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ARS Home » Plains Area » Manhattan, Kansas » Center for Grain and Animal Health Research » Grain Quality and Structure Research » Research » Publications at this Location » Publication #226041
Title: Modification of sorghum proteins for enhanced functionality

Author
item DE MESA, N. JHOE - KANSAS STATE UNIVERSITY
item ALAVI, SAJID - KANSAS STATE UNIVERSITY
item Bean, Scott
item Schober, Tilman

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/15/2008
Publication Date: 9/21/2008
Citation: De Mesa, N.E., Alavi, S., Bean, S., Schober, T.J. 2008. Modification of sorghum proteins for enhanced functionality. Meeting Abstract. Cereal Foods World. 53:A56.

Interpretive Summary:

Technical Abstract: Sorghum is the third most widely produced crop in the United States (U.S.) and fifth in the world during fiscal year 2006/07(USDA-FAS, 2007). The use of sorghum in foods faces functional and nutritional constraints due, mainly, to the rigidity of the protein bodies. The disruption and modification of these protein bodies can improve protein functionality and increase the use of sorghum in food applications. This study explores various ways to achieve this, including extrusion processing with the simultaneous conjugation of sorghum proteins to sugars. Sorghum flour (SF) and a sorghum flour-dextrose (SFD) blend (2:1 by weight) were processed in a twin-screw extruder at two barrel temperature settings (low or = 80 degrees Celsius and high or = 100 degrees Celsius), two extruder screw speeds (165 and 225 rpm) and varying in-barrel moisture contents (MC; 11-37% wet basis). Sorghum proteins from extruded SF and SFD were sequentially extracted with water and sodium dodecyl sulphate (SDS), followed by size exclusion-high performance liquid chromatography (SE-HPLC). SE-HPLC of SDS extracts more efficiently differentiated treatments. The molecular weight distribution of proteins extracted from extruded SF and SFD were higher than those of kafirin monomers. Dextrose increased protein solubility in both water and SDS. Higher MC increased protein solubility, while increasing processing temperature reduced it. Protein solubility was greater at higher screw speeds only at the lower process temperature. In general, lower specific mechanical energy (SME) input during extrusion resulted in higher protein solubility. Confocal scanning laser microscopy (CSLM) micrographs of representative sorghum extrudates showed disruption of the protein matrix during the extrusion process. Making sorghum proteins digestible and available for interactions opens avenues for applications in gluten-free food products. In addition to thermo-mechanical treatments, research is underway on enzymatic and chemical methods of modifying sorghum proteins.