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Storage of Wheat Grains at Elevated Temperatures Increases Solubilization of Glutenin Subunits

¹Faculty of Agriculture, Food and Natural Resources, The University of Sydney, NSW, 2006 Australia. ²Corresponding author. Phone: +61 2 9351 2439. Fax: +61 2 9351 5108. E-mail: m.wilkes@usyd.edu.au

Grains of two wheat (Triticum aestivum L.) cultivars, Sunco and Sunsoft, were stored at 4°C and 30°C for 270 days to examine changes in proteins during storage. When whole meal flour extracted from the grains was analyzed using an unfractionated protein extraction procedure, no significant changes were found in protein content or SDS-PAGE profile for either cultivar in samples stored at 30°C compared with those stored at 4°C. Fractionation of the flour samples from stored grain into soluble and insoluble proteins revealed increases in soluble protein content for both cultivars stored at 30°C compared with 4°C. The soluble protein content, expressed as a percentage of the total protein, increased by 1.5% (P = 0.032) for Sunco and by 8.0 % (P = 0.158) for Sunsoft during storage at 30°C compared with those samples stored at 4°C. Analysis by SDS-PAGE and subsequent protein identification revealed that the most evident change that occurred during storage at 30°C was an increase in the content of high molecular weight glutenin subunits (HMW-GS) in the soluble fraction. The potential effect of changes in solubility of HMW-GS on functional properties is discussed.