Relationship between flour protein composition determined by size-exclusion high-performance liquid chromatography and dough rheological parameters

The relationship between protein composition, measured by size-exclusion high-performance liquid chromatography (SE-HPLC), and rheological dough properties, evaluated by alveographic test, were investigated in bread wheat cultivars grown at two locations in North and Central Italy. Total polymeric proteins were separated into two size groups on the basis of their solubility in 2% sodium dodecyl sulfate-phosphate buffer with and without reducing agents. Relative and absolute amounts of total polymeric proteins, determined by SE-HPLC after sonication, showed variable (nonsignificant to significant) relationships with rheological properties, particularly dough tenacity (alveographic index P) and strength (alveographic index W). On the other hand, absolute or relative amounts of insoluble polymeric proteins correlated positively with dough strength and tenacity and accounted for up to 30-40% more variation in these parameters than did total polymeric proteins. Correlations of both absolute and relative amounts of soluble polymeric proteins with dough strength and tenacity were not significant and significantly negative, respectively, whereas the correlation with dough extensibility (alveographic index L) was significantly positive