bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Germination and Water Content on the Microstructure and Rheological Properties of Two Rye Doughs
Authors: Autio K. , Fabritius M. , Kinnunen A.
Published: June 2007

Two rye cultivars, Marder and Motto, with falling numbers 314 and 309, respectively, were germinated in vitro. Relative to the native grains, germination induced minor local changes in the microstructure of cell walls and proteins in the kernels. Kernels of germinated and native grains were milled, and doughs were prepared from the flours, with water content and incubation time varied according to experimental design. The viscoelastic properties of the doughs were measured just after mixing and after various incubation times. The area of blue fluorescence, a measure of intact cell walls, was quantified by computer‐assisted image analysis in thin sections of rye dough after mixing and incubation, and the starch structure was studied under the microscope after iodine staining. The water content of the doughs was explained well by the rheological behavior. Doughs made from flours of germinated grains were always softer than doughs made from flours of native grains, and Marder doughs were always more rigid than Motto doughs. The higher the water content, and the longer the incubation time, the greater the rheological changes during incubation. Microstructural studies showed that germination and incubation caused changes in the cell wall structures of dough that might explain the softening of the doughs.
Relating Rice Milling Quality Changes During Adsorption to Individual Kernel Moisture Content Distribution
Authors: Siebenmorgen T. J. , Perdon A. A. , Chen X. , Mauromoustakos A.
Published: June 2007

Several varieties of rough rice that were either stored for an extended period of time or freshly harvested were conditioned to initial moisture contents ranging from 10 to 17%. After the individual kernel moisture content distributions were measured, the samples were soaked in water at temperatures ranging from 10 to 40°C. The samples were then dried and milled. The bulk critical moisture content, at which head rice yield began to decline due to moisture adsorption, ranged from 12.5 to 14.9%, depending on the variety, harvest moisture content, and storage conditions. The kernel critical moisture content, determined from each sample from the cumulative kernel moisture content frequency distribution, increased with increasing sample initial moisture content.
Automated Color Classification of Single Wheat Kernels Using Visible and Near‐Infrared Reflectance
Authors: Dowell F. E.
Published: June 2007

Modification of an existing single kernel wheat characterization system allowed collection of visible and near‐infrared (NIR) reflectance spectra (450–1,688 nm) at a rate of 1 kernel/4 sec. The spectral information was used to classify red and white wheats in an attempt to remove subjectivity from class determinations. Calibration, validation, and prediction results showed that calibrations using partial least squares regression and derived from the full wavelength profile correctly classed more kernels than either the visible region (450–700 nm) or the NIR region (700–1,688 nm). Most results showed >99% correct classification for single kernels when using the visible and NIR regions. Averaging of single kernel classifications resulted in 100% correct classification of bulk samples.
Identification and Characterization of U.S. Wheats Carrying Null Alleles at the wx Loci
Authors: Graybosch R. A. , Peterson C. J. , Hansen L. E. , Rahman S. , Hill A. , Skerritt J. H.
Published: June 2007

Granule‐bound starch synthase (GBSS) is the primary enzyme responsible for the synthesis of amylose in amyloplasts of cereal endosperm cells. Bread wheats, due to their hexaploid genetic system, carry three genes (wx loci) encoding GBSS. Purification and separation of GBSS from more than 200 North American hexaploid wheats allowed the identification of genotypes that carry null alleles at either the wx‐A1 and wx‐B1 loci. In addition, the cultivar Ike carried both wx‐A1 and wx‐B1 null alleles. No wx‐D1 nulls were detected. Null alleles were found in 10% of the hard winter wheats tested, but in only 2% of the sampled soft winter wheats. Amylose contents of wheats carrying single null alleles at either the wx‐A1 or wx‐B1 loci often were lower than those of wild type wheats, but greater reduction in amylose content was observed in Ike. Monoclonal antibodies were used to quantify water‐extractable GBSS in both wild‐type and null genotypes. Gene dosage compensation was evident, although GBSS content, as measured by ELISA, was significantly lower in Ike than in all other wheats. The identification of null alleles in adapted genotypes suggests the development of wheats with a wide range of amylose contents will be possible by simple genetic crossing and selection.
Effect of Additional Separation and Grinding on the Chemical and Physical Properties of Selected Corn Dry‐Milled Streams
Authors: Jamin Fen F. , Flores Rolando A.
Published: June 2007

Three streams of corn dry‐milled products (corn grits, corn cones, and corn flour) from three different commercial corn dry‐millers were further separated by particle size according to the major portion of each stream. They were separated into corn grits (1.190 and 0.841 mm), corn cones (0.595, 0.420, and 0.297 mm), and corn flour (0.297 and 0.210 mm). Besides separation, corn grits were also ground and then separated into ground corn grits (0.297 and 0.210 mm). The original streams, streams with additional separation, and streams with additional grinding were analyzed for protein content, ash content, crude fat content, and color properties. Duncan's significant difference tests (P < 0.01) showed that additional separation and grinding of the commercial corn grits, corn cones, and corn flour affected protein, crude fat content, and color parameter (L, a, and b) distribution of the products. The tristimulus parameters (L, a, and b) were good indicators of the protein content of the corn dry‐milled streams studied.
Method for Determining the Rate and Extent of Accelerated Starch Retrogradation
Authors: Jacobson Mark R. , BeMiller James N.
Published: June 2007

