bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Modulated Differential Scanning Calorimetry (MDSC) Variables on Thermodynamic and Kinetic Characteristics During Gelatinization of Waxy Rice Starch
Authors: Lai Vivian M.‐F. , Lii Cheng‐Yi
Published: June 2007

The total, reversing, and nonreversing thermal properties during gelatinization of waxy rice starch (starch‐to‐water ratio = 1:2, w/w) were examined by modulated differential scanning calorimetry (MDSC). The effect of MDSC operating variables (i.e., the amplitude and frequency of temperature modulation and the underlying heating rate) on these thermal properties was determined by response surface methodology (RSM) and statistical analysis. The frequency of temperature modulation and the underlying heating rate significantly influenced the gelatinization temperatures and enthalpy changes in total and nonreversing endotherms. In addition, the combination of 0.025Hz and 4–8°C/min with a properly low degree of oscillation was suitable for characterization of starch gelatinization by MDSC. The enthalpy changes in the reversing (thermodynamic) endotherms increased, but those in the nonreversing (kinetic) endotherms decreased with increasing periods (i.e., decreasing frequencies) and underlying heating rates. However, the total enthalpy changes were only slightly influenced by the MDSC variables studied. In addition, the activation energies for the total and nonreversing events were 281.8–417.3 and 386.3–739.7 kJ/mol, respectively, depending on the MDSC conditions. From the compensation relationship between the activation energy and frequency factor, we concluded that the total and nonreversing endotherms were linked to the same single transition.
Use of Extensibility to Measure Corn Tortilla Texture
Authors: Suhendro E. L. , Almeida‐Dominguez H. D. , Rooney L. W. , Waniska R. D. , Moreira R. G.
Published: June 2007

An objective extensibility test was evaluated to measure texture of corn tortillas. A tortilla strip is pulled apart by a tensile force during the test. Force at 1 mm deformation, force required to rupture the tortilla strip, modulus of deformation, and extensibility distance were correlated to subjective rollability and flexibility scores. Hard, firm tortillas required more force to deform and to rupture and had greater moduli of deformation than soft, flexible tortillas. Tortilla texture was affected by manufacturer of commercial tortillas and by aging. The coefficient of variation ranged from 6.0 to 16.7% for force at 1 mm deformation and work required to rupture, respectively. The extensibility technique is sensitive, fast, simple, and repeatable.
Annealing of Long‐Term Stored Rice Grains Improves Gelatinization Properties
Authors: Yamamoto Aijiro , Shirakawa Kiyoka
Published: June 2007

We found new characteristics of annealing (or warm water treatment) in this rheological study. Japonica rice grains from long‐term storage at an ambient temperature for 10–24 years showed gelatinization properties analogous to that of indica rice but recovered properties similar to that of newly harvested rice after annealing at 55°C for 24 hr. Annealing signifcantly augmented the enthalpy from differential scanning calorimetry of raw and treated rice. This treatment also strengthened peak heights of the A pattern of rice in the X‐ray diffraction intensity diagram. Annealing of long‐term stored rice grains showed reverse effects to that of newly havested rice and purified starches. This effect of annealing on long‐term stored rice might be useful for industrial purposes.
Effect of Batter Solids and Starch Type on the Structure of Baked Starch Foams
Authors: Lawton J. W. , Shogren R. L. , Tiefenbacher K. F.
Published: June 2007

The effects of starch type on the properties of baked starch foams were investigated. Starch types used for baking were normal corn, normal potato, waxy corn, high‐amylopectin potato, wheat, and tapioca. Solids content of the starch batters used to bake foam trays ranged from 25 to 45%. Processing parameters and physical properties of the foams were examined. Starch‐foamed trays were formed by heating a starch batter inside a closed mold. Scanning electron micrographs showed that the thin‐walled foamed trays have a dense outer skin and a less dense interior with large cells. The weight of the foamed trays and density of the foam depended on the amount of batter cooked inside the mold, the percent solids of the batter, and the type of starch used. The high‐amylopectin starches made the lightest trays, while the normal cereal starches made the heaviest trays. Baking time depended on percent solids of the batter, the batter volume added to the mold, and starch type. The normal cereal starches had the longest baking times and the high‐amylopectin starches had the shortest baking times Strength and flexibility of the trays are correlated with tray weight and foam density. Heavier trays had greater strength and less flexibility than did lighter trays. Physical properties of the trays can be tailored to meet specific criteria by changing the starch type used and the batter solids.
Biochemical Characterization of the Wheat Waxy A Protein and Its Effect on Starch Properties
Authors: Demeke T. , Hucl P. , Abdel‐Aal E.‐S. M. , Båga M. , Chibbar R. N.
Published: June 2007

