bluuebunny/crossref_metadata_2025 huggingface dataset:
Extrusion Chemistry of Wheat Flour Proteins: II. Sulfhydryl‐Disulfide Content and Protein Structural Changes
Authors: Rebello C. A. , Schaich K. M.
Published: June 2007

Effects of twin‐screw extrusion conditions on wheat flour proteins were studied, using a two‐level fractional factorial experimental design (11 and 14% protein content, 160 and 185°C, 16 and 20% moisture, 300 and 500 rpm screw speed, mass flow rate of 225 and 400 g/min). Total protein detectable by solid‐phase bicinchoninic acid assay decreased slightly after extrusion, with greatest protein loss at 16% moisture and 160°C. Sulfhydryl content of both flours increased after extrusion at 185°C and 16% moisture with moderate specific mechanical energy (SME ≈ 400–600 kJ/kg) or 160°C and 16% moisture with high SME (SME > 1,000 kJ/kg). Disulfide bonds increased under comparable conditions but with moderate shear (SME = 510–540 kJ/kg). At 20% moisture and either temperature, sulfhydryl and total thiol contents decreased without corresponding increases in disulfides. Reversed‐phase HPLC indicated gliadins were the fractions most affected by extrusion; high molecular weight glutenin subunits also were affected. Changes in gliadins were extensive at 185°C and 16% moisture and were minimal at 160°C and 20% moisture. SDS‐PAGE confirmed the disappearance of protein bands and appearance of new material at low and high molecular weights, presumably resulting from polypeptide fragmentation followed by random radical recombination. Both protein fragmentation and cross‐linking appeared to involve free radicals.
Dynamic Viscoelastic Behavior of High‐Pressure‐Treated Wheat Gluten
Authors: Apichartsrangkoon A. , Bell A. E. , Ledward D. A. , Schofield J. D.
Published: June 2007

The effects on the viscoelastic behavior of hydrated wheat gluten after treatment at different pressures (200–800 MPa), temperatures (20, 40, and 60°C), and holding times (20 and 50 min) were investigated by controlled stress rheometry. Because of the wide range of properties, four different torque amplitudes were used (0.5, 1.00, 3.00, and 6.00 mNm). Significant effects on rheological properties were observed, except when samples were analyzed at 0.5 mNm (limited heat and pressure treatments). Both storage modulus (G′) and loss modulus (G″) were more affected by temperature than pressure. The holding time had substantial effect on the slopes of both moduli at mild treatments; for the more severe treatments, the intercepts of the storage moduli in particular were extensively affected.
Effects of Different Cereal Fibers on Cholesterol and Bile Acid Metabolism in the Syrian Golden Hamster
Authors: Rieckhoff Dörte , Trautwein Elke A. , Mälkki Yrjö , Erbersdobler Helmut F.
Published: June 2007

This study examined the effects of various cereal fibers and various amounts of β‐glucan on cholesterol and bile acid metabolism. Hamsters were fed semisynthetic diets containing 0.12% cholesterol, 20% fat, and either 16% total dietary fiber (TDF) from wheat bran (control) or 10% TDF from oat bran, 13% TDF from oat bran concentrate or barley grains, 16% TDF from oat fiber concentrate, barley flakes, or rye bran. After five weeks, plasma total cholesterol and liver cholesterol concentrations were significantly lower (20 and 50%, respectively) only in hamsters fed rye bran. Diets containing any of the oat ingredients or barley had no effect on total cholesterol. Changes in the pattern of biliary bile acids occurred in hamsters fed 16% TDF from barley flakes or 10% TDF from oat bran. Hamsters fed rye bran had a significantly higher fecal bile acid excretion when compared with controls fed wheat bran. Because rye bran caused the most pronounced lowering effect of total cholesterol despite the lowest content of β‐glucan and soluble fibers, components other than β‐glucan and soluble fibers seem to be involved in its hypocholesterolemic action. Since the effects of the oat and barley ingredients were not solely correlated to the β‐glucan content, structural changes occurring during processing and concentrating of the products may have impaired the hypocholesterolemic potential of the β‐glucans, and other factors such as solubility and viscosity of the fiber components seem to be involved.
Effects of Milling on the Physicochemical Characteristics of Waxy Rice in Taiwan
Authors: Chen J. J. , Lu S. , Lii C. Y.
Published: June 2007

Three types of mills and six milling methods were employed to mill two waxy rice varieties (TCSW1, long grain; TCW70, short grain), and the physicochemical and functional properties of rice flour were examined. The results showed that dry‐milling maintained a higher level of the chemical components than other milling methods. Wet‐milling slightly increased solubility as test temperatures increased, and significantly increased swelling power at 75 and 85°C for TCSW1 and TCW70, respectively. Hammer and semi‐dry hammer milling gave higher percentages of coarse particles (100–300 μm); cyclone and turbo milling led to a more even particle‐size distribution, and the wet‐milling gave the finest particles (10–30 μm). Dry hammer‐milled rice had higher gelatinization and pasting temperatures, and semi‐dry grinding milling resulted in the lowest pasting temperature, setback viscosity, and enthalpy value among the mills. The final quality of the two waxy rice varieties was profoundly affected by the mill type and milling method.
Link Between Mixing Requirements and Dough Strength
Authors: Wooding A. R. , Kavale S. , MacRitchie F. , Stoddard F. L.
Published: June 2007

