Location: Corn, Soybean and Wheat Quality Research
2017 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 potentials of eastern soft wheat varieties by developing accurate and reliable quality testing methods, identifying 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: An experimental high ratio cake baking method for non-chlorinated flour was established by optimizing the formula from the method for chlorinated flour with consideration of cake volume and contour. The volume of cakes prepared from non-chlorinated flour using the new method exhibited a significant correlation with the volume of cakes baked from chlorinated flour. As a simple, non-baking method to determine the cake baking potential of wheat flour, we examined the viscosities of flour-water and flour-water-sucrose batters using a flow viscometer and a rapid visco analyzer (RVA), and their relationships with cake volume. We observed that the RVA viscosities of both flour-water and flour-sucrose-water batters determined without heating showed significant correlation with the volume of cakes prepared from non-chlorinated flours using the new cake baking method. The RVA viscosity measurement of flour-water batter appears to serve as an effective estimate for the cake baking potential of wheat flour.
Quality characteristics of soft winter wheat for non-conventional and whole grain food products: We determined the influence of gluten strength on dough properties and steamed bread quality by adding gluten of varying strengths to a base flour. We found that steamed bread made from flour containing added strong gluten exhibited a smoother surface, better crumb structure and higher total score than steamed bread made from flour containing added weak gluten, and that gluten strength had positive correlations with steamed bread specific volume and stress relaxation. Our results indicate that consideration of gluten protein strength in the evaluation and selection of wheat varieties is necessary for the production of high quality steamed bread. Soft red winter wheat varieties producing grain with relatively high protein content, and specifically high gluten strength, seem to be suitable for the production of steamed bread.
The quality characteristics of eastern soft wheat grain important for making baking powder biscuits have not been clearly identified, and consequently no known quality targets or target values are available. We determined the comprehensive grain and flour characteristics of thirteen red and two white varieties and related them to the quality attributes of biscuits including height, volume, shape and crumb hardness. We found that protein content, SDS sedimentation volume as a measure of protein strength, starch damage and water retention capacity had relationships with biscuit quality attributes.
Wheat bran obtained from milling can differ widely in compositional, nutritional, physical and biochemical characteristics among the sources of grain and varieties, affecting the product quality and sensory acceptance of whole wheat foods. We obtained bran from the milling grain for 17 soft red winter wheat varieties and determined their protein, dietary fiber, arabinoxylan and phenolic acid contents. Bran from each variety was blended with the same flour to make 17 whole wheat flours for determination of the dough properties and quality of whole wheat pancakes, biscuits and steamed bread. We observed that the protein content of bran was related to the quality of whole wheat pancakes and biscuits, and that the bound and total phenolic acid, water-soluble arabinoxylan and insoluble dietary fiber contents of bran were related to the quality of steamed bread.
Sprouting before harvest negatively affects the end-use quality of wheat grain and leads to price reduction. We screened soft red and soft white wheat varieties for their resistance to pre-harvest sprouting, and also compared the characteristics of wheat grain obtained under non-sprouting conditions with those of grain subjected to sprouting conditions to identify relationships between the genetically controlled grain characteristics and sprouting resistance. Even under severe sprouting conditions in the field, 14 of 150 varieties exhibited no signs of sprouting damage, indicating differences in sprouting resistance among wheat varieties. We also observed that soft red winter wheat and awnless varieties tended to be more resistant to sprouting than soft white winter wheat and awned varieties, respectively. The test weight of wheat grain obtained under non-sprouting conditions had a significant positive relationship with the degree of sprouting of wheat grain, indicating its potential connection to sprouting resistance.
Develop eastern soft wheats with different complements of waxy alleles: Waxy wheat grain contains starch primarily composed of amylopectin molecules and could be used to prepare fillings with non-gelling properties and extend the shelf life of baked goods. Currently, waxy winter wheat varieties adapted to grow in the northeastern U.S. do not exist. Two fully waxy varieties, each homozygous for the three waxy alleles, were crossed into three soft red winter wheat cultivars adapted to the northeastern U.S. climate with low, medium, or high flour yield. We have completed four backcrosses to the recurrent parent for three different wheat lines each with one, two, or three waxy alleles by marker assisted selection (MAS).
Biochemical, physical and genetic factors associated with flour yield: To identify the physical and chemical characteristics of bran affecting the separation of endosperm from bran during milling, which influences the flour yield of wheat grain, we obtained the bran from wheat grain with high and low flour yields and tested them for composition including protein, phenolic acid, arabinoxylan and phytate contents. Phenolic acid, especially ferulic acid in the aleurone layer, is known to crosslink arabinoxylan and other cell wall components including protein and lignin, influencing the physical properties of bran, which could consequently affect the separation of endosperm from bran during milling. We observed that bran obtained from wheat grains of relatively high flour yield had a higher protein content, water retention capacity, bound phenolic content and phytate content, but a lower arabinoxylan content than bran obtained from the wheat grains of relatively low flour yield in four selected soft wheat varieties. We plan to further examine the obtained results and determine the relationship between bran characteristics and flour yield using more than 20 varieties with contrasting flour yield potentials.
To improve the milling quality traits of eastern soft wheat we have continued to introgress into elite wheat cultivars a potential superior allele of a sucrose synthase gene located on chromosome 2B that might impact multiple quality traits. We have successfully introgressed the favorable alleles into three cultivars and planted them for the 2017 harvest. Quality traits of the field-grown wheat will be compared to the original cultivars grown in the same field. Seed of four more cultivars are being increased for field evaluation. When enough seed is generated cultivars will be sent to other locations for evaluation in multiple environments.
