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.     

Development of a Novel Staining Procedure for Visualizing the Gluten–Starch Matrix in Bread Dough and Cereal Products

A novel staining procedure has been developed to visualize the gluten– starch matrix in wheat flour dough. Dough samples mixed to the final stage were stained with 26 fluorescent reagents, and each stained sample was observed with three sets of fluorescence filters (blue, green, and red). Of all the combinations of reagents and filters, the combination of acid magenta and the blue fluorescent filter set was the most effective in distinguishing starch granules from gluten network structure. Its effectiveness was further demonstrated with gluten and starch granule samples, in which the contrast was clearer when observed with the blue fluorescent filter set than without any fluorescent filter. Visualizing the gluten–starch matrix in dough samples at four mixing stages with the same procedure resulted in clear identification of the changes in gluten network structure because of the differences in mixing stages. The same procedure also enabled us to distinguish starch from gluten in white salted noodles, baked cookies, and flour particles. The proposed procedure is quicker, simpler, and has a lower risk of altering the sample than other conventional ones, and it is expected to become a useful tool in cereal studies.     

Impact of a Reduced Wheat Meal Sample Size on the Falling Number Test

The impact of a smaller sample of whole meal wheat (5.5 or 6.0 g) to replace the official 7.0 g used in the Falling Number test was investigated using samples of Canada Western Amber Durum (CWAD) and Canada Western Red Spring (CWRS) wheat. Use of either of the smaller sample sizes resulted in a significant shortening of the analysis time of the test. Reproducibility studies, using high and low falling number (FN) CWRS and CWAD samples, with three analyses per day over six days indicated no appreciable change in the coefficient of variation for the test using a smaller sample size. The maximum daily standard deviation of three replicates, 25.7 sec, was observed using the official 7.0‐g moisture‐corrected CWAD sample and was not significantly different from the 23.0 sec value obtained for a 5.5‐g sample of CWRS. The maximum average standard deviations observed over the six days of analysis were 13.7, 7.7, and 5.3 sec for the 5.5‐, 6.0‐, and 7.0‐g sample sizes, respectively, and were all associated with the sound, high FN, CWRS sample. While the use of 5.5 g allowed significant differentiation between high and low FN CWRS samples, the ability to discriminate high and low FN CWAD samples was lost at this sample size. FN analysis of CWRS (n = 144) and CWAD (n = 141) at 7.0 vs. 6.0 g, yielded correlation coefficients of 0.95 and 0.88, respectively. Regression analysis indicated a ±14.1 sec error associated with estimating a 7.0‐g FN value using 6.0 g of CWRS which increased to 26.4 sec for CWAD. Particle size analyses of whole meal after grinding indicated that the harder CWAD wheat fractured into a significantly greater percentage of larger particles than the corresponding CWRS. This difference may be a contributing factor to the greater variance associated with the CWAD 6.0‐g test and the inability to differentiate sound and slightly sprouted wheat at 5.5 g. Use of the 6.0‐g method, stopping the test after 200 sec, would also be applicable for screening purposes at commercial facilities where normal testing times (350–450 sec) could be reduced to meet designated quality requirements. This would offer a savings of 2.5 min/sample over the conventional method.     

Generation of a Mixolab Profile After the Evaluation of the Functionality of Different Commercial Wheat Flours for Hot‐Press Tortilla Production

Refined wheat flours commercially produced by five different U.S. and Mexican wheat blends intended for tortilla production were tested for quality and then processed into tortillas through the hot‐press forming procedure. Tortilla‐making qualities of the flour samples were evaluated during dough handling, hot pressing, baking, and the first five days on the shelf at room temperature. The predominant variables that affected the flour tortilla performance were wet gluten content, alveograph W (220–303) and P/L (0.70–0.94) parameters, farinograph water absorption (57%) and stability (10.8–18.7 min), starch damage (5.43–6.71%), and size distribution curves (uniform particle distribution). Flours produced from a blend of Dark Northern Spring (80%) and Mexican Rayon (20%) wheat had the highest water absorption, and tortillas obtained from this blend showed the highest diameter and lowest thickness. The whitest and best textured tortillas were obtained from the flour milled from three hard types of Mexican wheat blend. A Mixolab profile was generated from the best tortilla flours, those produced by mills 3 and 4. The Mixolab profile showed that a good flour for hot‐press tortillas had a relatively lower absorption and short dough mix time compared with a bread flour and should have a significantly higher gluten compared with an all‐purpose flour. Compared with bread flour, the tortilla flour had higher retrogradation and viscosity values. The Mixolab profile proved to be a good preliminary test to evaluate flours for hot‐press tortillas.     