A method to accelerate and quantitate retrogradation of starch pastes using a freeze‐thaw cycle (FTC) process and turbidometric analysis has been developed. Using this method and differential scanning calorimetry (DSC), it was determined that the rate of retrogradation in 2.5% waxy maize pastes was inversely correlated to the rate of freezing, and that the thawing temperature affected perfection of the crystallites in retrograded amylopectin. DSC and X‐ray diffraction were used to determine whether the crystallites formed during the FTC process were the same as those formed in starch pastes held isothermally at 4°C. Analysis of retrogradation of pastes of starches from various botanical sources indicated that the method reflects retrogradation in higher concentration pastes. Retrogradation rates were reduced by the addition of sodium dodecyl sulfate. Microstructures of freeze‐thaw processed waxy maize and common corn starch pastes were examined.
Heat‐Shock Protein 70 and Dough‐Quality Changes Resulting from Heat Stress During Grain Filling in Wheat
Authors: Blumenthal C. , Stone P. J. , Gras P. W. , Bekes F. , Clarke B. , Barlow E. W. R. , Appels R. , Wrigley C. W.
Published: June 2007

In an attempt to further elucidate the molecular mechanisms that determine the loss of dough strength associated with heat stress of growing wheat, the roles of heat‐shock proteins (HSP) and heat‐shock elements upstream of glutenin genes were investigated. A range of genotypes differed in the extent of synthesis of high molecular weight glutenin subunits (HMW‐GS) and HSP during heat stress. The concentration of HSP 70 remaining in mature grain increased as a result of a few days' heat stress of wheat plants. The amount of HSP 70 in mature grain samples from heat‐stressed plants of 45 genotypes was not strongly correlated with loss of dough strength. There was much less evidence for this mechanism than for other molecular hypotheses from the literature, particularly, changes in glutenin‐to‐gliadin ratio, size distribution of the glutenin polymer, and the involvement of HSP and chaperones during grain‐protein synthesis. HSP 70 was purified from heat‐stressed grain, and was added to (or incorporated into) dough in the direct‐drive mixograph. The HSP behaved similarly to several other hydrophilic proteins when added at a level of 2 mg/2 g of flour. It showed no dramatic effects on dough properties that could constitute a major explanation for the dough‐weakening effects of heat stress, even though the level of addition was well above the maximum levels that might be encountered in field‐grown, mature grain. Furthermore, sequencing of the genes (upstream of the coding region) for HMW‐GS failed to show the presence of heat‐shock promoters, even for genotypes that differed considerably in their reactions to heat stress. The findings simplify the range of possibilities that cause heat‐related loss of dough strength, focusing attention on the degree of polymerization of the glutenin chains, and on the roles of HSP and chaperones in the developing grain.
Purification and Characterization of a Hexose Oxidase with Excellent Strengthening Effects in Bread
Authors: Poulsen Charlotte , H⊘strup Pernille Bak
Published: June 2007

Hexose oxidase (EC 1.1.3.5) (HOX) was purified 51‐fold from the red algae Chondrus crispus, by several chromatography methods, including hydrophobic interaction, chelating Sepharose, anion exchange, gel filtration, and chromatofocusing. Purified HOX was subjected to native PAGE and activity staining with nitroblue tetrazolium. For HOX electroeluted out of the gel and digested with endoproteinase Lys‐C, the internal peptide sequence determined was: D‐P‐G‐Y‐I‐V‐I‐D‐V‐N‐A‐G‐T‐(V or P)‐D‐K‐P‐D‐P‐X. The molecular mass, determined by gel filtration, was 126 kDa, versus 65 kDa determined by SDS‐PAGE. The pI was determined to 4.64 and 4.79 as a double band on an isoelectrofocusing gel. Km was determined to 2.7 mM for D‐glucose, 3.6 mM for D‐galactose, 20.2 mM for cellobiose, 43.7 mM for maltose, 90.3 mM for lactose, 102 mM for xylose, and 531 mM for arabinose. The oxidation of thiol groups in gluten was determined by using Ellman's reagent: 5,5′‐dithiobis (2‐nitrobenzoic acid). The effect of HOX was compared to that of glucose oxidase. Both enzymes caused a dose‐responsive reduction in the free thiol groups. Extensigraph measurements and baking tests confirmed that HOX caused increased dough strength and increased bread volume more efficiently than glucose oxidase used in the same dosage.
Effect of Mixing Conditions on the Behavior of Lipoxygenase, Peroxidase, and Catalase in Wheat Flour Doughs
Authors: Delcros Jean‐François , Rakotozafy Lalatiana , Boussard Aline , Davidou Sylvie , Porte Catherine , Potus Jacques , Nicolas Jacques
Published: June 2007

The effect of mixing has been tested on the extractable activities of lipoxygenase, peroxidase, and catalase from dough after 2, 5, and 20 min of mixing, and 30 min of rest period after 20 min of mixing. Different mixing conditions have been studied including temperature, atmosphere, speed, amount of water added to the dough, buffer solutions between pH 3.6 and 7.5 added to the dough, and different additives (linoleic acid, guaiacol, hydrogen peroxide, ascorbic acid, cysteine, yeast, and sodium chloride). In all the mixing conditions tested, the dough peroxidase activity remains equivalent to the initial flour activity, whereas losses in lipoxygenase and catalase activities largely varied according to mixing conditions. The results show that a self‐destruction mechanism as well as physicochemical denaturation are responsible for these losses. Lipoxygenase losses seem mainly associated with the former mechanism, whereas catalase losses are highly increased in acidic conditions (physicochemical denaturation). Therefore, the relative impact of the three oxidoreducing enzymes may be largely modulated by mixing conditions.
Freeze‐Thaw Stability of Amaranth Starch and the Effects of Salt and Sugars
Authors: Baker L. A. , Rayas‐Duarte P.
Published: June 2007

