X‐ray Image Analysis to Detect Infestations Caused by Insects in Grain

Insect infestations in stored wheat affect the chemical characteristics and baking qualities of wheat flour, and insect‐infested flours are unacceptable in the baking industry. The efficiency of the soft X‐ray method to detect infestations caused by Cryptolestes ferrugineus (Stephens), Tribolium castaneum (Herbst), Plodia interpunctella (Hübner), Sitophilus oryzae (L.), and Rhyzopertha dominica (F.) in wheat kernels was determined in this study. Wheat kernels infested by different insects were prepared by artificial implantation of insect eggs or by introducing adult insects in wheat samples. Kernels infested by different stages of the insects were X‐rayed until the adults emerged from the kernels. A total of 57 features using histogram groups, histogram and shape moments, and textural features were extracted from the X‐ray images and a linear‐function parametric classifier was used to identify the insect‐infested kernels. The parametric classifier identified more than 84% of infestations due to C. ferrugineus and T. castaneum larvae. The infestations by C. ferrugineus pupae‐adults and P. interpunctella larvae were identified with >96% accuracy. Kernels infested by different stages of S. oryzae and R. dominica larvae were identified with >98% accuracy. Using the Berlese funnel method, 67, 51, and 81% of first, second, and third instars of C. ferrugineus, respectively, were extracted in 6 hr. The same infested kernels were all categorized as infested by the parametric classifier. When kernels infested by different insects were pooled together, the parametric classifier correctly identified 74% of uninfested and 94% of infested kernels by the internal and external grain feeders. The 26% false positives identified from the independent test was caused by one sample infested by T. castaneum. When that sample was removed from the training set, the false positives were reduced to 16%, and 92.7% of infested kernels by different insects were correctly identified.     

Near‐Infrared Spectroscopic Method for Identification of Fusarium Head Blight Damage and Prediction of Deoxynivalenol in Single Wheat Kernels

Fusarium Head Blight (FHB), or scab, can result in significant crop yield losses and contaminated grain in wheat (Triticum aestivum L.). Growing less susceptible cultivars is one of the most effective methods for managing FHB and for reducing deoxynivalenol (DON) levels in grain, but breeding programs lack a rapid and objective method for identifying the fungi and toxins. It is important to estimate proportions of sound kernels and Fusarium‐damaged kernels (FDK) in grain and to estimate DON levels of FDK to objectively assess the resistance of a cultivar. An automated single kernel near‐infrared (SKNIR) spectroscopic method for identification of FDK and for estimating DON levels was evaluated. The SKNIR system classified visually sound and FDK with an accuracy of 98.8 and 99.9%, respectively. The sound fraction had no or very little accumulation of DON. The FDK fraction was sorted into fractions with high or low DON content. The kernels identified as FDK by the SKNIR system had better correlation with other FHB assessment indices such as FHB severity, FHB incidence and kernels/g than visual FDK%. This technique can be successfully employed to nondestructively sort kernels with Fusarium damage and to estimate DON levels of those kernels. Single kernels could be predicted as having low (<60 ppm) or high (>60 ppm) DON with ≈96% accuracy. Single kernel DON levels of the high DON kernels could be estimated with R² = 0.87 and standard error of prediction (SEP) of 60.8 ppm. Because the method is nondestructive, seeds may be saved for generation advancement. The automated method is rapid (1 kernel/sec) and sorting grains into several fractions depending on DON levels will provide breeders with more information than techniques that deliver average DON levels from bulk seed samples.     