Industrial bakeries in Australia and New Zealand using the mechanical dough development (MDD) process have experienced undesirable increases in dough mixing requirements. This problem is an unwanted outcome of breeding programs that have endeavored to increase dough strength as a desirable characteristic. Research was undertaken to determine the nature of the link between dough strength and mixing requirements and its relevance to the MDD process across a wide range of wheat lines. Data from three similar trials of 20 wheat lines confirmed the existence of an apparently tight, positive correlation between mixing requirements and dough strength. Although a wide range in genotypes and environments was used, no significant outliers were found, despite the belief that the link between these quality attributes was breakable or at least flexible. This creates a dilemma, as it would be desirable to reduce work input (WI) for economic reasons but not at the expense of loaf quality, which could have a deleterious effect on product marketability. The resultant nexus between mixing requirements, as measured by MDD WI, and dough strength measured by extensigraph resistance to extension (Rmax), appeared to be influenced by the application of nitrogen fertilizer during cultivation, while the nexus between mixing requirements as measured by mixograph development time (MDT) and Rmax, was influenced by other factors associated with crop location. The nexus between farinograph development time (FDT) and Rmax was affected by both location and nitrogen fertilizer application. The rates of increase in WI, MDT, and FDT against Rmax appeared to differ between high molecular weight glutenin subunits (HMW‐GS) 5+10 or 2+12 (the Glu‐D1 alleles). The Glu‐A1 and Glu‐A3 loci also played a significant role, indicating that by manipulating them it may be possible to shift or manipulate the nexus between mixing requirements and dough strength. Alleles at these loci appeared to be additive in effect on WI, MDT, and FDT, as well as Rmax.
Effect of Polarity of Complexing Agents on Thermal and Rheological Properties of Rice Starch Gels
Authors: Chien John T. , Lien Ya‐Yi , Shoemaker C. F.
Published: June 2007

The ability of rice starch to complex with ligands of various polarities was studied to examine the mechanism of complex formation in an aqueous solution. Differential scanning calorimetry (DSC) showed that TNuS19 rice starch (27.9% amylose) formed inclusion complexes with all 12‐C complexing agents. The onset melting temperatures (To) of the complexes were ≈93–96°C. The saturation concentrations of added ligands with high polarity, lauric acid (LA), and lauryl alcohol (LOH), had a range of 2–4% (w/w) of the starch, and both of the corresponding melting enthalpies (ΔH) were ≈3.0 J/g. In contrast, the saturation concentrations of ligands with low polarity, methyl laurate (ML) and dodecane (DO), were ≈1–2% (w/w), and the ΔH were 1.87 and 1.80 J/g, respectively. This implied that solubility of ligands had a significant effect on the extent of complexation. The To and ΔH increased with an increase of annealing time at 85°C, and the optima for the partially reversible complex formation were 2 hr of annealing in all cases. When measured by a dynamic rheometer, the TNuS19 rice starch gel with added LA or LOH showed a higher storage modulus (G′) than that with no complexing agent added during heating. The G′ and tan δ of the complexed gel were further increased during 12 hr of storage. The increase of G′ indicated that the elastic structure of the concentrated rice starch gels could be improved by complex formation and annealing, whereas the increase of tan δ suggested incompatibility of starch components during storage.
Multiple Measurements of Physical Properties of Individual Cooked Rice Grains with a Single Apparatus
Authors: Okadome Hiroshi , Toyoshima Hidechika , Ohtsubo Ken'ichi
Published: June 2007

Multiple measurements of physical properties of cooked rice grains were applied to 55 rice samples with waxy to high amylose contents using a single apparatus (Tensipresser). The multiple measurements consisted of low, high, and continuous progressive compression tests (LC, HC, CPC). The overall hardness (H2) determined by the HC test, and the surface hardness (H1) determined by the LC test, were used as indices to classify the samples into the several groups corresponding to amylose content. The surface hardness was more suitable than the overall hardness for differentiating the effect of protein contents. The difference of stickiness among the cooked rice samples could be detected by the surface adhesion distance (L3) using the LC test. The ratio of elastic limit length (RELL), estimated by the back pressure curve on the CPC test, increased with amylose content. These three tests were meaningful in characterizing the physical properties of cooked rice samples with waxy to high amylose contents.
Estimation of Free Glycolipids in Wheat Flour by HPLC
Authors: Ohm J. B. , Chung O. K.
Published: June 2007

The chloroform‐acetone mixture (4:1, v/v) was an effective solvent for eluting the nonpolar lipid fraction, including free fatty acids, from the polar lipid (glycolipid and phospholipid) fractions from free lipids of 21 hard winter wheat flours using a solid‐phase extraction system. Amounts of monogalactosyldiglycerides (MGDG) and digalactosyldiglycerides (DGDG) in the glycolipid fraction were determined by normal‐phase HPLC with a gradient system using an evaporative light‐scattering detector (ELSD) and a diode array detectors (DAD). Unsaturated fatty acids showed higher UV absorbances from 200 to 213 nm when compared with saturated palmitic acid. However, significant linear correlation coefficients were obtained between the peak areas measured by a DAD and GL contents determined by an ELSD, suggesting that fatty acid composition of flour GL could be fairly constant. Using an ELSD as a reference, equations for determination of MGDG or DGDG quantities were derived from the peak areas of a DAD by multivariate regression methods. Determination of MGDG and DGDG quantities was also possible using only a DAD.
Effect of Gaseous Acetic Acid Treatment on Breadmaking Properties of Flour
Authors: Hayashi Machiko , Seguchi Masaharu
Published: June 2007