Freeze‐thaw stability of amaranth, corn, wheat, and rice starches was determined measuring the percent of syneresis by centrifugation. Thermal properties were calculated by differential scanning calorimetry (DSC). The effects of salt (NaCl at 2 and 5%) and sugars (sucrose, glucose, and fructose at 10, 20, and 30%) on the freeze‐thaw stability of amaranth starch were also studied. Based on DSC and centrifugation methods, amaranth starch had better stability after freezing and thawing through four cycles than did corn, wheat, and rice starches. Amaranth starch with added salt showed similar stability as compared with a control when measured by centrifugation and showed increased stability when measured by DSC. Adding sugars to amaranth starch gels had varying results, but for the most part, they showed similar or increased stability when compared with a control.
Retrogradation of Amaranth Starch at Different Storage Temperatures and the Effects of Salt and Sugars
Authors: Baker L. A. , Rayas‐Duarte P.
Published: June 2007

The retrogradation of amaranth, corn, wheat, and rice starches at different storage temperatures (‐20, 4, and 25°C) was measured by differential scanning calorimetry (DSC). Sodium chloride (2 and 5%), glucose, sucrose, and fructose (10, 20, and 30%) were added to amaranth starch gels. The retrogradation was measured as the percent of gelatinization enthalpy (ΔH
g) of the retrograded gel when compared to the original nonretrograded sample. The data were analyzed fitting an exponential first‐order equation by regression, assuming a first‐order process. A modified equation was used for the data that showed several days of lag time before retrogradation was observed. Retrogradation percentage of amaranth gels at all three storage temperatures was lower than those of corn, wheat, or rice starches. Amaranth starch showed ≈2–9 times slower retrogradation rates than corn, wheat, and rice starches at 4 and ‐20°C, and up to ≈2.8 times lower maximum percent of retrogradation than the other starches at all three temperatures. After 21 days, amaranth, corn, and wheat starches exhibited the highest retrogradation (45, 77, and 67%, respectively) at 4°C, compared to 25 and ‐20°C. Rice starch had a higher retrogradation percentage (55%) at ‐20°C, compared to 25 and 4°C. The percent of retrogradation of gels with 5% NaCl addition decreased ≈2 and 1.7 times at 25 and 4°C, respectively, and increased ≈1.2 times at ‐20°C, compared to the control. The addition of sugars had similar effects in reducing retrogradation at 25 and 4°C and increasing retrogradation at ‐20°C when compared to samples with no sugar added.
Physical Properties of Extruded Wheat Starch‐Additive Mixtures
Authors: Singh N. , Cairns P. , Morris V. J. , Smith A. C.
Published: June 2007

The effects of the addition of fatty acids, monoglycerides (MG), and wheat germ oil (WGO) on the level of crystallinity and the crystalline structure of extrusion‐cooked wheat starch have been studied using twin‐screw extruders. Measurements of water solubility and water absorption indices were made on the extrudates, together with specific mechanical energy (SME) consumption and die pressure for the extruder. MG and the fatty acids added to a level of 4% caused an increase in Vhydrate type crystallinity. WGO addition to a level of 8% caused no change in crystallinity, although the Ehydrate type was favored at lower moisture contents. All additives caused a decrease in SME and an increase or maximum in die pressure. WGO behaved differently than MG and fatty acids in that its addition caused the water solubility index and expansion to increase, as previously observed for other oils added to flours.
Effect of Extrusion Process Parameters on the Quality of Buckwheat Flour Mixes
Authors: Rayas‐Duarte P. , Majewska K. , Doetkott C.
Published: June 2007

A response surface analysis using a second‐order central composite design was used to study the effect of extrusion process parameters on the extrudate quality of three blends containing buckwheat flour. The extrudates were prepared as three blends. Blend 1 was a 55:40:5 (w/w) mix of light buckwheat flour, wheat flour, and nonfat dry milk (NFDM). Blend 2 was a 40:55:5 mix of light buckwheat flour, corn meal, and NFDM. Blend 3 was a 30:60:10 mix of light buckwheat flour, corn meal, and NFDM. The blends were processed in a twin‐screw extruder with factorial combinations of the parameters including: process temperatures of 95–150°C, dough moisture of 15–22%, and screw speeds of 260–390 rpm. The linear components alone significantly explained most of the variation of expansion index, bulk density, water absorption, and breaking strength. The greatest amount of variability was explained by process temperature for blend 1. Dough moisture accounted for the greatest amount of variation for blends 2 and 3. Maximum predicted expansion index values and high water absorption percentages were obtained at low dough moisture levels. Dough moisture and process temperatures were the most important factors predicting bulk density. Sensory evaluation of texture, color, flavor, and general acceptability scores of selected samples ranked blend 3 > blend 2 > blend 1. The in vitro protein digestibility values ranked blend 1 > blend 2 > blend 3. An increase of up to 9.5% units in the protein digestibility values was observed when compared to the nonextruded raw blends.
Macromolecular Features of Amaranth Starch
Authors: Bello‐Pérez Luis Arturo , Colonna Paul , Roger Philippe , Paredes‐López Octavio
Published: June 2007

