Solvent Retention Capacity Values in Relation to Hard Winter Wheat and Flour Properties and Straight‐Dough Breadmaking Quality

Solvent retention capacity (SRC) was investigated in assessing the end use quality of hard winter wheat (HWW). The four SRC values of 116 HWW flours were determined using 5% lactic acid, 50% sucrose, 5% sodium carbonate, and distilled water. The SRC values were greatly affected by wheat and flour protein contents, and showed significant linear correlations with 1,000‐kernel weight and single kernel weight, size, and hardness. The 5% lactic acid SRC value showed the highest correlation (r = 0.83, P < 0.0001) with straight‐dough bread volume, followed by 50% sucrose, and least by distilled water. We found that the 5% lactic acid SRC value differentiated the quality of protein relating to loaf volume. When we selected a set of flours that had a narrow range of protein content of 12–13% (n = 37) from the 116 flours, flour protein content was not significantly correlated with loaf volume. The 5% lactic acid SRC value, however, showed a significant correlation (r = 0.84, P < 0.0001) with loaf volume. The 5% lactic acid SRC value was significantly correlated with SDS‐sedimentation volume (r = 0.83, P < 0.0001). The SDS‐sedimentation test showed a similar capability to 5% lactic acid SRC, correlating significantly with loaf volume for flours with similar protein content (r = 0.72, P < 0.0001). Prediction models for loaf volume were derived from a series of wheat and flour quality parameters. The inclusion of 5% lactic acid SRC values in the prediction model improved R² = 0.778 and root mean square error (RMSE) of 57.2 from R² = 0.609 and RMSE = 75.6, respectively, from the prediction model developed with the single kernel characterization system (SKCS) and near‐infrared reflectance (NIR) spectroscopy data. The prediction models were tested with three validation sets with different protein ranges and confirmed that the 5% lactic acid SRC test is valuable in predicting the loaf volume of bread from a HWW flour, especially for flours with similar protein contents.     

Relationships of Free Lipids with Quality Factors in Hard Winter Wheat Flours

Hard winter wheat (Triticum aestivum L.) flours (n = 72) were analyzed for free lipids (FL) and their relationships with quality parameters. The two main glycolipid (GL) classes showed contrary simple linear correlations (r) with quality parameters. Specifically, kernel hardness parameters, flour yields, and water absorptions had significant negative correlations with monogalactosyldiglycerides (MGDG) but positive correlations with digalactosyldiglycerides (DGDG). MGDG showed negative correlations with gluten content but positive correlations with gluten index. The percentages of DGDG in FL had significant positive correlations among cultivars (n = 12) with mixograph and bake mix times (r = 0.71, P < 0.01 and r = 0.67, P < 0.05, respectively), mixing tolerance (r = 0.67, P < 0.05), and bread crumb grain score (r = 0.71, P < 0.01). These results suggest that increasing DGDG in FL could contribute to enhancing wheat quality attributes including milling, dough mixing, and breadmaking quality characteristics. FL content and composition (ratio of MGDG or DGDG to GL) supplement flour protein content to develop prediction equations of mixograph mix time (R² = 0.89), bake mix time (R² = 0.76), and loaf volume (R² = 0.72).     

Effect of Wheat Genotype and Environment on Relationships Between Dough Extensibility and Breadmaking Quality

Dough extensibility affects processing ease, gas retention, and loaf volume of finished products. The Kieffer dough extensibility test was developed to assess extensibility of small dough samples and is therefore adapted for use in breeding programs. Information is lacking on relationships between wheat growing environments and dough properties measured by the Kieffer dough extensibility test. This study documents the variability of dough extensibility (Ext), maximum resistance to extension (Rmax), and area under the extensibility curve (Area) in relation to breadmaking quality, and the effect of wheat growing environments. Mixograph, Kieffer dough extensibility, and bake tests were performed on flour milled from 19 hard red spring wheat (Triticum aestivum L.) genotypes grown during three growing seasons (2007‐2009) at six South Dakota locations. Although both genotype and environment had significant effects on Kieffer dough extensibility variables, environment represented the largest source of variation. Among genotype means, Area was most correlated (r = 0.63) with loaf volume, suggesting that by selecting lines with increased Area, loaf volume should improve. Rmax was positively correlated (r = 0.58) with loaf volume among genotype means but negatively correlated (r = –0.80) among environmental means. Ext was positively correlated (r = 0.90) with loaf volume among environmental means. Weather variables were correlated with Rmax, Ext and loaf volume and therefore could help predict end‐use quality.     

