2009 Annual Report
Multi-instrument SKCS comparisons and calibrations with researchers in Kansas, Nebraska, and Texas will be completed. The effect of environment on protein content and composition of isolated hard and soft endosperm fractions will be determined. Wet milling, dry milling, extrusion and fermentation quality of selected sorghum lines will be conducted. Color compounds, phenolics, and other small molecules in sorghum from weathered and sound grain; evaluate grains for markers of insect and fungal damage and infestation will be characterized and cataloged.
Exotic germplasm will be evaluated for desirable processing traits (e.g. ethanol yield). GxE stability of processing quality in sorghum lines showing desirable processing traits will be evaluated. Impact of compounds found in sorghum grains as a result of weathering, mold, insects, or fungal invasion on food and processing quality will be determined. Processing methods to reduce or eliminate impact of environmental damage will be investigated.
Improved techniques for extracting and analyzing sorghum proteins will be developed. Methods for extracting and purifying sorghum proteins for industrial and food applications will be determined. Formulations for the production of wheat free sorghum foods from batter type systems will be optimized.
Optimization of batter type product formulations for production of wheat free sorghum based foods will be continued. Visco-elastic dough formation in artificial sorghum protein-starch dough systems will be investigated and changes to sorghum proteins during mixing will be elucidated and compared to wheat proteins during mixing. Methods for disruption of sorghum protein bodies in sorghum flour to free proteins for interaction during mixing will be developed. Starch and protein content and composition from diverse sorghum lines will be determined and related to ethanol and lactic acid yields. The extent of protein-protein interaction and protein-starch interaction in artificial sorghum dough systems will be determined. Methods for the use of reduction-oxidation systems to form a visco-elastic dough directly from sorghum flour will be developed. Sorghum proteins and starch will be modified to improve functionality in food. Pre-treatment methods for altering protein and starch composition in sorghum for improved ethanol and lactic acid yields will be developed.
Several fungi, including Fusarium thapsinum (FT) and Curvularia lunata (CL), colonize sorghum grain during development. Several sorghum lines (Sureno, Tx2911, SC170, BTx623, BTx631, and Tx430) were experimentally infected at anthesis with both pathogens. Using the single kernel characterization system (SKCS), grain was measured for hardness, weight, moisture and diameter. Total protein and kafirins (gamma and non-gamma) were also measured. SKCS data indicated that inoculations with FT and CL reduced weight and diameter of harvested grain. Inoculations had a significant effect upon total protein accumulation in grains (P < 0.05); the response varied by genotype and treatment. Levels of gamma-kafirin also varied by genotype and treatment, whereas non-gamma varied by genotype only. Gamma-kafirin content and hardness increased in FT- and CL-inoculated 'Sureno' (GMR). Further studies are needed to elucidate the underlying structural characteristics associated with high quality grain and resistance to GM fungi. One factor related to mold resistance in sorghum is the level of phenolic compounds. Phenolic compounds were measured in a set of sorghum hybrids developed at different time periods during the last 40 years. Phenolics were measured in these samples to determine if major changes in the grain were seen over time.
Sorghum based food production: Visco-elastic dough formation in two different proteins was studied. We had previously shown that visco-elastic dough could be formed from isolated zein (maize proteins). Our research has focused on using zein as they are commercially available and therefore can easily be obtained on a sufficient scale for baking experiments. Since the zein proteins must first be isolated before they are functional, research was conducted to examine the effect of the isolation procedure on zein functionality. Proteins were also extracted from sorghum flour and the effect of isolation on their functionality examined. For the zeins, it was found that removal of lipids during the extraction appears to be a key factor in their functionality. Furthermore, the mechanism of dough formation in zein appears to be substantially different from what occurs in wheat proteins. A second type of protein, carob germ flour, was used to form visco-elastic dough. This protein was capable of forming dough without first isolating it. Bread quality of carob based dough was compared to that of wheat and sorghum breads. Carob proteins were characterized by techniques typically used to characterize wheat proteins to gain a better understanding of how they are able to form dough. It was found that unlike zein, the carob proteins appeared to form dough along similar lines as wheat proteins do.
Park, S., Arthur, F.H., Bean, S., Schober, T.J. 2008. Impact of differing population levels of Rhyzopertha dominica (F.) on milling and physicochemical properties of sorghum kernel and flour. Journal of Stored Products Research 44: 322-327.
Zhao, R., Bean, S., Wang, D. 2008. Sorghum Protein Extraction by Sonication and Its Relationship to Ethanol Fermentation. Cereal Chem. 85:837-842.
Zhao, R., Bean, S., Wu, X., Wang, D. 2008. Assessing fermentation quality of grain sorghum for fuel ethanol production using rapid visco-analyzer. Cereal Chem. 85:830-836.
Schober, T.J., Bean, S. 2008. Sorghum and Maize. In: Arendt, E.K. and Bello, F.D. editors. Gluten-Free Cereal Products and Beverages. Academic Press. Chapter 5. p. 101-118.
Schober, T.J., Bean, S., Boyle, D.L., Park, S. 2008. Improved viscoelastic zein-starch doughs for leavened gluten-free breads: Their rheology and microstructure. Journal of Cereal Science. 48:755-767.
Schober, T.J., Bean, S., Wang, D. 2009. Capillary Electrophoresis as a Tool for Evaluating Lactic Acid Production from Sorghum. Cereal Chemistry. 86(2):117-121.
Sang, Y., Bean, S., Seib, P.A., Pedersen, J.F., Shi, Y. 2008. Structure and Functional Properties of Sorghum Starches Differing in Amylose Content. J of Agric Food Chem. 56:6680-6685.