Location: Corn, Soybean and Wheat Quality Research2020 Annual Report
Objective 1: Develop accurate and efficient laboratory methods for end-use quality evaluation of soft winter wheat breeding lines and varieties. Sub-objective 1a: Improve the cake baking test procedure of non-chlorinated flour by identification of ways to increase cake volume. Sub-objective 1b: Determine the feasibility of flour batter and extract viscosities for prediction of the cake baking quality potential of wheat flour. Objective 2: Establish quality characteristics of soft winter wheat non-conventional and whole grain food products and enable new and/or expanded commercial uses. Sub-objective 2a: Identify the quality traits of eastern soft winter wheat required for making steamed bread. Sub-objective 2b: Determine variation in the characteristics of soft wheat bran among wheat varieties, and identify ways to improve the functional properties of bran for making whole grain soft wheat foods with improved product quality and sensory acceptance. Sub-objective 2c: Develop eastern soft wheats with different complements of waxy alleles. Objective 3: Identify the biochemical, physical and genetic factors associated with flour yield and endosperm separation from bran during milling. Sub-objective 3a: Determine the variation in bran micro-structural characteristics and remnant endosperm among soft wheat genotypes in relation to flour yield. Sub-objective 3b: Evaluate effect of TaSus2 alleles at QTL on chr. 2B on milling yield and flour quality. Sub-objective 3c: Compare expression of TaSus2-2B transcripts in near-isogenic lines carrying different complements of HapL, HapH and HapG. Objective 4: Congressionally designated as a direct mission of service, and non-hypothesis driven, the USDA-ARS will identify, evaluate, and screen the intrinsic end-use quality to enhance cultivar development.
Sub-Objective 1a: Evaluate the cake baking performance of non-chlorinated flour with heat and/or acid pretreatments. Determine the effects of waxy, cold water swelling and pre-gelatinized starches on the cake baking performance of non-chlorinated flour. Establish an improved cake baking method and validate its effectiveness. Conduct a collaborative study for the established cake baking method with the AACCI Soft Wheat Flour Technical Committee (SWFTC). Sub-Objective 1b: Determine the viscosities of cake batter, simplified batter and aqueous flour extract using various viscosity tests. Determine the relationships between batter and flour extract viscosity, and cake quality attributes. Establish the batter or extract viscosity test as a routine test of flour for cake baking quality. Sub-Objective 2a: Determine the flour characteristics of soft red winter wheat varieties important for making steamed bread. Determine the quality of steamed breads prepared from soft red wheat flours. Determine the influences of protein and starch characteristics on steamed bread quality. Develop a quality profile of soft red wheat flour for making steamed bread. Sub-Objective 2b: Determine the variation in characteristics of bran among soft red winter wheat varieties. Evaluate the quality of whole grain biscuits and pancakes prepared from a blend of wheat flour and bran from different varieties. Identify bran characteristics of soft red wheat affecting whole wheat biscuits and pancakes. Improve functional properties of bran. Sub-objective 2c: Waxy alleles from fully and partial waxy lines will be introgressed into regionally grown, good milling soft red and white winter wheats to produce lines needed for testing the role of high amylopectin flours on the quality of conventional and non-conventional soft wheat products. Sub-objective 3a: Evaluate the starch content of bran as an estimate of remnant endosperm on bran. Determine the residual endosperm content of bran as an indicator of endosperm separation efficiency. Determine arabinoxylan content of residual endosperm of bran. Evaluate the microstructural differences of bran of contrasting remnant endosperm content. Sub-objective 3b: HapH and HapG alleles will be introgressed by three backcrosses to the recurrent parent. Seed will subsequently be increased for field trials. Sub-objective 3c: We will characterize the sequence and expression of TaSus2-2B to determine if there is a correlation between gene structure and/or expression and high flour yield and kernel softness. Goal 4: Annually evaluate over 6,000 soft red and white wheat grain samples for milling and baking quality from about 21 public and private wheat breeding programs in the eastern half of the United States. Wheat grain samples are classified into ‘preliminary’, ‘intermediate’ or ‘advanced’ groups, depending on the stage of breeding generation and the intensity of quality evaluation needs, and evaluated for their end-use quality potential using AACCI Methods and established procedures.
