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United States Department of Agriculture

Agricultural Research Service

Research Project: CHARACTERIZATION OF GRAIN BIOCHEMICAL COMPONENTS RESPONSIBLE FOR END-USE QUALITY

Location: Grain Quality and Structure Research Unit

2005 Annual Report


1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter?
The baking industry encounters tremendous loss in the areas of quality assurance to customers, consistency of product, processing parameters and product waste. It is estimated that as much as 10% of a company's product is relegated to waste due to lack of flour consistency. This variability in composition and quality of wheat flour is dependent upon genetic, environmental and supply chain factors. For example, not only will the protein content vary from lot to lot, but within a given protein content range (specified by end user requirements), the quality of the protein will vary considerably. Even when basic product specifications, such as ash, moisture, and protein content are met, the dough forming and baking characteristics of a given lot of flour are highly unpredictable.

Similarly, ingredient and processing variability translates into large economic losses in the baking industry. The U.S. baking industry annually uses about 42 billion pounds of flour, valued at about $4.2 billion, to produce an estimated $33 billion of baked goods. Variability in flour quality means that there are opportunities for large savings in the areas of raw material selection, processing, and distribution. Further, improved methodologies to better analyze the root causes of flour variability will open the door to the production of higher value products. The baking industry has limited tools at its disposal to deal effectively with the variability of wheat flour, its major raw material. All currently utilized industry tools for assaying and/or testing flour are highly empirical, offering little insight into the biochemical basis of (a) what constitutes a “quality” flour, (b) how a particular lot of flour can be characterized for its suitability for a given application, or (c) how a particular lot of flour should be processed to maximize product quality.

The objectives of this project are to: (1) Determine the roles and interactions of the major biochemical components of cereal grains (starch, storage proteins and enzymes) as they relate to food quality and functionality; (2) Define the role of the environment on functional properties of biochemical components that affect end-use properties; (3) Apply information generated in previous objectives towards development and refinement of methods to rapidly predict grain quality. Towards this end, investigation to determine role(s) of wheat starch granule size distributions on variations in functionality during bread-making will be performed. These approaches will utilize differential scanning calorimetry to provide thermal data on individual starch granule populations and starch fractions (pure A- and B- type granules) will be used for reconstitution experiments to determine how size classes affect bread-making quality. The mechanism(s) of action of oxidative enzyme addition to flour on storage proteins and non-storage proteins will be determined by addition of enzymes followed by functional analysis and examination of protein fractions and polymers using SDS-PAGE, size exclusion HPLC, and multi-angle laser light scattering. Environmental effects on starch and storage proteins will be determined using the above approaches with samples that have been exposed to controlled temperature and irrigation regimes during development. The potential of novel microfluidic devices will be thoroughly examined as a means to develop extremely rapid and highly reproducible separations of proteins for grain cultivar identification and quality prediction.

Advances in the knowledge of grain biochemical characteristics that determine the physical and functional properties critical to processing and end-product quality, and development of rapid, accurate methods to measure these quality determinants are essential to maintain a competitive position for U.S. grain in global markets. This project will provide the cereal food industry with the tools needed to define the end-use performance of cereal grains.

The research is under National Program 306 Quality and Utilization of Agricultural Products”, specifically on component 1 “Quality Characterization, Preservation, and Enhancement”. Multiple Problem Areas of this component are directly addressed in the objectives -- Problem Areas 1a (Definition and Basis for Quality); 1b (Methods to Evaluate and Predict Quality) and 1c (Factors and Processes that Affect Quality). The elucidation of fundamental biochemical processes and their role in determining product quality is paramount for the development of accurate methods for quality measurement.


2.List the milestones (indicators of progress) from your Project Plan.
Objective 1: Investigate roles and interactions of the major biochemical components of cereal grains (starch, non-starch carbohydrates, storage proteins and enzymes) as they relate to food quality and functionality. Specific milestones include:

• Isolation of large quantities of starch, separated into size fractions for baking and chemical testing. Continued testing the correction model for starch size distributions by laser diffraction sizing (LDS). Bake studies using reconstituted gluten and starch fractions. Begin testing, amylose /amylopectin ratios, pasting profiles, differential scanning calorimetry (DSC) temperatures and lipids of A, B, and C-type starch fractions. Chemical analysis of the starch fractions. Correlation analysis comparing bake data, starch size distributions and chemical analysis.

