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Development of viscoelastic doughs from non‐wheat proteins allows for a wider range of gluten‐free products. Little work has been completed to describe mechanisms of zein functionality in food systems. To identify factors responsible for dough development in zein–starch mixtures and their influence on zein bread quality, a mixture of 20% zein–80% maize starch was mixed with water and various reagents. Salts, NaSCN, NaCl, and Na2SO4were evaluated at concentrations from 0 to 2M for their influence on the properties of zein–starch dough systems. NaSCN at low concentrations produced softer dough. Ethanol treatments produced softer more workable dough in the absence of salts. Increasing concentrations of NaCl and Na2SO4resulted in coalescing of the proteins and no dough formation. The addition of β‐ME had minimal softening effects on zein–starch dough. Specific volumes of zein–starch bread increased with decreasing NaCl addition in bread formulations. Likewise, including 5% ethanol (v/v) in the bread formula increased bread quality.

Zein is a prolamine protein found in corn and has good potential in the development of industrial bioplastics. In this work, zein was modified with several isocyanates and diisocyanates in solution to evaluate its potential usage in bioplastics. The major reaction pathways were identified with the help of NMR and FTIR. For all the isocyanates employed, the surface free energy of the modified zein decreased, which phenomenon indicates decreased hydrophilicity. The moisture uptake decreased with isocyanate and diisocyanate modifications. Gel electrophoretic patterns showed that diisocyanate cross-linked a portion of zein to generate higher molecular weight species. DSC data showed single glass transition temperatures in all cases indicative that homogeneous blends were formed. The mechanical properties of modified zein were either similar to unmodified zein or reduced in some cases. Based on results from NMR and FTIR findings a reaction scheme is proposed. Our findings suggest that the reaction of zein with diisocyanates has potential usage in bioplastics formulations.

Corn protein (zein) was melt-processed with methylenediphenyl 4,4′-diisocyanate (MDI) using triethylamine (TEA) as a catalyst to facilitate the reaction of the isocyanate groups with the nucleophilic moieties present on zein. The product of the reaction was examined using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to monitor changes in molecular weight. Techniques used to evaluate property changes after reaction included FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and evaluation of mechanical properties. Our findings demonstrated that zein reacts with MDI in the melt state generating higher molecular weight compounds that after compression molding have improved physical properties and solvent resistance.

A commercial pressurized solvent extractor was used to remove lipid and non-lipid material from cornstarch using n-propanol/water and ethanol/water mixtures. Yields and chemical composition of the extract fractions were determined. Cornstarch samples were characterized using pasting properties and shear storage modulus measurements. The n-propanol/water extracted slightly higher amounts of both lipids and non-lipids. The lipid fractions contained mostly linoleic, palmitic and oleic free fatty acids. The non-lipid fraction contained mostly protein in the form of zein. The extracted starch had lower peak and setback viscosities than did the unextracted starch. The starch extracted with n-propanol/water had the lowest shear storage modulus values. Conversely, the samples extracted with ethanol/water had the highest shear storage modulus values. It is hypothesized that low amounts of zein present in conjunction with the starch is responsible for this observed effect.

Successful utilization of commercial zein products for certain food, pharmaceutical, cosmetic and medical applications requires a decolorized/deodorized zein of high purity that can be achieved by column filtration of commercial yellow zein solutions through Zeolite 5A and activated carbon. The objective of this investigation was to devise a combination of methodologies to assess purity and degree of deodorization and decolorization. Off-odor removal is defined by a UV spectroscopic ratio of 280:325 nm where diferuloylputrescine is the major contributor. Removal of yellow color, attributed to xanthophylls in zein, was followed by visible spectroscopic assays of a series of dilutions at 448 nm. SDS-PAGE analysis demonstrated removal of β-zein in combination with diminished sulfur content by sulfur analysis. Zein purity was assessed by Dumas nitrogen and FTIR of commercial zein before and after column filtration. Spectral differences were observed in the amide I (1,650 cm−1) peak, amide II region (1,530 and 1,550 cm−1) and the amide III peak at 1,240 cm−1, where ratio of the dominant peaks were strongly dependent on purity of sample. Circular dichroism (CD) analyses validated the FTIR results by showing increased α-helical content for the column purified zeins. Combinations of these methodologies can be used to define zein products as a quality control measure for a commercial operation.

Melt-processed blends of zein and polyvinylpyrrolidone (PVP) of varying molecular weights (55K, 360K and 1.3M) were compared based on mechanical and thermal properties. Generally, all samples stored at 50% RH exhibited a slight improvement in tensile strength, with the PVP360K samples showing the greatest improvement. At the higher levels of PVP, samples stored at 70% RH showed a decrease in tensile strength. Elongation was also more significantly impacted at higher humidity, with the higher levels of PVP causing greater elongation increases. Differential scanning calorimetry data for the blends showed single T g values intermediate between the zein and PVP controls. Kinetic thermogravimetric data suggested a multi-step degradation interaction for the zein/PVP blends. Scanning electron microscope imaging of compression molded samples showed homogeneous surface contours for even the 20% PVP1.3M blend. Melt-processed blends of zein with polyvinylpyrrolidone of various molecular weights appear to be compatible. This work represents the first melt-processed blend of zein with PVP to generate a compatible blend.

Glutaraldehyde was used as a crosslinking reagent to produce electrospun zein fibers with improved physical properties and solvent resistance. Using 8% glutaraldehyde, round and ribbon fibers were produced with diameters between 1 and 70 μm. All fibers readily dissolved in acetic acid. Heating the zein/glutaraldehyde fibers at temperatures from 80 to 180 °C for different times provided various degrees of insolubility to the fibers. A model was developed relating the extent of dissolution with the amount of glutaraldehyde used and the temperature/time at which the fiber was exposed. The fibers were found to be birefringent; upon heating, the amount of α-helix in the fiber was reduced.

