionality in extrusion.

Extruded Corn Meal as a Partial Replacement for Steam Flaked Corn in Finishing Diets for Feedlot Cattle: Growth Performance and Digestive Function of Feedlot Cattle

Sixty-four Holstein steers (247 ± 4 kg) were used in a 70-d experiment to evaluate the effects of partial replacement of steam flake corn (SFC) with extruded corn meal (EC) on growth performance and dietary net energy. Treatments consisted of a steam flaked corn-based finishing diet containing 0%, 10%, 20%, or 30% EC, where EC replaced 0%, 15%, 30%, or 45% of SFC (DM basis). Replacement of SFC with increasing levels of EC did not affect (P > 0.10) ADG, DMI, and gain efficiency. When EC replaced 15% to 30% of SFC, observed dietary NE was 99% of expected. Whereas, when EC replaced 45% of SFC, observed dietary NE was 94% of expected. Four Holstein steers (210 ± 7 kg) with cannulas in the rumen and proximal duodenum were used in a 4 × 4 Latin square experiment to evaluate treatment effects on characteristics of digestion. Partial replacement of SFC with EC did not affect (P > 0.10) flow of undegraded feed N and microbial N and to the small intestine, and ruminal microbial N efficiency (g microbial N/kg OM fermented). Likewise, there were no treatment effects (P > 0.10) on ruminal digestion of OM, NDF, starch and feed N. As expected, total tract digestion of starch for all treatments exceeded 99%. However, partial replacement of SFC with EC decreased total tract digestion of DM and OM (linear effect, P = 0.02), and dietary DE (linear effect, P = 0.03). These effects were more pronounced where EC replaced 45% of SFC. Partial replacement of SFC with EC did not affect (P > 0.10) ruminal pH, total VFA concentration, molar proportions of acetate, propionate, and butyrate, and estimated methane production. It is concluded that partial replacement of SFC with EC does not have a beneficial effect on ruminal microbial efficiency and digestive function. The feeding value of extruded corn for feedlot cattle is comparable to that of steam flaked corn provided the inclusion rate does not exceed 20% of diet dry matter.

Usability of residual oat flour in the manufacture of extruded corn snacks

Extrusion technology is used to produce snacks from various raw materials, including by-products. One such by-product is residual oat (Avena sativa L.) flour (ROF), which is obtained as a by-product in the production of Betaven. The aim of this study was to prepare extrudates based on cornmeal with varying proportions of ROF, and to investigate the influence of applied additives on nutritional and pro-health compounds and the texture and functional properties of the snacks. Cornmeal extrudates with varying proportions of ROF were analyzed. Products obtained at a 1:2 compression ratio with 10% ROF exhibited the highest expansion, least density and hardness, and the highest water-binding capacity. The use of a 10% addition level caused an increase in soluble dietary fiber by 63%, insoluble fiber by 25%, polyphenols by 23%, and antioxidant activity by 22%. The above-mentioned extrudates had the best sensory quality, and therefore this level of ROF addition is recommended for industrial processing.

Properties of extruded chia–corn meal puffs

This study investigated the properties of extruded corn meal puffs containing chia. Mixtures of corn meal and chia seeds (0–20 g/100 g) were processed in a laboratory-scale twin-screw extruder at different moisture contents (18–22 g/100 g) and final heating zone temperatures (120–160 °C). Extrusion processing provides a simple method for grinding the seeds, which is necessary for making the fatty acids available. The expansion of cylindrical extrudates decreased with increasing chia content, increasing moisture and increasing final heating zone temperature. The hardness of the extrudates increased with increasing moisture content and decreased at intermediate chia levels. The specific mechanical energy of the extrusion process decreased with increasing chia content.

Non-destructive, quantitative characterization of extruded starch-based products by magnetic resonance imaging and X-ray microtomography

Magnetic resonance imaging (MRI) was used for non-destructive characterization of the pore structure of starch-based extruded products. The samples were obtained by extrusion cooking of corn meal in a twin screw extruder. The samples were extruded at varying mechanical energy input and, subsequently, the pore size distributions were analyzed. Two different sample preparation methods were introduced and discussed. Negative imaging was the favorable technique. In this method, the pores are filled with cyclohexane and the solvent is detected by MRI. The analysis method was validated by glass beads of known size as reference samples. The pore sizes detected by MRI were slightly higher than the real size of the glass beads. When extruded corn meal samples were analyzed, we were able to show, that despite an equal expansion index, samples can have different pore size distributions. Finally, the pore size distributions were compared to analysis via X-ray microtomography and advantages and limitations of both methods were discussed.