High‐performance size‐exclusion chromatography (HPSEC), static light scattering (SLS) and dynamic light scattering (DLS) techniques were used for the structural characterization of amaranth starch, solubilized in water by microwave heating in a high‐pressure vessel. Apparent average molar mass (M
w) gyration radius (R
G), and hydrodynamic radius (R
H) values were obtained from Berry and Zimm treatment of light‐scattering data. When heating time increased from 35 to 90 sec, the M
w, R
G, and R
H decreased, demonstrating a possible polymer degradation due to temperature. Apparent M
r values from HPSEC at 35 sec (27 ± 2 × 107 g/mol) and 50 sec (20 ± 2 × 107 g/mol) were lower than those determined by SLS (35 sec = 69 × 107 g/mol, 50 sec = 56 × 107 g/mol). However, at 70 and 90 sec, the inverse pattern was obtained. The fractal dimensions (d′f) from HPSEC study for samples dissolved for 35 (3.26), 50 (3.24), and 70 sec (3.14) are characteristic of a particle that has the internal structure of hard sphere, and for samples dissolved for 90 sec (2.19), are characteristic of a fully swollen, randomly branched macromolecule. From SLS, d′f decreased with increasing treatment time (d′f = 2.44, 2.18, 1.50, and 1.03 for 35, 50, 70, and 90 sec, respectively). The particle‐scattering factors and Kratky plots, well‐suited for studying the internal structure of a macromolecule, showed a sample degradation when treatment time increased. Results from DLS showed bimodal distributions with differences in the peak locations when treatment time increased. The ratio of R
G to R
H (ρ) for samples analyzed were between 0.88 and 1.3; these values are characteristic of a sphere or globular structure.
Methods to Evaluate Hydration and Mixing Properties of Nixtamalized Corn Flours
Authors: Lobeira R. , Almeida‐Dominguez H. D. , Rooney L. W.
Published: June 2007

Rapid ViscoAnalyser (RVA), consistometer, and mixograph methods were developed to evaluate the pasting, hydration, and mixing characteristics of commercial nixtamalized corn flours (NCF) used for masa production. The effect of moisture level (51–58%) on the mixing characteristics of NCF was evaluated with the mixograph. Masas were subjectively evaluated for machinability properties. Masa with a low moisture level (51%) had reduced mobility and firmer texture, resulting in higher and wider mixograms. The mixograph was able to differentiate between the various stages of masa preparation. The first stage involves hydration of NCF particles, which causes the force to increase. Then masa develops cohesiveness and reaches maximum consistency. Finally, masa develops stickiness due to overmixing, which makes the curve narrower and lower. At a high moisture level (58%), masa is lubricated and plasticized and yields a softer texture with reduced mixing consistency, evident on the mixograph and in lower subjective hardness readings. Flours with higher water absorption capacities produced thick slurries with increased RVA viscosities and shorter consistometer travel distances. Short consistometer travel distances were significantly correlated to increased initial and maximum viscosities in the RVA. The mixograph, RVA, and consistometer methods can be used in NCF quality control programs.
Rheological Properties of (1→3),(1→4)‐β‐d‐Glucans from Raw, Roasted, and Steamed Oat Groats
Authors: Zhang D. , Doehlert D. C. , Moore W. R.
Published: June 2007

Effects of hydrothermal treatments (steaming, roasting) of oat grain on β‐glucan extractability and rheological properties were tested on oat cultivars with low (Robert) and high (Marion) β‐glucan content. Steaming of grain reduced the amount of β‐glucan that could be extracted, compared with raw or roasted grain, but the extracts from steamed grain had much greater viscosity. Increased extraction temperatures increased the amount and the average relative molecular mass (M
r) value of β‐glucan extracted. In boiling water extractions, the average M
r values among raw, roasted and steamed oat samples were equivalent, but extracts from steamed oat grain had significantly higher intrinsic viscosity than the extracts from roasted or raw oat grains. β‐glucan solutions purified from steamed grain extracts were very viscous and highly pseudoplastic, as described by the power law equation. Oat β‐glucan from steamed samples were more viscoelastic than β‐glucan from roasted or raw oat samples. Because viscous properties of β‐glucan from boiling water extracts are influencedhydrothermal treatments without affecting polymer molecular weight, polymer interaction with the solvent must be affected. Steaming may disrupt intramolecular cross‐linkings in native β‐glucan, allowing a linear chain configuration to generate greater viscosity.
Effects of Cultivar and Temperature During Grain Filling on Wheat Protein Content, Composition, and Dough Mixing Properties
Authors: Uhlen A. K. , Hafskjold R. , Kalhovd A.‐H. , Sahlström S. , Longva Å. , Magnus E. M.
Published: June 2007

Three wheat cultivars, Bastian, Polkka, and Tjalve, were grown in growth chambers at 9, 12, 15, 18, and 21°C during grain filling in 1994, 1995, and 1996. The wheat samples were analyzed for protein content and sodium dodecyl sulfate (SDS) sedimentation volume. The mixing properties of sifted flours were determined by mixograph, and the flour protein composition was determined by size‐exclusion fast protein liquid chromatography (SE‐FPLC). The protein content, sedimentation volume, and mixogram parameters were affected by the temperature during grain filling. The protein content increased as the temperature increased. The sedimentation volumes and the mixograph data showed temperature effects that could not be explained by variation in protein content. The proportion of the polymeric flour proteins increased with increasing temperature. Positive correlations were found between the proportion of polymeric proteins and SDS sedimentation volume and, within each year, between the proportion of polymeric proteins and mixograph peak time. Negative correlations were found between the proportion of low molecular weight flour proteins (proportion of fraction IV) and sedimentation volume. The differences in these quality parameters among cultivars exceeded the effect of temperature during grain filling.
Large‐Scale Purification and Characterization of Barley Limit Dextrinase, a Member of the α‐Amylase Structural Family
Authors: Kristensen Michael , Planchot Véronique , Abe Jun‐ichi , Svensson Birte
Published: June 2007