Eleven different wheat flours of varying protein content were treated with gaseous acetic acid. Each wheat flour exhibited maximum breadmaking properties (bread height and specific volume) at different levels of gaseous acetic acid treatment. There was a relationship (r = +0.7384) between the level of gaseous acetic acid treatment required for maximum breadmaking properties and the protein content of the wheat flour. Wheat flours with higher protein contents were more resistant to the decrease in pH value due to acetic acid treatment.
Controlled Stepwise Reduction of Disulfide Bonds and Heat‐Induced Modification of Wheat Dough Proteins
Authors: Xu Feng , Brown Kimberly M. , Dybdal Lone , Forman Todd M. , Fuglslang Claus C. , Wagner Peter
Published: June 2007

A reducing solution of 2‐mercaptoethanol and its oxidized form 2‐hydroxyethyl disulfide, whose variable concentrations set variable disulfide reduction potentials, was applied to progressively reduce the disulfide bonds of proteins extracted from doughs made from Meneba and Robin Hood flour. Several dough proteins had disulfide bonds stronger than those of other dough proteins. A SDS‐sedimentation method was applied to monitor the baking of dough into bread. Dough proteins susceptible to heat (baking) were studied by SDS‐fractionation, extraction with reducing alcoholic solution, SDS‐PAGE, and N‐terminal protein sequencing. High or low molecular weight glutenins, α, β, and γ‐gliadins, α‐amylase inhibitor, and α‐amylase trypsin inhibitor were identified among the dough proteins modified by heat (as shown by reduced solubility in aqueous‐SDS solution). The heat‐induced modification of the gliadins and glutenins might contribute to the coagulation of dough proteins, while the heat‐induced modification of the amylase or trypsin inhibitors might contribute to the regulation of endogenous or exogenous amylolytic or proteolytic activities in dough or bread.
Recovery of Lysine from Corn Steepwater
Authors: O'Brien Dennis J. , Craig James C.
Published: June 2007

One approach to increasing the utilization of agricultural products is fractionation of low‐value materials to yield high‐value products. In this study, lysine recovery from corn steepwater, an internal processing stream generated in the wet‐milling of corn, was investigated. A weakly acidic cation exchange resin was employed to selectively recover lysine from corn steepwater at pH 7.0. In column studies, the product from the ion exchange operation had a lysine content of 4–6% (db). The only other amino acid in the product was arginine. The presence of sodium, potassium, and magnesium ions at significant concentrations in the steepwater limited the lysine content of the product because of competitive adsorption on the resin. The lysine‐enriched product reported here is 4–10 times higher in lysine content than other corn milling coproducts and could potentially be useful as a lysine supplement in animal feeds.
Determination of Bran Contamination in Wheat Flours Using Ash Content, Color, and Bran Speck Counts
Authors: Kim Y. S. , Flores R. A.
Published: June 2007

A fast new method based on image analysis, ScanPro Speck Expert (SPX), to determine the bran contamination in wheat flour was studied and compared with existing methods (air‐oven, ash, and color measurements) using an Agtron color meter and a Minolta chromameter. Twenty‐one hard red winter wheat flour samples with ash contents of 0.30–0.58% were collected from the Kansas State University pilot mill and used for this study. Intrinsic variability in the flour sample because of randomness of bran speck orientation and distribution in the sample holder could result in variation in the speck count. Simple and multiple linear regression analyses showed that estimation of flour ash content from the SPX results (R2 = 0.91) would be more accurate than the results from color measurements (R2 = 0.66 [Agtron color meter] and 0.74 [L*]). The added capability of SPX image analyzer to not only count the number of bran specks but also to measure their areas probably increases the accuracy of determining the bran contamination in wheat flour by image processing.
Some Physicochemical Properties of Small‐, Medium‐, and Large‐Granule Starches in Fractions of Waxy Barley Grain
Authors: Tang H. , Ando H. , Watanabe K. , Takeda Y. , Mitsunaga T.
Published: June 2007

Barley grain was divided into eight fractions from the surface layer to the center with a machine used to polish brewers' rice. Small‐, medium‐, and large‐granule starches were isolated from classified barley flour, and their physicochemical properties were investigated. The starch granules were oval to round with a median size of 2 μm for small, 10 μm for medium, and 12–19 μm for large granules. From the surface layer to the center, both the median sizes and the ratio of large granules decreased, and the ratio of medium‐ and small‐granules increased. The starches had A‐type X‐ray diffraction patterns typical of cereal starches. The moisture sorption showed a negative correlation to the granule size. The gelatinization temperatures of starch granules in each layer were approximately the same, but the enthalpies decreased in the order of large, medium, and small granules.
Dough Microextensibility Method Using a 2‐g Mixograph and a Texture Analyzer
Authors: Suchy J. , Lukow O. M. , Ingelin M. E.
Published: June 2007