Procedure for Obtaining Stable Protein Extracts of Cereal Flour and Whole Meal for Size‐Exclusion HPLC Analysis

Experiments were conducted to determine the extent of instability of size‐exclusion HPLC extracts prepared from flour, semolina, or whole meal. Procedures to obtain stable extracts were investigated. Whole meal extracts of durum wheat and triticale were the most unstable samples, whereas bread wheat showed smaller changes. Samples prepared from crushed maturing grains, especially during early stages, were greatly influenced by the instability process. By using protease inhibitors, evidence was obtained that endogenous proteases were the source of the instability. Reproducible peak 1 (polymeric protein) results were obtained for a period of at least 72 hr after extract preparation if protein extracts were heated for 2 min at 80°C in a water bath immediately after filtration into the sample vials and before SE‐HPLC analysis. This treatment is a viable solution to avoid sample instability in whole meal and developing grain extracts, particularly when large sample sets are prepared for automatic injection into the HPLC.     

Effects of Falling Number Sample Weight on Prediction of α‐Amylase Activity

Reports vary on the effects of falling number (FN) sample weight on test precision, reproducibility, and predictability of α‐amylase activity. Straight grade flours of 200 samples (25 cultivars × 2 locations × 2 N₂ levels × 2 repetitions) were assayed for α‐amylase activity and FN. Location significantly affected α‐amylase activity and FN values. The coefficients of variation (CV) for the FN tests were 5.75, 2.12, 1.93, 1.72, 4.27, and 14.47%, when assayed with sample weights of 7, 6, 5.5, 5, 4.5, and 4 g, respectively. The FN test with the greatest reproducibility between sample replicates (lowest LSD and highest ratio of range/LSD) was also produced using the 5‐g sample weight. By reducing FN sample weight from 7 to 5 g, FN values that averaged 350 sec, considered essentially sound, averaged 215 sec, thus shortening the FN test time by an average of 2 min and 15 sec when assaying sound wheat flour. The results suggest a review of the 7‐g stipulation of AACC Approved Method 56‐81B for FN in favor of reduced sample weight.     

Application of Wheat Meal Solvent Retention Capacity Tests Within Soft Wheat Breeding Populations

The solvent retention capacity (SRC) test is a relatively new AACC Approved Method (56‐11) for evaluating soft wheat flour quality. The test measures the ability of flour to retain a set of four solvents (water, 50% sucrose, 5% sodium carbonate, and 5% lactic acid) after centrifugation. The objective of this study was to evaluate the utility of wheat meal sodium carbonate and lactic acid SRC tests and SDS sedimentation volume within three populations of soft spring wheat inbred lines as tools for selecting for improved flour SRC profiles, flour extraction, and cookie and pastry quality. The populations were derived from the crosses Vanna/Penawawa, Kanto 107/IDO488, and M2/IDO470 and were grown in replicated, irrigated trials in 2000 and 2001 near Aberdeen, Idaho. Within each of the three populations, wheat meal sodium carbonate SRC effectively predicted straight‐grade flour sodium carbonate (r = 0.69–0.81) and sucrose SRC (r = 0.74–0.84). Wheat meal sodium carbonate SRC also was negatively correlated with flour extraction and sugar snap cookie diameter. Wheat meal lactic acid SRC predicted straight‐grade flour lactic acid SRC in only one population. In contrast, SDS sedimentation volume predicted straight‐grade flour lactic acid SRC in all three populations (r = 0.74–0.93). Moreover, SDS sedimentation volume and wheat meal sodium carbonate SRC were independent in two of the three populations. This suggests that the SDS sedimentation and sodium carbonate SRC may measure different intrinsic characteristics. Therefore, a combination of sodium carbonate SRC and SDS sedimentation volume analyses of wheat meal may be an efficient approach to selecting toward target SRC profiles, increased flour extraction, and larger sugar snap cookie diameter in soft wheats.     