Granule bound starch synthase1 (GBSS1) is a key enzyme in amylose biosynthesis and is encoded by the A, B and D GBSS1 wx loci in wheat. Wheat lines with mutations at the three GBSS1 loci have been identified. We have characterized and compared the grain starch of CDCW6 wheat line (null B and D for GBSS1) with PI235238 (null A and B for GBSS1), waxy (null A, B and D for GBSS1), and AC Reed (wild type wheat) grain starches. The grain starch of waxy, CDCW6, PI235238, and AC Reed lines contained ≈0, 12, 23, and 25% amylose (w/w), respectively. Waxy, partially waxy, and wild wheat grain starches showed significant differences in onset and peak transition temperatures as determined by differential scanning calorimetric analysis. Grain starches extracted from waxy, CDCW6, and PI235238 also had higher enthalpy of gelatinization values than did wild wheat starch. X‐ray diffraction analysis revealed the highest crystallinity for starch extracted from waxy wheat, followed by CDCW6. The starch produced from the CDCW6 line may find special food and industrial applications because of its relatively low amylose concentration.
Effect of Free Fatty Acids Addition on Corn Grits Extrusion Cooking
Authors: Desrumaux A. , Bouvier J. M. , Burri J.
Published: June 2007

The influence of added fatty acids on extrusion cooking of corn grits and extrudate properties was studied. Samples with three average corn grits particle sizes were processed in a twin‐screw extruder; fatty acids content (0.2–0.8%, wb) varied, and experimental conditions were kept constant (moisture content 18.4% wb, barrel temperature 150°C, screw speed 165 rpm). The effect of adding fatty acids was studied by analyzing water solubility and absorption indices, expansion indices, and mechanical (puncture test) and structural (computerized image analysis) extrudate properties. When fatty acids were added, water solubility and absorption indices decreased, radial expansion index decreased, longitudinal expansion index increased, number of cells increased, and mechanical resistance of extrudates decreased. The influence of added fatty acids was attributed to the formation of fatty acids‐amylose complexes.
Molecular Weight Distribution of Wheat Proteins
Authors: Southan M. , MacRitchie F.
Published: June 2007

The molecular weight distribution (MWD) of wheat proteins is becoming recognized as the main determinant of physical dough properties. Studies of high polymers have shown that properties such as tensile strength are related to a fraction of polymer with molecular weight above a critical value and the MWD of this fraction. Elongation to break is treated as a kinetic process with energies of activation for breaking noncovalent bonds and for chain slippage through entanglements. These considerations are related to tensile properties of wheat flour doughs such as those measured by the extensigraph. The MWD of wheat proteins is determined by the relative amounts of monomeric and polymeric proteins and the MWD of the polymeric proteins. The latter, in turn, depends on the ratio of high molecular weight glutenin subunits (HMW‐GS) to low molecular weight glutenin subunits (LMW‐GS), the specific HMW‐GS that result from allelic variation, and the presence of modified gliadins that act as chain terminators. The role of these compositional variables in determining dough extensional properties is discussed in terms of present knowledge. Determination of MWD of wheat proteins is hindered by the difficulty of their solubilization and the lack of methods for reliably measuring very high molecular weights. Among the promising techniques for achieving these measurements are multiangle laser light scattering (MALLS) and field flow fractionation (FFF).
Wheat Gluten Swelling and Partial Solubility with Potential Impact on Starch‐from‐Gluten Separation by Ethanol Washing
Authors: Robertson G. H. , Cao T. K. , Ong I.
Published: June 2007

Swelling of wheat gluten may be a contributing factor in washing or displacement separation of gluten and starch using cold ethanol. To test this hypothesis, dissolution and swelling (settled volume or mass absorption) of a commercial gluten are reported here for the first time as a function of both temperature and ethanol solution concentration. In this test system, instant and substantial volumetric swelling was observed over most of the range of ethanol concentrations but not at 100%, v/v, ethanol. Settled volume reached a maximum of 50–70%, v/v, ethanol, and this was up to 3.5× the volume in absolute ethanol at 22°C and 2× the volume at −15°C. This maximum closely corresponds to the maximum dissolution of whole gluten and prior literature reports of full dissolution of gliadin. The reduction of settled volume at low temperature reflects the possible role of undissolved, gliadin‐class proteins in reinforcing the gluten structure and limiting the ultimate swelling. The data suggest gluten‐swelling properties as a contributing factor to the success of the cold ethanol, glutenfrom‐starch separation process.
Assessing Degree of Cook During Corn Nixtamalization: Impact of Processing Variables
Authors: Sahai D. , Mua J. P. , Surjewan I. , Buendia M. O. , Rowe M. , Jackson D. S.
Published: June 2007

Nixtamalization involves cooking and steeping corn in a lime solution, washing the corn (nixtamal), and stone grinding nixtamal to form a corn dough or masa. Masa is used to produce nixtamalized products (corn tortillas, tortilla chips, corn chips, taco shells, etc.) by forming and baking or deepfat frying. The degree of corn kernel cook determines the quality and texture of masa. Response surface methodology (RSM) was used as an experimental design to study the impact of process variables (cook temperature, cook time, initial steep temperature, and steep time) on the degree of cook measured using a Rapid Visco Analyser (RVA) and differential scanning calorimetry (DSC). RSM data exhibited significant (P < 0.005), although not predictive, linear models for RVA peak viscosity (r2 = 0.63), setback (r2 = 0.61), final viscosity (r2 = 0.61), and peak time (r2 = 0.57), indicating a dependence of these parameters on nixtamalization conditions. Peak viscosity, setback, and final viscosity increased linearly with steep time. DSC enthalpy (r2 = 0.83) and peak temperature (r2 = 0.89) of freezedried masa also exhibited significant (P < 0.0001) linear regression models with processing variables. DSC enthalpy increased with an increase in steep time, suggesting that starch is annealed during steeping. This study demonstrated that fundamental starch properties were altered on extended steeping during nixtamalization.
Recovery of Fiber in the Corn Dry‐Grind Ethanol Process: A Feedstock for Valuable Coproducts
Authors: Singh Vijay , Moreau Robert A. , Doner Landis W. , Eckhoff Steven R. , Hicks Kevin B.
Published: June 2007