We have produced near isogenic lines for three alleles of a sucrose synthase gene in three cultivars. Homozygous sets of each allele in each background were verified using a marker we developed based on a 35 base pair missing sequence in the gene promoter. This marker can differentiate the superior allele in a single step and will be useful to breeders for MAS. No sequence differences leading to protein changes for the alleles and single copies of the gene on chromosome 2B were confirmed. Preliminary experiments testing quantitative gene expression for two of the three alleles of the sucrose synthase gene in two backgrounds indicated a two-fold increase in expression of the superior allele. The remaining allele and more backgrounds will be tested. RNA libraries from grain at three timepoints during development were created for the near isogenic lines and sent to the Stoneville, Mississippi lab for RNA sequencing. A whole genome expression analysis will be performed to gauge the impact of the introgressed sucrose synthase gene on other genes in the near isogenic lines. These lines are also being grown to increase seed for field quality tests.
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 5,897 wheat breeding lines and varieties harvested in 2016. These efforts are essential for, and directly contribute to, the development of wheat varieties possessing superior quality. We have continued our cooperative research with eastern soft winter wheat researchers at five universities by conducting comprehensive milling and baking quality evaluations for research projects.
Accomplishments
1. Establishment of a cake baking method for non-chlorinated wheat flour. An experimental cake baking method applicable to non-chlorinated wheat flour is not available, even though flour chlorination is either prohibited or discouraged due to the associated health and safety issues. ARS scientists in Wooster, Ohio, established an experimental cake baking method applicable to non-chlorinated wheat flour by optimizing the formula used for chlorinated flour with consideration of cake volume and contour. The new method allows the wheat quality testing laboratories to better evaluate wheat breeding lines for making cake, and the milling and baking companies to assess wheat flour for baking cake for better product quality control without chlorination.
2. Protein quality of soft wheat important for making steamed bread. Soft wheat flour protein content and quality together are known to be the major factors determining steamed bread quality, but their independent roles were unknown. The protein content of wheat is largely affected by climatic conditions and cultural practices; however, protein quality is determined by genetics, and can be controlled by wheat breeding. ARS scientists in Wooster, Ohio, elucidated the role of protein quality in making steamed bread, and found that soft wheat flour containing strong gluten protein produced steamed bread with a smoother surface, higher volume, better crumb structure and texture, and higher total quality score compared to flour with relatively weak gluten protein. This information will serve as a screening guide in the development of wheat varieties suitable for making steamed bread-type products and effective testing criteria in the procurement and quality control of wheat flour by food manufacturers.
3. Wheat flour quality requirements for baking powder biscuits. The flour quality requirements for making baking powder biscuits have not been clearly determined, despite their popularity as breakfast foods. Accordingly, no quality targets for soft wheat to be used in making baking powder biscuits are available, hampering efforts to identify high priority wheat breeding lines and optimal wheat flour for making biscuits. ARS scientists in Wooster, Ohio, determined that protein quantity and quality of soft wheat varieties was positively correlated with good height and shape attributes of baking powder biscuits, while grain hardness and damaged starch content negatively impacted the specific volume of baking powder biscuits. Soft wheat flour with high protein, weak-to-medium gluten strength and low damaged starch is recommended for biscuit production. This information will strengthen our understanding of soft wheat quality needs for making baking powder biscuits, and will be helpful for breeding programs in the development of soft wheat varieties and for the wheat milling and baking industry for better quality control of their products.
4. Wheat bran delivers many nutritional benefits to whole wheat foods, but at the same time negatively affects food product quality and sensory acceptance. It is necessary to minimize the negative influences of bran on whole wheat foods while maintaining the associated health benefits. Wheat varieties of diverse genetic backgrounds are presumed to yield brans with different physical and biochemical characteristics, which influence the quality of whole wheat foods in different ways. ARS scientists in Wooster, Ohio, observed wide variation in the composition and physical properties of bran obtained from seventeen soft wheat varieties. These results will be helpful for the identification of wheat varieties yielding bran with desirable characteristics, and provide guidelines for formulating whole wheat flour yielding better quality and sensory properties of whole wheat steamed bread by blending wheat flour and bran.
Review Publications
Ma, F., Ji, T., Baik, B.V. 2017. Quality characteristics of northern-style Chinese steamed bread prepared from soft red winter wheat flours with waxy wheat flour substitution. Journal of Cereal Science. 73:99-107. https://dx.doi.org/10.1016/j.jcs.2016.12.002.
Ji, T., Kang, M., Baik, B.V. 2017. Volatile organic compounds of whole grain soft winter wheat. Cereal Chemistry. 94(3):594-601. https://doi.org/10.1094/CCHEM-09-16-0243-R.
Lindsey, L.E., Lentz, E., Baik, B.-K. 2016. Row width influences wheat yield, but has little effect on wheat quality. Crop, Forage & Turfgrass Management. doi:10.2134/cftm2015.0158.
Baik, B.-K. 2016. Current and potential barley grain food products. Cereal Foods World. September-October 2016 61(5):188-196.
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.H., 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. 2017. ‘GA 03564-12E6’: A high-yielding soft red winter wheat cultivar adapted to Georgia and the southeastern regions of the United States. Journal of Plant Registrations. 11:159-164.