Variability and Relationships Among Mixolab,Mixograph, and Baking Parameters Based on Multienvironment Spring Wheat Trials

Because of the large number of cultivars that require examination in the development of spring wheat (Triticum aestivum L.) cultivars, breeding programs use predictive methods to test end use quality. The Mixograph is a widely used predictive test with which end use quality of many genotypes can be assessed in a short time. By comparison, the Mixolab is a relatively new device with additional capability that might be used for the same purpose. Our objective was to document variability of, and relationships among, 20 parameters obtained from Mixolab, Mixograph, and bake tests. Tests were performed on flour from 18 genotypes grown in 20 environments. Both genotype and environment had significant effects on quality parameter values. Several Mixograph and Mixolab parameters were highly significantly correlated, particularly when genotype mean values over environments were considered. Correlations between loaf volume and Mixolab parameters within environments were inconsistent and suggest that average genotype values over environments will be most useful. For example, the correlation between Mixolab stability and loaf volume (r = 0.25, P < 0.001) was much higher when genotype averages (r = 0.70, P < 0.001) were considered. Our results show that selection for Mixolab stability and water absorption should help delineate and improve the selection of genotypes with greater loaf volume.     

Correlations Between Empirical and Fundamental Rheology Measurements and Baking Performance of Frozen Bread Dough

Empirical and fundamental rheology measurements were made on fresh and frozen dough to investigate the effects of freezing, frozen storage, and additives. These results were compared with results of a standard baking test. Four formulations were tested: a control dough, and doughs with additions of 100 ppm of ascorbic acid (AA), 0.5% sodium stearoyl lactylate (SSL), and 0.5% diacetyl tartaric acid esters of monoglycerides (DATEM). Rheological and baking tests were performed on fresh doughs and on doughs after two, five, and eight weeks of frozen storage. Resistance to extension was higher for doughs with additives in fresh and frozen doughs. There was a decrease in resistance to extension due to freezing. Complex modulus in fresh doughs was highest for doughs with SSL. There was a decrease complex modulus after freezing and thawing. In frozen doughs at 10 Hz, doughs with additives had higher complex modulus values and lower phase angle values when compared to the control. The additives used all had a positive effect on proof time, loaf volume, and crumb firmness, and all formulations deteriorated in quality during frozen storage. Resistance to extension and complex modulus were positively correlated with loaf volume (r = 0.86 and r = 0.64, P < 0.01). Phase angle was negatively correlated with loaf volume (r = -0.74, P < 0.01).     

Protein and Quality Characterization of Complete and Partial Near‐Isogenic Lines of Waxy Wheat