• Determination of the effects of oxidative enzymes and transglutaminase upon quality characteristics. Biochemical analysis on the effect of enzymes on protein interactions. Characterization of enzyme effects on protein interactions between glutenin and albumins. Determination of the contribution of individual glutenin subunits on enzyme mediated crosslinking in gluten functionality. Objective 2: Define the environmental impact upon functional properties of biochemical components that affect end-use properties. Specific milestones include:

• Use LDS and our correction model to detect environmental differences in starch ratios and chemical analysis of starch. Compare starch size distributions and chemical analysis to different environments. Relate polymer sizes and molecular weight distributions to quality characteristics, provided by the HWWQL.

• Determine if particular proteins/ starch granule ratios are markers for quality traits.

• Correlate information obtained in this year 1 and 2 study with the data on bread or tortilla quality characteristics, provided by the HWWQL. Objective 3: Apply information generated in objectives 1 and 2 to the development and improvement of methods to rapidly predict grain quality. Specific milestones include:

• Develop rapid microfluidic “lab-on-a-chip” technology to extract and separate wheat proteins, and identify wheat varieties and/or the quality of wheat varieties or mixtures in seconds.


4a.What was the single most significant accomplishment this past year?
Treatment of Flour with Glucose Oxidase changes Proteins. Chemical oxidants are routinely added to flour to modify dough properties (shorten mixing time, improve gas retention, lower energy requirements for dough mixing, etc.) and enhance breadbaking performance (increase loaf volume and improve crumb structure). The elimination of potassium bromate, and possibly other chemical oxidant additives, presents a challenge to the baking industry. Oxidoreduction enzymes such as glucose oxidase have been proposed as alternative improvers. We generated wheat flour with and without the presence of glucose oxidase and the different classes of proteins were extracted and analyzed. The most significant effects were observed to occur in the albumin (water soluble) and gliadin (alcohol soluble) protein groups. A significant increase in protein concentration and molecular weight distribution was observed in the albumin fraction. Further analysis revealed that this was due to changes in the gliadin solubility. Gliadins are generally not soluble in water, however, the inclusion of glucose oxidase enzyme in the mixing renders the gliadins more water soluble.


4b.List other significant accomplishments, if any.
Microfluidics system purchased. Knowledge of cereal proteins is important both for predicting end-use performance and for identification. The development of new or improvement of existing methods for deriving models for predicting quality traits and/or quickly identifying grain cultivars will assist in determining their roles in relation to quality. Microfluidic systems (lab-on-a-chip) produce fast separations using very small liquid volumes. We have purchased a microfluidics instrument and begun to identify quality-related protein patterns and unique proteins associated with specialty wheats, particularly waxy wheats. The effect of environment on proteins and quality might be available through analysis of HMW-GS isoforms or through quantification of albumins and globulins. In addition, it is envisioned that the gliadin patterns, amounts of albumins and globulins, and HMW-GS isoforms of specific wheat varieties with known quality traits will be stored in a database and when one of those patterns (or combinations) is matched, it will tag the sample as a good quality sample.

Starch size distribution and bake quality.

Wheat storage proteins have received a greater amount of attention compared to starch due to their unique properties of extension and elasticity, which gives them their unique dough forming properties. Starch, however, constitutes a much greater weight portion of wheat endosperm (~75% v. ~15%) and it contributes to foods its own unique functional qualities such as volume, texture, appearance and staling rate. Varying ratios of large type-A and smaller type-B granules has been proposed to change the baking potential of bread. Bread made from reconstituted flour with 30% type-B to 70% type-A ratios gave optimum crumb grain scores and peak fineness values and second highest elongation ratios. As the proportion of type-B granules increased, it yielded bread with a softer texture and maintained that texture better during storage. Due to the unique properties of the different size starch granules in wheat, it is reasonable to consider starch size distribution as having a significant impact on baking performance.