This is the final report for this project which terminated in June 2020. See the replacement project, 5082-43440-002-00D, “Enhancement of Eastern U.S. Wheat Quality, Genetics and Marketability” for additional information. This project aimed to improve the milling and baking quality of eastern soft wheat varieties by developing accurate and reliable quality testing methods, identifying the biochemical and genetic characteristics of wheat important for extended uses and whole grain foods as well as for flour milling yield, and contributing to the development of wheat varieties by conducting the end-use quality evaluation of wheat breeding lines. Objective 1. Develop accurate and efficient laboratory methods for end-use quality evaluation of soft winter wheat breeding lines and varieties. An experimental high ratio cake baking method applicable to wheat flour without prior flour chlorination was developed with improvements in the volume and contour of cakes baked through selection of the baking powder, and reduced amounts of sugar and shortening. The new cake baking test performed similarly to the conventional method in differentiating flour quality for baking cakes and exhibited a correlation with the latter in the volume of cakes. The cake baking method was further simplified by using a fixed water amount of 120% and two-step batter mixing (instead of variable water levels and three-step batter mixing) without negatively affecting cake shape and volume. The feasibility of using flour-water and flour-water-sugar batter viscosities was examined to develop a simple, non-baking method for the estimation of wheat flour quality for making cakes. The viscosities of flour-water and flour-water-sugar batters determined using both a consistometer and a viscometer showed relationships with the quality attributes of cakes baked from 20 wheat flours, with correlation coefficients ranging from -0.61 to -0.67, demonstrating the potential of wheat flour-water and flour-water-sugar batter viscosity for the estimation of wheat flour quality for making cakes. Objective 2. Establish quality characteristics of soft winter wheat non-conventional and whole grain food products and enable new and/or expanded commercial uses. The suitability of eastern soft wheat for making steamed bread (representing a product requiring dough and gluten development) was evaluated. The characteristics of starch and protein required for producing steamed bread of superior quality were determined; it was found that 1) a reduced starch amylose content of flour increased the specific volume and crumb softness of steamed bread; and 2) wheat flour with a reduced starch amylose content retarded staling of steamed bread. The influence of gluten strength on dough properties and steamed bread quality was studied; it was found that 1) steamed bread with added strong gluten exhibited a smoother surface, better crumb structure and higher total score than steamed bread with added weak gluten, and 2) gluten strength exhibited positive correlations with steamed bread specific volume and stress relaxation, indicating that soft red winter wheat of relatively high protein content and gluten strength is suitable for the production of steamed bread. The desirable characteristics and appropriate pre-treatments of wheat bran for the production of whole wheat products of improved quality and consumer acceptance were identified. The compositional and physical characteristics of soft red winter (SRW) wheat bran showed relationships with the dough mixing properties and quality attributes of whole wheat steamed bread, pancakes and biscuits prepared from blends of a flour and 17 different brans. The protein content of bran significantly influenced the quality of whole wheat pancakes and biscuits, whereas the quality of steamed bread was affected more by the bound and total phenolic acid, water-soluble arabinoxylan and insoluble dietary fiber contents. The effects of hydrothermal and pressure treatments of bran on the functional properties, dough/batter properties and quality of whole wheat steamed bread and pancakes prepared from blends of wheat flour and treated brans were determined. The treated brans (with the exception of the roasted one) exhibited a higher water absorption, water solubility and water retention capacity than untreated bran. The insoluble fiber content of bran decreased, while the soluble fiber content increased, with autoclaving, roasting, jet-cooking and extrusion treatments. Extrusion and autoclaving of bran were identified to be effective in improving the processing quality of steamed bread and the moistness of pancakes, respectively. Waxy and partial-waxy eastern soft wheat germplasms, whose starches have varying degrees of reduced amylose content, were developed by the introduction of a waxy trait into three soft red winter wheat cultivars, followed by four to five backcrosses to the recurrent parent and identification using a combination of marker assisted selection, an endosperm iodine staining test and a granular bound starch synthase test. Thirty-five to fifty-three waxy and partial waxy lines of each cultivar background were planted in the field in 2018 to obtain grain for the determination of amylose content, pasting properties and swelling powers. Objective 3. Identify the biochemical, physical and genetic factors associated with flour yield and endosperm separation from bran during milling. The residual endosperm content of bran (REB) varied widely among soft red winter wheat varieties and had a stronger relationship with flour yield than other grain characteristics, and thus is a major contributor to flour yield. The biochemical compositions of the outer endosperm, flour and bran of ten soft red winter wheat varieties exhibiting varying flour yields, and their relationships with flour yield, were