The objective of this study was to evaluate protein composition and its effects on flour quality and physical dough test parameters using waxy wheat near‐isogenic lines. Partial waxy (single and double nulls) and waxy (null at all three waxy loci, Wx‐A1, Wx‐B1, and Wx‐D1) lines of N11 set (bread wheat) and Svevo (durum) were investigated. For protein composition, waxy wheats in this study had relatively lower albumins‐globulins than the hard winter wheat control. In the bread wheats (N11), dough strength as measured by mixograph peak dough development time (MDDT) (r = 0.75) and maximum resistance (R_max) (r = 0.70) was significantly correlated with unextractable polymeric protein (UPP), whereas in durum wheats, moderate correlation was observed (r = 0.73 and 0.59, respectively). This may be due to the presence of high molecular weight glutenin subunits (HMW‐GS) Dx2+Dy12 at the Glu‐D1 locus instead of Dx5+Dy10, which are associated with dough strength. Significant correlation of initial loaf volume (ILV) to flour polymeric protein (FPP) (r = 0.75) and flour protein (FP) (r = 0.63) was found in bread wheats, whereas in durum wheats, a weak correlation of ILV was observed with FP (r = 0.09) and FPP (r =0.51). Significant correlation of ILV with FPP in bread wheats and with % polymeric protein (PPP) (r = 0.75) in durum lines indicates that this aspect of end‐use functionality is influenced by FPP and PPP, respectively, in these waxy wheat lines. High ILV was observed with 100% waxy wheat flour alone and was not affected by 50% blending with bread wheat flour. However, dark color and poor crumb structure was observed with 100% waxy flour, which was unacceptable to consumers. As the amylopectin content of the starch increases, loaf expansion increases but the crumb structure becomes increasingly unstable and collapses.     

Relationship of Bread Quality to Kernel,Flour, and Dough Properties

This study measured the relationship between bread quality and 49 hard red spring (HRS) or 48 hard red winter (HRW) grain, flour, and dough quality characteristics. The estimated bread quality attributes included loaf volume, bake mix time, bake water absorption, and crumb grain score. The best‐fit models for loaf volume, bake mix time, and water absorption had R² values of 0.78–0.93 with five to eight variables. Crumb grain score was not well estimated, and had R² values ≈0.60. For loaf volume models, grain or flour protein content was the most important parameter included. Bake water absorption was best estimated when using mixograph water absorption, and flour or grain protein content. Bake water absorption models could generally be improved by including farinograph, mixograph, or alveograph measurements. Bake mix time was estimated best when using mixograph mix time, and models could be improved by including glutenin data. When the data set was divided into calibration and prediction sets, the loaf volume and bake mix time models still looked promising for screening samples. When including only variables that could be rapidly measured (protein content, test weight, single kernel moisture content, single kernel diameter, single kernel hardness, bulk moisture content, and dark hard and vitreous kernels), only loaf volume could be predicted with accuracies adequate for screening samples.     

Gluten‐Free Bread from Sorghum: Quality Differences Among Hybrids

Gluten‐free breadmaking quality of 10 sorghum flours was compared using (relative basis) decorticated sorghum flour (70), corn starch (30), water (105), salt (1.75), sugar (1), and dried yeast (2). Batter consistency was standardized by varying water levels to achieve the same force during extrusion. Crumb properties were evaluated by digital image analysis and texture profile analysis (TPA). Significant differences (P < 0.001) in crumb grain were found among the hybrids with mean cell area ranging from 1.3 to 3.3 mm² and total number of cells ranging from 13.5 to 27.8/cm². TPA hardness values of the crumb also varied significantly (P < 0.001). Based on significant correlations (P < 0.01), starch damage, influenced by kernel hardness, was identified as a key element for these differences. Breads differed little in volume, height, bake loss, and water activity. Investigation of added ingredients on bread quality was conducted using response surface methodology (RSM) with two sorghum hybrids of opposite quality. Addition of xanthan gum (0.3–1.2% flour weight basis [fwb]) and skim milk powder (1.2–4.8% fwb) and varying water levels (100–115% fwb) were tested using a central composite design. Increasing water levels increased loaf specific volume, while increasing xanthan gum levels decreased the volume. As skim milk powder levels increased, loaf height decreased. Quality differences between the hybrids were maintained throughout the RSM.     