Circular dichroism studies were performed on zein to determine how the secondary and tertiary structure changes with different solvents, temperatures, or pH. Alcoholic solvent type and common denaturants such as SDS and low amounts of urea had little effect on the secondary structure of zein. Utilization of dimethylformamide or acetic acid as solvent gave changes in tertiary structure. Solutions of zein in 8M urea produced solutions with large changes in tertiary structure. The dissolution of zein in 50 mM sodium hydroxide produces a zein with large changes in secondary and tertiary structure and little loss in primary structure. Increasing the temperature of zein to 70°C in 80% ethanol-water gave reversible changes in the primary structure (20% reduction in absolute magnitude of [θ]λ at 208 and 222 nm) and tertiary structure (40% reduction in absolute magnitude of [θ]λ at 268 nm).

The objective of this research was to generate zein ribbons on an extruder in which physical property analyses can be performed to determine whether physical properties were dependent on the testing direction. The extruded zein ribbon samples had between 10 and 15% triethylene glycol (TEG) and were conditioned at relative humidities between 23 and 70% before testing to determine the impact of sample testing direction on physical properties. Tensile strengths in the machine direction were between 18 and 64% higher than in the transverse direction. Elongations in the machine direction were between 33 and 291% higher than in the transverse direction. The magnitude of the difference between the machine and transverse direction was dependent on relative humidity and formulation. The impact of relative humidity was larger when the samples were tested in the machine direction; for example, tensile strength was reduced by 36% in the transverse direction and by 49% in the machine direction for the 15% TEG formulation when relative humidity was increased from 23 to 70%. With increased amounts of TEG, the magnitude of these differences was increased. The transverse direction tensile strength was reduced by 22% for a 10% TEG formulation, and by 36% for a 15% TEG formulation when relative humidity was increased from 23 to 70%. Polarized IR spectra of zein ribbons displayed differences between the spectra taken in the machine direction versus that taken in the transverse direction. Examination of the ribbons using polarizing light microscopy demonstrated that the ribbon was birefringent (δn = 0.0004). These results demonstrate that molecular orientation occurred during extrusion and that orientation impacts physical properties.

Methods must be developed to improve both the processability and physical properties of zein-based articles. Typical plasticizing agents that improve processability have a negative impact on physical properties at elevated humidities. Continued efforts must be employed to discover improved plasticizers. Carboxylic acids having more than one carboxylic acid moiety have been evaluated in zein melt formulations produced in a torque rheometer. These reagents were effective plasticizers for zein, lowering zein viscosity, and delaying the onset of rapid viscosity increase. These reagents altered viscosity differently than the traditional plasticizers such as triethylene glycol. These additives also lowered the tensile strength (TS) of zein formulations at 50% RH. Surprisingly, TS at 70% RH was higher than that at 50% RH at elevated levels of these additives. NMR analysis of Soxhlet extracted samples showed that these multivalent carboxylic acids do not cross-link the zein under the reaction conditions employed.

To improve the mechanical properties of zein films, a commercial white zein was reacted in glacial acetic acid (HAc) with glutaraldehyde (GDA) from 0.5 to 16% by weight based on the weight of zein. Amounts of 4% or higher GDA-modified zein, when cured in a closed system, generated a gel. That gel was insoluble in organic solvents known to solubilize zein. Zein solutions cast within a silicon rubber gasket sealed onto Teflon-coated plates, when air dried, generated 0.7-0.9-mm thick films. Those films from 8% GDA-modified zein had a water vapor permeability of 5.9 � 10 � 8 g cm/Pa s m 2 . Overall, results indicate that our thicker films gave higher water vapor permeability than values reported in the literature. To achieve consistent and comparable results with differ- ential scanning calorimetry (DSC) and dynamic mechanical analyses (DMA), film samples had to be heated to remove residual HAc. An increase in the glass transition tempera- tures for those films from GDA-modification of zein, observed with both DSC and DMA, was attributed to the crosslinking of zein. Physical testing of tensile bars cut from GDA-modified zein films showed minor enhance- ment of tensile strength, percent elongation, and Young's modulus in the 0.5% GDA-modified zein films, which increased and leveled off with 4% or higher amounts of GDA for the modifications. When the 4 to 16% GDA results are averaged, the tensile strength for the modified zein films increased 1.8-fold when compared with unmodi- fied zein control films. On the same note, percent elonga- tion showed a 1.8-fold increase and Young's modulus showed a 1.5-fold increase. GDA reaction with zein gener- ated films with improved tensile strength, ductility, and stiffness when compared with respective zein control films that retained their integrity when subjected to either boil- ing water or extensive soaking. 2007 Wiley Periodicals, Inc. J Appl Polym Sci 105: 2877-2883, 2007

The linear and nonlinear rheological properties of defatted lupin proteins produced by ultrafiltration-diafiltration were investigated. Five concentrations ranging from 10 to 30% of the defatted ultrafiltered-diafiltered (DUD) lupin proteins were prepared. The viscoelastic properties strongly depended on concentrations. Below 12%, the DUD lupin proteins exhibited more fluid-like behavior. At 15%, lupin proteins became more viscoelastic, and above 20%, the viscoelastic solid-like properties became stronger. Below 12%, the high-frequency behaviors of moduli were proportional to ω1/2, as expected for a semiflexible coil. Above 20%, the high-frequency behaviors of moduli were proportional to ω1/2, indicating a flexible coil. The nonlinear steady shear rheological properties were also concentration-dependent and showed shear-thinning behavior, which could be described by a power law constitutive model. The trend of the power law exponent shift is very consistent with the linear viscoelastic behavior change with the lupin protein concentration. These results suggest DUD lupin proteins undergo a structural change between 12 and 20%.