Shortened Temperature Program for Application with a Rapid Visco Analyser in Prediction of Noodle Quality in Wheat

The use of the Rapid Visco Analyser (RVA) for application in the screening of wheat breeding lines for starch quality and potential noodle quality has been limited by relatively low sample throughput. Current methods generally enable only 20–30 samples to be tested each day. This study sought to develop a more rapid time‐temperature profile that could be applied to whole meal samples. A profile that involved a total analysis time of 7.5 min/sample gave measurements of peak viscosity (PV) and breakdown (BD) on whole meal that were highly correlated with corresponding measurements obtained using a more conventional profile that had been applied to low‐extraction flours. BD and PV were also highly correlated with the total texture score of ramen (Chinese‐style alkaline noodles as manufactured in Japan), but only when 1 mM AgNO₃ was used to eliminate the effects of α‐amylase.     

Impact of Fusarium culmorum on the polysaccharides of wheat flour

To assess the effects of Fusarium infection on the polysaccharides of winter wheat grain (Triticum aestivum L.), grain samples obtained from plants artificially inoculated with Fusarium culmorum were analyzed. Microscopy revealed obvious damage to the starch granules in the seriously infected samples. The Fusarium infection had no analytically detectable influence on the starch and total insoluble dietary fiber content of the wheat grain. There were significantly positive relationships between alpha-amylase activity, cellulase activity, total soluble dietary fiber content, pentosan content, and degree of infection quantified by an enzyme-linked immunosorbant assay, which would indicate the importance of fungal enzymes. A distinct higher Hagberg falling number (FN) was determined in the seriously infected samples, while the viscosity and sucrose content of the flour decreased. However, the addition of a liquid medium contaminated with F. culmorum led to a significant decrease in the FN. Depending on the type of buffer used, the alpha-amylase of F. culmorum demonstrated its maximum activity between pH 5.5 and pH 7.0 at 30-50 degrees C. Remarkably, this fungal alpha-amylase showed a thermostable characteristic and was active over a wide range of temperatures, from 10 to 100 degrees C. This type of thermostability suggests that the alpha-amylase of F. culmorum may damage starch granules throughout the processing of wheat flour, thereby inducing weak dough properties and unsatisfactory bread quality.     

Frozen and Unfrozen Water Contents of Wheat Flours and Their Components

The properties of frozen and unfrozen water in two different wheat flours (hard and soft), and in their main components (gluten, starch, damaged starch, water‐soluble and water‐insoluble pentosans), were described using modulated differential scanning calorimetry (DSC). As a reference, enthalpy values of crystallization (298 J/g) and melting (335 J/g) of pure water were determined from the total heat flow curves. The separation of thermal events between the reversing and nonreversing heat flows with modulated DSC was not effective due to disturbances in the modulated temperature scan. For wheat flours and their components, linear regressions described well the changes in frozen water content calculated from enthalpies of freezing (R² = 0.970–0.982) or melting (R² = 0.783–0.996). The unfrozen water content (UFWC) calculated for the hard wheat flour (29–31%, db) was close to that calculated for the soft wheat flour (30–32%). The UFWC of wheat gluten (38–47%), starch (38–42%), damaged starch (37–40%), water‐soluble pentosans (51%), and water‐insoluble pentosans (40–44%) were higher than the corresponding values for the flours. The simple summation of the contributions of each component cannot be used to estimate the overall behavior of flours.     