Development of a small‐scale method to measure dough extensibility, using a 2‐g mixograph and the TA.XT2 texture analyzer (TA) equipped with Kieffer rig, suitable for early‐generation wheat quality screening is presented. Three hook speeds 3.3, 7.0, and 10.0 mm/sec were tested on the TA. Only at the lower hook speed of 3.3 mm/sec were wheats, varying in quality, clearly differentiated. The ability to differentiate between wheats using the TA was compared with the Brabender Extensigraph. The sample ranking based on the resistance to extension (Rmax) from the TA at a hook speed of 10.0 mm/sec correlated highly (r = 0.99) to the ranking obtained on the extensigraph. Dough extensibility data from the extensigraph and the TA, using hook speed 10.0 mm/sec, was correlated (r = 0.90) to loaf volume. Similarly, dough extensibility on the TA, using hook speed 3.3 mm/sec, was correlated to loaf volume (r = 0.96). The effect of three dough water contents (farinograph absorption, farinograph absorption + 6%, and 2‐g mixograph water absorption) on physical properties of dough were evaluated by mixing the dough in a 2‐g mixograph and testing the extensibility on the TA. Dough prepared at farinograph absorption + 6% and at mixograph absorption allowed differentiation between wheats based on the resistance to extension (Rmax).
Effects of Commercial Hydrolytic Enzyme Additives on Canadian Short Process Bread Properties and Processing Characteristics
Authors: Harada O. , Lysenko E. D. , Preston K. R.
Published: June 2007

The effects of increasing levels of eight commercial enzymes representing four types of fungal hydrolytic enzymes (α‐amylases, proteases, xylanases, and cellulases) on Canadian short process (CSP) bread quality and processing characteristics were studied. Addition of all enzymes types at optimum levels resulted in increased loaf volume and bread score and softer crumb. All four types of enzymes appeared to be equally effective in improving bread properties compared with the controls. At high levels, greater tolerance to the addition of xylanases and cellulases compared with the addition of α‐amylases and proteases was apparent. Mixing requirements increased with increasing levels of α‐amylase but no change was apparent with the other enzymes. Addition of all enzymes reduced sheeting work requirements, indicating a dough softening effect. Optimum bread properties for all enzymes were attained within a relatively narrow range of dough sheeting work values, which presumably correspond to optimum dough handling properties. The similarity in response of bread and sheeting characteristics at optimum levels of addition for all four enzyme types suggests a common nonspecific mechanism for improver action that is probably related to water release and the resulting impact on physical dough properties.
Effect of Processing, Formula and Measurement Variables on Alkaline Noodle Color—Toward An Optimized Laboratory System
Authors: Morris C. F. , Jeffers H. C. , Engle D. A.
Published: June 2007

A standardized laboratory method for assessing the color potential of flours for yellow alkaline (Cantonese) noodles is needed, especially for evaluating large numbers of small‐scale samples such as found in wheat breeding populations. To develop such a method, a number of processing and formula parameters were varied and judged for optimum level based on 1) discrimination and mean separation of flours, 2) sensitivity to minor variation in the protocol parameter, 3) practicality and simplicity for the technician, and 4) time efficiency. Four flours milled from single‐cultivar grain lots representing two with good and two with poor color potential were made into alkaline noodle sheets varying in thickness of 0.75–2.00 mm, water absorption of 33.0–39.0%, mixing time of 2–6 min, and NaCl levels of 0–4% (all flour weight basis). Commission Internationale de l'Eclairage (CIE) tristimulus color space (L*, a*, b*) values were measured at 0–24 hr using white, yellow, and black background tiles. Noodle sheet side and a dough resting period were examined. The flours themselves were a consistently large, significant source of variation for color, especially lightness (L*). Based on the optimization criteria, a noodle sheet thickness of 1.5–2.0 mm, an optimum to slightly over optimum water absorption (36% for the flours in this study) with some adjustment for protein content and dough handling properties, a mixing time of 4 min, no dough resting period, and 2% NaCl were selected. Color measurement at 24 hr on a white or otherwise light‐colored background tile was judged best using a consistent side of the noodle sheet. Resting doughs for 1 hr slightly improved handling and sheeting characteristics but was not included for time efficiencies.
Protein Content of Bulk Wheat from Near‐Infrared Reflectance of Individual Kernels
Authors: Delwiche Stephen R. , Hruschka William R.
Published: June 2007

Protein content of wheat by near‐infrared (NIR) reflectance of bulk samples is routinely practiced. New instrumentation that permits automated NIR analysis of individual kernels is now available, with the potential for rapid NIR‐based determinations of color, disease, and protein content, all on a single kernel (sk) basis. In the event that the protein content of the bulk sample is needed rather than that of the individual kernels, the present study examines the feasibility of estimating bulk sample protein from sk spectral readings. On the basis of 318 wheat samples of 10 kernels per sample, encompassing five U.S. wheat classes, the study demonstrates that with as few as 300 kernels bulk sample protein content may be estimated by sk NIR reflectance spectra at an accuracy equivalent to conventional bulk kernel NIR instrumentation.
Modeling Starch Gelatinization Kinetics of Milled Rice Flour
Authors: Ojeda Carlos A. , Tolaba Marcela P. , Suárez Constantino
Published: June 2007