Environmental effect on starch size distribution. Environmental changes not only affect protein quality but may affect starch size distribution and its chemical composition. Work has been initiated to contrast weather conditions (temperature and precipitation) to starch size distribution in developing wheat. With samples collected over multiple years it will be possible to trace the impact of changes in environmental growing conditions to critical growing phases in starch development. This may be useful in developing a data base incorporating environmental information during the growing season to ideal starch development for optimum end-use quality. A differential scanning calorimeter (DSC) has been purchased which will be used to study gelatinization profiles (melting) of isolated starches and differences within the various size populations. This information is important in detecting biochemical changes such as amylose/amylopectin ratios and lipid content in these isolated starches.


4c.List any significant activities that support special target populations.
None


5.Describe the major accomplishments over the life of the project, including their predicted or actual impact.
Major accomplishments of this project include optimization of starch granule sizing methods. This is a critical development in the study of wheat starch size distribution as it allows analysis with the speed of LDS but the accuracy of IA. This will provide determination of environmental effects on starch granule size distributions and end-use functionality.


6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
Microfluidics system for cultivar identification is in early testing stages and we have held discussions with FGIS/GIPSA to obtain samples for library development and the resulting data will be shared with this agency.


7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
Waniska, R. D., Cepeda, M., King, B. S., Adams, J. L., Rooney, L. W., Torres, P. L., Lookhart, G. L., Bean, S. R., Wilson, J. D. and Bechtel, D. B. 2004. Effects of flour properties on tortilla qualities. Cereal Foods World 49:237-244.

Wilson, J. D. and Maningat, O. 2004. Symposium --Starch: Size Does Matter. Cereal Foods World 49:205.


Review Publications
Bechtel, D.B., Wilson, J.D. 2005. Endosperm structural changes in wheat during drying of maturing caryopses. Cereal Chemistry. 82:385-389.

Park, S., Chung, O.K., Seib, P.A. 2005. Effects of varying weight ratios of large and small wheat starch granules on experimental straight dough bread. Cereal Chemistry. 82:166-172

Park, S., Chung, O.K., Seib, P.A. 2004. Size distribution and properties of wheat starch granules in relation to crumb grain score of pup-loaf bread. Cereal Chemistry. Vol 81 (6): 699-704.

Tilley, M., Benjamin, R.E., Tilley, K.A. 2004. Non-enzymatic preparative-scale synthesis of dityrosine and 3-bromotyrosine. Analytical Biochemistry. 334:193-195

Tilley, M., Tilley, K.A. 2005. Modifying tyrosine crosslink formation in wheat dough by controlling innate enzymatic activity. p. 142-146. Using cereal science and technology for the benefit of consumers. Proceedings of the 12th ICC Cereal and Bread Congress. S.P. Cauvain, S.B. Salmon, and L.S. Young, eds. CRC Press. Boca Raton, FL.

Benjamin, R.E., Tilley, M., Reamer, E.M., Srivarin, P., Tilley, K.A. 2005. Detection of tyrosine crosslink in wheat kernels at various stages of development. Program Book of the 3rd International Wheat Quality Conference. 2005. Abstract p. 393. Meeting Abstract.

Tilley, M. 2005. Glucose oxidase effects on wheat flour albumins and gliadins. Program Book of the 3rd International Wheat Quality Conference. Meeting Abstract. p. 392

Tilley, M., Tilley, K.A. 2005. Tyrosine crosslink formation in wheat dough: Innate enzymatic activity. Program Book of the 3rd International Wheat Quality Conference. Meeting Abstract. p.392

Wilson, J.D., Bechtel, D.E. 2005. Laser diffraction sizing: studying wheat flour and starch particle sizes. Program Book of the 3rd International Wheat Quality Conference. Meeting Abstract. p.397

Wilson, J.D., Bechtel, D.B. 2004. Measuring wheat starch size distribution using image analysis and laser diffraction technology. Presented to the symposium titled "Starch: Size Does Matter" for the American Association of Cereal Chemists held in San Diego, CA, Sept. 19-22, 2004. Meeting Abstract.

Park, S., Bean, S., Wilson, J.D. 2005. Investigation of conditions for rapid cereal starch isolation using sonication. Program Book of the 3rd International Wheat Quality Conference. 2005. Abstract. p.397

Last Modified: 9/10/2014
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