A low carbohydrate bread formula was prepared using hard red spring wheat flour, soy protein and vital gluten. Soy protein was treated with ethanol and jet-cooked to remove the beany taste. Vital gluten and soy protein blends were prepared and added to the control flour in order to reduce the final starch content by 52%. The ratio of soy protein:vital gluten was adjusted, based on the Farinograph profile of the blend relative to the control flour. AACC Method 10-09, Straight dough, was used for the baking. The amounts of shortening and yeast were increased, to improve the dough consistency and to reduce beany taste, respectively. A blend of 70% gluten and 30% soy protein was added to replace 50% of the control flour. This blend gave a loaf value similar to the control. Overall, the loaf was softer, darker in colour and the grain was more open than the control. Another blend, with 50% soy nuggets and 50% vital gluten, was added to replace 50% of the control flour. This produced a loaf with 35% less volume, darker colour, and a grain similar to the control. The protein content of the final product was 56%, which is much higher than that reported in the literature. Bread with high protein content is more suitable for use in low carbohydrate diets than bread formulations currently used.

Zein, the predominant protein in corn, may be used as an alternative to various commercial plastics. Plastics produced from zein tend to be brittle, so plasticizers such as triethylene glycol (TEG) and water were used in this study to alleviate brittleness. When zein is blended with water and subjected to heat and shear in a torque rheometer, zein readily generates aggregates that produce a rapid increase in viscosity. This rapid increase in viscosity is manifested as a torque increase, which can be detrimental to industrial processes such as extrusion. The primary objective of this study was to control the viscosity rise during torque rheometry by adding known amounts of water, TEG, and/or sodium dodecyl sulfate (SDS), a known protein denaturant. Our findings with torque rheometry showed that water alone allowed zein to generate higher molecular weight species in approximately 1 min. Varied combinations of TEG and water delayed the torque rise to 2–4 min. When SDS was added to zein and combined with water and TEG, it significantly delayed the viscosity increase in a linear relationship dependent on the amount of SDS added. Because extrusion is a standard method for processing plastics, the second objective of this study was to assess the mechanical properties of extruded, SDS-modified zein. To accomplish this, zein was blended with a fixed amount of water and TEG with varying amounts of SDS. The mixtures were subjected to extrusion processing on a single-screw extruder equipped with a 2 mm round die, and the resulting rope was pelletized. One half of the weight of pellets was re-extruded through a 2 cm ribbon die, and the other half was freeze-ground and compression molded. The mechanical properties of tensile bars from the compression mold and those cut from the ribbon die were evaluated at either 50 or 70% relative humidity on an Instron with a crosshead speed of 50 mm/min. Tensile strength and Young's modulus diminished, whereas elongation increased with increasing amounts of SDS. Therefore, the addition of SDS did not improve the strength of the tensile bars, but it did improve the ductility. The results from torque rheometry and the mechanical testing of extruded products show that the addition of SDS to zein blends of water and TEG can be used to develop an acceptable formulation for both processing and end-use requirements.

Endosperm from hand-dissected and- dehulled Lupinus albus seeds was milled into meal, sieved through a 40-mesh screen, and suspended in phosphate buffers (pH 4, 6.8, and 8) at 20% (wt/vol). The suspensions were treated at 75, 90, or 100°C for 1 h. The heat-treated protein was characterized by SDS-PAGE, free zone capillary electrophoresis (FZCE), and DSC; and its surface hydrophobicity, surface tension, and rheological properties were examined. The presence of high M.W. aggregates was apparent from SDS-PAGE and FZCE results. Solubility was lowest at pH 4 and 100°C. DSC analysis was performed on low moisture content samples (3.1%) and 20% (wt/vol) suspensions. DSC analysis at 3.1% moisture content showed a glass transition around 85°C and an exothermic transition at 160°C, whereas the protein suspension showed a more thermally stable protein as indicated by the higher ΔH values. Lupin protein was surface active as demonstrated by its effectiveness in reducing the surface tension of the aqueous phosphate buffer. Surface hydrophobicity of the heat-treated protein decreased as the treatment temperature increased, which supports the SDS-PAGE results. The highest level of aggregation was noted at 90°C and pH 6.8 as indicated by low surface hydrophobicity values. Rheological studies showed direct relationships between the shear storage modulus (G′) of the lupin meal suspension and both pH and temperature treatment, although this effect is minimal at the highest temperature (100°C) and pH 6.8.

Ultrafiltration followed by diafiltration (UF-DF) was evaluated for the production of protein products from partially defatted soybean meal or undefatted lupin (Lupinus albus L.2043N) meal. This study determined the effects of UF-DF on functional properties of the extracted proteins and compared the results with those of protein prepared by acid-precipitation (AP). UF-DF produced only protein concentrates (73% crude protein, dry basis, db), while AP produced protein isolates (about 90% crude protein, db). Soybean protein produced by UF-DF showed markedly higher values for solubilities up to pH 7.0, surface hydrophobicity index, emulsion activity index, and foaming capacity than did the AP soybean protein. UF-DF soy protein was also the most heat-stable among all protein samples tested. With lupin proteins, only the surface hydrophobicity and emulsion activity indices were significantly improved by using UF-DF. UF-DF generally had no adverse effects on, and in most cases even improved, the functional properties of soy protein concentrate produced by this method. UF-DF did not produce a comparable improvement in functional properties of lupin proteins as it did for soybean protein.

Zein, a predominant corn protein, is an alcohol-soluble protein extracted from corn and is an excellent film former. The characteristic brittleness of zein diminishes its usefulness as a film. It is well known that zein has a propensity for forming aggregates in solution. When zein molecules were cross-linked with 1-[3-dimethylaminopropyl]-3-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), it was found that the film-forming property was improved and the aggregation phenomenon in solution was suppressed. At the air/water interface, native zein forms brittle film with rough surface, whereas cross-linked zein forms rigid film with very smooth and even surface. Tensile strengths of the films were shown to be greatly increased by cross-linking. Objectives of this study are to determine the cross-linking mechanism of zein, the optimum reaction conditions, characteristics of the reaction product, and mechanical properties of cross-linked zein film. Through viscosity and dynamic light scattering, the cross-linking reaction was monitored. Optimum amount of EDC and NHS was determined to be 30 mg each per gram of zein. The cross-linking of zein with EDC and NHS seemed to be self-terminating because the cross-linking reaction did not proceed to precipitation.