Fate of Dwarf Bunt Fungus Teliospores During Milling of Wheat into Flour

Wheat contaminated with teliospores of Tilletia controversa Kühn (TCK) was mixed with uncontaminated wheat and processed through the Kansas State University pilot mill. Two 50-bu lots of the contaminated mixture were cleaned, tempered, and milled. Approximately 500 samples of wheat, cleanings, and mill fractions were collected and examined for the presence of intact and broken TCK teliospores. Whole wheat samples (50 g) were washed, sieved through a 60-μm nylon sieve, and pelleted by centrifugation. Contents of the pellet were examined microscopically for the presence of TCK spores. The procedure was modified as needed to accommodate cleanings and mill fractions. Levels of spore contamination in whole wheat samples decreased at each step during the handling process, and large numbers of spores were found in materials that were sieved or aspirated from the grain. Very few spores were found in bran, germ, and shorts; none were detected in red dog or straight-grade flour. The results showed that a high percentage of spores can be removed from wheat by mechanical cleaning but that it is not feasible to remove all of them.     

Comparison of Asian Noodles from Some Hard White and Hard Red Wheat Flours

Asian noodles were prepared by an objective laboratory method that included adding optimum water to the dry ingredients, mixing the ingredients to homogeneous salt distribution, and sheeting of the dough under low shear stress. The lightness (L*) values of alkaline‐ and salt‐noodle doughs made from 65% extraction hard white wheat flours (except KS96HW115 flour at ≈70% extraction) were higher than those from 60% extraction hard red wheat flours (except Karl 92 flour at ≈70% extraction). A hard white spring wheat, ID377s, and a Kansas line of hard white winter wheat, KS96HW115, to be released in 2000, gave the highest L* values for dough sheets stored for 2 and 24 hr at 25°C. Cooking losses were 5–9 percentage points higher for alkaline noodles than salt noodles, but the cooking yields of the two types of Asian noodles were almost the same. Cooked alkaline noodles made from a high‐swelling flour (SP₉₃≈21 g/g) gave higher tensile strength than those made from several low‐swelling flours (SP₉₃ ≈15 g/g) with the same protein contents (≈12.5%). However, the cooked salt noodles gave the same tensile strength.     

Effects of Particle Size on the Quality of Winter Wheat Flour,with a Special Focus on Macro‐ and Microelement Concentration

Abstract

In countries with suitable conditions for growing winter wheat, there are millions of tons of poor‐baking‐quality wheat harvested every year. In this investigation, representative samples of low‐quality‐wheat lots were analyzed. The baking quality properties, protein, ash, and macro‐ and microelement concentrations were determined for different particle‐size fractions of flour. Flour fractions of different particle sizes sieved from the same flour samples yielded significantly different analyses for protein, ash, and macro‐ and microelements. It was determined that the particle fraction of 125–63 µm had better baking parameters than the original flour sample, and it constituted 32.5% of the total mass of the original amount of flour. In addition, the mineral‐element concentration was also found to be much higher than that of the original flour, which means that besides its better baking quality, it also had a higher nutritional value. The single, unmixed utilization of the 125‐ to 63‐µm flour fraction would mean more economic production for the baking industry and a higher value end product for the consumer. Based on our findings, we also recommend that in the chapters on materials and methods of the articles dealing with different kinds of flour, the authors should indicate the particle sizes of the flour samples analyzed because these may result in more objective evaluations of the readings.     

Composition and Distribution of Pentosans in Millstreams of Different Hard Spring Wheats

Six commercially grown samples of hard spring wheat were milled using a tandem Buhler laboratory mill. Individual flour streams and branny by‐products, as well as whole‐grain wheat and straight‐grade flour, were characterized in terms of total (TP), water‐extractable (WEP), and water‐unextractable (WUP) pentosans. One representative cultivar sample was analyzed for its ratio of arabinose to xylose (A/X). TP and WEP of whole grain wheat of the six samples had ranges of 5.45–7.32% and 0.62–0.90% (dm), respectively. Neither TP nor WEP of whole grain was related to ash content variation. There was significant variation in the distribution and composition of pentosans in 16 millstreams of all the wheat samples, including bran and shorts fractions; TP and WEP contents had ranges of 1.69–32.4% and 0.42–1.76% (dm), respectively. When ash contents exceeded ≈0.6% (dm), strong positive correlations were obtained between ash and TP contents, and between ash and WUP contents for all the millstreams. Among bran and shorts fractions, TP and WUP content increased in the order of coarse bran > fine bran > shorts; while WEP, WEP/WUP and A/X showed the opposite pattern of variation of shorts > fine bran > coarse bran. Bran and shorts fractions had pentosan contents several times higher than would be predicted from the relationship between pentosan and ash contents of the flour streams. Pentosans therefore represented a much more sensitive marker of flour refinement compared with ash content. Pentosans of endosperm were substantially different in their extractability and composition from those of bran. On this basis, different functionalities of pentosans of bran and endosperm would be expected. Results demonstrated the importance of milling extraction and millstream blending in the functionality and quality of wheat flour for breadmaking.     