Effects of Pearling on Falling Number and α‐Amylase Activity of Preharvest Sprouted Spring Wheat

Preharvest sprouted wheat is often characterized by the falling number (FN) test. FN decreases in preharvest sprouted wheat as enzymatic degradation of the starchy endosperm increases. Wheat with FN values <250–275 is often discounted at the time of sale. The intent of this investigation was to evaluate the effects of debranning or pearling on the flour quality traits of five samples of wheat rated as low, med‐low, medium, med‐high, and sound that exhibited a range in FN values of 62–425 sec. Replicates of each sample were pearled for 30, 60, and 120 sec to remove portions of the outer bran layers before milling. FN was highly correlated with α‐amylase activity (r > ‐0.97) in the med‐low, medium, and med‐high FN sample sets as pearling time increased. FN increased in the medlow, medium, and med‐high FN samples by 128, 123, and 80%, respectively, after 120 sec of pearling. Pearling had no effect on flour FN of the low FN sample but α‐amylase activity was significantly decreased. Pearling had little or no effect on FN and α‐amylase activity of the sound sample. FN was moderately to strongly correlated with Rapid Visco Analyser (RVA), alveograph, and farinograph properties, and poorly correlated with protein content, flour yield, and bread loaf volume. In subsequent breadmaking studies, bread loaf volume, and crumb characteristics of flour from pearled wheat were not significantly different from loaf volume and crumb characteristics of flour from the corresponding nonpearled wheat.     

Size Distribution and Properties of Wheat Starch Granules in Relation to Crumb Grain Score of Pup‐Loaf Bread

Twelve hard winter wheat flours with protein contents of 11.8–13.6% (14% mb) were selected to investigate starch properties associated with the crumb grain score of experimentally baked pup‐loaf bread. The 12 flours were classified in four groups depending on the crumb grain scores, which ranged from 1 (questionable‐unsatisfactory) to 4 (satisfactory). Flours in groups 1, 2, 3, and 4 produced breads with pup‐loaf volumes of 910–1,035, 1,000–1,005, 950–1,025, and 955–1,010 cm³, respectively. Starches were isolated by a dough handwashing method and purified by washing to give 75–79% combined yield (dry flour basis) of prime (62–71%) and tailing (7–16%) starches. The prime starch was fractionated further into large A‐granules and small B‐granules by repeated sedimentation in aqueous slurry. All starches were assayed for weight percentage of B‐granules, swelling power (92.5°C), amylose content, and granular size distribution by quantitative digital image analysis. A positive linear correlation was found between the crumb grain scores and the A‐granule sizes (r = 0.65, P < 0.05), and a polynomial relationship (R² = 0.45, P < 0.05) occurred between the score and the weight percentage of B‐granule starch. The best crumb grain score was obtained when a flour had a weight percentage of B‐granules of 19.8–22.5%, shown by varietal effects.     

Effect of Kernel Size and Mill Type on Protein,Milling Yield,and Baking Quality of Hard Red Spring Wheat

Optimization of flour yield and quality is important in the milling industry. The objective of this study was to determine the effect of kernel size and mill type on flour yield and end‐use quality. A hard red spring wheat composite sample was segregated, based on kernel size, into large, medium, and small kernels, as well as unsorted kernels. The four fractions were milled in three roller mills: Brabender Quadrumat Jr., Quadrumat Sr., and Bühler MLU‐202 laboratory mills. Large kernels had consistently higher flour yield than small kernels across mills, with the Quadrumat Jr. mill showing the lowest flour yield. Mill type and kernel size significantly affected variation in flour protein molecular weight distribution. When compared with larger kernels, flour milled from the small‐kernel fraction contained a higher gliadin fraction and SDS‐unextractable high‐molecular‐weight polymeric proteins, which had positive correlations with bread loaf volume (r = 0.61, P < 0.05) and mixograph peak time (r = 0.84, P < 0.001). Overall, small kernels could contribute to enhancing flour breadmaking quality while having a detrimental effect on milling yield.     