Homogeneous barley limit dextrinase (LD) was isolated on a large scale in a yield of 9 mg/kg of 10‐day germinated green malt. This represents a 9,400‐fold purification and 29% recovery of the activity in a flour extract in 0.2M NaOAc (pH 5.0) containing 5 mM ascorbic acid. The purification protocol consists of precipitation from the extract at 20–70% saturated ammonium sulfate (AMS), followed by diethylaminoethyl (DEAE) 650S Fractogel anion‐exchange chromatography, and affinity chromatography on β‐cyclodextrin‐Sepharose in the presence of 2M AMS. LD was eluted by 7 mMβ‐cyclodextrin and contains a single polypeptide chain of 105 kDa (SDS‐PAGE) and pI 4.3. Sequence analysis of tryptic fragments, prepared from 2‐vinylpyridinylated LD and purified by RP‐HPLC, identified short motifs recognized in β‐strand 2, 3, and 5 characteristic of a catalytic (β/α)8‐barrel domain of the α‐amylase family of amylolytic enzymes. Barley LD has ≈50 and 85% sequence identity to bacterial pullulanases and rice starch debranching enzyme, respectively. By using 1H‐NMR spectroscopy, LD hydrolyzes specifically α‐1,6‐glucosidic linkages in pullulan and a branched oligodextrin, 62‐O‐α‐maltotriosyl‐maltotriose, with retention of the α‐anomeric configuration. β‐Cyclodextrin competitively inhibits the LD activity with Ki of 40 μM, while Ki is 1.9 mM and 2.4 mM for α‐cyclodextrin and γ‐cyclodextrin, respectively.
Substitution of Concentrated Ethanol for Water in the Laboratory Washing Fractionation of Protein and Starch from Hydrated Wheat Flour
Authors: Robertson G. H. , Cao T.
Published: June 2007

An unprecedented, ethanol‐based, washing process was used at a laboratory scale to produce both concentrated protein and starch fractions from hydrated wheat flour. In this multistep process, flour was first hydrated and mixed to a batter and then chilled and rested. The cold batter was then mixed and washed in chilled and concentrated ethanol using a modified device that normally applies the water‐based Martin process. Control of the separation was affected by each of these steps. For instance, the hydration of the flour, the time of mixing, the temperature of the wash, the ethanol concentration, and the time of washing were influential. The method produced a gluten concentrate similar in yield and protein content to that reported for a pilot‐scale Martin process but without the need for added salt. Notably, ethanol washing resulted in nonsticky, partially disintegrated curds that dried easily, whereas water washing resulted in a sticky, glutinous, cohesive mass that dried slowly. The process has commercial potential to reduce water and energy use, reduce wastewater generation and environmental impact, and improve product recovery. The process also has the potential to reduce the capital complexity of the drying step and create convenient opportunities for protein subfractionation.
Starch Molecular Mass and Size by Size‐Exclusion Chromatography in DMSO‐LiBr Coupled with Multiple Angle Laser Light Scattering
Authors: Yokoyama W. , Renner‐Nantz J. J. , Shoemaker C. F.
Published: June 2007

The weight average molar mass (Mw) and root mean square radii of starches from waxy maize (Amioca), waxy rice flour, cassava, Hylon V, Hylon VII, and potato amylose were determined by size‐exclusion chromatography (SEC) and multiple‐angle laser light scattering (MALLS). Dimethylsulfoxide (DMSO) containing 50 mM LiBr was used to dissolve the starches and also served as the mobile phase. SEC with large particle size polystyrene divinylbenzene packing materials and MALLS instrumentation were evaluated for the ability to separate and determine molar mass (MM) of starch polymers, respectively. The determination of Mw by MALLS is necessary because the Mw of many cereal starches exceeds the available molecular standards by one or two orders of magnitude. The Mw depends on the method of calculation. The Mw (Berry method) of starch from waxy corn was 2.27 × 108 Da, waxy rice 8.9 × 107 Da, cassava 5.7 × 107 Da, Hylon V 2.7 × 107 Da, Hylon VII 4.8 × 106 Da, and potato amylose 1.9 × 105 Da. Recovery dropped dramatically for molecules with root mean square radii >200 nm.
Improvement of Brown Bread Quality by Prehydration Treatment and Cultivar Selection of Bran
Authors: Nelles Elizabeth M. , Randall Philip G. , Taylor John R. N.
Published: June 2007

Different bran pretreatments and bran cultivars were investigated with the aim of alleviating the adverse effects caused by bran addition in brown (fiber‐rich) bread. Three different bran treatments: hydration, wet heat, and wet oxidation, all hydrate bran before its addition to other breadmaking ingredients. Four different bran cultivars were investigated. All treatments improved brown bread quality significantly, resulting in larger, softer loafs. All treatments resulted in an increase in the water absorption of brown bread doughs and a decrease in potentially oxidizable substances (POS) in brans. It is suggested that prehydration treatment activates bran lipoxy‐Different bran pretreatments and bran cultivars were investigated with the aim of alleviating the adverse effects caused by bran addition in brown (fiber‐rich) bread. Three different bran treatments: hydration, wet heat, and wet oxidation, all hydrate bran before its addition to other breadmaking ingredients. Four different bran cultivars were investigated. All treatments improved brown bread quality significantly, resulting in larger, softer loafs. All treatments resulted in an increase in the water absorption of brown bread doughs and a decrease in potentially oxidizable substances (POS) in brans. It is suggested that prehydration treatment activates bran lipoxygenase which oxidizes POS in bran, reducing bran's contribution to brown bread dough. A further reduction of these substances is caused by a washout effect of the treatments. On average across all bran cultivars, the hydration and wet oxidation treatments improved brown bread quality significantly more than the wet heat treatment, which also reduced the bran POS significantly less than the other treatments, probably due to its rapid inactivation of lipoxygenase. The bran cultivars differed significantly in their effects on brown bread quality, suggesting that bran selection according to cultivar should be considered.
Effects of Oat Grain Hydrothermal Treatments on Wheat‐Oat Flour Dough Properties and Breadbaking Quality
Authors: Zhang D. , Moore W. R. , Doehlert D. C.
Published: June 2007

