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Preparative Method for In Vitro Production of Functional Polymers from Glutenin Subunits of Wheat

¹CSIRO Plant Industry, Grain Quality Research Laboratory, PO Box 7, North Ryde, NSW 1670, Australia; and Quality Wheat Cooperative Research Center Ltd., Locked Bag 1345, North Ryde, NSW 1670, Australia. ²Current address: School of Wine and Food Sciences, Charles Sturt University, Locked Bag 588, Wagga Wagga NSW 2678 Australia. ³Corresponding author. Phone: +61 2 9490 8437. Fax: +61 2 9490 8419. E-mail:f.bekes@pi.csiro.au

An in vitro method for preparative-scale production of artificial glutenin polymers utilizes a controlled environment for the oxidation of glutenin subunits (GS) isolated from wheat flour to achieve high polymerization efficiency. The functionality of in vitro polymers was tested in a 2-g model dough system and was related to the treatment of the proteins before, during, and after in vitro polymerization. When added as the only polymeric component in a reconstituted model dough (built up from gliadin, water solubles, and starch fractions), in vitro polymers could mimic the behavior of native glutenin, demonstrating properties of dough development and breakdown. Manipulating the high molecular weight (HMW)-GS to a low molecular weight (LMW)-GS ratio altered the molecular weight distribution of in vitro polymers. In functional studies using the 2-g mixograph, simple doughs built up from homopolymers of HMW-GS were stronger than those using homopolymers of LMW-GS. These differences may be accounted for, at least in part, by different polymer size distributions. The ability to control the size and composition of glutenin polymers shows the potential of this approach for investigating the effects of glutenin polymer size on dough function and flour end-use quality.