Before conducting larger scale studies utilizing highly concentrated zein blends on an extruder, it is advisable to carry out experiments on a torque rheometer. Water and tri(ethylene glycol) (TEG) are known plasticizers for zein, however, the effects these materials have on zein rheology has not been studied using a torque rheometer. The amount of each plasticizer in zein was varied between 5 and 30%. It was demonstrated that water and TEG interact differently with zein. When the amount of water was above 10% at 90 °C, torque increased rapidly. With TEG, torque increased linearly with time and only at 120 °C did the rapid torque increase occur. Multiple torque increases for zein mixtures were observed, suggesting that processes that increase viscosity are an on-going process. Significant cross-linking is not the main source for the increased torque. The energy of activation of flow was determined when using 20% TEG. A model was developed relating %water, %TEG, temperature and rpm with initial torque.

Salicornia bigelovii Torr. is an annual salt-marsh oilseed plant. Hexane-defatted salicornia meal was extracted sequentially with 0.5 M sodium chloride (2x), water, 70% ethanol, and 0.1 N sodium hydroxide (2x). Each sodium chloride extract was dialyzed against deionized water and centrifuged to separate a water-soluble fraction (albumin) from a salt-soluble fraction (globulin) before freeze-drying. Ethanol extracts and neutralized sodium hydroxide extracts (glutelin) were dialyzed against water and freeze-dried. Globulin accounted for the highest amount of protein nitrogen, followed by glutelin and albumin. SDS-PAGE of reduced albumin, globulin, and glutelin showed a number of protein bands. Nitrogen solubility of defatted salicornia meal from pH 2 to 11 indicated a minimum solubility of 22%, around pH 4.5. Nonprotein nitrogen of defatted meal was 23% of total nitrogen, higher than defatted soybean, sunflower, and rapeseed meals. Albumin had the highest proportion of lysine and sulfur amino acids per 16 g nitrogen among all the fractions analyzed.

Soybean hulls contain peroxidase (SBP) and Bowman–Birk type protease inhibitor (BBI). SBP is used in the European bread-baking industry, and BBI isolated from dehulled, defatted soy flour possesses cancer-preventive and anticarcinogenic properties. Because hulls possess a low percentage of nitrogen, with fibre and other carbohydrates being the major components, our objective was to determine whether air classification of milled hulls could be used to fractionate and enrich these value-added proteins. Hulls were pin milled three times at 18 000 rpm, followed by air classification to yield fractions with particle size distributions ranging from 30 µm. The finely ground fractions with particle sizes ranging from

DSC heating–cooling cycles (0–200 ◦ C) were repeated on poly(lactic acid)/poly(hydroxy ester ether) (PLA/PHEE) blends to study the miscibility of the two polymers. Initial thermograms show two distinguishable Tg values corresponding to the respective neat polymers, accompanied by a crystallization and a melting peak for the PLA. Subsequent DSC runs show that the thermogram profiles depend on the number of heating–cooling cycles the blends are subjected to. As the number of cycles

The yellow color of corn and corn processing co-products is due to xanthophylls and β-carotene. Colorless zein commands a premium price and the resulting extracted carotenoids possess nutraceutical value. Our objectives were to devise methods for decolorizing zein and develop methodology to quantify color removal. Decolorizing methods include: subcritical propane and supercritical fluid extraction with carbon dioxide of zein with ethanol entrainers; ultrafiltration/diafiltration on a tangential flow system; partitioning with toluene; column chromatography on Sephadex LH-60; batch treatment with activated carbon. Residual color was assessed by dissolving zein control or decolorized product in glacial acetic acid, filtration, and reading absorbances of dilutions at 448 nm. Analysis of covariance from comparative logarithmic regressions of control zein and decolorized product dilutions was evaluated to determine the extent of residual color. Because, a covariate by treatment interaction was detected in treatments for supercritical fluid extractions an Analysis of Variance model comparing treatment method means at each dilution factor level was used. Results showed that subcritical propane extraction of zein with ethanol entrainer gave the least color removal. A commercial white zein possessed a similar degree of residual color as did ethanolic zein solutions partitioned with toluene. Almost complete removal was achieved by extractions of zein from corn gluten meal followed by batch treatment of those extracts with activated carbon. However, recovered yield was lowest with this procedure. Supercritical fluid extraction with carbon dioxide of zein with 15% ethanol entrainer for 15 min at 68,950 kPa and 70 °C decolorized zein slightly less than did either the column chromatographic method with Sephadex LH-60 or a diafiltration of zein ethanolic solutions ultrafiltered through the 5000 Da molecular weight cut-off membrane. These three methods gave excellent recoveries of decolorized zein product. The supercritical fluid method has the advantages of no need to spray-dry the final product and does not require the copious volumes of ethanol needed for color removal by the other methods. This method would utilize the carbon dioxide and ethanol byproducts generated by the fermentation process used for producing ethanol.

Commercial soybean hulls (14.6% crude protein) were pin milled and then air classified into five fractions to determine whether the hull structure can be disrupted and the protein constituents concentrated. The number of pin millings had only a small effect on the weight distribution of the five fractions. After one grinding, the sum of fractions 1 and 2 ( 30 μm) shifted from 75 to 69% on three pin millings to compensate for the shifts noted in fractions 1–3. Scanning electron microscopy revealed that fractions 1 and 2 consisted of the parenchymal cell layers (innermost portion) of the hulls; these fractions had three times the protein content and more than twice the amount of lipids found in the ground starting material. Fraction 3 contained many of the hou...