A new process was developed to recover corn fiber from the mash before fermentation in dry‐grind ethanol production. In this process, corn is soaked in water (no chemicals) for a short period of time and then degermed using conventional degermination mills. In the remaining slurry, corn coarse fiber is floated by increasing the density of the slurry and then separated using density differences. The fiber recovered is called quick fiber to distinguish it from the conventional wet‐milled fiber. This study evaluated the percent of quick fiber recovery for a normal yellow dent and high oil corn hybrid. The quick fiber was analyzed for levels of corn fiber oil, levels of ferulate phytosterol esters (FPE) and other valuable phytosterol components in the oil and compared with conventional wet‐milled corn coarse and fine fiber samples. Fiber samples were also analyzed and compared for yields of potentially valuable corn fiber gum (CFG, hemicellulose B). Comparisons were made between the quick fiber samples obtained with and without chemicals in the soakwater. An average quick fiber yield of 6–7% was recovered from the two hybrids and represented 46–60% of the total fiber (fine and coarse) that could be recovered by wet‐milling these hybrids. Adding steep chemicals (SO2 and lactic acid) to the soakwater increased the quick fiber yields, percent of FPE recoveries, and total percent of phytosterol components to levels either comparable to (for the dent corn hybrid) or higher than (for the high oil corn hybrid) those recovered from the total conventional wet‐milled fiber samples. CFG yields in the quick fiber samples were comparable to those from the wet‐milled fiber samples. CFG yields in the quick fiber samples were not significantly affected by the addition of chemicals (SO2 and lactic acid) to the soakwater.
Use of Regression and Discriminant Analyses to Develop a Quality Classification System for Hard Red Winter Wheat
Authors: Baker Scott , Herrman Timothy J. , Loughin Thomas
Published: June 2007

An attempt to create a segregation system that uses rapid quality detection instrumentation and represents value to millers and bakers led to the development of a single value called “dough factor.” The dough factor value represents the amount of flour‐water dough that can be produced by a given unit of wheat. Samples of hard red winter wheat (≈100/location) collected from five Kansas country elevators during the 1995 and 1996 harvests were evaluated for dough factor. Single kernel properties, sample protein content, and test weight measurements were subjected to regression and discriminant analyses for the purpose of developing a dough factor classification system. Regression analysis identified kernel weight, kernel weight standard deviation, and protein as important characteristics for predicting dough factor, however, the resulting model possessed poor predictive ability (adjusted R2 = 0.39). Classifying wheat into dough factor groups of <107, 107–112.9, and ≥113 using discriminant analysis resulted in an accuracy of 56%, while discriminant analysis correctly placed wheat into two dough factor groups (<113 and ≥113) with an 80% accuracy. Creation of a dough factor classification system using single kernel measures, kernel protein, and wheat cultivar correctly classified 86.3 and 68.8% of the wheat samples into dough factor groups <113 and ≥113, respectively. In the dough factor group ≥113, cost savings associated with higher flour yields and water absorption were $0.15/cwt of flour and $0.65/1,000 lb of dough, respectively. Increases in processing efficiency for both the miller and the baker would be expected to further differentiate the value between the two dough factor groups.
Antioxidant Activity and Phenolic Contents of Oat Groats and Hulls
Authors: Emmons Cheryld L. , Peterson David M.
Published: June 2007

Research was initiated to measure antioxidant activity of extracts from oat (Avena sativa L.) groats and hulls and the concentrations of phenolic substances that may contribute to antioxidant activity. Antioxidant activity of ethanolic extracts of four cultivars was evaluated by an in vitro assay that measures the inhibition of coupled autoxidation of linoleic acid and β‐carotene. Total phenolic content was determined using Folin and Ciocalteau's phenol reagent and was expressed as gallic acid equivalents. Phenolic compounds were separated by reversed‐phase HPLC and detected at 290 nm. Peaks were identified by comparing retention times and spectra with known standards and verified with internal standards. Groats had significantly higher antioxidant activity than hulls. For two cultivars, total phenolic content was similar in groats and hulls, whereas one cultivar had higher and another lower total phenolic content in groats than hulls. Ten phenolic compounds were separated and identified in extracts, and one flavan‐3‐ol and three avenanthramides were tentatively identified. The concentrations of many of these compounds differed among cultivars and between fractions. In general, caffeic acid and the avenanthramides were predominantly found in groats, whereas many of the other phenolics were present in greater concentrations in hulls.
Comparison of Small and Large Deformation Measurements of Whole Meal Rye Doughs
Authors: Autio K. , Flander L. , Heinonen R. , Kinnunen A.
Published: June 2007