Flour Protein Composition and Functional Properties of Transgenic Rye Lines Expressing HMW Subunit Genes of Wheat

Flours from nonsprouted (ns) kernels and dried sprouted (s) kernels of transgenic rye expressing HMW glutenin subunits (HMW‐GS) 1Dy10 (L10) or 1Dx5+1Dy10 (L5+10) from wheat were compared with flours from the corresponding wildtype rye (Lwt). The crude protein content of nonsprouted flours ranged from 9.2% (Lwt) to 10.4% (L5+10) and was lowered by ≈1% due to sprouting. Flour proteins were separated into albumins/globulins, prolamins, and glutelin subunits by a modified Osborne fractionation and into SDS‐soluble and insoluble fractions. Portions of the prolamin fractions were reduced in the same manner as glutelins. The different fractions were then characterized and quantified by RP‐HPLC on C₈ silica gel. The proportion of albumins/globulins did not significantly differ between transgenic lines and wildtype. The proportions of alcohol‐insoluble glutelins and SDS‐insoluble proteins drastically increased in transgenic rye due to a shift of HMW and γ‐75k secalins into the polymeric fractions. Significant differences in the proportion of highly polymeric proteins between nonsprouted and sprouted flours could not be detected. The quantitative data demonstrated that the expression of HMW‐GS led to a higher degree of polymerization of storage proteins in rye flour. The HMW‐GS combination 1Dx5+1Dy10 showed stronger effects than 1Dy10 alone. The analyzed flours contained two HMW secalins (R1, R2), whose amino acid compositions were closely related to those of 1Dy10 and 1Dx5, respectively. The amounts of R1 in Lwt flours determined by RP‐HPLC were 221 mg (ns) and 186 mg (s) per 100 g and those of R2 were 344 mg (ns) and 298 mg (s), respectively. These amounts increased to 240 mg (ns)/201 mg (s) (R1) and 479 mg (ns)/432 mg (s) (R2) in L10 flours. In L5+10 flours, the amount of R1 decreased to 150 mg (ns)/132 mg (s) while R2 increased to 432 mg (ns)/338 mg (s). The amount of HMW‐GS 1Dy10 was almost the same as that of R2 in L10 flours but was strongly increased in L5+10 flour (633 mg [ns]/538 mg [s]). HMW‐GS 1Dx5 was, by far, the major subunit in L5+10 flours (987 mg 7[ns]/896 mg [s]). The summarized amounts of all HMW subunits increased from ≈0.5 g (Lwt) to ≈1.1 g (L10) and ≈2.0 g (L5+10). Thus only L10 flours were similar to wheat flours in HMW subunit content. The baking performance of L10 flour determined by a microbaking test was improved compared with Lwt flour, whereas L5x10 flour showed very poor properties obviously due to the strongly increased proportion of highly cross‐linked glutelins. The breadmaking quality of flours from 1Dy10 seeds and wildtype seeds was reduced by the same degree when flours from sprouted seeds were analyzed.     

