Location: Corn, Soybean and Wheat Quality Research
2018 Annual Report
Objectives
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.
Approach
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.
Progress Report
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.
Accurate and efficient laboratory methods development: To further simplify the newly established experimental high ratio cake baking method, examined the possible use of a fixed water level in the formula and a reduction of the batter-mixing steps. Baking with a fixed water amount (120%) in the formula yielded cakes comparable in volume and shape to those baked with the optimal water level. The two-step batter mixing method with two-time water addition and two-time batter scraping produced cakes of comparable shape and volume to the three-step method. The results indicate that a fixed water amount of 120% and two-step batter mixing (instead of variable water levels and three-step batter mixing) can be used for baking cakes without negatively affecting their shape and volume, further simplifying and shortening the baking procedure.
Quality characteristics of soft winter wheat for non-conventional and whole grain food products: The physicochemical properties of wheat bran are largely responsible for the undesirable characteristics of whole wheat foods; thus, the modification of bran is needed to improve its functional properties and whole wheat product quality. Pretreated wheat bran using various hydrothermal and pressure methods including autoclaving, roasting, jet-cooking, extrusion, and high-temperature-high-pressure cooking, determined the changes in hydration properties and composition, and identified the optimal water absorption and dough preparation methods for making whole wheat steamed bread from wheat flour and bran blends. 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.
To identify wheat varieties resistant to pre-harvest sprouting (PHS) damage and the grain characteristics related to PHS resistance, collected wheat grains of 150 soft red winter wheat varieties before and after subjection to sprouting conditions and analyzed them for grain characteristics for the former and falling number and alpha-amylase activity for the latter. Five soft red winter wheat varieties were identified to have greater PHS resistance than others. It was also confirmed that red seed and awnless varieties tend to be more resistant to sprouting than white seed and awned varieties, respectively. As observed in previous years, the genetic potential for test weight exhibited a significant relationship with the degree of pre-harvest sprouting damage, indicating its potential connection to sprouting resistance.
Incompletely digested gluten peptides are believed to trigger coeliac disease and are potentially responsible for non-coeliac gluten sensitivity and allergy. Analyzed the grain and protein characteristics of five modern and three ancient wheat species and classes, and explored their relationships with protein digestibility. Wheat classes were ranked as follows for protein digestibility: soft red winter > hard red winter = einkorn > club = spelt > hard red spring = emmer > durum. No evident differences in protein digestibility were observed between modern and ancient wheat species. Kernel hardness and albumin content were identified to be the major factors influencing the protein digestibility differences between wheat classes. For soft red winter and hard red winter wheat, flour protein and gliadin contents showed relationships with protein digestibility among cultivars.
High molecular weight glutenin subunit composition and rye translocation, and their association with gluten strength, are poorly understood for soft wheat even in the production of soft wheat products requiring gluten development. Selected 149 eastern soft wheat genotypes and analyzed them for gluten strength, high molecular weight glutenin subunit composition and rye translocation. Two subunits (1* and 12 sub 1) with frequencies of 1.6% and 21.9%, respectively, were newly identified in eastern soft wheat. The subunits including 2*, 7+8, 2+12 and 5+10 were observed to be predominant in eastern soft wheat genotypes with frequencies of 71.1, 47.7, 36.7 and 35.2%, respectively. Two rye translocations, 1B/1R and 1A/1R, were observed in 21.5% and 11.4% of the eastern soft wheat genotypes, respectively. Four subunit profiles (2*, 7+8, 2+12 sub 1), (2*, 7+8, 5+10), (2*, 7+9, 2+12) and (2*, 7+8, 2+12) were observed to be predominant, making up 13.3, 13.3, 13.3 and 10.2% of the tested eastern soft wheat varieties, respectively. The 1B/1R rye translocation exhibited a negative influence on gluten strength.
Develop eastern soft wheats with different complements of waxy alleles: Waxy wheat grain could be used to extend the shelf life of baked goods and blended with normal wheat for making noodles to improve textural properties. Currently, waxy soft winter wheat varieties adapted to grow in the northeastern U.S. do not exist. Three full-waxy homogeneous lines having the genetic backgrounds of two widely grown soft red wheat cultivars (Kristy and Milton) were obtained by four backcrosses to the recurrent parents, marker assisted selection, and confirmed using an endosperm iodine staining test. Twenty-five partial-waxy homogeneous lines carrying single-null or double-null waxy alleles in the genetic backgrounds of two soft red wheat cultivars (Kristy and Wilson) were also identified.