The rheological properties of rye flour‐water‐salt doughs prepared from different flour types (different falling number and coarseness) at different water levels were studied after mixing and after 90 min of incubation (30°C and 80% rh). Both the effect of water and the coarseness of the flour had significant effects on storage modulus (G′) measured by oscillatory test in the linear viscoelastic region and on compressional force measured at large deformation. The results of the two rheological methods correlated very well with each other (correlation coefficients varied in the different doughs at r = 0.975–0.999). Dough rheological measurements suggested that falling number did not have a statistically significant effect on dough rheology after mixing or incubation. Although the two rheological methods correlated well, the responses for incubation were different. In the small deformation method, the storage modulus of all doughs, independent of the falling number, decreased during incubation, whereas in the large deformation method, only the hardness of doughs made from flours with lower falling number decreased during incubation. The rheological measurements of doughs after mixing and the viscosity measurements of flourwater suspension at 30 and 40°C did not correlate with each other. Total pentosans have great effect on viscosity measurements of flour‐water suspensions, whereas flour particle size and soluble pentosans correlated more with rheological properties of doughs (r = 0.851 between G′ and soluble pentosans).
Allelic Variation at Glu‐D1 Locus for High Molecular Weight (HMW) Glutenin Subunits: Quantification by Multistacking SDS‐PAGE of Wheat Grown Under Nitrogen Fertilization
Authors: Zhu J. , Khan K. , Huang S. , O'Brien L.
Published: June 2007

Two biotypes of an Australian wheat cultivar, Warigal, differing only in the Glu‐D1 high molecular weight (HMW) glutenin subunits 5+10 and 2+12 were used in this study. The objective was to examine the effects of nitrogen fertilization and allelic variation at the Glu‐D1 locus on the characteristics of glutenin polymers. Unreduced proteins containing the SDS‐soluble glutenins and the other protein classes were analyzed by multistacking SDS‐PAGE which separates the glutenin into six distinctly different‐sized aggregates. The results showed that nitrogen fertilization significantly increased protein quantity, ratio of polymers to monomeric proteins, and sizes of SDS‐soluble glutenins. Nitrogen fertilization affected the proportions of HMW subunits in both SDS‐soluble and SDS‐insoluble glutenin polymers and the ratio of x to y subunits in SDS‐insoluble glutenin polymers. Nitrogen fertilization, however, did not cause a significant change in ratio of SDS‐soluble to SDS‐insoluble glutenins. SDS‐insoluble glutenins had a greater ratio of HMW to LMW and x to y subunits, especially with a higher increase of 1Dx subunits, than SDS‐soluble glutenins. The HMW/LMW subunit ratio and the x/y subunit ratio may be used to predict sizes of glutenin polymers. The biotype with 5+10 subunits had a greater x/y subunit ratio in the SDS‐insoluble glutenins than the 2+12 type. A greater proportion of subunit 5 was formed than subunit 2 in the SDS‐insoluble glutenin polymers. Both nitrogen fertilization and allelic variation at Glu‐D1 loci could affect the characteristics of glutenin polymers.
Wheat Starch Effects on the Textural Characteristics of Puffed Brown Rice Cakes
Authors: Orts W. J. , Glenn G. M. , Nobes G. A. R. , Wood D. F.
Published: June 2007

A process was described for creating puffed wheat starch based or hybrid starch and rice snack foods processed in a rice cake puffing machine. Puffed cakes consisting of wheat starch and whole grain brown rice, created by mixing wheat starch beads with brown rice before processing and puffing for 10 sec (cooking time) at 210°C, exhibited greater flexibility and fracture strength than traditional rice cakes. The density of puffed wheat starch cakes decreased with increasing moisture content independent of particle size for particles 0.8–5 mm in diameter. The addition of sucrose and shortening promoted the formation of lower density puffed cakes at lower moistures, while salt had little effect.
Application of the Single‐Kernel Characterization System to Durum Wheat Testing and Quality Prediction
Authors: Sissons M. J. , Osborne B. G. , Hare R. A. , Sissons S. A. , Jackson R.
Published: June 2007

The Single Kernel Characterization System (SKCS 4100) measures single kernel weight, width, moisture content, and hardness in wheat grain with greater speed than existing methods and can be calibrated to predict flour starch damage and milling yield. The SKCS 4100 is potentially useful for testing applications in a durum improvement program. The mean SKCS 4100 kernel weight and moisture values from the analysis of 300 individual kernels gave good correlations with 1,000 kernel weight (r2 = 0.956) and oven moisture (r2 = 0.987), respectively. Although significant correlations were obtained between semolina mill yield and SKCS 4100 weight, diameter, and peak force, they were all very low and would be of little use for prediction purposes. Similarly, although there were significant correlations between some SKCS 4100 parameters and test weight and farinograph parameters, they too were small. The SKCS 4100 has been calibrated using either the single kernel hardness index or crush force profile to objectively measure the percentage vitreous grains in a sample with reasonable accuracy, and it correlates well with visual determination. The speed and accuracy of the test would be of interest to grain traders. An imprecise but potentially useful calibration was obtained for the prediction of semolina mill yield using the SKCS 4100 measurements on durum wheat. The SKCS 4100 is useful for some traits such as hardness, grain size and moisture for early‐generation (F3) selection in a durum improvement program.
Yield, Protein Content, and Viscosity of Starch from Wet‐Milled Corn Hybrids as Influenced by Environmentally Induced Changes in Test Weight
Authors: Yang P. , Shunk R. J. , Haken A. E. , Niu Y. X. , Zou S. H. , Buriak P. , Eckhoff S. R. , Tumbleson M. E.
Published: June 2007