Quantitative Characterization of Polar Lipids from Wheat Whole Meal,Flour, and Starch

Lipids constitute only a minor proportion of total flour components but the composition and structure of wheat flour polar lipids influence the end‐use quality of bread. So it is important to determine which specific lipid class and molecular species are present in wheat. Lipid profiling is the targeted, systematic characterization and analysis of lipids. The use of lipid profiling techniques to analyze grain‐based food has the potential to provide new insight into the functional relationships between a specific lipid species and its functionality. The objective of this study was to utilize lipid profiling techniques to quantitatively determine the polar lipid species present in whole wheat meal, flour, and starch. Two commonly grown wheat cultivars, Alpowa and Overley, were used in this study. Direct infusion electrospray ionization tandem mass spectrometry was used to identify and quantitatively determine 146 polar lipid species in wheat. The predominant polar lipid classes were digalactosyldiglycerols, monogalactosyldiglycerols, phosphatidylcholine, and lysophosphatidylcholine. ANOVA results concluded that the wheat fraction contributed a greater source of variation than did cultivar on total polar, total phospholipid, and total galactolipid contents. Wheat whole meal, flour, and surface starch contained greater concentrations of total galactolipids, whereas internal starch lipids contained greater concentrations of monoacyl phospholipids. This research provides evidence that lipid profiling will provide the ability to determine the functional relationships between specific lipid species and the impact on end‐use quality.     

Rheological Properties of Soft Wheat Flour Doughs: Effect of Salt and Triglycerides

The small deformation rheological properties of wheat flour doughs in relation to their structure and hydration were studied by dynamic mechanical thermal analysis, differential scanning calorimetry, and electron spin resonance. The effect of salt and triglycerides was also examined and compared with results we obtained previously on starch dispersions. Moisture content was adjusted to 48 or 60% (w/w, wb). Samples contained 0–16% NaCl (g/100 g of flour‐water) and 0–18% triolein or lard (g/100 g of flour‐water). The obtained results suggested that starch has an active role in determining the evolution of dough rheological characteristics during heating. The main factors controlling rheological behavior during thermal treatment are the volume fraction and deformability of starch granules. Gluten changes the viscoelasticity of the continuous phase and competes with starch for water. The addition of sodium chloride to flour dispersions shifted the structural disorganization and rigidity increased during heating to higher temperatures. At >7% NaCl, the reverse effect was observed. The mechanism controlling the effect of salt on dough rheological behavior was explained in terms of effect on water properties and on starch structure and hydration. Triglycerides had a lubricant effect (i.e., lowering G′ modulus) on the wheat flour dough system. These effects are of great importance for production and quality of bakery products.     

Pasting Properties and Surface Characteristics of Starch Obtained from an Enzymatic Corn Wet‐Milling Process

Recently, we reported the development of an enzymatic corn wet‐milling process that reduces or eliminates sulfur dioxide requirements during steeping, considerably reduces steep time, and produces starch yields comparable to that of conventional corn wet‐milling. The best results so far, using the enzymatic corn wet‐milling procedure, were achieved when a particular protease enzyme (bromelain) was used. In this study, pasting properties and surface characteristics of starch obtained from six different enzyme treatments (three glycosidases [β‐glucanase, cellulase, and xylanase] and three proteases [pepsin, acid protease, and bromelain]) using the enzymatic corn wet‐milling procedure were evaluated and compared with those from starch obtained using the conventional corn wet‐milling procedure. Significant effects from enzymatic milling were observed on all the three starch pasting properties (peak, shear thinning, and setback). The setback viscosities of starch from all enzyme treatments were significantly lower compared with those of the control sample, indicating that starch polymers from enzymatic corn wet‐milling do not reassociate to the same extent as with the control. Comparison between bromelain treatment and the control sample showed that starch samples obtained from bromelain treatment are very similar to control starch in water‐binding capacity, molecular breakdown, and time to swell when cooked in water. Significant effects from enzymatic milling were observed on the surface characteristics of starch granules. The glycosidase treatments, especially the β‐glucanase samples, showed holes in the starch granules. No visual differences were observed in starch granules between bromelain and control samples.     

