CONTRIBUTIONS OF PROTEIN-FRACTIONS TO DOUGH HANDLING PROPERTIES OF WHEAT RYE TRANSLOCATION CULTIVARS

Fractionation and reconstitution studies have been undertaken to assess the contribution of various flour components to dough stickiness and mixing properties, comparing rye translocation lines with their recurrent parents. For one line, approximately one third the stickiness originated in the water-soluble fraction and about two thirds in the gluten and, for another line, contributions from these two fractions each accounted for about half the stickiness. Reduction in the amount of water solubles below their natural level in the reconstituted flours improved Mixogram properties and decreased stickiness score. Similarly, dough stickiness was reduced by addition of flour protein fractions concentrated in glutenin proteins. When gluten was separated into two roughly equal fractions by differential solubility in dilute HCl, interchange experiments established that the difference in their effects on stickiness could be almost wholly attributed to the soluble portion. SE-HPLC revealed that the acid-soluble fraction from the translocation line SUN 89D had a lower proportion of glutenin than that of its parent Cook, whereas the HPLC profiles of the two acid-insoluble fractions were similar. SDS-PAGE analysis of protein fractions indicated that water-soluble and gluten acid-soluble fractions of translocation lines contained most of the rye secalins. The interchange experiments suggest that the weak and sticky dough properties of the translocation lines arise from a shift in the balance of the proportions of polymeric and monomeric proteins. This was supported by experiments in which this balance was varied by addition of specific protein fractions. © 1990, Academic Press Limited. All rights reserved.