Soybean Bowman–Birk inhibitor (BBI), possessing a molecular weight (MW) of 8 kD, is a known cancer chemopreventative and anticarcinogenic agent Aqueous extracts of soybean seed coats, rigorously screened to remove cotyledons, contained peroxidase along with three unknown proteins each of which possessed an estimated MW of

Static and dynamic light-scattering techniques were used to study biodegradable thermoplastic poly(hydroxy ester ether) in N,N-dimethylacetamide (DMAc). A weight-average molecular weight MW = 6.4 × 104 g/mol, radius of gyration RG = 9.4 nm, second-virial coefficient A2 = 1.05 × 10−3 mol mL/g2, translational diffusion coefficient D = 1.34 × 10−7 cm2/s, and hydrodynamic radius RH = 8.3 nm are reported. In addition, the effect of H2O on the polymer chain's conformation and architecture in a DMAc/H2O solution is evaluated. Results suggest that H2O makes the mixed solvent poorer as well as promotes polymer chain branching via intramolecular transesterification. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1737–1745, 2001

Commercially available corn zeins from co-products of the corn ethanol industry possess yellow color and off-odors that deter their usage in food, medical, pharmaceutical and cosmetic industries. A pilot-scale process (patent pending) was developed to purify those products. Our objective is to investigate a series of activated carbons and zeolites, clay-based particles acting as molecular sieves, as potential column media for that process. A batch process was used to evaluate each of five different activated carbons and zeolites to determine the adsorption characteristics of protein and the color and off-odor components. Adsorptive properties of those media were performed by spectral analyses at wavelengths 280 nm for the protein component and 325 nm for the contaminants. Statistical evaluation of the batch adsorption data from each series demonstrated that activated carbon generated from coconut hulls and zeolite 5 A (5 angstrom pore size) adsorbed the least amount of protein relative to contaminant adsorptions. Our selection of column media for the pilot-scale process was based on these findings.

Citric acid (CA) was thermochemically reacted with corn coproducts from the ethanol industry, i.e. corn gluten meal (CGM), produced from corn wet milling, and distillers’ dried grains (DDG), produced from corn dry milling, to generate value-added, acid-insoluble reaction products with enhanced metal-binding properties. Heated CA produced an anhydride that reacted with the nucleophilic hydroxyl groups of starch and fiber as well as the hydroxyl, sulfhydryl, and amino groups of protein to produce ester or acyl derivatives. Short-term reactive extrusion of 1:1 w/w ratios of each corn product with CA by two passages at 20 rpm of each blend through a Brabender Plasti-Corder PL 2000, 1.9 cm single screw, 30:1 (L:D) fitted with a 1:1 screw and no die, through zone temperatures of 140, 200, and 196°C yielded reaction products that possessed similar degrees of carboxylation as a lengthy, 24 h oven-baking procedure at 120°C previously reported. Metal ion binding of the extruded derivatives increased with increasing pH from 3.0–5.0 where the solubility of the metal ions was unaffected by pH. At a pH of 4.5, where the charged ligand acts as an electron pair donor and at a metal ion concentration of 200 mg/l, the equilibrium binding efficiency for CGM/CA derivative under this set of conditions was: 0.54, 0.33, 0.85, 1.00, 0.59, 0.28, 0.30, 0.72, and 0.45 mmol/g for Cd2+, Co2+, Cu2+, Fe2+, Pb2+, Mn2+, Ni2+, Ag+, and Zn2+, respectively; whereas, for the DDG/CA derivative the metal binding was: 0.78, 0.66, 1.04, 1.08, 0.64, 0.51, 0.60, 1.02, and 0.73 mmol/g, respectively. The ability of citrate derivative to chelate metals varied with each derivative. Based on a comparison of metal binding data to heated CGM and DDG controls with no CA, the pendant carboxyl groups contributed by the CA moiety gave significantly higher metal ion binding. Comparison of metal binding ability for both the CGM/CA and DDG/CA derivatives with a sulfonic acid, styrene type analytical grade cation exchange resin, AG50W-X8, showed that CGM/CA possessed 13–44% of the capacity to bind metals, whereas DDG/CA possessed 23–47%. The corn-based derivatives produced in this study were biodegradable and could be produced at a considerably lower cost compared with petroleum-based resins.

The primary objective was to determine whether salts will stabilize soy storage proteins against the denaturing effects of alcohols or the heat and pressure used in supercritical CO2 during the defatting process. Nitrogen solubility index (NSI) and differential scanning calorimetry (DSC) were used to monitor the denaturation of proteins. A variety of salt solutions used to hydrate full-fat soy grits increased the thermal stability of both 7S and 11S storage proteins. DSC was used to monitor their denaturation temperature. Neutral salt hydrations followed the lyotropic series for protein stabilization. Of the salts evaluated, the test results indicate that the reducing salt, sodium sulfite, and the neutral salt, sodium sulfate, when used to steep beans, yielded significantly higher NSI than did the water-steeped controls or other salt treatments after partial defatting with absolute isopropanol or ethanol and supercritical CO2. However, these same salt treatments did not as effectively stabilize the proteins against the denaturing effects of ethanol more aqueous than 84% when these alcohols were used as the defatting medium.

Corn is one of the most important food and industrial crops in the United States. Zein constitutes about half of the endosperm proteins in corn. Potential applications of zein include use in fibers, adhesives, inks, cosmetics, textiles, and chewing gum. Recently, attempts have been made to utilize zein for food coatings and biodegradable materials. The new applications of zein require it to be resistant to water. Thus, we are interested in new routes for chemical modification of zein (Biswas et al, unpublished). 2-Octenyl succinic anhydride (OSA) is extensively used in modifying food starches. Our objective was to take advantage of OSA hydophobicity, flexibility, and compatibility with nonpolar groups and incorporate OSA onto zein. This OSA-modified zein would possess the best of both OSA and zein. A zein solution in dimethyl formamide (DMF) was reacted with various levels of OSA to give modified zein. In a microwave reactor, the reactions proceeded tremendously fast and they were over in 5 min. ...