Milled long‐grain rice samples were evaluated by differential scanning calorimetry (DSC) to determine the kinetics of starch gelatinization. The experiments were conducted with milled rice flour with a 10.6% degree of milling. DSC thermograms were obtained from 35 to 110°C using heating rates between 1°C/min and 15°C/min. The rate constants were evaluated, and two activation energies were found for different temperature ranges. At <70.1°C gelatinization was not completed. It was assumed that at <70.1°C gelatinization would only affect the amorphous regions. During the subsequent phase the crystalline regions destabilized by the amorphous component begin to gelatinize. For moisture content of 70%, wet basis, and a heating rate of 12°C/min, the enthalpy of gelatinization reaches a constant value of 7.3 J/g.
Stability and Dietary Contribution of Vitamin E Added to Bread
Authors: Ranhotra G. S. , Gelroth J. A. , Okot‐Kotber B. M.
Published: June 2007

Daily intake levels of vitamin E in the range of 200–800 IU are now recommended for its antioxidant effect. However, only vitamin E supplements or fortified foods may provide these high intake levels. As a fortified food, breads were prepared containing 200, 400, 800, or 1,600 IU of added vitamin E (dl‐α‐tocopheryl acetate) per pound loaf. These levels of fortification exerted no adverse effects on bread quality. However, only about two‐thirds of the added vitamin E was retained (recovered) in the breads, with retention values showing no further significant change during the seven‐day shelf‐life of the product. In fresh breads, vitamin E retention values were nearly the same (range 66.3–68.5%, average 67.2%) at all levels of vitamin E tested; this may hold true for levels not tested. Factoring in an average retention value of 67.2%, and actual potency (81.8%) of the vitamin E source used, a 50‐g serving of bread fortified with 1,600 IU of vitamin E per loaf would provide nearly one‐fourth of a suggested daily intake of 400 IU.
Effect of Kiln Drying on Falling Number of Oats
Authors: Kaarlehto T. , Salovaara H.
Published: June 2007

The suitability of the falling number method for oats was studied using samples of oat groats, oat bran, oat endosperm flour, and rolled oats. Sample sizes of 4.5–8 g were tested. The results showed that a standard 7‐g sample falling number determination would be suitable for oats, the falling number of samples varying from 328 to 721 sec. Due to high gelatinization temperature of oat starch, falling number values <300 sec showed greater variation than those >300 sec. Oat groat samples from two separate kiln drying processes showed that kiln drying increased the falling number values by 30–89%. The falling number determination is a potential tool for estimating the adequacy of kiln drying of oats. However, further modifications of the method should be developed to better consider the pasting properties of oat starch.
Convenient Method to Determine Free Fatty Acid of Rice Using Thin‐Layer Chromatography and Flame‐Ionization Detection System
Authors: Nishiba Yoichi , Sato Tetsuo , Suda Ikuo
Published: June 2007

A convenient method which possessed simplicity and high sensitivity was designed to investigate the changes in free fatty acid (FFA) of rice during storage using a thin‐layer chromatography and flame‐ionization detection (TLC/FID) system. In this method, two different solvent systems for TLC were used according to the purpose of experiments. Solvent system A (hexane and diethyl ether and acetic acid 80:20:1) was suitable to obtain a chromatogram showing the overall state of rice lipid degradation. Using solvent system A, the degradation of triglyceride or the increase in FFA during storage was clearly visualized as changes in the chromatogram. Solvent system B (hexane and acetic acid 100:1) was used to improve the low reproducibility of the TLC/FID method. When methyl stearate was used as an internal standard with solvent system B, high reproducibility of the FFA value was obtained, and very small changes were detectable in stored white milled rice. This method has small sample size and simple operation and is more sensitive than the standard titration method. Therefore, this seems to be an especially convenient method for small‐scale storage tests or for experiments using many samples.
Relationship of Kernel Size to Flour Water Absorption for Canada Western Red Spring Wheat
Authors: Morgan B. C. , Dexter J. E. , Preston K. R.
Published: June 2007

Canada Western Red Spring (CWRS) wheat exhibits consistent positive relationships between kernel weight and farinograph and baking water absorption. These relationships are sufficiently robust to be statistically significant (P < 0.05) for historical Canadian Grain Commission harvest survey data generated one year apart for 17 years, and for historical data on individual cultivars in advanced Canadian wheat breeding trials, also generated annually. Verification of the relationships were obtained by analyzing different kernel size fractions obtained by sieving CWRS harvest survey samples and pure CWRS cultivars from various origins. In all cases, highly significant positive relationships were observed between kernel size and water absorption. The relationships were evident for individual streams from pilot‐scale millings of sized fractions from CWRS harvested in two different years. Strong correlations of kernel weight to farinograph and baking absorption also were shown for sized fractions from commercial samples of American Dark Northern Spring and Australian Prime Hard wheat. The strong statistical association between kernel size and water absorption could not be explained on the basis of wheat hardness (flour starch damage), protein content, or dough strength. In view of the importance of flour water absorption to bakers, further investigation is warranted to identify the cause for the association between large kernel size and high water absorption.
Viscoelasticity of Cowpea Starch Gels
Authors: Won So‐Yoon , Choi WonSeok , Lim Hyesook S. , Cho Ki‐Yul , Lim Seung‐Taik
Published: June 2007