determined to identify the endosperm characteristics governing its detachment from bran during roller milling. The water-soluble arabinoxylan content of the REB and flour exhibited significant relationships with flour yield. Wheat varieties of high flour yield were lower in water-soluble arabinoxylan content of the REB than the varieties of low flour yield, implicating it in the separation of endosperm from bran during milling of wheat grain. Sucrose synthase plays a key role in starch synthesis and its increased expression leads to increased kernel weight and yield. The effects on flour milling quality have not been tested which could affect the marketability of wheat with increased sucrose synthase activity. Previous studies have shown the part of the chromosome where the sucrose synthase gene is located affected thousand kernel weight in wheat, corn and rice as well as several milling characteristics of wheat. The effects of sucrose synthase expression in soft winter wheat Near Isogenic Lines (NILs) in two genetic backgrounds, one with higher kernel weight and milling quality and the other exhibiting lower kernel weight and milling quality, were tested. The NILs with either a native or higher expressing sucrose synthase gene grown in two locations for two years showed that thousand kernel weight was not different in the good milling, higher kernel weight NILs with a higher expressing sucrose synthase, but significantly increased in the poor milling, lower kernel weight NILs with higher sucrose synthase expression. Increased sucrose synthase expression leads to increased thousand kernel weight in soft winter wheat varieties with no apparent changes in milling quality. The number of varieties that can be improved is still to be determined. Preharvest sprouting (PHS) reduces value and marketability of wheat and sources of resistance are needed. A genome-wide association study performed for two years found four locations of resistance in soft winter wheat. Three were found in year one and one in year two indicating significant environmental effects. Additional genes are being located by RNA sequencing expression analysis using genetically related varieties that are susceptible or resistant. Gene expression libraries under conducive and non-conducive PHS conditions have been made and sent to ARS scientists at Stoneville, Mississippi, to perform RNA sequencing. The genetics of flour quality traits except for protein content are not well understood. Six varieties, chosen by genetic relatedness and flour quality trait differences, were grown in the greenhouse and RNA from seeds collected at three critical timepoints according to literature from hard winter wheat: early grain filling, mid grain filling, and late grain filling. RNA sequencing expression analysis will be performed to find genes differentially expressed that relate to flour quality traits. Objective 4. Identify, evaluate, and screen for intrinsic end-use quality to enhance cultivar development. The milling and baking quality evaluation of four to five thousand samples each year submitted by 13 to 15 public and private breeding programs of eastern soft winter wheat was performed. The test results were summarized and distributed to the breeding programs, directly contributing to the development of new wheat varieties possessing superior quality. Collaborative research projects with eastern soft winter wheat researchers at five public universities that aimed to identify the genetic markers for milling and baking quality traits of eastern soft wheat were carried out by conducting comprehensive milling and baking quality evaluations. The Soft Wheat Quality Council (SWQC) annual evaluation of new varieties and advanced breeding lines was coordinated and carried out by milling grain, distributing flour to collaborators, performing quality trait evaluations and preparing a report that collates quality evaluations among the collaborators for presentation at the annual SWQC Meeting.
1. Development of soft red winter waxy and partial waxy wheat germplasms. Starch amylose content is a major determinant of cooked paste properties and end-use quality of wheat and is controlled by three waxy genes in common wheat. Wheat flour of reduced amylose content, as milled from waxy and partial-waxy wheat, is known to be desirable for extending bread shelf life, improving textural properties of thawed products, and making white salted and instant fried noodles of improved cooking and textural properties. ARS scientists at Wooster, Ohio, developed soft red winter (SRW) wheat germplasms of reduced starch amylose content by the incorporation of null waxy genes into three SRW wheat cultivars. Thirty-five to fifty-three waxy and partial-waxy germplasms for each SRW wheat cultivar background were selected from the backcrosses to the respective parent cultivar four to five times using marker-assisted selection, an endosperm iodine staining test and a waxy protein test, followed by confirmation with starch amylose content determination. Starch amylose contents of waxy and partial-waxy germplasms ranged from 2.0 to 7.2% and 17.3 to 27.1%, respectively, which resulted in a much higher hot-paste viscosity and swelling power of wheat flour than the parent cultivars of normal amylose content. SRW wheat germplasms of reduced amylose content have been provided to a wheat breeding program for the development of wheat varieties carrying unique starch characteristics. Waxy and partial-waxy wheats are expected to deliver soft wheat flour with unique starch characteristics, which would be desirable not only for the production of food products requiring such starch characteristics (including instant fried noodles and white salted noodles), but also readily used by millers and bakers as new and novel ingredients for product quality improvement and new uses.