Forty‐three yellow dent corn samples of five different hybrids varying in test weight and moisture content were obtained from 14 different locations in 1993. The locations for acquired samples were selected randomly to cover a wide range of test weights based on preliminary data from eight states of the corn belt where 94% of the U.S. corn crop was produced in 1993. Samples were wet‐milled using a 100‐g standard laboratory‐scale wet‐milling procedure. Protein content in starch and starch viscosity were determined. Starch yield, protein content in starch, and starch viscosity were not affected significantly by test weight.
Simple Determination of Gluten Protein Types in Wheat Flour by Turbidimetry
Authors: Wieser Herbert
Published: June 2007

A simple method based on turbidimetry has been developed for the quantitative determination of total gliadins, glutenin subunits, and high and low molecular weight (HMW and LMW) subunits of glutenin. The standard procedure includes the subsequent extraction of wheat flour (100 mg) with a salt solution, with 50% 2‐propanol (gliadins), and with 50% propanol under reducing conditions and increased temperature (glutenin subunits). Aliquots of the gliadin and the glutenin extracts are mixed with 2‐propanol to a final concentration of 83%, and the turbidity of the precipitates is measured photometrically at 450 nm and 20°C after 40 min. Another aliquot of the glutenin extract is mixed with acetone to a final concentration of 40% acetone, and precipitated HMW subunits are determined turbidimetrically after 30 min. The sample is then filtered, and an aliquot of the filtrate is mixed with 2‐propanol to a final concentration of 77% to determine the precipitated LMW subunits. Control analyses with reversed‐phase HPLC on C8 silica gel indicate that the precipitation of the different protein types is quantitative and specific, and studies of 16 different wheat flours demonstrate the strong correlation between quantification by HPLC and turbidimetry. The turbidimetric measurements are reproducible, linear over a wide absorbance range (0.2–1.7), and sufficiently sensitive to analyze 40 μg of protein or 20 mg of flour. The absolute amounts of protein types in flour can be determined by means of calibration curves with protein standards (gliadins, HMW, and LMW subunits). Altogether, the developed method is simple, accurate, sensitive, and specific for the different protein types. The total procedure takes ≈6 hr for the analysis of six flour samples in parallel or ≈4 hr for three samples in overlapping extraction steps. The chemicals used are inexpensive, scarcely toxic, and easy to dispose.
Sensory and Instrumental Relationships of Texture of Cooked Rice from Selected Cultivars and Postharvest Handling Practices
Authors: Lyon Brenda G. , Champagne Elaine T. , Vinyard Bryan T. , Windham William R.
Published: June 2007

Measurement of cooked rice texture attributes by sensory and instrumental methods is important because of the increased popularity of rice and rice products by globally diverse cultures. Many factors influence cooked rice texture, including cultivar, physicochemical properties, postharvest handling practices (milling degree, drying conditions, and final moisture), and cooking method. Information on the relationships between sensory, physical, and chemical characteristics will lead to better methods to quickly evaluate and predict end‐use qualities, which will help to match rices with specific characteristics to populations that demand those attributes. This article reports the relationships between two modes of measuring texture attributes of rices: sensory and instrumental texture analyzers. Six medium‐ and short‐grain rice samples differing by cultivar or growing location were dried to achieve final moisture levels of 12 or 15% and then regular‐ or deep‐milled (n = 120). Correlations between individual sensory descriptive attributes and instrumental texture profile parameters were weak. Of only 12 significant correlations, the highest value was r = 0.624. Combined sensory and instrumental data were factor‐analyzed. This analysis revealed that sensory attributes still accounted for the most variation (35.32% out of 76.55%). Sensory descriptive analysis was more sensitive to subtle changes in initial texture perception including parameters relating to stickiness and adhesiveness. The two‐cycle compression test for texture profile parameters (i.e., hardness, cohesiveness, adhesiveness, gumminess, springiness, and chewiness) accounted for less variation in the data on texture differences.
Atomic Force Microscopy (AFM) Study of Interactions of HMW Subunits of Wheat Glutenin
Authors: Humphris Andrew D. L. , McMaster Terence J. , Miles Mervyn J. , Gilbert Simon M. , Shewry Peter R. , Tatham Arthur S.
Published: June 2007

Atomic force microscopy (AFM) has been used to study the noncovalent interactions of alkylated HMW subunit 1Dx5 and a M
r 58,000 peptide derived from the central repetitive domain. Both protein and peptide align side‐by‐side to form fibrils, the HMW subunit forming a branched network, and the peptide forming linear rods. The N‐ and C‐terminal domains of the subunit would, therefore, appear to contain regions that interact through noncovalent interactions in the absence of disulfide bond formation. These regions may be of importance in facilitating disulfide bond formation during protein body development.
Effects of Microencapsulated High‐Fat Powders on the Empirical and Fundamental Rheological Properties of Wheat Flour Doughs
Authors: O'Brien C. M. , Grau H. , Neville D. P. , Keogh M. K. , Reville W. J. , Arendt E. K.
Published: June 2007