The role of non-covalent interactions in the formation of visco-elastic material from zein was investigated. Hydrophobic interactions were evaluated through the addition of various salts from the Hofmeister series. Urea, ethanol, and beta mercaptoethanol (β-ME) were used to evaluate the effects of protein denaturation and disulfide bonds on zein’s ability to form a visco-elastic material. The addition of NaI and NaSCN altered the properties of visco-elastic materials made from zein, making them softer and more extensible, as did urea and ethanol. The addition of NaCl and Na2SO4 negatively impacted the ability of zein to from a visco-elastic material and at higher concentrations completely disrupted the formation of visco-elastic material. These results indicate that manipulating non-covalent interactions in zein can alter and in some cases, completely disrupt the formation of a visco-elastic material. Specifically this may be due to disruption of hydrophobic interactions within individual zein proteins or interactions between proteins. The reducing agent β-ME had little effect on zein’s ability to form a visco-elastic material. Therefore, the visco-elastic properties of zein arise as a result of non-covalent interactions.

Fish rations containing 16 to 29% of corn gluten meal, corn gluten feed, or corn distillers' grains with solubles and a control commercial feed were fed to tilapia. A trained, 10-member sensory panel evaluated the flavor characteristics of harvested, cooked tilapia fillets. The intensities of flavor characteristics of cooked fillets from tilapia raised on pellets containing 16% of corn gluten meal or corn gluten feed, as well as 19% of corn distillers' grains with solubles, were not significantly different than fish fed commercial fish feed. In general, the commercial feed resulted in similar protein and ash contents but higher total fat in the fillets compared with those containing ethanol by-products.

A series of wax ester blends was constructed by transesterifying native jojoba oil with 50-500 g kg- 1 completely hydrogenated jojoba wax esters. This series, when subjected to a standardised differential scanning calorimetry (DSC) tempering method gave either 1, 2 or 3 enthalpic events which represented the diunsaturated, monounsaturated and saturated species. These species were veri­ fied by measuring the melting points of a native and completely hydrogenated jojoba wax ester and also by demonstration that DSC thermograms of a syn­ thetic monounsaturated wax ester possessed an endotherm with a melt between the diunsaturated and completely saturated species. The heats of fusion and heats of crystallisation enthalpies of all three enthalpic events exhibited excellent correlation with the level of saturation. Chemometric indices were devised from heats of fusion and crystallisation enthalpies to estimate the level of saturation in these blends. From these indices and also from regression analyses of each species' individual events we could optimise the level of saturation needed to best mimic the melt and crystallisation properties of cocoa butter. The wax ester blend with 400 g kg- 1 saturation most closely resembled the thermal properties of cocoa butter where the monounsaturated species of the jojoba blend gave identical thermograms to tempered cocoa butter.

Ten experimental diets and one control diet were fed to 720 tilapia (20 fish × 12 cages × three replicates) in a recirculating aquaculture system to determine the economic significance of replacing fishmeal with fishmeal analogs if the fishmeal analogs were processed on-site by the producer. All experimental diets were produced at Illinois State University using an Insta-Pro Model 600 Jr. extruder plus grinding, weighing and mixing equipment commonly found on commercial livestock operations. Primary diet protein sources included corn gluten meal, corn gluten feed and distillers dried grains. All diets were balanced for amino acid requirements of the fish, and both 32 and 36% crude protein diets were fed. There was no significant difference in feed conversion ratio (FCR) between diets with fishmeal and diets without fishmeal. There was no significant difference in FCR between 32 and 36% crude protein diets. An economic engineering model which included all equipment necessary for extruding and handling pelleted feed on-site was developed. Annualized investment and operating costs were estimated to determine the total cost of processing each of the 10 experimental diets. There was a significant difference in cost of gain among the 10 experimental diets and the control diet. Cost of production was highly sensitive to volume of feed extruded.

Soy protein is a major food component, but the secondary structure of its major proteins is not well established, especially after heat treatment in the presence of moisture. To study secondary structure changes that take place in glycinin upon hydration using infrared spectroscopy, the effect of bound water must be removed from the protein spectra. This study examined the effects of added water on glycinin infrared spectra. Samples hydrated from 2.6 to 95% water, but not heated, showed significant broadening in the amide I region and changes in the amide I to amide II maximum absorbance ratio as water content increased. A spectral ratio method to derive coefficients for multiplying and subtracting spectra was used to obtain the bound water component spectrum and protein component spectra. The spectrum of dry glycinin could then be regenerated by subtracting the bound water component from glycinin that had added water. Curve-fitting of deconvoluted spectra gave the same secondary structure at all levels o...

Distilled fatty acids from Egyptian waste soapstock were blended with cottonseed or olive oils and interesterified via pancreatic lipase. The reaction was conducted at 55 °C for 10 h to reach equilibrium at which point 45% interesterification was accomplished. The specificity of 1,3 lipase was apparently reduced by the acid environment of the interesterification reaction. Acyl migration was observed among all the carbons of the glycerol moiety of the interesterified triacylglycerol products. Differential scanning calorimetry was used to evaluate changes in melting and crystallizing properties of vegetable oil–soapstock fatty acid blends before and after enzymic interesterification. Melting and crystallizing temperatures of the interesterified blends were significantly lowered.

Corn gluten feed, a coproduct from the wet milling of corn, was incorporated in diets containing 32 and 36% protein. A 103-d feeding study with Nile tilapia (Oreochromis niloticus) indicated that 32 and 36% protein diets containing corn gluten feed produced weight gains and feed conversion ratios similar to a control diet of commercial 36% protein catfish feed. Protein efficiency ratios of the 32% protein diets were better than those of the 36% protein diet and the control diet. The differences in weight gain and feed conversion ratio between the 32 and 36% protein diets were not significant. The 32% protein diet with fish meal (6%) had no advantage in weight gain or feed conversion ratio over the 32% protein diet without fish meal.