Biochemical, physical and genetic factors associated with flour yield: The amount of endosperm remaining attached to bran after milling was identified to be one of the major factors affecting flour yield in our previous study. To further investigate the causes of the variation in bran endosperm content, brans obtained from grains of wheat varieties exhibiting large differences in flour yield were tested for compositional characteristics before and after removal of the remaining endosperm, and related to the flour yield of the wheat grains from which the brans were obtained. Higher phytate and free phenolic contents before removing endosperm, and higher protein and phytate contents after removing endosperm were observed in brans from wheat grains with a high flour yield potential than in brans from wheat grains with a low flour yield potential. Regardless of endosperm removal, phytate content exhibited a significant relationship with the flour yield of grain, indicating its role in endosperm separation from bran during milling.
Compare expression of TaSus2-2B transcripts in near-isogenic lines and evaluate their effect on milling quality. In hard winter wheat sucrose synthase (TaSus2-2B) expression can impact 1000 kernel weight and this gene is near multiple milling quality chromosome 2B locations in soft winter wheat. Testing the effect of sucrose synthase on milling quality such as flour yield, physical characteristics associated with flour quality and milling yield, thousand kernel weight and expression of other genes in soft winter wheat to understand how sucrose synthase expression impacts expression of these genes and ultimately physical traits. RNA sequencing of three alleles of the gene TaSus2B was completed in two backgrounds. Differential expression of genes in the pathway to produce starch in the seed and involved in producing the cell wall were discovered. Successfully bulked seeds for multiple lines each in three different varieties with either high or low expressing TaSus2-2B genes for planting in the field to test the effect on flour traits.
Identify wheat varieties with similar genetic backgrounds but different pre-harvest sprouting resistance. Four pairs of wheat varieties with one resistant and the other susceptible to pre-harvest sprouting were selected based on similar genetic backgrounds from over 2000 markers placed on 189 diverse varieties and confirmed by analyzing pedigrees. Those eight wheat varieties were grown in the greenhouse, transferred to growth chambers 27 days after seed fertilization and subjected to high humidity and spike wetting or low humidity and no wetting as a negative control. Seeds were collected for later RNA expression analysis at 4 time points during grain filling period previously determined to be important for characterizing the trait.
Improve milling flour yield and other quality traits through genetic analysis of diverse soft winter wheat varieties. Genetic maps were constructed showing the relatedness of 189 diverse soft winter wheat varieties based on over 2000 genetic markers. Flour and baking quality traits such as: gluten strength, flour protein, cookie diameter, break flour yield, and softness equivalent measured and averaged from trials at seven year/locations were overlaid on the maps.
Milling and baking quality evaluation of wheat breeding lines: The ARS in Wooster, Ohio, worked cooperatively with 15 regional public and private wheat breeding programs on the development of eastern soft wheat varieties carrying desired end-use quality by evaluating 5,550 wheat breeding lines and varieties harvested in 2017. These efforts are essential for, and directly contribute to, the development of wheat varieties possessing superior quality. Continued the cooperative research with eastern soft winter wheat researchers at five universities by conducting comprehensive milling and baking quality evaluations for research projects.
Accomplishments
1. U.S. eastern soft winter wheat varieties resistant to pre-harvest sprouting and the associated wheat/grain characteristics. Pre-harvest sprouting damage is a recurring problem in the production of eastern soft winter wheat and significantly lowers the quality, value and marketability of the wheat grain produced. No list of wheat varieties resistant to pre-harvest sprouting is currently available, nor are the effective screening tools for the resistant varieties available. ARS scientists in Wooster, Ohio, identified a number of eastern soft winter wheat varieties possessing pre-harvest sprouting resistance though a multi-year project involving field and laboratory tests, and found that the genetic potential for high test weight (bulk density) of grain, in addition to red seed coat color and absence of hair (awn), contributes to an increased resistance to pre-harvest sprouting. The list of pre-harvest sprouting resistant wheat varieties will be helpful for wheat growers in selecting wheat varieties for planting with less concern for pre-harvest sprouting damage of grain. Test weight potential of wheat grain, identified as a grain trait associated with pre-harvest sprouting resistance will provide wheat breeders with an effective screening tool for wheat breeding lines with pre-harvest sprouting resistance.