Quality Characteristics of Fresh and Dried White Salted Noodles Enriched with Flour from Hull‐less Barley Genotypes of Diverse Amylose Content

Fresh and dried white salted noodles (WSN) were prepared by incorporating up to 40% flour from hull‐less barley (HB) genotypes with normal amylose, waxy, zero amylose waxy (ZAW), and high amylose (HA) starch into a 60% extraction Canada Prairie Spring White (cv. AC Vista) wheat flour. The HB flours, depending on genotype, contained four to six times the concentration of β‐glucan of the wheat flour, offering potential health benefits. The HB‐enriched noodles were made with conventional equipment without difficulty. Noodles containing 40% HB flour required less work input during sheeting, probably due to higher optimum water absorption and weakening of the dough due to dilution of wheat gluten. The addition of HB flour had a negative impact on WSN color and appearance, as evident from decreased brightness, increased redness, and more visible specking. The impact of HB flour on cooked WSN texture varied by starch type. Enrichment with HA or normal starch HB flour produced WSN with bite and chewiness values equivalent to or superior to the wheat flour control. Addition of waxy and ZAW HB flour resulted in WSN with lower values for bite and chewiness. The diversity of HB starch types allows tailoring of WSN texture to satisfy specific markets. HB flour also has potential as an ingredient in novel noodle products targeting health‐conscious consumers who associate darker colored cereal‐based foods with superior nutritional composition.     

A Rapid,High Throughput Micro Sugar‐Snap Cookie Quality Test Procedure Using Asymmetrical Centrifugal Mixing

A modified AACC 45‐g flour cookie procedure using asymmetrical centrifuge mixing as a replacement for conventional mixing has been developed. Ingredients are added to a pin cup in the same proportion as in the Approved Method 10‐50D (AACC 2000) sugar‐snap cookie test and mixed in a single step for 15 sec at 2,500 rpm. The dough is then processed and the resulting cookies are scored according to the AACC Approved Method 10–52 40‐g flour micro cookie test method. Cookies produced from a control cookie flour and four commercial soft wheat flours with the new mixing method did not show the characteristic surface cracking patterns normally obtained with conventional three‐stage mixing. However, with the exception of one spread value, no significant differences in spread, thickness, or the ratio of spread to thickness were evident when results were compared with those obtained with the AACC Approved Method 10‐50D 225‐g flour test method using a Hobart mixer equipped with a paddle. Cookies produced from two sets of advanced soft white spring wheat breeder lines, including control cultivars, using the asymmetrical centrifuge mixing procedure were also very comparable in spread, thickness, and ratio compared with those produced using 225 g of flour in the AACC Approved Method. Reproducibility of test results for all cookie parameters for both commercial and advanced plant breeder samples were comparable to the AACC Approved Method 10‐50D 225‐g flour test method. The very short mixing time and the ability to quickly clean or use multiple pin cups should allow very high throughput of flour samples relative to the use of conventional mixers for cookie testing.     

Physicochemical and Structural Characteristics of Flours and Starches from Waxy and Nonwaxy Wheats

A waxy spring wheat (Triticum aestivum L.) genotype was fractionated into flour and starch by roller and wet‐milling, respectively. The resultant flour and starch were evaluated for end‐use properties and compared with their counterparts from hard and soft wheats and with commercial waxy and nonwaxy corn (Zea mays L.) starches. The waxy wheat flour had exceptionally high levels of water absorption and peak viscosity compared with hard or soft wheat flour. The flour formed an intermediate‐strength dough that developed rapidly and was relatively susceptible to mixing. Analysis by differential scanning calorimetry and X‐ray diffractometry showed waxy wheat starch had higher gelatinization temperatures, a greater degree of crystallization, and an absence of an amylose‐lipid complex compared with nonwaxy wheat. Waxy wheat and corn starches showed greater refrigeration and freeze‐thaw stabilities than did nonwaxy starches as demonstrated by syneresis tests. They were also similar in pasting properties, but waxy wheat starch required lower temperature and enthalpy to gelatinize. The results show analogies between waxy wheat and waxy corn starches, but waxy wheat flour was distinct from hard or soft wheat flour in pasting and mixing properties.     