Hydrothermal treatments, which are routine in oat processing, have profound effects on oat flour dough rheological properties. The influence of roasting and steam treatments of oat grain on dough mixing and breadbaking properties was investigated when hydrothermally treated oat flour was blended with wheat flour. Roasting of oat grain (105°C, 2 hr) resulted in oat flours that were highly detrimental to wheat flour dough mixing properties and breadbaking quality. Steaming (105°C, 20 min) or a combination of roasting and steaming of oat grain significantly improved the breadbaking potential of the oat flours. The addition of oat flours increased water absorption and mixing requirements of the wheat flour dough and also decreased bread loaf volume. However, at the 10% substitution level, steamed oat flours exhibited only a gluten dilution effect on bread loaf volume when wheat starch was used as a reference. Oat flour in the breadbaking system decreased the retrogradation rate of bread crumb starch. The results indicate that adequate hydrothermal treatments of oat grain are necessary for oat flour breadbaking applications. Steamed oat flours used at a 10% level retarded bread staling without adversely affecting the loaf volume.
Enzymatic Hydrolysis of Barley Starch Lipids
Authors: Shamekh S. , Mustranta A. , Poutanen K. , Forssell P.
Published: June 2007

The efficiency of phospholipase and lipase preparations in the hydrolysis of lysophospholipids of native and gelatinized barley starch was examined. The degree of hydrolysis was analyzed by determination of the amount of released fatty acids by an enzymatic method. Thermal and structural properties of the enzyme‐treated starch were studied by differential scanning calorimetry and light microscopy. Lysophospholipids of the gelatinized barley starch were easily hydrolyzed, in contrast to the lipids of the granular starch. The maximum degree of hydrolysis achieved for the gelatinized starch was 80% and for the native starch ≈20%. Gelatinization enthalpies and micrographs indicated that even though the amount of the released fatty acids from the native starch was small, formation of free fatty acids inhibited swelling and gelatinization of starch granules.
Effects of (1→3)(1→4)‐β‐d‐Glucans of Wheat Flour on Breadmaking
Authors: Wang Lin , Miller R. A. , Hoseney R. C.
Published: June 2007

Water‐soluble nonstarch polysaccharides were extracted from commercial hard red winter wheat flour and separated into three fractions by graded ethanol precipitation. The three fractions, F15, F40, and F60, varied in polysaccharide composition. Fraction F15 was rich in watersoluble (1→3)(1→4)‐β‐d‐glucans, and fractions F40 and F60 were rich in arabinoxylans. Addition of individual fractions to a bread formula did not affect bread loaf volume. Addition of fraction F15 to the formula improved bread crumb grain. Treatment of (1→3)(1→4)‐β‐D‐glucan‐rich fraction F15 with lichenase before its addition to the bread formula resulted in bread with poor crumb grain. Treatment of the F15 fraction with β‐xylanase before its addition to the bread formula resulted in bread with slightly improved crumb grain. Presumably, the (1→3)(1→4)‐β‐D‐glucans in fraction F15 improved crumb grain by stabilizing air cells in the bread dough and preventing coalescence of the cells. Addition of pentosan‐rich fractions F40 and F60 to the bread formula did not improve crumb grain and interfered with the improving effect of (1→3)(1→4)‐β‐D‐glucan‐rich fraction F15. Hydrolysis of the arabinoxylans in flour by adding β‐xylanase to the bread formula resulted in improved crumb grain.
Steam Flaking Characteristics of Sorghum Hybrids and Lines with Differing Endosperm Characteristics
Authors: McDonough C. M. , Anderson B. J. , Acosta‐Zuleta H. , Rooney L. W.
Published: June 2007

Commercial and food‐type sorghum hybrids with differing kernel and endosperm characteristics were grown under comparable conditions and steam flaked in each of three years. The raw‐grain kernel characteristics and proximate analyses were homogenous over the three‐year period. The waxy hybrid produced large, translucent, durable flakes that had significantly higher enzyme‐susceptible starch values for all years compared to the other varieties. Flakes with lower amylose contents (waxy endosperm) were positively correlated with percent whole flakes (r2 = 0.509), flake diameter (r2 = 0.846), and enzyme‐susceptible starches (r2 = 0.564) and negatively correlated with higher flake fragility (r2 = ‐0.647), test weight (r2 = ‐0.626), and flake breakage (r2 = ‐0.560). The heterowaxy flakes had a good appearance and were generally comparable in quality to the nonwaxy commercial and experimental hybrids. Heterowaxy sorghum hybrids with good grain yields can provide improved quality grain and flakes without sacrificing agronomic performance and yields. No difference in flaking performance was detectable among the kernels with different pericarp colors; flakes from the white food‐type sorghums had excellent appearance. Nontempered control samples were inferior in quality to all conditioned treatments.
Effects of Pollination Method and Growing Location on Starch Thermal Properties of Corn Hybrids
Authors: Krieger K. M. , Pollak L. M. , Brumm T. J. , White P. J.
Published: June 2007