Corn gluten meal was incorporated into tilapia diets containing 32 and 36% protein from corn and soybean with and without fish meal and soy lecithin, respectively. A 75-day feeding study indicated that the five diets containing corn gluten meal yielded higher weight gain, higher protein efficiency ratio, and better or equal feed conversion ratio values oftilapia than a commercial fish feed containing 36% protein and fish meal. Tilapia fed 32% protein diets had the same weight gain as 36% protein diets. No advantage was realized when fish meal (6%) was incorporated into the diet. Likewise, diets containing soy lecithin (1 %) did not result in enhanced weight gain relative to diets devoid of lecithin.

Hydration effects on the thermal stability of glycinin (soybean 11S protein) were examined by differential scanning calorimetry (DSC). In a model system with pure glycinin, the denaturation temperature (Td) decreased with increasing moisture. Between 22 and 44% moisture, two endotherms were observed, where the lower-temperature endotherm became progressively reduced in magnitude with a concomitant increase in a higher-temperature transition. At 45.5% moisture, only a single endotherm was observed. The regression curves over the entire moisture range from 2 to 66% were derived as asymptote functions, where M equals the percentage total moisture. Equations were developed from the curves, and the relationship between Td and moisture were: Td=92.4+196.5e−0.068M and, for the low-temperature endotherm, 82.4+144.3e−0.068M. By interaction of 11S protein with either ethanol, a neutral detergent (Triton X-100) or 40% sucrose, both one- and two-endotherm curves were generated. Such calorimetric behavior is indicative of nonequilibrium denaturation and supports the notion that structure reorganization during DSC is water content-dependent. Our findings suggest that either glycinin’s acidic/basic subunits or a change in secondary protein structure may give rise to two endotherms.

Six isonitrogenous, isocaloric diets containing commercially defatted, toasted and lightly toasted soy flours (SF) (diets 1 and 2) and four soy protein concentrates (SPC) (diets 3–6) as replacements for 40% of animal protein were fed to satiation to juvenile shrimp (Penaeus vannamei) for 10 weeks. The SPCs used in diets 3 and 5 were chemically modified products with reduced trypsin inhibitor (TI) content. The chemical modification of SF in diet 2, which resulted in an SPC for diet 3, and of SPC in diet 4 consisted of heating at 70°C for 1 hr with 50 mM Na2S2O5, followed by dialysis to remove salt residues. To keep all diets isocaloric, cornstarch was added to replace the oli-gosaccharides lost during processing to an SPC. The TI contents, in mg TI/g diet, were 0.77, 6.14, 0.64, 1.40, 0.92 and 1.72 for diets 1–6, respectively. Shrimp fed lightly toasted SF had the highest weight gain, which was significantly higher than shrimp fed SPC diets 4, 5 and 6, but not significantly higher than shrimp fed diets 1 and 3. No significant difference was observed in survival rates. Shrimp fed diet 3 (with lowest TI) had the highest body percentages of crude protein, while toasted soy flour diet 1, also with low TI, had the lowest content of this constituent. In general, a high body protein reflects good health of the animal and excellent utilization of the feed. At the replacement levels of soy evaluated, TI content did not affect overall weight gain.

This study aimed to optimize chemical treatments to destroy Kunitz (KTI) and Bowman- Birk (BBI) type protease inhibitors in model systems, and to destroy total trypsin inhibitor activity in soy flour. Time, temperature, and reagent concentration were studied and 40 to more than 85% inactivation of KTI and BBI were observed by treatment with 0.6 mM Na2S2O5,10 mM ascorbic acid + 0.8 mM CuSO4 or 20 mM H2O2 + 0.8 mM CuSO4 at 65- 90°C for 0.5- 1 hr. Upon treatment with Na2S2O5, KTI and BBI amino acid composition had no significant change. In contrast, AH + CU2+ treatment of both KTI and BBI markedly increased aspartic acid + asparagine and glutamic acid + glutamine contents, and significantly decreased histidine, tyrosine, and methionine. With soy flour, only Na2S2O5 effectively inactivated both protease inhibitors. Steeping soybean flour in 50 mM Na2S2O5 at 65°C for 1 hr inactivated about 98% BBI and 95% KTI. The information conveyed is basic to developing chemical methodology needed to inactivate both KTI and BBI protease inhibitors in soy protein products.

Corn zein was cross-linked with glutaraldehyde (GDA) using glacial acetic acid (HAc) as catalyst. The objectives are to evaluate the swelling characteristics of GDA cross-linked zein gels in water, ethanol, and their combinations. Similar formulations, upon solvent evaporation, form films. The mechanical properties of the films are compared to compression molded tensile bars from GDA melt-processed zein as a second objective. Chemistry of the cross-linking reaction was based on the aldehyde binding characteristics defined by use of fluorescence spectroscopy; sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to demonstrate the cross-linking reaction; FTIR to observe absorption differences of the cross-linked product; differential scanning calorimetry, dynamic mechanical analysis and thermogravimetric analysis to assess thermal properties; and the use of Instron Universal Testing Machine to evaluate mechanical properties. A reaction mechanism for acid catalyzed GDA cross-linking of zein is proposed. Thermal and mechanical properties of tensile bars cut from either film or formed by compression molding were similar, where both showed increased tensile strengths, ductility and stiffness when compared with unmodified controls. Samples that were reacted with 8% GDA by weight based on weight of zein from either process retained their integrity when tensile bars from each were subjected to boiling water for 10 min or soaking in either water or HAc for 24 h. The melt-processed, cross-linked zein is a more environmentally friendly method that would eliminate the need for HAc recovery.