Alkaline‐Carbonate Noodles from Hard Winter Wheat Flours Varying in Protein,Swelling Power,and Polyphenol Oxidase Activity

The effects of wheat protein and starch on yellow‐alkaline noodles have not been fully clarified. Twenty‐four hard winter wheats with varying protein, hot‐water swelling power (SP₉₅), and polyphenol oxidase (PPO) activity were milled into long‐patent and short‐patent flours. Protein, SP₉₅, and PPO activity in the 48 flours were 8.2–12.9%, 16.2–24.1 g/g, and 80–157 ΔA₄₈₀/mg of protein/min, respectively. Lightness of raw noodles declined with increasing protein and PPO levels but yellowness decreased and then increased. Tensile force to break the cooked noodles was positively correlated with SP₉₅ and protein. Compression (50%) force of noodles made from flour with high SP₉₅ ≈21 g/g, averaged ≈20% below those made from low SP₉₅ ≈17 g/g of flour. Compression force was measured in the long dimension of a single noodle strand using a rectangular probe. The instrumental measurements suggest that alkaline noodles made from a single‐null partial‐waxy wheat with medium SP₉₅ ≈19.9 g/g will have a tender bite and a cohesive texture compared with those from a low SP₉₅ wheat with a hard bite and fracturable texture. Furthermore, alkaline noodles from a double‐null partial‐waxy wheat with high SP₉₅ will have an extra soft bite unless flour protein is above ≈12.5%. Hard‐white, dual‐purpose wheat should have a low level of PPO and, depending on the preferred noodle‐eating texture, a low to medium SP₉₅ level. Such wheats with medium protein levels (11–12%) are well suited for alkaline noodles because of improved color and surface smoothness, whereas the same wheats with 12–13% protein are well suited for bread. Wheats with medium SP₉₅ also reduce cooking loss and increase cooked yield.     

Phenolic Content and Antioxidant Activity of Pearled Wheat and Roller‐Milled Fractions

Wheat contains phenolic compounds concentrated mainly in bran tissues. This study examined the distribution of phenolics and antioxidant activities in wheat fractions derived from pearling and roller milling. Debranning (pearling) of wheat before milling is becoming increasingly accepted by the milling industry as a means of improving wheat rollermilling performance, making it of interest to determine the concentration of ferulic acid at various degrees of pearling. Eight cultivar samples were used, including five genotypes representing four commercial Canadian wheat classes with different intrinsic qualities. Wheat was pearled incrementally to obtain five fractions, each representing an amount of product equivalent to 5% of initial sample weight. Wheat was also roller milled without debranning. Total phenolic content of fractions was determined using the modified Folin‐Ciocalteau method for all pearling fractions, and for bran, shorts, bran flour, and first middlings flour from roller milling. Antioxidant activity was determined on phenolic extracts by a method involving the use of the free radical 2,2‐diphenyl‐l‐picrylhydrazyl (DPPH). Total phenolics were concentrated in fractions from the first and second pearlings (>4,000 mg/kg). Wheat fractions from the third and fourth pearlings still contained high phenolic content (>3,000 mg/kg). A similar trend was observed in antioxidant activity of the milled fractions with ≈4,000 mg/kg in bran and shorts, ≈3,000 mg/kg in bran flour, and <1,000 mg/kg in first middlings flour. Total phenolic content and antioxidant activity were highly correlated (R² = 0.94). There were no significant differences between red and white wheat samples. A strong influence of environment (growing location) was indicated. Pearling represents an effective technique to obtain wheat bran fractions enriched in phenolics and antioxidants, thereby maximizing health benefits associated with wheat‐based products.     

High‐Speed NIR Segregation of High‐ and Low‐Protein Single Wheat Seeds

Wheat breeders need a nondestructive method to rapidly sort high‐ or low‐protein single kernels from samples for their breeding programs. For this reason, a commercial color sorter equipped with near‐infrared filters was evaluated for its potential to sort high‐ and low‐protein single wheat kernels. Hard red winter and hard white wheat cultivars with protein content >12.5% (classed as high‐protein, 12% moisture basis) or < 11.5% (classed as low‐protein) were blended in proportions of 50:50 and 95:5 (or 5:95) mass. These wheat blends were sorted using five passes that removed 10% of the mass for each pass. The bulk protein content of accepted kernels (accepts) and rejected kernels (rejects) were measured for each pass. For 50:50 blends, the protein in the first‐pass rejects changed as much as 1%. For the accepts, each pass changed the protein content of accepts by ≈0.1%, depending on wheat blends. At most, two re‐sorts of accepts would be required to move 95:5 blends in the direction of the dominant protein content. The 95:5 and 50:50 blends approximate the low‐ and high‐protein mixture range of early generation wheat populations, and thus the sorter has potential to aid breeders in purifying samples for developing high‐ or low‐protein wheat. Results indicate that sorting was partly driven by color and vitreousness differences between high‐ and low‐protein fractions. Development of a new background specific for high‐ or low‐protein and fabrication of better optical filters for protein might help improve the sorter performance.     