Starch gelatinization and retrogradation properties of corn were studied to determine the effect of controlled (self) pollination versus noncontrolled pollination on analytical determinations, and the potential to eliminate the expensive and time‐consuming step of self‐pollinating before research screening of corn genotypes. Twenty‐four hybrids were grown in two Iowa locations, Story City and Ames. At Story City, all hybrids received three pollination treatments: self‐pollination; small‐plot, openpollination (representing corn from small test plots); and large‐plot, openpollination (representing corn from a farmer's field). Self‐pollinated and small‐plot, open‐pollinated corn were grown in replicated two‐row plots, whereas large‐plot, open‐pollinated corn was grown in unreplicated plots of 12.8 m × 8 rows. At Ames, the small‐plot, open pollination treatment was not done. Starch was extracted from samples of corn harvested from each plot, and gelatinization and retrogradation properties were determined using differential‐scanning calorimetry (DSC). Hybrids exhibited different starch gelatinization and retrogradation properties. Significant differences (P ≤ 0.05) in starch gelatinization and retrogradation properties occurred among pollination methods and between locations. Pollination method did not influence gelatinization enthalpy values, but onset temperature values for gelatinization, and range values for retrogradation differed significantly among pollination methods. At Ames, treatments gave different values for retrogradation enthalpy and percentage of retrogradation. Because of differences in some starch characteristics associated with pollination methods, self‐pollination is recommended when growing samples in small plots for research purposes.
Discovery of Grain Sorghum Germ Plasm with High Uncooked and Cooked In Vitro Protein Digestibilities
Authors: Weaver Charlotte A. , Hamaker Bruce R. , Axtell John D.
Published: June 2007

Grain sorghum has been documented to have low protein digestibility relative to other cereal grains. Low protein digestibility of sorghum is most pronounced in cooked foods and is ranked slightly lower than corn as a feed grain. In this article, sorghum germ plasm is identified that has substantially higher uncooked and cooked flour in vitro protein digestibility than normal cultivars. Sorghum lines were found within a high‐lysine opulation derived from the mutant P721Q that have ≈10–15% higher uncooked and ≈25% higher cooked protein digestibilities using a pepsin assay. Highly digestible sorghum grain showed little reduction in digestibility after cooking, compared to the large reduction that is typical of normal sorghum cultivars. Using the three‐enzyme pH‐stat method, we showed that the highly digestible lines had the same degree of peptide bond hydrolysis in ≈5 min, as was found in 60 min in the normal cultivar, P721N. Differences in protein digestibility were related to enyzme susceptibility of the major storage prolamin, α‐kafirin, that comprises ≈50–60% of the total sorghum grain protein. Using the enzyme‐linked immunosorbent assay (ELISA) technique to track the pepsin digestion of α‐kafirin, the highly digestible lines had ≈90–95% α‐kafirin digested in 60 min compared to 45–60% for two normal cultivars. γ‐Kafirin, a minor structural prolamin found mainly at the periphery of protein bodies, was also somewhat more digestible in the highly digestible sorghums. Highly digestible grain was of a floury kernel type, though recently this trait has been found in a modified background. More digestible protein from sorghum grain, that additionally is high in lysine content and has a fairly hard endosperm, could be of important benefit to populations who lack adequate protein in their diets, and may, pending further studies, prove to increase the value of sorghum as a feed grain.
A Rapid General Method for Appraising the Rheological Properties of the Starchy Endosperm of Cereal Grains
Authors: Haddad Y. , Benet J. C. , Abecassis J.
Published: June 2007

A rapid, simple method was developed to prepare small, parallelepipedal test samples of endosperm of wheat, corn, and rice grains. Compression tests performed on endosperm samples revealed the following mechanical properties: modulus of elasticity (E, GPa), breaking stress (σrup, MPa), and maximum breaking strain (∊rup, %). All tests were performed on several endosperm test samples of each cereal species. The results displayed good repeatability and several significant differences in the mechanical behavior of different endosperm structures, especially among soft, hard, and durum wheats. Rice and corn endosperm displayed mechanical behavior similar to that of durum wheat endosperm. The method proposed appears to be sufficiently sensitive and repeatable for studying the incidence of hardness and vitreousness of cereal grain endosperm in relation to its suitability for milling.
Role of Phosphorus in Viscosity, Gelatinization, and Retrogradation of Starch
Authors: Lin P.‐Y. , Czuchajowska Z.
Published: June 2007

The effect of starch crystallinity and phosphorus on starch gelatinization and retrogradation were studied using wide‐angle X‐ray powder diffraction, cross polarization/magic angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR) spectroscopy, 31P NMR spectroscopy, Rapid Visco Analyzer (RVA) and differential scanning calorimetry (DSC). Two starches differing significantly in peak viscosity (cv. Stephens, 283 BU; cv. Crew, 560 BU) were comparable in amylose content and starch crystallinity, while differing significantly in phospholipids content. Starch of lower peak viscosity had a higher phospholipids content and showed a slower rate of retrogradation. Starch from Stephens (0.098% phosphorus) had an enthalpy value of retrograded starch of 2.2 J/g after 14 days of storage, while starch from Crew (0.062% phosphorus) had an enthalpy value as high as 4.4 J/g. Defatting with a hot n‐propanol and water (3:1) mixture caused substantial changes in peak viscosity. Peak viscosity for starch from Crew decreased by 75 RVU due to defatting, while starch from Stephens decreased by as much as 125 RVU. After defatting with the hot n‐propanol water mixture, the rate and extent of starch retrogradation were comparable between the prime starches, which differed significantly in peak viscosity.
Granule Size Distribution and Chemical Composition of Starches from 12 Soft Wheat Cultivars
Authors: Raeker M. Ö. , Gaines C. S. , Finney P. L. , Donelson T.
Published: June 2007