Physicochemical and antioxidant properties of extruded cornmeal with natural cocoa powder

The mixtures of natural cocoa powder (NCP) (0–20%) and corn meal (CM) were processed in a twin-screw extruder at melting temperature ranging from 130 to 150oC to produce expanded extrudates. The specific mechanical energy (SME) input, expansion indexes, piece density, water absorption index (WAI), water solubility index (WSI), mechanical properties, microstructure, and antioxidant properties of extrudates were investigated. SME input and piece density were significantly affected by the melting temperature, while increasing the NCP increased the SME input and reduced piece density. An inverse relationship between sectional and longitudinal expansion indexes was confirmed. When NCP was added, numerous air cells, smaller pore size, apparent elastic modulus, breaking strength, WSI, protein, fat, and ash contents significantly increased whereas the WAI, moisture and carbohydrate contents were reduced. The influence of added NCP was attributed to the formation of lipidamylose complexes. The use of NCP on the extruded corn meal is an alternative to improve nutritional values and good texture characteristics.

CORN MEAL IN BROILER CHICKEN NUTRITION

This paper gives the effect of application of none extruded corn meal (T1, T2) and extruded corn meal (T3, T4) in broiler chicken nutrition. In meals the corn grain (C) was replaced by corn meal in the amount of 50% (T2, T4) and 100 % (T1, T3). The experiment lasted 42 days in system 5 × 4 (5 treatments × 4 repetitions). In every treatment 300 chickens were included. Feeding of chicken was ad libitum, with three types of meals: starter with 23.30 % CP and 12.78 MJ/kg ME; grower with 20.30 % CP and 13.10 MJ/kg ME, and finisher 17.70 % CP and 13.25 MJ/kg ME. The results of investigation were body weight of chicken C – 2161 g, T1 – 2168 g, T2 – 2164 g, T3 – 2261 g, and T4 – 2244 g; daily growth C – 51.45 g, T1 – 51.62 g, T2 – 51.52 g, T3 – 53.84 g, and T4 – 53.43 g; mortality of chicken C – 5.00 %, T1 – 5.71 %, T2 – 3.64 %, T3 – 3.81 %, and T4 – 6.36 %; feed conversion ratio C – 1.93 kg/kg, T1 – 1.84 kg/kg, T2 – 1.84 kg/kg, T3 – 1.86 kg/kg, and T4 – 1.84 kg/kg. Differences in production parameters were not statistically significant, except differences in body weights between the group T3 and T1, T2 and K groups which were statistically significant (P < 0.001) and between T4 and T1, T2 and C were statistically significant (P < 0.001). Processing percentages were unified among groups with minimal differences in contents of abdominal fat in carcass. There were only statistically significant (P < 0.05) differences in the abdominal fat between the groups of males and females T1 and T2 and all other groups.

Relative effect of particle size on the physical properties of corn meal extrudates: Effect of particle size on the extrusion of corn meal

Corn meal of various particle sizes ranging from 180 to 710 lm were processed in a twin-screw extruder to produce directly expanded extrudates. The extrusion process effects on the specific mechanical energy (SME), expansion indexes (radial, longitudinal and volumetric), pasting viscosity, water absorption index (WAI) texture properties, and microstructure were determined. Increasing the particle size decreased the SME input. Extrudates produced with corn meal of higher particle sizes expanded more than extrudates produced with smaller particle sizes. For all treatments there was no peak viscosity at 95 C. But expanded corn meal extrudate from the 180 lm fraction showed a discontinuous gel matrix phase. Increasing corn meal particle size decreased WAI values. The mechanical resistance of the extrudates from the smallest particle size was significantly higher (p < 0.05) than that of the largest particle size. The microstructure of raw corn meal revealed large fractured particles with small rounded particles adhering to the surface.