2. Identification of protein profiles determining gluten strength of U.S. eastern soft wheat. Protein molecules, especially high molecular glutenin subunits and those from acquired rye genes, have a dominant influence on the gluten strength of wheat, but their profiles not fully understood nor have they been established for eastern soft wheat despite the considerable variation in gluten strength among genotypes and in the requirements for making different food products. By screening a large number of eastern soft wheat varieties for high molecular glutenin subunits and rye gene protein, ARS scientists in Wooster, Ohio, identified two new glutenin subunits, determined the frequency of occurrence of the glutenin subunit profile, and elucidated the relationships between glutenin subunit and rye gene protein profiles, and gluten strength. They proved that the presence of rye proteins resulting from rye translocation weakens gluten, while the presence of specific glutenin subunits strengthens gluten. This information will greatly help wheat breeding programs in the screening of breeding lines for gluten strength and millers and bakers in the identification of wheat grain possessing the appropriate gluten strength required for each food product.
3. Protein composition and digestibility of ancient and modern wheat species and classes. Some wheat protein molecules are incompletely digested and present various degrees of discomfort to those individuals who are sensitive and/or allergic to them. It is often believed that ancient wheat species contain proteins that can be more easily digested and induce fewer adverse responses compared to modern wheat species; however, there is no concrete substantiating evidence. ARS scientists in Wooster, Ohio, analyzed grain characteristics and protein digestibility of five modern wheat classes and three ancient wheat species and found no evident differences in protein digestibility between modern and ancient wheat species. Kernel hardness and albumin content negatively and positively affected protein digestibility, respectively, suggesting that kernel hardness and albumin content are the major factors influencing the protein digestibility differences among wheat classes. In soft and hard red winter wheat, flour protein and gliadin contents appear to be responsible for differences in protein digestibility among varieties. The obtained results prove that ancient wheat is not necessarily better in protein digestibility, and therefore does not induce a less adverse response upon consumption, than modern wheat. The identified wheat grain and protein characteristics influencing protein digestibility would be valuable for the selection of wheat grain and the development of wheat varieties that pose minimal concern to individuals with sensitivities or allergies to incompletely digested wheat proteins.
Review Publications
Nsabimana, P., Powers, J.R., Mattinson, S., Baik, B.V. 2017. Effects of deep-fat frying temperature on antioxidant properties of whole wheat doughnuts. International Journal of Food Science and Technology. 53(3):665-675. https://doi:10.1111/ijfs.13641.
Baik, B-K., Donelson, T.S. 2018. Post-harvest and post-milling changes in wheat grain and flour quality characteristics. Cereal Chemistry. 95:141-148.
Ma, F., Baik, B-K. 2018. Soft wheat quality characteristics required for making baking powder biscuits. Journal of Cereal Science. 79:127-133.
Ma, F., Lee, Y., Baik, B-K. 2018. Bran characteristics influencing quality attributes of whole wheat Chinese steamed bread. Journal of Cereal Science. 79:431-439.
Johnson, J.W., Chen, Z., Buck, J.W., Buntin, G.D., Babar, M.A., Mason, R.E., Harrison, S.A., Murphy, J.P., Ibrahim, A.M., Sutton, R.L., Simoneaux, B.E., Bockelman, H.E., Baik, B-K., Marshall, D.S., Cowger, C., Brown Guedira, G.L., Kolmer, J.A., Jin, Y., Chen, X., Cambron, S.E., Mergoum, M. 2018. ‘Savoy’: An adapted soft red winter wheat cultivar for Georgia and the South East regions of the USA. Journal of Plant Registrations. 12:85-89.
Park, E., Fuerst, E.P., Baik, B.-K. 2017. Effects of bran pre-hydration on functional characteristics and bread baking quality of bran and flour blends. Cereal Chemistry. 94(5):834-839.
Ma, F., Baik, B.-K. 2017. Qualitative effect of added gluten on dough properties and quality of Chinese steamed bread. Cereal Chemistry. 94(5): 827-833.