Textural Comparisons of Gluten‐Free and Wheat‐Based Doughs,Batters, and Breads

Studies were conducted with two newly developed gluten‐free bread recipes. One was based on corn starch (relative amount 54), brown rice (25), soya (12.5), and buckwheat flour (8.5), while the other contained brown rice flour (50), skim milk powder (37.5), whole egg (30), potato (25), and corn starch (12.5), and soya flour (12.5). The hydrocolloids used were xanthan gum (1.25) and xanthan (0.9) plus konjac gum (1.5), respectively. Wheat bread and gluten‐free bread made from commercial flour mix were included for comparison. Baking tests showed that wheat and the bread made from the commercial flour mix yielded significantly higher loaf volumes (P < 0.01). All the gluten‐free breads were brittle after two days of storage, detectable by the occurrence of fracture, and the decrease in springiness (P < 0.01), cohesiveness (P < 0.01), and resilience (P < 0.01) derived from texture profile analysis. However, these changes were generally less pronounced for the dairy‐based gluten‐free bread, indicating a better keeping quality. Confocal laser‐scanning microscopy showed that the dairy‐based gluten‐free bread crumb contained network‐like structures resembling the gluten network in wheat bread crumb. It was concluded that the formation of a continuous protein phase is critical for an improved keeping quality of gluten‐free bread.     

Protein Composition‐Functionality Relationships for a Set of Argentinean Wheats

Relationships between flour functional properties and protein composition were studied using a set of 138 Argentinean wheat samples. Among different protein groups, the incremental increase of gliadin with increasing grain protein content was highest followed by polymeric protein with albumin‐globulin content much lower. Functional properties could be divided into two groups based on dependence on protein composition. Properties such as dough extensibility and bake test loaf volume correlated highly with the percentage of polymeric protein in the grain. Properties such as mixograph dough development time were best correlated with the percentage of polymeric protein in the protein (PPP). Alveograph tenacity showed no significant dependence on PPP. as found previously for extensigraph maximum resistance, but it was correlated with the percentage of unextractable polymeric protein in the protein. Energy (W) appeared to be a more useful alveograph parameter for predicting flour quality.     

Starch Properties and Stability of Club and Soft White Winter Wheats from the Pacific Northwest of the United States

Based on examination of 192 club and soft white winter (SWW) wheat samples, club and SWW wheat flours showed comparable levels of starch damage and flour peak viscosity, while differing significantly in starch content. Varietal differences and growing conditions had strong influence on the characteristics of both classes of wheat flour. Club wheat flour exhibited better stability in starch content and starch damage than did SWW wheat flour. A significant correlation between starch damage and cookie diameter in both club and SWW wheat was observed (r = -0.480, P < 0.0001 for club wheat and r = -0.430, P < 0.0001 for SWW wheat). Sponge cake volume was positively correlated with starch content in both classes of wheat (r = 0.362, P < 0.01 for club wheat and r = 0.181, P < 0.05 for SWW wheat). When wheat samples were grown in one location over three years, club and SWW wheat flours had comparable starch content. However, flour and prime starch peak viscosities were significantly different in club than in SWW wheat. Club wheat flour had lower starch damage and amylose content, as measured by high-performance size-exclusion chromatography (HPSEC), than did SWW wheat flour. Crop year and varietal differences had significant effect on amylose content, starch damage, and flour and starch peak viscosities, but not on starch content, in both classes of wheat flour. When wheat samples were grown in one year over seven locations, club wheat flour was higher in starch content, lower in starch damage, and comparable in amylose to SWW wheat flour. Both flour and prime starch viscosities were significantly higher in club wheat than in SWW wheat. Varietal differences and growing location had strong influence on starch properties in both classes of wheat. Peak viscosity of the isolated starch did not correlate well with the corresponding flour, indicating that flour pasting property does not reflect the pasting property of starch. The fine structure of isoamylase-debranched amylopectins from club and SWW wheats had a similar tri-modal pattern, with maximum at ≈DP 15 and two valleys at ≈DP 20 and 45, respectively. Although wheat flour samples differed widely in their prime starch peak viscosity, no significant difference between debranching patterns was obtained. These results indicate that the fine structure of amylopectin might not be responsible for the large differences in prime starch pasting property.     