Tocopherol and Tocotrienol Content in Commercial Wheat Mill Streams

The content of tocopherols and tocotrienols, collectively known as vitamin E (tocols), was determined in fractions of roller‐milled wheat grains. The results showed that vitamin E components are present in all major flour fractions of wheat, but that the vitamin E content and composition differed significantly between fractions. The total content of vitamin E, calculated as alpha‐tocopherol equivalents, changed from 16.1 mg α‐TE/g in wheat grain to 12.2 mg α‐TE/g in roller‐milled wheat flour. The germ fraction had the highest content of tocopherols, and the content of α‐tocopherol (195.2 μg/g) was 16 times higher (on average) than in any other fraction. The content of tocotrienols was distributed more uniform in the wheat grain with the highest content in the bran fractions, and the content of β‐tocotrienol was higher than the content of α‐tocopherol in all milling fractions except the wheat germ. The content of β‐tocotrienol was 24.1 μg/g in wheat grain, 25.3–31.0 μg/g in the bran fractions, and 14.3–21.9 μg/g in the fractions of endosperm. Overall, germ and fine bran fractions represent good sources of vitamin E and might be used in breadmaking.     

Fermentation Reduces Free Asparagine in Dough and Acrylamide Content in Bread

Free asparagine is an important precursor for acrylamide in cereal products. The content of free asparagine was determined in 11 milling fractions from wheat and rye. Whole grain wheat flour contained 0.5 g/kg and whole grain rye flour 1.1 g/kg. The lowest content was found in sifted wheat flour (0.2 g/kg). Wheat germ had the highest content (4.9 g/kg). Fermentation (baker's yeast or baker's yeast and sourdough) of doughs made with the different milling fractions was performed to investigate whether the content of free asparagine was reduced by this process. In general, most of the asparagine was utilized after 2 hr of fermentation with yeast. Sourdough fermentation, on the other hand, did not reduce the content of free asparagineas efficiently but had a strong negative impact on asparagine utilization by yeast. This indicates that this type of fermentation may result in breads with higher acrylamide content than in breads fermented with yeast only. The effect of fermentation time on acrylamide formation inyeast‐leavened bread was studied in a model system. Doughs (sifted wheat flour with whole grain wheat flour or rye bran) were fermented for a short (15+15 min) or a long time (180+180 min). Compared with short fermentation time, longer fermentation reduced acrylamide content in bread made with whole grain wheat 87%. For breads made with rye bran, the corresponding reduction was 77%. Hence, extensive fermentation with yeast may be one possible way to reduce acrylamide content in bread.     

Physical and Milling Characteristics of Wheat Kernels After Enzyme and Acid Treatments

The current wheat milling process separates bran from endosperm by passing tempered wheat kernels through successive break rolls and sifters. Using hydrolytic enzymes during tempering degrades bran and aleurone layers and can improve milling efficiency and yield. This study was conducted to evaluate the effects of chemical and enzymatic treatments of wheat kernels before milling on physical and milling characteristics of the resulting wheat and flour quality. Hard wheat kernels were soaked in dilute acid or water and dried back to original moisture before being tempered with enzymes in water. Kernel physical and milling characteristics (600 g) were evaluated. Dilute acid soaking did not affect the 1,000‐kernel weight and diameter but softened treated kernels. When treated kernels were pearled, bran removal was mostly from ends; and the reducing sugar content in enzyme‐treated bran was significantly higher than the control. Compared with the control, acid‐soaked enzyme‐tempered kernels showed small but significant improvement in straight flour yield, with virtually no difference in protein content, and flour color. Chemical and enzyme treatment resulted in higher ash in flour. These differences were not seen in milling of larger batches (1,500 g) of kernels.     