2. Heat, moisture and pressure treatments of wheat bran for improved functional properties for making whole wheat steamed bread and pancakes. Bran increases the nutritional value, but reduces the quality and taste, of whole wheat foods, thus reducing consumer acceptance. Improvement of the bran properties before incorporation into whole wheat foods could be one of the most effective strategies for mitigating its negative influences on food products. ARS scientists at Wooster, Ohio, determined the effects of treating wheat bran with heat, moisture, pressure and their combinations on the processing, quality and sensory acceptance of whole wheat steamed bread and pancakes, and identified that extrusion (high pressure, temperature and shear) and autoclaving (moist-heat and pressure) treatments of bran were effective for improving the product quality and taste of steamed bread and pancakes prepared from bran and flour blends, respectively. The treated bran exhibited significant changes in compositional and water absorption characteristics, and dough and batter mixing properties of bran and wheat flour blends. Extrusion of bran improved the crumb structure, spread ratio and springiness of steamed bread while maintaining surface smoothness, texture, flavor, and overall quality. Moist-heat and pressure treated bran improved the moistness of whole wheat pancakes while maintaining flavor, texture and overall quality of whole wheat pancakes. The extrusion and autoclaving treatments of bran could be effective options for improving the quality and taste of whole wheat steamed bread and pancakes, respectively, and bear the potential to be readily applicable to other whole wheat foods.
3. Processing effects on wheat protein digestibility. The presence and incomplete digestion of specific gluten protein molecules are responsible for celiac disease, sensitivity and allergy. A better understanding of the influence of ingredients and processing on protein digestibility of wheat flour would be valuable for reducing its allergenic potential. ARS scientists at Wooster, Ohio, elucidated the effects of food ingredients and processing on protein digestibility in steamed bread, white-salted noodles, pancakes, biscuits and cookies. Cooked noodles were highest in protein digestibility, followed by steamed bread, biscuits, cookies and pancakes. Compared to the corresponding flours, steamed bread and cooked noodles exhibited higher protein digestibility, whereas pancakes, biscuits and cookies exhibited lower protein digestibility. Dough mixing, fermentation and steaming for the preparation of steamed bread exhibited no significant effects on protein digestibility, while boiling of noodles improved protein digestibility in comparison to uncooked noodles. Biscuit and cookie doughs and pancake batter exhibited lower protein digestibility than wheat flour, indicating that the ingredients (rather than the processing) are largely responsible for decreases in protein digestibility. The obtained information provides food manufacturers with guidance for improving the protein digestibility of wheat products through modifications of formula and processing, which would reduce gluten protein-related illnesses caused by the undigested protein molecules.
4. Sucrose synthase expression affects the expression of other starch pathway genes and thousand kernel weight. Changes in the expression of the sucrose synthase gene in a spring wheat variety led to differences in 1000 kernel weight (TKW), a grain yield trait indicative of starch synthesis and yield. Increased sucrose synthase expression but no change in thousand kernel weight were observed in durum wheat. The effect of sucrose synthase expression in soft winter wheat was unknown. In soft winter wheat, ARS scientists at Wooster, Ohio, found a chromosome region of about 1000 genes including the sucrose synthase gene may be involved in milling quality traits. However, the expression of sucrose synthase had no effect on milling quality traits in two seasons of testing. They also found that higher expression of sucrose synthase in some soft winter wheat varieties led to increased expression of other starch synthesis pathway genes and thousand kernel weight, a grain yield trait important to farmers. The reason for differences in sucrose synthase expression may be a small deletion in the promoter region reducing expression of sucrose synthase in some varieties. Increased yield and flour quality traits are desired by farmers, millers, and bakers.
5. Varietal differences in soft winter wheat can be used to locate pre-harvest sprouting (PHS) resistance. PHS is the germination of wheat grain on the head of the plant in the field before harvest under a few consecutive days of rain and cool temperature, which occur in the region about once every two years. Much is known about the biochemical process of PHS but little is understood about the genetics of PHS. PHS reduces the value and marketability of wheat. When significant PHS occurs in the field, farmers can lose approximately 30% of their crop value which translates into ~$420M annually in the United States where soft winter wheat is grown. Resistant lines show much reduced to no signs of PHS under the inducing weather conditions. Because the genetic nature is not well understood, few markers exist for breeders to use in developing resistant lines but are greatly desired. ARS scientists at Wooster, Ohio, completed a survey of PHS resistance in a population of nearly 200 diverse soft wheat breeding lines over three years and over two years in a second, more diverse population of older varieties. Five soft winter wheat varieties were identified as PHS tolerant over multiple years and PHS inducing conditions in the first study in 2018 and four additional varieties plus four potential chromosomal locations were identified in the second study in 2020. These findings provide important information for breeders about varieties with tolerance to PHS and the potential for future breeding of PHS resistance.
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