Application of Response Surface Methodology in the Development of Gluten‐Free Bread

The formulation of gluten‐free (GF) bread of high quality presents a formidable challenge as it is the gluten fraction of flour that is responsible for an extensible dough with good gas‐holding properties and baked bread with good crumb structure. As the use of wheat starch in GF formulations remains a controversial issue, naturally GF ingredients were utilized in this study. Response surface methodology was used to optimize a GF bread formulation primarily based on rice flour, potato starch, and skim milk powder. Hydroxypropylmethylcellulose (HPMC) and water were the predictor variables. Analyses of the treatments from the design were made 24 hr after baking. Specific volume and loaf height increased as water addition increased (P < 0.01). Crumb firmness decreased as water levels increased (P < 0.01). Significant interactions (P < 0.01) between HPMC and water were found for the number of cells/cm². The number of large cells (>4 mm²) decreased with increasing levels of HPMC and water. Optimal ingredient levels were determined from the data obtained. The optimized formulation contained 2.2% HPMC and 79% water flour/starch base (fsb) and measured responses compared favorably to predicted values. Shelf‐life analysis of the optimized formulation over seven days revealed that, as crumb firmness increased, crust firmness and crumb moisture decreased.     

Distribution of Protein Composition in Bread Wheat Flour Mill Streams and Relationship to Breadmaking Quality

Wheat protein quantity and composition are important parameters for wheat baking quality. The objective of this study was to use fractionation techniques to separate the proteins of flour mill streams into various protein fractions, to examine the distribution of these protein fractions, and to establish a relationship between protein composition and breadmaking quality. Nine break streams, nine reduction streams, and three patent flours obtained from three samples of Nekota (a hard red winter wheat) were used in this study. A solution of 0.3M NaI + 7.5% 1-propanol was used to separate flour protein into monomeric and polymeric proteins. The protein fractions, including gliadin, albumin+globulin, HMW-GS, and LMW-GS, were precipitated with 0.1M NH₄Ac-MeOH or acetone. The fractions were statistically analyzed for their distribution in the mill streams. The quantities of total flour protein and protein fractions in flour were significantly different among mill streams. The ratio of polymeric to monomeric proteins in break streams was significantly greater than in the reduction streams. The relationship between protein composition and breadmaking quality showed that the quantities of total flour protein, albumin+ globulin, HMW-GS, and LMW-GS in flour were significantly and positively correlated with loaf volume. The ratio of HMW-GS to LMW-GS had little association with loaf volume. The gliadin content in total flour protein was negatively and significantly correlated with loaf volume. These results indicated that the quantity and composition of protein among the mill streams was different, and this resulted in differences in breadmaking quality.     

Quality Trait Variation in Major Hard Red Spring Wheat Cultivars Released in North Dakota Since 1968

Over the last 40 years, grain yield of hard red spring wheat (HRSW) (Triticum aestivum L.) has increased dramatically in North Dakota and neighboring regions. This yield increase has caused some concern that recent higher yielding cultivars might be released at the expense of quality performance. A two‐year study was initiated in 2004 to examine the changes in quality performance of HRSW cultivars released by North Dakota State University (NDSU) over the past 40 years. The experiment was conducted in North Dakota at three and two sites in 2004 and 2005, respectively. The study included 33 HRSW genotypes laid out in a randomized complete‐block design with four replicates. Grain protein content, flour‐extraction yield, mixogram scores, Falling Number, glutograph scores, water absorption, dough character score, and loaf volumes did not vary significantly with year of release. Linear regression of cultivar means on year of release showed an annual increase in crumb color score of 0.4%/yr since 1968. Grain volume weight showed a significant and positive correlation with crumb color score (r = 0.62, P < 0.01). Given the yield increase achieved over the past 40 years, the data in this study suggest an increase in grain protein yield per hectare with no decline in breadmaking quality.     