OPTIMIZATION OF EXTRUSION COOKING OF CORNMEAL AS RAW MATERIAL FOR BAKERY PRODUCTS

ABSTRACT The objective of this work was the optimization of extrusion process for the production of extruded cornmeal (ECM) that may be used in the production of corn bread by a direct procedure. The extrusion process variables, barrel temperature, Et (111–159C), moisture content, Mc (12.10–24.77%) and screw speed, Ss (160–460 rpm), were considered and their influence on moisture content of milled extrudates (ME), expansion index (EI), bulk density (BD), water solubility index (WSI), water absorption index (WAI) and cold paste viscosity (CPV) of extrudates was investigated. The influence of ECM addition on viscosity of wheat flour and cornmeal mixture was monitored. The optimimum combination of extrusion conditions was Mc = 21.21%; Et = 145C; Ss = 263.5 rpm. The properties of ECM under optimal extrusion conditions were Mc, 10.97%; EI, 4.22; WAI, 7.84 g gel/g dm; WSI, 14.88%; BD, 36.35 g/100 mL and CPV, 1,220 BU. In the quantity of 30% calculated on the wheat flour quantity, the ECM can be used for the production of corn breads by a direct procedure. PRACTICAL APPLICATIONCorn flour obtained by dry milling of maize, namely in a mixture with wheat flour, has been used in Southeastern Europe for centuries in theproduction of bakery products. Cornstarch granules swell more slowly and gelatinize at a higher gelatinization temperature than starch granules of wheat flour, while corn proteins are incapable of dough formation. The properties of finished corn bakery products depend significantly on the quantity and temperature of the boiling water used for the mix (60–100% of total water quantity added to the mix) and the steaming time of the corn flour (3–12 h), which is the first and critical stage in the process of corn bread and rolls production. The quality of finished products depends significantly on the baker's experience.The purpose of this work was to determine the optimal extrusion process variables for the production of the gelatinized cornmeal that can be used in the production of bakery products by a direct procedure, without prior steaming of cornmeal. This could significantly reduce the processing time and energy consumption, while the product will still be of consistent and even better quality.

Effect of the Corn Breaking Method on Oil Distribution between Stillage Phases of Dry-Grind Corn Ethanol Production

The majority of fuel ethanol in the United States is produced by using the dry-grind corn ethanol process. The corn oil that is contained in the coproduct, distillers' dried grains with solubles (DDGS), can be recovered for use as a biodiesel feedstock. Oil removal will also improve the feed quality of DDGS. The most economical way to remove oil is considered to be at the centrifugation step for separating thin stillage (liquid) from coarse solids after distilling the ethanol. The more oil there is in the liquid, the more it can be recovered by centrifugation. Therefore, we studied the effects of corn preparation and grinding methods on oil distribution between liquid and solid phases. Grinding the corn to three different particle sizes, flaking, flaking and grinding, and flaking and extruding were used to break up the corn kernel before fermentation, and their effects on oil distribution between the liquid and solid phases were examined by simulating an industrial decanter centrifuge. Total oil contents were measured in the liquid and solids after centrifugation. Dry matter yield and oil partitioning in the thin stillage were highly positively correlated. Flaking slightly reduced bound fat. The flaked and then extruded corn meal released the highest amount of free oil, about 25% compared to 7% for the average of the other treatments. The freed oil from flaking, however, became nonextractable after the flaked corn was ground. Fine grinding alone had little effect on oil partitioning.

Continuum thermodynamic modeling of drying capillary particulate materials via an edge-based algorithm

The numerical modeling of the coupled heat and mass transfer processes prevalent in drying non-hygroscopic and hygroscopic capillary particulate materials is dealt with. A set of volume averaged governing equations is employed for this purpose. An improved unstructured hybrid vertex-centered edge-based finite volume algorithm is used for spatial discretization purposes. Enhancements include reformulation of boundary integral flux-averaging in conjunction with the use of a compact stencil in the computation of diffusive terms. A significant increase in accuracy is demonstrated. For validation purposes the drying of a non-hygroscopic brick and hygroscopic extruded corn meal are modeled. Predicted results for the former case are shown to compare reasonable well with experimental data while for the latter case a very good agreement is obtained.

Effects of Selected Process Parameters on Expansion and Mechanical Properties of Wheat Flour and Whole Cornmeal Extrudates

Mechanical properties of cereal extrudates are recognized by consumers as quality criteria. These properties are affected by process variables. The effect of process variables, such as water injection rate, barrel temperature, and screw speed on the expansion and selected mechanical properties of wheat flour and whole cornmeal extrudates was determined. A laboratory-scale twin-screw extruder with an L/D ratio of 25.0 was used. The cross-sectional expansion, the specific length, and the elastic moduli and breaking strength in bending and compression were measured. Water injection rate and barrel temperature significantly affected the cross-sectional expansion index (SEI) (P < 0.01), specific length (P < 0.01), elastic modulus in compression (P < 0.05), and breaking strength in bending (P < 0.05). The SEI was increased with a decrease in water injection rate and/or an increase in barrel temperature. The elastic modulus and breaking strength in bending decreased with the decrease in water injection rate. The SME input, which was dependent on the process variables tested, also influenced the expansion and mechanical properties of extrudates. The higher the SME input was, the lower the elastic moduli and breaking strength were. This result confirmed that the texture of extruded product was controlled by changing the SME input.