Microencapsulated high‐fat powders are a healthy and convenient alternative to fats normally used in cereal‐based products. In powder form they are easier to use than block fat. Microencapsulation involves dispersion of the fat using homogenization. The globules are then fixed by spray‐drying. Empirical and fundamental rheological tests were conducted on doughs containing commercial vegetable fat and four microencapsulated high‐fat powders. The doughs were compared with a standard dough containing no fat. The powders contained 70% vegetable fat or milk fat. The encapsulating agent used was either sodium caseinate or whey protein concentrate (5–10%). Sucrose or lactose were also present in the powders (20–25%). The powders were manufactured at low‐ or high‐pressure homogenization. Farinograph and extensigraph tests were performed on all doughs. Dynamic oscillation tests were conducted in the linear visco‐elastic region of the dough. Addition of fat and microencapsulated high‐fat powders produced using low‐pressure homogenization reduced the complex modulus of the doughs. The results showed an increase in phase angle with incorporation of commercial fat and the microencapsulated high‐fat powders. Scanning electron microscopy was conducted to examine the effects of the additives on dough structure. This study demonstrated that microencapsulated high‐fat powders, especially powders produced using low‐pressure homogenization, had some beneficial effects on dough rheology when compared with doughs produced with commercial fat.
Textural Optimization of Shelf‐Stable Bread: Effects of Glycerol Content and Dough‐Forming Technique
Authors: Barrett A. H. , Cardello A. V. , Mair L. , Maguire P. , Lesher L. L. , Richardson M. , Briggs J. , Taub I. A.
Published: June 2007

The effects of glycerol content and dough‐forming method on the physical, textural, and sensory characteristics of shelf‐stable bread were determined. Bread dough was produced with 0, 2, 4, and 6% nominal glycerol content, and formed into rolls by either dough‐dividing or extrusion‐forming methodologies. Baked products were evaluated by uniaxial compression and fitting of stress‐strain data to a three‐parameter mathematical model. A trained sensory panel quantified textural attributes using magnitude estimation methodology. Selected characteristics were also judged by an untrained consumer panel. Sensoryinstrumental relationships were determined. Products were tested instrumentally after different storage intervals to determine effects of glycerol level and dough‐forming process on degree of firming. Results showed that extrusion‐forming produced, on average, relatively more dense and less deformable products than did the dough‐dividing method; extrusionformed samples also had greater sensory firmness and were less similar to an ideal sensory texture. However, high glycerol concentrations in extrusion‐formed products gave sensory profiles that were substantially closer to the ideal. Sensory firmness and chewiness were closely correlated with parameters of power law functions that described compression behavior. Glycerol reduced ultimate firmness after storage.
Assessment of Oriental Noodle Appearance as a Function of Flour Refinement and Noodle Type by Image Analysis
Authors: Hatcher D. W. , Symons S. J.
Published: June 2007

Fresh alkaline and white salted noodle sheets prepared from patent and straight‐grade flours of the western Canadian wheat class Canadian Prairie Spring White (CPSW), Karma and Vista, were visually characterized by image analysis over a 24‐hr period. In both cultivars, the number of specks increased with time although the actual numbers were significantly influenced by both detection size and sensitivity. Maximum speck generation was observed in Karma's straight‐grade kansui noodle sheets, increasing from 12.9 specks/cm2 at 1 hr to 58.0 after 24 hr. Lowest speck numbers were observed in Vista's patent white salted noodle sheets with 4.5 specks/cm2 at 1 hr increasing to 5.6 after 24 hr. The image analysis system was able to show that in combination with a significant cultivar effect, both flour refinement and noodle type significantly influenced the number of discolored specks detected over time. Straight‐grade flours yielded more specks than the patent flours, while salted noodle sheets consistently had fewer specks compared with their kansui noodle sheets at all time intervals. No differences were detected in the average size of the specks due to cultivar or noodle type in the patent flour noodle sheets. Noodle sheets made from Karma straight‐grade flour had significantly larger specks than noodle sheets made from Vista's straight‐grade flour for both noodle types. Patent flour kansui specks were lighter than their salted counterparts. Straight‐grade noodle specks were darker than their corresponding patent flours, but this difference was significant only in the kansui noodle sheets. Specks of all noodle sheets were characterized by darkness distribution profiles that highlighted key differences between the wheat cultivar samples due to noodle type and flour refinement.
Effects of Extrusion on Dietary Fiber and Isoflavone Contents of Wheat Extrudates Enriched with Wet Okara
Authors: Rinaldi V. E. A. , Ng P. K. W. , Bennink M. R.
Published: June 2007

Okara is the residue left after soymilk or tofu production. In North America, okara is used either as animal feed, fertilizer, or landfill. The purpose of this study was to use wet okara to produce and enrich extruded cereal products and to study the effects of extrusion on the dietary fiber and isoflavone contents. Wet okara was combined with soft wheat flour to produce two different formulations (33.3 and 40% okara) and extruded using four combinations of two screw configurations and two temperature profiles. Various physicochemical properties, dietary fiber by enzymatic‐gravimetric method, and isoflavone content by HPLC were analyzed. The radial expansion ratio decreased as fiber content increased. On the other hand, both bulk density and breaking strength increased as fiber content increased. Combining okara with soft wheat flour resulted in increased protein, dietary fiber, and isoflavone contents compared with soft wheat flour alone. Extrusion of the formulations resulted in decreased insoluble fiber (≤25.5%) and increased soluble fiber (≤150%) contents of extrudates. Extrusion decreased the total detectable isoflavones (≤20%) and altered the distribution of the six detected isoflavones.
Sensory Quality of Cooked Long‐Grain Rice as Affected by Rough Rice Moisture Content, Storage Temperature, and Storage Duration
Authors: Meullenet Jean‐Francois , Marks Bradley P. , Hankins Jean‐Ann , Griffin Virginia K. , Daniels Melissa J.
Published: June 2007