The mechanical behavior of cowpea starch gels (10%, w/v) at small and large deformations were investigated in comparison with acorn, corn, and potato starches in storage at 4°C for seven days. The rapid viscograms of starch paste (7%, w/v) revealed that cowpea starch had a larger setback (1,135 cP) than other starches (465–830 cP), although peak viscosity (1,723 cP) and pasting temperature (76°C) were between those of corn and potato starches. Texture profile analysis of cowpea starch gel showed exceptionally higher values for hardness, gumminess, chewiness and initial modulus than other starch gels. Cowpea starch gel also exhibited higher G′ and smaller tan δ compared with other starch gels, regardless of the storage time. A creep test revealed that the cowpea starch gel could remain highly resistant to stress, showing the least deformation among the tested starch gels during storage up to seven days. The overall results disclosed that cowpea starch was capable of forming exceptionally strong and elastic gels with good storage stability.
Extrusion of Cross‐Linked Hydroxypropylated Corn Starches II. Morphological and Molecular Characterization
Authors: McPherson A. E. , Jane J.
Published: June 2007

A series of cross‐linked hydroxypropylated corn starches were extruded with a Leistritz micro‐18 co‐rotating extruder. Extrusion process variables including moisture (30, 35, and 40%), barrel temperature (60, 80, and 100°C), and screw design (low, medium, and high shear) were investigated. Scanning electron microscopy (SEM) of extruded starches showed a gel phase with distorted granules and granule fragments after extrusion at 60°C. After extrusion at 100°C only a gel phase was observed with no granular structures remaining. High performance size exclusion chromatography (HPSEC) equipped with multiangle laser light‐scattering (MALLS) and refractive index (RI) detectors showed extruded starches degraded to different extents, depending on extrusion conditions. The average molecular weight of the amylopectin of unextruded native corn starch was 7.7 × 108. Extrusion at 30% moisture, 100°C, and high shear reduced the molecular weight of amylopectin to 1.0 × 108. Hydroxypropylated normal corn starch extruded at identical conditions showed greater decreases in amylopectin molecular weight. With the addition of cross‐linking, the amylopectin fractions of the extruded starches were less degraded than those of their native and hydroxypropylated corn starch counterparts. Similarly, increasing moisture content during extrusion lowered amylopectin degradation in the extruded starches. Increasing temperature during extrusion of cross‐linked hydroxypropylated starches at high moisture content (e.g., 40%) lowered amylopectin molecular weights of the extruded starches, whereas increasing extrusion temperature at low moisture content (30%) resulted in less degraded molecules. This difference was attributed to the higher glass transition temperatures of the cross‐linked starches.
Study of Internal Structure of Waxy Wheat Starch Granules by KI/I2 Solution
Authors: Seguchi Masaharu , Yasui Takeshi , Hosomi Kazuko , Imai Tooru
Published: June 2007

Wheat starch granules were separated from waxy wheat flour by the acetic acid (pH 3.5) fractionation technique. Waxy wheat starch samples were stained red‐brown using KI/I2 solution. Subsequently, the concentration of the KI/I2 solution was increased to >2.5% KI and 1.0% I2. Then the appearance of the waxy wheat starch granules quickly became ghostlike. The internal structure of the ghost could be observed. This structure consisted of two parts with different colors: a red‐brown central part and a slightly pinkish surrounding part. Sonication of the ghost at 20 kHz for 20 sec separated the central part from the surrounding part. Each of the separated parts were subjected to gel‐filtration chromatography, and their chromatography profiles indicated only amylopectin and no amylose. The central and surrounding parts had molecular weights of 54.3 × 105 and 23.8 × 106 from Berry plots, respectively.
Influence of Sprout Damage on Oriental Noodle Appearance as Assessed by Image Analysis
Authors: Hatcher D. W. , Symons S. J.
Published: June 2007

Fresh alkaline (kansui) and white salted noodles prepared from sound and sprout damaged patent flours of the western Canadian wheat class Canadian Prairie Spring White (CPSW) cv. Vista were characterized by image analysis (IA). In all samples, the number of discolored spots increased with aging <24 hr (24 ± 1°C), although the number of spots per sample was significantly influenced by the degree of sprout damage. Alkaline kansui noodles made from severely sprouted wheat (Day 5) flours had the greatest number of spots per image at 1 hr (114) and increased to 256 spots per image by 7 hr. This represented an approximate fivefold greater number of spots as compared with the sound flour kansui noodle at 7hr. No further increase in spot numbers was detected in the severely sprouted sample with aging for 24 hr. Significantly fewer spots were observed in the white salted noodles (WSN) prepared from heavily sprouted wheat with 29 spots per image at 1 hr increasing to only 54.5 after 24 hr. The IA system was able to detect a significant difference in the size of the discolored spots over time due to sprout damage. The largest spot size was measured in the kansui noodles prepared from heavily sprouted wheat. All sprouted flours used to prepare both kansui and WSN had significantly larger spot sizes as compared with sound control flours. The mean darkness values for the noodle spots prepared from the heavily sprouted flours were significantly darker than the control flours for both WSN and kansui noodles. Spots of all noodles were characterized by darkness distribution profiles that highlighted key differences between noodle type and the degree of sprout damage. Addition of sodium metabisulfite to the kansui noodles at 1,000 ppm significantly decreased the number of spots formed, minimized the size, and lightened the spots over the first 7 hr, but they subsequently darkened after 24 hr.
Variability in a Starch Isolation Method and Automated Digital Image Analysis System Used for the Study of Starch Size Distributions in Wheat Flour
Authors: Bechtel Donald B. , Wilson Jeff
Published: June 2007