Effect of Soft Kernel Texture on the Milling Properties of Soft Durum Wheat

Worldwide, nearly 20 times more common wheat (Triticum aestivum) is produced than durum wheat (T. turgidum subsp. durum). Durum wheat is predominately milled into coarse semolina owing to the extreme hardness of the kernels. Semolina, lacking the versatility of traditional flour, is used primarily in the production of pasta. The puroindoline genes, responsible for kernel softness in wheat, have been introduced into durum via homoeologous recombination. The objective of this study was to determine what impact the introgression of the puroindoline genes, and subsequent expression of the soft kernel phenotype, had on the milling properties and flour characteristics of durum wheat. Three grain lots of Soft Svevo and one of Soft Alzada, two soft‐kernel back‐cross derived durum varieties, were milled into flour on the modified Quadrumat Senior laboratory mill at 13, 14, and 16% temper levels. Samples of Svevo (a durum wheat and recurrent parent of Soft Svevo), Xerpha (a soft white winter wheat), and Expresso (a hard red spring wheat) were included as comparisons. Soft Svevo and Soft Alzada exhibited dramatically lower single‐kernel characterization system kernel hardness than the other samples. Soft Svevo and Soft Alzada had high break flour yields, similar to the common wheat samples, especially the soft hexaploid wheat, and markedly greater than the durum samples. Overall, Soft Svevo and Soft Alzada exhibited milling properties and flour quality comparable, if not superior, to those of common wheat.     

Relationships of Quality Characteristics with Size‐Exclusion HPLC Chromatogram of Protein Extract in Soft White Winter Wheats

This study investigated relationships between molecular weight distributions of unreduced grain proteins and grain, flour, and end‐use quality characteristics of soft white winter wheats grown in Oregon. Absorbance area and area percentage values of protein fractions separated by size‐exclusion HPLC (SE‐HPLC) showed significant correlations with quality characteristics, indicating associations of molecular weight distributions of proteins with quality characteristics. Specifically, high molecular weight polymeric protein fractions appeared to have a detrimental effect on soft wheat quality. This was shown by significant positive correlations with single kernel hardness index, and mixograph water absorption and tolerance, and negative correlations with break flour yield, cookie diameter, and cake volume. Higher proportions of soluble monomeric protein fraction eluted after the main gliadin peak, were associated with soft wheat quality due to negative associations with single kernel hardness index and mixograph water absorption and tolerance, and positive associations with break flour yield, cookie diameter, and cake volume. Calibration models were developed by the application of multivariate analyses to the SE‐HPLC data. These models explained >90% of the variation in mixograph water absorption and cookie diameter and thickness.     

Description of a Micromill with Instrumentation for Measuring Grinding Characteristics of Wheat Grain

A new method for characterizing the grinding characteristics of wheat grain is described. A micromill was designed for this purpose and equipped with on‐line torque transducers to obtain accurate measurements of mechanical energy consumption during milling. This micromill can be used for testing the milling performance of small quantities of grain (100 g). It can distinguish between different types of wheat grain (soft wheat, hard wheat, durum wheat) on the basis of total specific energy during milling. Wheat characterization can be enhanced by taking particle sizes of the milled products into account. A milling index based on energy consumption and particle size reduction was developed to characterize wheat behavior during milling. This index had a high discriminatory potential, ranging from 100 kJ/kg for soft wheat flour to 600 kJ/kg for durum wheat flour. This micromill directly measures the grinding resistance of wheat kernels as a function of both the kernel hardness and vitreousness, contrary to standard kernel hardness measurements obtained by particle size index and near‐infrared reflectance analysis techniques that only reflect the fracture mode (fine particle reduction potential).     