Physicochemical Properties of Flours that Relate to Sorghum Couscous Quality

Flours from eight sorghum cultivars were evaluated for their couscous-making ability with the objective of finding predictive relationships between flour physicochemical properties and couscous quality. Chemical composition, physical characteristics, and pasting and gelatinization properties of the flours were determined. A laboratory procedure was used to prepare couscous. Couscous properties were evaluated and compared to a laboratory-prepared and a commercial durum wheat couscous. Hard grain produced flours containing a high proportion of coarse particles with low ash and high damaged starch content and yielded a higher proportion of desirable sorghum couscous granules. A variety of colors ranging from brown to yellow were obtained when flours were processed into couscous. Cooked sorghum couscous stickiness was positively correlated (r = 0.89, P < 0.01) with the amount of damaged starch in flour. Cooked couscous hardness correlated positively (r = 0.79, P < 0.05) with apparent amylose content of flour and correlated negatively (r = -0.75, P < 0.05) with flour peak viscosity. Durum wheat couscous was lighter and had more yellow color than sorghum couscous. Sorghum couscous was stickier and harder than durum wheat couscous. Addition of 2% oil to the cooking water considerably improved the texture of some sorghum couscous to a level comparable to that of durum wheat couscous.     

Relationship Between Solvent Retention Capacity and Protein Molecular Weight Distribution,Quality Characteristics,and Breadmaking Functionality of Hard Red Spring Wheat Flour

This research aims to investigate the relationship between the solvent retention capacity (SRC) test and quality assessment of hard red spring (HRS) wheat flour samples obtained from 10 HRS cultivars grown at six locations in North Dakota. The SRC values were significantly (P < 0.05) correlated with flour chemical components (protein, gluten, starch, and damaged starch contents, except arabinoxylan); with farinograph parameters (stability [FST], water absorption, peak time [FPT], and quality number); and with breadmaking parameters (baking water absorption [BWA], bread loaf volume [BLV], and symmetry). Differences in locations and cultivars contributed significantly to variation in quality parameters and SRC values. Suitability of SRC parameters for discriminatory analysis of HRS wheat flour is greatly influenced by molecular weight distribution (MWD) of SDS‐unextractable proteins. SRC parameters, except for sucrose SRC, showed significant (P < 0.01) and positive correlations with high‐molecular‐weight (HMW) polymeric proteins in SDS‐unextractable fractions, whereas only lactic acid SRC exhibited significant (P < 0.01) correlations with low‐molecular‐weight polymeric proteins. HMW polymeric proteins also exhibited positive associations with FPT, FST, BWA, and BLV. The discrepant variation in association of SRC parameters with respect to MWD of SDS‐unextractable proteins could improve segregation of HRS wheat flour samples for quality.     

Sulfur,Protein Size Distribution,and Free Amino Acids in Flour Mill Streams and Their Relationship to Dough Rheology and Breadmaking Traits

The aim of this study was to analyze sulfur content, protein size distribution, and free amino acids in flour mill streams (FMS) and their associations to dough rheology and breadmaking traits. Break FMS had higher nitrogen and sulfur quantities than reduction FMS. The third break FMS had the highest nitrogen and sulfur contents among FMS but low bread loaf volume partly due to high ash content. Sulfur quantity had greater or equivalent correlations with dough rheology and breadmaking properties compared with nitrogen quantity when the effect of percent ash content was removed statistically. FMS also showed significant quantitative variation in HMW polymeric proteins of the SDS‐unextractable fraction that had greater association with sulfur content and dough rheology and breadmaking traits than other protein fractions. Asparagine, which is a major amino acid in flour, was found at higher levels in the third break and third reduction FMS. Ratio of nitrogen to sulfur was significantly correlated with asparagine concentration (r = 0.73, α = 0.01). This study indicates that information on sulfur, protein size distribution, and free amino acid is potentially useful in research for more precise blending of FMS in commercial flour mills to meet customer specifications for high quality flour.