A starch isolation method and digital image analysis system were developed to accurately measure size distributions of the starch populations in wheat. The image analysis system was coupled directly to a light microscope equipped with computer controlled step stage and automatic focus. Automation of data acquisition and processing eliminated some of the labor intensive steps previously required for analyzing starch granule size distributions. This system was used to standardize starch isolation methods and compare variation and precision of the system. Operational variations were determined and statistically assessed. The number of fields of view required for low standard errors and acceptable speed of analysis was determined to be fifty. A major advantage of the system has been the increased resolution. The use of higher magnifications and stage automation allowed the analysis of starch granules as small as 0.84 μm in diameter while analyzing thousands of starch granules per sample.
Starch Retrogradation in Cooked Pasta and Rice
Authors: Riva M. , Fessas D. , Schiraldi A.
Published: June 2007

Effect of cooking time on starch retrogradation and water distribution was studied in pasta (spaghetti) and rice (parboiled and arborio) using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) Optimum cooking times (OCT) were 8, 16, and 18.5 min for spaghetti, parboiled, and arborio rice, respectively. Swelling was observed by image analysis. OCT spaghetti and rice showed various starch retrogradation rates at various aging times and temperatures. Based on the classical Avrami function, the retrogradation rate at 5°C followed the order spaghetti > parboiled rice > arborio rice, while extent was in the opposite order. At higher temperature (20°C), the rates decreased by 20× in all cases. Thermogravimetric analysis (TGA) investigations were undertaken to check the distribution of water within these products and its relationship to starch retrogradation. During heating, water was released in two distinguishable steps at ≈80 and 100°C. Results supported the conclusion that the more tightly bound water might not participate or facilitate starch retrogradation. In this study, the overall water content did not change during storage, and water appeared to migrate from sites of stronger binding to sites of weaker binding. The temperature dependence of the Avrami constant was described with the Vogel‐Tamman‐Fulcher empirical expression.
Effect of Morphology of Mechanically Developed Wheat Flour and Water on Starch from Gluten Separation Using Cold Ethanol Displacement
Authors: Robertson G. H. , Cao T. K. , Wood D. F.
Published: June 2007

The mechanical development of wheat flour and water creates micro and macro structures in dough or batter that critically influence the ability to separate starch from protein by fluid displacement. This study sought to identify specific structural and rheological features and to relate these to separation as indexed by the separation factor. Structural features, especially protein and starch distributions, were examined using visible light microscopy applied to dough samples that had been exposed to a protein dye. Flour and water samples were developed in a Brabender microfarinograph at conditions (water content and time of development) generally suitable for use of the USDA Western Regional Research Center, cold‐ethanol fluid‐displacement method. No truly homogenous structures were observed. However, distinct segregation of protein and starch were apparent at all conditions. Structural features correlated qualitatively with the success of separation indexed by the overall separation factor (αp/s) for the separation process. Highly segregated states characterized by large protein bands, clustered starch, and large open spaces were obtained with intermediate development (25 ± 5 min) and were most readily separated (αp/s = 118 ± 7). Segregated states with relatively thin protein bands (≤10 μm dia) in complex networks entrapping starch were obtained after additional development (≥45 min) and were less completely separable (αp/s = 32 ± 2). Segregated states with irregularly organized protein in the form of clumps and bands were obtained with minimal development and were partially separable (αp/s = 65 ± 4). Consistency indicated on the microfarinograph increases monotonically throughout and beyond the period of maximum separability. However, elasticity changes and a high rate of increase in consistency evident in the microfarinogram may reflect changes in the structure that also reduce separability. The study demonstrated the use of the ethanol method to isolate development from displacement phenomena forindependent study.
Rapid Gas Chromatographic Technique for Quantifying 2‐Acetyl‐1‐Pyrroline and Hexanal in Rice (Oryza sativa, L.)
Authors: Bergman C. J. , Delgado J. T. , Bryant R. , Grimm C. , Cadwallader K. R. , Webb B. D.
Published: June 2007