Zein is a naturally occurring protein polymer, obtained as a product of industrial corn processing. It could be possibly used as a coating, ink, fiber, adhesive, textile, chewing gums, cosmetic and biodegradable plastics.Thus, we sought to develop a methodology to chemically modify the zein structure so that zein mechanical properties can be manipulated. A method to prepare acyl derivatives of zein was developed. Zein was dissolved in dimethyl formamide (DMF) and acylated with anhydrides and acid chlorides. The reactions were done by reacting zein DMF solution with anhydrides at 70C or at room temperature with acid chloride. The amine/ hydroxyl group of zein reacted to form ester/amide link. The structure was confirmed with proton NMR and IR spectra. These acetyl, benzoyl and butaryl amide/ester derivatives of zein were compression molded and their mechanical properties were measured. This study provided structure/ mechanical property relationships for these derivatives. It was found that chemical modifications by acetylation did have little impact on the mechanical properties. We also used dianhydrides to crosslink zein. At low level, i.e. 2-5% of dianhydrides zein showed significant improvement in tensile strength. When dianhydrides were used at higher level the products were crosslinked and insoluble.

A variety of published physical measurements, computational algorithms, and structural modeling methods have been used to create a molecular model of 19 kDa alpha-zein (Z19). Zetaeins are water-insoluble storage proteins found in corn protein bodies. Analyses of the protein sequence using probability algorithms, structural studies by circular dichroism, infrared spectroscopy, small-angle X-ray scattering (SAXS), light scattering, proton exchange, NMR, and optical rotatory dispersion experiments suggest that Z19 has approximately 35-60% helical character, made up of nine helical segments of about 20 amino acids with glutamine-rich "turns" or "loops". SAXS and light-scattering experiments suggest that in alcohol/water mixtures alpha-zein exists as an oblong structure with an axial ratio of approximately 6:1. Furthermore, ultracentifugation, birefringence, dielectric, and viscosity studies indicate that alpha-zein behaves as an asymmetric particle with an axial ratio of from 7:1 to 28:1. Published models of alpha-zein to date have not been consistent with the experimental data, and for this reason the structure was re-examined using molecular mechanics and dynamics simulations creating a new three-dimensional (3D) structure for Z19. From the amino acid sequence and probability algorithms this analysis suggested that alpha-zein has coiled-coil tendencies resulting in alpha-helices with about four residues per turn in the central helical sections with the nonpolar residue side chains forming a hydrophobic face inside a triple superhelix. The nine helical segments of the 19 kDa protein were modeled into three sets of three interacting coiled-coil helices with segments positioned end to end. The resulting structure lengthens with the addition of the N- and C-terminal sections, to give an axial ratio of approximately 6 or 7:1 in agreement with recent experiments. The natural carotenoid, lutein, is found to fit into the core of the triple-helical segments and help stabilize the configuration. Molecular dynamics simulations with explicit methanol/water molecules as solvent have been carried out to refine the 3D structure.

Rheological studies were carried out on solutions of zein in N,N-dimethylformamide (DMF), where the specific lot of zein, concentration, time, and temperature were varied. DMF is a good solvent for zein, giving clear, relatively low viscosity solutions. It was found that all of the zein solutions behaved in a non-Newtonian fashion. At high concentration and elevated temperature, zein solutions will increase in viscosity with time. A temperature study on the rate of viscosity rise illustrated that at temperatures above 40 degrees C, the rate of viscosity rise increased in a non-Arrhenius fashion. There can be significant lot to lot variations in commercially obtained zein that gives rise to differences in viscosity and rate of viscosity rises. With the samples studied, viscosity was found to double from one lot of zein to another. Size exclusion chromatography suggests that compositional differences between the lots drive the observed differences in viscosity.

Differential scanning calorimetry (DSC) thermograms of fatty esters can give valuable information on melting characteristics and heats-of-fusion enthalpy (ΔH). A series of jojoba liquid wax esters was constructed by transesterifying native jojoba oil with 5–50% completely hydrogenated jojoba wax esters. This series, when subjected to a standardized DSC tempering method with heating/cooling cycles, exhibited an excellent correlation for level of saturation based on area changes in endothermic ΔH. Endothermic events were recorded for native (ΔHA) and completely hydrogenated (ΔHC) jojoba wax esters. A third endotherm, ΔHB, was observed when they were transesterified. Based on a multiple regression program, the best fit (R2=0.98) using ΔH data was: % saturation=16.847–0.162 (ΔHA)+0.209 (ΔHB)+0.600 (ΔHC). Standard errors for predictions were approximately 1.045 at 0% saturation, 0.770 at 25% saturation, and 1.158 at 50% saturation. Endothermic events A, B, and C each represent the respective diunsaturated, mounounsaturated, and saturated contents of wax esters in the transesterified blends. This was verified by measuring the dropping points for both the native and completely hydrogenated wax esters. These findings provide an index which can predict the degree of saturation in transesterified wax ester blends and serves as a research tool in process and product developments.

Bowman-Birk inhibitor, a major trypsin and chymotrypsin inhibitor from soybean, has 71 amino acids with 7 disulfide bonds. Conformation of Bowman-Birk inhibitor in native state, after heating, and after disulfide bonds were broken by sodium metabisulfite was determined by circular dichroism. The native Bowman-Birk inhibitor has 61% β-sheet, 38% unordered form, 1% β-turn, and no a-helical structure. There was no significant change in conformation after Bowman-Birk inhibitor was heated at 80 o C for 1 h in phosphate buffer. There was a decrease in β-sheet and an increase in β-turn structure after Bowman-Birk inhibitor was heated at 80 o C for 1 h in sodium metabisulfite-phosphate buffer

Corn distiller’s grains with solubles (CDGS), which is the residue from ethanol fermentation of corn, were incorporated in tilapia (a warm-water fish) diets that contained either 36% protein without fish meal or 32% protein with and without fish meal. A 103-day feeding study indicated that the three diets containing CDGS resulted in higher weights of tilapia than fish fed a commercial fish feed containing 36% protein and fish meal. The difference in weight gains between 32 and 36% protein diets was not significant. Incorporating fish meal (6%) in diet had no advantage over a diet without fish meal.