Cereal Chemist

• DISCIPLINE:
  Cereal Chemistry
  
  
• AREA OF EXPERTISE:
  Cereal chemistry and technology
  
  
• GENERAL AREAS OF RESEARCH:
• Wheat gluten visco-elasticity evaluation using new methods of analysis; relationships between wheat dough extensibility and strength and gluten polymeric structure; studies on dough properties, dough chemistry and end use acceptability; contribution to the understanding at the molecular level of the effect of ingredients on the functionality of gluten and dough, specifically on their mechanical properties.
• CONTACT:
  Address: Oklahoma State University
  Robert M. Kerr Food & Agricultural Products Center
  123 FAPC
  Stillwater, OK 74078
  Phone: 405-744-6468
  Fax: 405-744-6313
  E-mail: pat.rayas_duarte@okstate.edu
  
  

• CURRENT RESEARCH PROJECTS:
  
  
• Material properties of wheat gluten polymers and contributions of covalent and non-covalent bonds to their structure.

We focused on the structure attributes of gluten polymers and their relationship with key end products quality indicators. The structure of gluten polymers is studied directly with rheological tests and indirectly by polymer selective solubility (a function of their molecular size), charge-to-mass ratio and interactions in the form of inter- and intra-chains of proteins by modulating specific covalent and non-covalent bonds.

Selected attributes were studied by rheological tests and modeling of the response of the structure by the evaluation of quantitative differences of the coefficients of elasticity, retarded elasticity and viscosity. Correlations with empirical quality indicators used in the form of baking and mixing properties have revealed complementary information of the material properties of gluten.

We also studied the effects of hydrogen-disrupting agents on the viscoelastic properties of gluten using a creep-recovery test by applying 40 Pa shear stress. The creep-strain response was fitted with a Burgers model (r2>0.999, P<0.001). The pure elastic, retarded elasticity and viscous flow coefficients from creep-strain modeling complemented the information obtained from evaluation parameters of quality of dough mixing and baking, while the latter ones provided redundant information. Our team compared the contribution of covalent bonds to quality predictors and related them to gluten elastic and flow properties.

• Test of gluten elastic, viscoelastic and viscous properties of the genotypes from OSU hard red winter wheat breeding program.

We analyzed the rheological properties of advanced wheat breeding lines and cultivars from the OSU breeding program using creep-recovery and compression-recovery tests. The tests were carried out on isolated gluten from flour and its response under the mentioned tests described the polymeric material behavior at the molecular level. Our lab team is analyzing the correlations with commonly used indicators of quality in the form of mixing, fermentation and bread-making properties. These are important contributions to understand the functionality of the gluten based on the formation of polymer chains with different properties.



• Biochemical properties of cryoprotective active compounds.

The Rayas-Duarte laboratory is part of an international team analyzing cryoprotective compounds from vegetable origin that safeguards the quality of frozen dough. This lab completed the characterization and yeast cryoprotective performance for thermostable ice-structuring proteins from Ligustrum vulgare leaves.

We extracted and partially characterized proteins with thermostability and cryoprotective properties from Privet leaves. The lab studied the effects of such extracted proteins on physicochemical properties of yeast cells and dough. The extract prevented breakdown of gluten proteins in frozen yeast suspension dough. It also improved rheofermentation of frozen yeast suspensions doughs.