The aroma of rice plays a role in its consumer acceptability. The popcorn‐like smell of aromatic rice stemming primarily from its 2‐ acetyl‐1‐pyrroline (2‐AP) content is considered desirable by many consumers. Conversely, hexanal has been correlated with off odors in rice that develop from lipid oxidation. A rapid method for 2‐AP and hexanal quantification suitable for use in breeding programs, large‐scale research efforts, and quality assurance programs is needed. While developing such a method, sample preparation (degree of milling, particle size), solvent extraction time and temperature, and gas chromatographic parameters were studied. Particle size had no influence on 2‐AP or hexanal recovered. One extraction solubilized ≈80% of the 2‐AP and 56% of the hexanal present in milled rice. The optimum extraction method was assessed to require 0.3 g of ground brown or milled rice in methylene chloride held at 85°C for 2.5 hr. The complete gas chromatographic run requires ≈25 min, and 50 samples can be analyzed per day. The optimized method's linear response (R2 = 0.99) and reproducibility was demonstrated. The stability of 2‐AP and hexanal in frozen milled rice and in refrigerated methylene chloride extracts was excellent for at least six months. Milled and unmilled commercial and breeders' aromatic rice samples contained 10–1,104 ng/g of 2‐AP and 148–2,541 ng/g of hexanal. Genotype had the greatest effect on the 2‐AP and hexanal content of two lines grown over four years and in four states.
Effects of Leavening Acids and Dough Temperature in Wheat Flour Tortillas
Authors: Cepeda Minerva , Waniska Ralph D. , Rooney Lloyd W. , Bejosano Feliciano P.
Published: June 2007

Functionality of four leavening acids (sodium aluminum phosphate [SALP], sodium aluminum sulfate [SAS], monocalcium phosphate [MCP] and sodium acid pyrophosphate [SAPP‐28]) was evaluated during processing of wheat flour tortillas. Formulas were optimized to yield opaque, large‐diameter tortillas with pH 5.9–6.1. Each leavening acid and sodium bicarbonate was first evaluated at 38°C and then evaluated in combination with fumaric acid at 34 and 38°C. Ionic and pH interactions of leavening salts adversely affected dough properties and resting time. Opacity and pH of tortillas prepared with MCP was lower than for other treatments. Higher dough temperature required more leavening acid and base to compensate for some of the loss of CO2 incurred during dough mixing and resting at 38°C. The addition of fumaric acid decreased the amount of leavening acid, the dough‐resting time and tortilla pH, and improved storage stability. Combinations of MCP, SALP (or SAS), and fumaric acid produced dough and tortillas with good qualities. Tortillas prepared using SALP (or SAS) and fumaric acid tended to be of better quality.
Prediction of Cooked Rice Texture Using Extrusion and Compression Tests in Conjunction with Spectral Stress Strain Analysis
Authors: Sitakalin Chanintorn , Meullenet Jean‐Francois C.
Published: June 2007

Sensory texture attributes of cooked rice from two cultivars (Bengal and Cypress) harvested in 1997 (56 samples) were predicted using extrusion and compression tests along with spectral stress strain analysis. Predictive models for each of nine sensory texture attributes studied were evaluated using force values from the instrumental tests in conjunction with partial least squares regression. All sensory attributes were well predicted using both the extrusion and compression tests (relative ability of prediction > 0.70). However, the extrusion test consistently provided more accurate and discriminative predicted models (root mean square error of prediction < 0.55, Stot/RMSEP > 2.0). Spectral stress strain analysis predictive models for adhesiveness to lips and hardness were explained.
Instrumental Assessment of Cooked Rice Texture Characteristics: A Method for Breeders
Authors: Meullenet Jean‐Francois , Champagne Elaine T. , Bett Karen L. , McClung Anna M. , Kauffmann Domitille
Published: June 2007

Sensory textural characteristics of cooked rice (61 samples) were predicted using a miniature extrusion cell and the novel data analysis method Spectral Stress Strain Analysis (SSSA). Thirteen sensory texture characteristics evaluated using a trained descriptive panel and stress values from an extrusion test were used in combination with partial least squares regression to evaluate predictive models for each of the sensory attributes studied. Among the textural attributes evaluated by the panel, four (stickiness, hardness, cohesiveness of mass, and uniformity of bite [relative ability of prediction values (RAP) > 0.6, n = 61]) could be satisfactorily predicted using an instrumental test and subsequent SSSA. The quality of the models determined varied for the two grain types evaluated. This instrumental method provides a valuable screening tool for rice breeders.
Reducing Steep Time by Adding Lactic Acid During Countercurrent Steeping of Corn with Different Initial Moisture Contents
Authors: Yang P. , Eckhoff S. R.
Published: June 2007

Reducing corn steep time by adding lactic acid instead of relying on in situ fermentation was studied. Corn at two initial moisture levels (15 and 20%) was steeped for 18 hr in a countercurrent steep system. The initial SO2 target concentration in steepwater was 2,000 or 3,000 ppm, while the initial lactic acid concentration in steepwater was 0, 0.28, or 0.55%. Adding lactic acid under all steeping conditions decreased steepwater pH, accelerated SO2 absorption, and increased the amount of solids released from corn. Adding lactic acid during steeping also increased the first grind slurry density and made germ skimming easier than when no lactic acid was added. Starch yields for the hybrid used in this study under all steep conditions were comparable to those from 24‐hr steeping, except when steeping corn with an initial moisture content of 15% in ≈2,000 ppm of SO2 alone. For the 20% moisture corn, adding lactic acid to fresh steepwater significantly improved the starch yield at ≈2,000 ppm of SO2 for 18‐hr steeping. At ≈3,000 ppm of SO2, adding lactic acid did not increase the starch yield for the hybrid used. The protein content in starch was significantly lower when lactic acid was added. Pasting properties of starch were not affected by adding lactic acid. The hybrid used in this study had an initial moisture content of 20% and could be wet‐milled without affecting starch yield, starch protein content, and pasting properties.