Effects of Calcium Hydroxide and Processing Conditions on Corn Meal Extrudates

ABSTRACTThe effects of added calcium hydroxide (0.0, 0.15, 0.25, and 0.35%) and processing conditions, feed moisture content (mc) (16, 18, and 20%) and barrel temperature (130 and 150°C) on characteristics of corn meal extrudates were studied. Extruder screw speed was maintained at 130 rpm. Corn meal was extruded with a single‐screw extruder (Brabender model GNF 1014/2) with a screw compression ratio of 3:1. The highest values (P &lt; 0.05) for radial expansion and the lowest values for density and breaking force of extrudates were found for the treatment with 0.00% calcium hydroxide extruded at 16% feed mc and 130°C barrel temperature. This treatment was statistically different from the other treatments. Best values for radial expansion of samples extruded with added calcium hydroxide were for the samples with 0.15% calcium hydroxide at 18% feed mc and 130°C barrel temperature, followed by the sample with 0.35% calcium hydroxide at 16% feed mc and 130°C barrel temperature. Water absorption index and water solubility index were affected by calcium hydroxide and extrusion conditions evaluated. Extrudates had large numbers of flattened and sheared granules. Increases in calcium hydroxide increased extrudate yellowness. The combined action of calcium hydroxide and extrusion conditions completely modified the organized structure of the starch and suggest the formation of a starch‐calcium complex (crystalline region). The texture of the extruded products was crispy after puffing.

SEM IMAGE PROCESSING FOR FOOD STRUCTURE ANALYSIS

ABSTRACTImage processing techniques were developed to characterize the cellular structure of puffed corn meal extrudates from their scanning electron microscope (SEM) images. Cross‐section SEM images were taken and digitized for product samples of different degrees of expansion. Two major approaches were developed to extract structure‐related image features. The air cells were also manually measured as the true characteristics of the cellular structure. Correlation and regression analyses were conducted to determine the effectiveness of the image features as measures of the structural characteristics. A number of image features were found to be good indicators of cell size and cell uniformity (R2‐values up to 0.95). The image processing techniques developed were useful in cellular structure characterization and they provide a rapid and consistent way for food cellular structure quantification and analysis.

EFFECTS OF EMULSIFIER AND SOY FIBER ADDITION ON SENSORY PROPERTIES OF CORN MEAL EXTRUDATE

ABSTRACTYellow dent corn meal was extruded in a twin‐screw extruder with a monoacylglycerol (MAG) and soybean fiber. A ten member descriptive analysis panel was employed to study the effects of four extrusion treatment variables on the textural properties and microstructure of extruded corn meal products. The treatment variables studied included MAG and soybean fiber contents in the feed, extruder screw speed, and feed rate. The microstructure of extruded samples was also studied to support the sensory texture evaluations. MAG addition was found to be the most significant factor affecting texture. Low levels of MAG (0.375%) and soybean fiber additions (5%) resulted in improved overall texture quality. Higher screw speeds were associated with higher cohesiveness and adhesiveness, and feed rate had the least influence. Most of these effects could be attributed to the microstructural property changes under the treatments.

EVALUATION of DIE SWELL and VOLUMETRIC EXPANSION IN CORN MEAL EXTRUDATES1

A method to determine die swell in the presence of volumetric expansion due to moisture vaporization in extruded food products is proposed. the method is applied to twin screw extrusion of corn meal in a study to investigate the effects of extruder die parameter (exit capillary length and entrance cone angle), screw speed, and specific feeding load on die swell and volumetric expansion. the die swell results are compared with known effects for nonexpanded polymers.Die swell tended to decrease with increasing exit length, but had only a weak response to entrance angle. Increasing specific feeding load (SFL) increased die swell, where as increasing screw speed produced increases or decreases in die swell, depending on the SFL. Die swells ranged from approximately 1.2 to 1.7, accounted for approximately 10 to 22% of the total radial expansion, and for approximately 18 to 38% of the extrudate cross sectional area.Volumetric expansion increased with increasing die exit length, but was insensitive to entrance angle with a slight concave upward response. Increasing screw speed produced large increases in volumetric expansion, while increasing SFL produced only slight increases.Observations about die swell compare favorably with previous studies of nonexpanded polymers, suggesting that the proposed analysis method may be useful for food viscoelasticity evaluation studies.