The effects of postharvest conditions (i.e., rough rice moisture content, storage temperature, and storage duration) on sensory quality of one longgrain rice cultivar grown in Arkansas (Cypress) were evaluated using a professional descriptive sensory panel. Eight textural (adhesion to lips, hardness, cohesiveness of mass, roughness of mass, toothpull, particle size, toothpack, and loose particles) and six flavor attributes (overall rice impression, sulfur, starch, grainy, metallic, and cardboard) were identified as most important in describing the sensory characteristics of cooked Cyress rice. Postharvest conditions had significant effects on rice sensory quality, and regression models illustrated the effects of each postharvest variable and their interactions.
Effects of Temperature and Mechanical Input on Semisweet Biscuit (Cookie) Quality and Dough Characteristics
Authors: Charun E. , Abecassis J. , Contamine A.‐S. , Roulland T.‐M. , Vergnes B. , Morel M.‐H.
Published: June 2007

The effects of specific mechanical energy (SME) and dough temperature at the end of mixing (Tf) on semisweet biscuit dough characteristics and biscuit quality were studied using an experimental mixer fitted with monitoring devices. The fluid circulating in the double jacket of the mixing bowl was regulated at variable temperatures and mixed dough samples were prepared at Tf of 23, 30, and 37°C for three levels of SME input (20, 60 and 120 kJ/kg). Correlation analysis showed that semisweet biscuit length and thickness were independent quality parameters, influenced respectively by the Tf of dough and SME. Biscuit thickness and volume increased with SME input, but SME had no significant influence on the physicochemical characteristics of the dough. Biscuit length was related to the density and stickiness of the dough and to rheological behavior as assessed by fundamental and empirical measurements. A rise in dough temperature >35°C induced a dramatic increase in viscoelastic properties, leading to biscuit shrinkage. The increase of dough density with Tf seemed to be related to the melting of solid fat in the dough recipe. Melting of fat during mixing could also be a source of viscoelastic changes in the dough at Tf.
Molecular Characterization of Corn Starch Using an Aqueous HPSEC‐MALLS‐RI System Under Various Dissolution and Analytical Conditions
Authors: You SangGuan , Lim Seung‐Taik
Published: June 2007

Molecular characteristics based on absolute weight‐average molecular weight (Mw) and z‐average radius of gyration (Rg) of normal corn starch were analyzed by high‐performance size‐exclusion chromatography (HPSEC) attached to multiangle laser‐light scattering (MALLS) and refractive index (RI) detectors under different starch dissolution and analytical conditions. Autoclaving (121°C, 20 min) or microwave heating (35 sec) provided better HPSEC recovery and higher Mw for starch molecules than simple dissolution in hot water. The Mw for the autoclaved corn amylopectin and amylose fractions separated with a TSK G5,000 column at 60°C were 201 × 106 and 3.3 × 106, respectively. The specific volume for gyration (SVg) calculated from Mw and Rg could be used for the comparison of molecular compactness which was inversely related to the degree of branching. The SVg values of amylopectin and amylose fractions in the chromatogram (TSK G5,000, autoclaved for 20 min) were 0.092 and 0.529, respectively. But a portion (20–30%) of large amylopectin molecules did not pass the injection membrane filter (3.0 μm) and the SEC column, resulting in incomplete recovery. The unfiltered portion varied according to the dissolution treatment. Homogenization (7,000 rpm, 5 or 10 min) of the starch solution improved the recovery of the amylopectin fraction, but significantly increased the Mw of the amylose fraction (17 × 106). Sonication for 5 min degraded starch molecules. For accurate analysis of a native starch using an aqueous SEC, the starch should be fully dissolved with proper treatment such as autoclaving or microwaving, and the column should be improved for full recovery of large amylopectin molecules.
Relationship of Gelatinization and Recrystallization of Cross‐Linked Rice to Glass Transition Temperature
Authors: Chatakanonda Pathama , Varavinit Saiyavit , Chinachoti Pavinee
Published: June 2007

Nonwaxy rice starch was cross‐linked with sodium trimetaphosphate and sodium tripolyphosphate to obtain different degrees of cross‐linking (9.2, 26.2, and 29.2%). The objective was to investigate the influence of cross‐linking on thermal transitions of rice starch. Starch suspensions (67% moisture) were heated at 2°C/min using differential scanning calorimetry (DSC) to follow melting transition of amylopectin. Biphasic transitions were observed at ≈60–95°C in all samples. Melting endotherms of amylopectin shifted to a higher temperature (≤5°C) with an increasing degree of cross‐linking, while there was no dramatic change in enthalpy. Recrystallization during aging for 0–15 days was significantly suppressed by cross‐linking. The delayed gelatinization and retrogradation in crosslinked starch were evident due to restricted swelling and reduced hydration in starch granules. Glass transition temperature (Tg) measured from the derivative curve of heat flow was ‐3 to ‐4°C. No significant change in Tg was observed over the storage time studied.
Influence of Additives and Mixing Time on Crumb Grain Characteristics of Wheat Bread
Authors: Crowley P. , Grau H. , Arendt E. K.
Published: June 2007