In Vitro Starch Digestibility and Expected Glycemic Index of Kodo Millet (Paspalum scrobiculatum) as Affected by Starch–Protein–Lipid Interactions

The effect of starch–protein–lipid interaction on the in vitro starch digestibility and expected glycemic index (eGI) of kodo millet flour (MF) was investigated. Debranned MF and the flour with lipid removed, protein removed, or both lipid and protein removed (MF‐L‐P) were subjected to digestion assays. The in vitro starch digestibility and eGI of the millet samples and millet starch were compared with rice or wheat flour. Rapidly digestible starch, slowly digestible starch, and resistant starch (RS) of the samples were also calculated. Protease treatment and defatting resulted in significant reduction (P < 0.05) in protein and lipid contents of samples. Significant increases in the in vitro starch digestibility and eGI of samples were observed after removal of protein, lipid, or both. The effect of lipid removal on in vitro starch digestibility of kodo millet was found to be more significant, compared with when proteins were removed. The eGI increased from 49.4 for cooked MF to 62.5 for MF‐L‐P. The eGI of cooked kodo millet starch was significantly lower than that of cooked rice flour. The RS (1.61%) of cooked rice was the least among the samples. The in vitro starch digestibility and eGI of rice were significantly higher than those of MF. Processes applied to kodo millet, such as decortication, that result in the removal of proteins, lipids, or both (especially lipids) would result in an increase in its in vitro starch digestibility and eGI. We therefore advocate for the development of acceptable products from whole millets to maintain its hypoglycemic property.     

Falling Number Sampling Variation Within Trucks at First Point of Sale

Falling number (FN) is a test widely performed on raw samples of wheat and barley as a means to indicate the level of enzyme activity (α‐amylase) associated with seed germination. In most circumstances of wheat, high activity levels are associated with decreased quality of the end products and, because of this, grain lots with low FN are discounted at points of sale, including the first point of delivery when wheat is brought in from the field. Confidence in the validity of an FN assessed on a grain lot is dependent on knowledge of the precision of the analytical method as well as the sampling protocol. The current study examined the latter component; that is, the variation caused by sampling. Soft red and white commercial wheats from two seasons and two regions (states of Washington and Ohio) were sampled upon arrival at country elevators and a flour mill. By catch‐stream sampling or probe sampling, catches and probings were run in quadruplicate according to standard methodology for FN. Among‐catches and among‐probings variance estimates, inclusive of sampling error and method error, were typically less than 100 s², corresponding to a coefficient of variation of 3% or less. Estimated variances from the sampling alone, as determined by a mixed‐effects analysis of variance, were typically less than 50 s². Based on the among‐probings variance estimates and a simple model that assumes normality of FN and linearity in mathematically combining individual probe readings into the equivalent composite reading for a truck, retesting a truck in borderline FN conditions (i.e., FN ≤ 294 s) at the same facility will not yield a new FN value of 300 s or greater more than 95% of the time.     

Significance of Wheat Flour Particle Size on Sponge Cake Baking Quality

We evaluated the effect and magnitude of flour particle size on sponge cake (SC) baking quality. Two different sets of wheat flours, including flours of reduced particle size obtained by regrinding and flour fractions of different particle size separated by sieving, were tested for batter properties and SC baking quality. The proportion of small particles (<55 μm) of flour was increased by 11.6–26.9% by regrinding. Despite the increased sodium carbonate solvent retention capacity, which was probably a result of the increased starch damage and particle size reduction, reground flour exhibited little change in density and viscosity of flour‐water batter and produced SC of improved volume by 0.8–15.0%. The volume of SC baked from flour fractions of small (<55 μm), intermediate (55–88 μm), and large (>88 μm) particles of soft and club wheat was in the range of 1,353–1,450, 1,040–1,195, and 955–1,130 mL, respectively. Even with comparable or higher protein content, flour fractions of intermediate particle size produced larger volume of SC than flour fractions of large particle size. The flour fractions of small particle size in soft white and club wheat exhibited lower flour‐water batter density (102.6–105.9 g/100 mL) than did those of large and intermediate particle fractions (105.2–108.2 g/100 mL). The viscosity of flour‐water batter was lowest in flour fractions of small particle size, higher in intermediate particles, and highest in large particles. Flour particle size exerted a considerable influence on batter density and viscosity and subsequently on SC volume and crumb structure. Fine particle size of flour overpowered the negative effects of elevated starch damage, water absorption, and protein content in SC baking.     

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.