Comparisons of aroma extracts of heat-treated cereals

Extracts of popcorn, rice, dent corn, and sorghum were obtained using simultaneous distillation—extraction (SDE) and concentrated with a spinning band still. Gas chromatographic (GC) profiles of their extracts and gas chromatograph—mass spectrometer (GC-MS) identification showed that two compounds, N-furfuryl-pyrrole and N-furfuryl-2-formyl pyrrole, were present in extracts of popcorn, but present only in trace amounts in corn and not present in the extracts of rice and sorghum. This suggests these two compounds may be important for popcorn aroma. The GC profiles of popcorn extracts with and without germ were essentially the same, indicating that the germ does not play an important role in popcorn aroma. The two pyrroles above and certain other heat-induced aroma compounds found in popcorn extracts were not present in an extruded corn meal extract. This appears to account for the lack of aroma in extruded corn meal. GC profile comparison of the extracts from dent corn and dent corn supplemented with hydroxyproline showed that the peak areas of N-furfuryl-pyrrole and N-furfuryl-2-formylpyrrole in the supplemented corn increased 130 and 20 times, respectively.

Effect of ingredients on the rheological properties of extruded corn meal

A slit rheometer, mounted on a square cross section barrel extension, was attached to the exit of a single screw extruder to facilitate the simultaneous measurement of steady shear viscosity (ηsh), apparent planar extensional viscosity (ηpa), and the first normal stress differences (N1). The hole pressure method was used to determine N1 and the entrance pressure drop method with Cogswell’s analysis for abrupt planar contraction flow was used to determine ηpa. The effect of slot dimensions on N1 was investigated using low density polyethylene. Increasing the depth and width of the slot by 50% produced no significant change in the hole pressure. N1 predicted using the Higashitani–Pritchard–Baird (HPB) equation compared favorably with extrapolated N1 values obtained on a cone and plate rheometer. Addition of salt and sugar to corn grits affected the rheological properties of the melt, as observed by the changes in ηsh, N1, and ηpa. Of the three material functions, N1 and ηpa were more sensitive to the addition of ingredients. Corn grits exhibited thinning behavior in shear and planar extensional flows.

Fracture Intensity Distributions during Compression of Puffed Corn Meal Extrudates: Method for Quantifying Fracturability

ABSTRACTThe distribution of fracture intensities occurring during compression of puffed corn meal extrudates was described using an exponential function, and parameters from that analysis were used as fracturability indices. Since “jagged” or oscillating stress‐strain functions are typical for porous and brittle materials, fracture intensities were determined by measuring the abrupt, sequential reductions in stress produced during compression. Both distribution exponent and cumulative fracture stress correlated strongly with fracturability measured by other techniques, including fractal and Fourier analysis of stress‐strain functions. Distribution parameters also indicated textural differences due to process parameters (structural modification through addition of different levels of sucrose) and storage conditions (equilibration at various relative humidities).

Corn Meal‐Sunflower Meal Extrudates and Their Physicochemical Properties

ABSTRACTExtrudates of corn meal (CM), sunflower meal (SM), and CM‐SM blends at 15 (CM‐SM15) and 20% (CM‐SM20) protein were produced using a Wenger TX‐52 twin screw extruder. Protein, starch, fiber, lipid, chlorogenic acid (CGA) and ash in CM, SM, CM‐SM extrudates were the same as in unextruded material. Expansion ratios of CM, SM, and CM‐SM20 were lower and that of CM‐SM15 extrudate was not different from that of CM (P &lt; 0.05). Bulk densities and shear strength of SM, CM‐SM15 and 20 were higher (P &lt; 0.05) than those of CM extrudates. Total color differences (ΔE) were observed in SM and CM‐SM blended extrudates (P &lt; 0.05). Sensory evaluation showed that crispness of SM, CM‐SM15, and CM‐SM20 was different from CM (P &lt; 0.05).