Granule size distribution of wheat starch is an important characteristic that can influence its chemical composition, which in turn may affect its functionality. The granule size distribution and chemical composition of soft wheat starches were characterized and compared and relationships among those properties were identified. Thirty‐four starch samples from 12 soft wheat cultivars grown in the eastern half of the United States were examined. Granule size distribution was characterized using a laser light‐scattering technique. Amylose and phospholipid contents were determined using colorimetric procedures. A clear trimodal distribution of granule sizes was shown by 26 out of 34 starch samples: small granules with diameters <2.8 μm, midsize granules with diameters of 2.8–9.9 μm, and large granules with diameters >9.9 μm. Volume% distribution of granules within the three size classes had ranges of 9.7–15.2% (small), 13.4–27.9% (medium), and 57.9–76.9% (large). Highly significant differences were seen among the cultivars for volume% of granules within the ranges of 9.9–18.5 μm and 18.5–42.8 μm. Cultivar specific surface area means also differed. The environment affected granule size distribution, with some cultivars exhibiting more variation than others. Pioneer 2555 was the least variable, whereas Pioneer 2550 and Geneva were the most variable cultivars. Mean total amylose (TAM), apparent amylose (AAM), and lysophospholipid (LPL) values varied significantly among cultivars. TAM was positively correlated with the volume% of granules of 9.9–18.5 μm. LPL was negatively correlated with mean starch granule diameter and positively correlated with specific surface area of granules, indicating smaller granules tended to have higher lipid contents. Results suggest that significant differences exist in granule size distribution of soft wheat starches and affect starch chemical composition. Data also suggest it is possible that lipid is preferentially associated with the biosynthesis of small starch granules.
Influence of Barley and Malt Storage on Lipoxygenase Reaction
Authors: Kaukovirta‐Norja A. , Reinikainen P. , Olkku J. , Laakso S.
Published: June 2007

The dioxygenation of linoleic acid (LA) by aqueous flour suspensions of barley and malting samples was studied. The rate of this lipoxygenase (LOX) reaction varied as the malting process proceeded, giving a characteristic LOX reaction profile for a malting. The differences in the profiles from one malting to another were dramatic. It also appeared that during storage of dry, intact kernel samples from a single malting, a reduction in the rate of LOX reaction always occurred, and the rates of reduction with time were dependent on the stage of malting at the time of sampling. The kinetics of this aging could roughly be divided into four categories representing different stages of malting. Consequently, greatly varying LOX reaction profiles can be obtained from a single malting depending on the time of storage of kernels before assays. The results indicate that steeping, germination and the subsequent drying render the state of kernels unstable with respect to the LOX reaction for at least two to three weeks. Homogeneity of malt quality is important in the further applications of malt, especially in the brewing industry. Therefore, the rate of LOX reaction should be considered as a quality factor of malt.
Structure and Functionality of Barley Starches
Authors: Czuchajowska Z. , Klamczynski A. , Paszczynska B. , Baik B.‐K.
Published: June 2007

Amylose contents of prime starches from nonwaxy and high‐amylose barley, determined by colorimetric method, were 24.6 and 48.7%, respectively, whereas waxy starch contained only a trace (0.04%) of amylose. There was little difference in isoamylase‐debranched amylopectin between nonwaxy and high‐amylose barley, whereas amylopectin from waxy barley had a significantly higher percentage of fraction with degree of polymerization < 15 (45%). The X‐ray diffraction pattern of waxy starch differed from nonwaxy and high‐amylose starches. Waxy starch had sharper peaks at 0.58, 0.51, 0.49, and 0.38 nm than nonwaxy and high‐amylose starches. The d‐spacing at 0.44 nm, characterizing the amylose‐lipids complex, was most evident for high‐amylose starch and was not observed in waxy starch. Differential scanning calorimetry (DSC) thermograms of prime starch from nonwaxy and high‐amylose barley exhibited two prominent transition peaks: the first was >60°C and corresponded to starch gelatinization; the second was >100°C and corresponded to the amylose‐lipid complex. Starch from waxy barley had only one endothermic gelatinization peak of amylopectin with an enthalpy value of 16.0 J/g. The retrogradation of gelatinized starch of three types of barley stored at 4°C showed that amylopectin recrystallization rates of nonwaxy and high‐amylose barley were comparable when recrystallization enthalpy was calculated based on the percentage of amylopectin. No amylopectin recrystallization peak was observed in waxy barley. Storage time had a strong influence on recrystallization of amylopectin. The enthalpy value for nonwaxy barley increased from 1.93 J/g after 24 hr of storage to 3.74 J/g after 120 hr. When gel was rescanned every 24 hr, a significant decrease in enthalpy was recorded. A highly statistically significant correlation (r = 0.991) between DSC values of retrograded starch of nonwaxy barley and gel hardness was obtained. The correlation between starch enthalpy value and gel hardness of starch concentrate indicates that gel texture is due mainly to its starch structure and functionality. The relationship between the properties of starch and starch concentrate may favor the application of barley starch concentrate without the necessity of using the wet fractionation process.