Stability of Vitamin E in Wheat Flour and Whole Wheat Flour During Storage

The stability of vitamin E during 297 days of storage of wheat flour and whole wheat flour ground on a stone mill or a roller mill, respectively, were studied. One day after milling, the total content of vitamin E, expressed in vitamin E equivalents (α‐TE), was 18.7 α‐TE and 10.8 α‐TE for stone‐milled and roller‐milled wheat flour, respectively. The difference in total vitamin E content was primarily due to the absence of the germ and bran fractions in the roller‐milled flour. The total loss of vitamin E during storage was 24% for stone‐milled wheat flour but 50% for roller‐milled wheat flour. These results indicate that vitamin E, which is present in high amounts in wheat germ, functions as an antioxidant in the stone‐milled wheat flour. Hexanal formation showed that lipid oxidation in roller‐milled flour occurred just after milling, whereas the formation of hexanal in the germ fraction displayed a lack period of 22 days, confirming that vitamin E functions as an effective antioxidant in the wheat germ. Results showed no significant difference in total loss of vitamin E for stone‐milled and roller‐milled whole wheat flour. Total loss after 297 days of storage for both milling methods was ≈32%.     

Physicochemical Properties of Wheat Fractionated by Wheat Kernel Thickness and Separated by Kernel Specific Density

Two wheat cultivars, soft white winter wheat Yang‐mai 11 and hard white winter wheat Zheng‐mai 9023, were fractionated by kernel thickness into five sections; the fractionated wheat grains in the 2.7–3.0 mm section were separated sequentially into three fractions according to kernel specific density. Physical properties of unfractionated, fractionated, and separated wheat grains and the physicochemical properties of processed wheat flour were determined. Test weight, relative density, and whiteness of flour in the middle kernel thicknesses were maximal and those properties decreased with increasing or decreasing kernel thickness; they also decreased with decreasing kernel specific density. Extensigraph properties showed the same results. Water absorption of flour and kernel hardness increased with increasing kernel thickness and decreasing kernel specific density. The farinograph properties also were related to kernel thickness and specific density. Pasting viscosity increased with increasing kernel thickness for sections from <2.5 mm to 3.0–3.2 mm, except that the >3.2 mm section was lowest; the kernels with the lightest specific density also were lowest. Thus, the quality of wheat grains with the greatest kernel thickness was not the best, and in fact may be the worst. The quality of wheat grains with small kernel thickness and light kernel specific density generally were worst. Most physicochemical properties of unfractionated and unseparated wheat grains were accurately predicted by the weighted‐average of the different kernel thickness sections and different kernel specific density fractions, except relative density, falling number, dough development time, and pasting temperature.     

Detection of Scab‐Damaged Hard Red Spring Wheat Kernels by Near‐Infrared Reflectance

Scab (Fusarium head blight) is a fungal disease that has become increasingly prevalent in North American wheat during the past 15 years. It is of concern to growers, processors, and the consumers because of depressed yields, poor flour quality, and the potential for elevated concentrations of the mycotoxin, deoxynivalenol (DON). Both wheat breeder and wheat inspector must currently deal with the assessment of scab in harvested wheat by manual human inspection. The study described herein examined the accuracy of a semi‐automated wheat scab inspection system that is based on near‐infrared (NIR) reflectance (1,000–1,700 nm) of individual kernels. Using statistical classification techniques such as linear discriminant analysis and nonparametric (k‐nearest‐neighbor) classification, upper limits of accuracy for NIR‐based classification schemes of ≈88% (cross‐validation) and 97% (test) were determined. An exhaustive search of the most suitable wavelength pairs for the spectral difference, [log(1/R)_λ1 ‐ log(1/R)_λ2], revealed that the slope of the low‐wavelength side of a broad carbohydrate absorption band (centered at ≈1,200 nm) was very effective at discriminating between healthy and scab‐damaged kernels with test set accuracies of 95%. The achieved accuracy levels demonstrate the potential for the use of NIR spectroscopy in commercial sorting and inspection operations for wheat scab.     

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.