The effect of additives and processing parameters on wheat bread were investigated objectively using image analysis (IA). Five different bread types were produced by varying the ingredients (standard, standard with fat, standard with emulsifiers) and changing the mixing times (90, 150, and 240 sec). A digital IA system for wheat bread was developed from generic commercial software. The system yielded reproducible results for a variety of bread crumb grain image features. Bread slices were scanned and evaluated using the IA system. Image characteristics were determined for each bread type. All data was statistically evaluated to detect significant differences between bread types. It was shown quantitatively that inclusion of fat or emulsifiers or extension of mixing time had a significant effect on crumb grain features such as mean cell area, total cell area, and number of cells/cm2. The five bread types could be distinguished solely by crumb grain characteristics.
Effect of Extrusion Cooking on the Primary Structure and Water Solubility of β‐Glucans from Regular and Waxy Barley
Authors: Gaosong Jiang , Vasanthan Thava
Published: June 2007

Water‐soluble β‐glucan from native and extrusion‐cooked barley flours of two barley cultivars, Candle (a waxy starch barley) and Phoenix (a regular starch barley), was isolated and purified. The purity of β‐glucan samples was 85–93% (w/w, dry weight basis) for Candle and 77–86% (w/w, dry weight basis) for Phoenix. The water solubility of β‐glucan (at room temperature, 25°C) in the native and extruded flours (primary solubility) was different from that of the purified β‐glucan samples (secondary solubility). The solubility of β‐glucan in the native and extruded Candle flour was substantially higher than that of β‐glucan in Phoenix. For both cultivars, β‐glucan in the extruded flours had solubility (primary solubility) values higher than in their native counterparts. The solubility of β‐glucan in the purified β‐glucan samples differed depending on the barley cultivar and the extrusion conditions employed. The glycosidic linkage profiles of purified soluble β‐glucan from native and extruded barley flours were determined in order to understand the changes in the primary structure of β‐glucan and the effect of extrusion on the β‐glucan structure‐solubility relationship.
Influence of Hydrothermal Treatment on Lipid Oxidation in Barley
Authors: Rutgersson A. , Toukkuri V.‐M. , Reinikainen P. , Lingnert H.
Published: June 2007

A steeping process of barley grains was evaluated regarding lipid oxidation. The steeping process was evaluated with respect to the temperature during the first steep and second steep, and the lactic acid concentration of the steep solutions. The study was conducted using a central composition circumscribed design, and response surface models were estimated with the use of partial least square. The change in the concentration of hexanal was used to monitor the oxidation during processing and subsequent storage at 30°C. In all samples there was hexanal development during processing and the hexanal concentration increased considerably during storage. The results show that it is possible to optimize the process to get a lower oxidation during the subsequent storage. The temperature during the second steep in the hydrothermal process and the level of lactic acid addition were the most important factors. Both of them should be kept low to favor the oxidative stability.
Air Classification of Barley Flours
Authors: Andersson A. A. M. , Andersson R. , Åman P.
Published: June 2007

Flour samples from seven different barleys, including covered and naked barleys and barleys with normal, waxy, and high‐amylose starches, as well as the high fiber barley Prowashonupana, were impact‐milled and air‐classified in a pilot unit. Six fractions (F1–F5 and C5) with increasing particle size were obtained from each barley. All fractions were analyzed for ash, protein, starch, dietary fiber, and total and unextractable β‐glucan. Ash was enriched in C5; covered barleys (4.3–5.7% of dry matter) had a higher ash content than naked barleys (2.1–3.2%). Starch was enriched in F4 for normal and waxy barleys (72–79%) and in F3 for high‐amylose barleys (72–75%). Protein was enriched in F1 (14–26%) for the different barleys. β‐glucan was enriched in F5 and C5 (7–23%), Prowashonupana had the highest value. The extractability of β‐glucan decreased with increasing particle size, probably because of lower amounts of endogenous β‐glucanase and poorer availability of the substrate in larger particles.
Thermal Behavior and Nonfreezing Water of Soybean Protein Components
Authors: Zhong Z. K. , Sun X. S.
Published: June 2007

Thermal denaturation and hydration of two soybean protein components were studied using differential scanning calorimetry (DSC). Results showed that temperature of denaturation (Td) of both 11S and 7S globulins decreased sharply with an increase in water content. Enthalpy of denaturation (ΔHd) of 11S increased with increasing water content at first, and then leveled off at high water content. However, ΔHd of both 7S and 11S components in 7S samples first increased and then decreased at high water content. The preparation method of samples influenced the ΔHd value significantly but had little effect on the Td. Nonfreezing water was determined from the DSC results. It increased in both 11S and 7S as water content increased but was more abundant in 7S, probably because of different compositions and structures. Threshold value of water content for the appearance of freezing water was 0.30–0.32 h (g of water/g of protein, mass ratio) for 11S. The water absorbed by both 11S and 7S during denaturation increased quickly at low water contents and remained almost constant at high water contents. The results were attributed to different structure and conformation of proteins before and after denaturation.