142 Rheological properties of durum wheat semolina doughs enriched with gluten protein fractions.

N. M. EDWARDS (1), J. E. Dexter (1), and M. G. Scanlon (2). (1) Canadian Grain Commission, Winnipeg, Canada R3C 3G8; (2) Dept. of Food Science, University of Manitoba, Winnipeg, Canada R3T 2N2.

Gluten, gliadin and glutenin were isolated from 4 durum wheat cultivars varying in strength, and were subsequently used to enrich a base semolina on a constant protein basis (increase of approx. 1% protein). Mixing curves were obtained using a 2g direct drive mixograph. Curves derived from gluten enrichment were similar to those of the semolina from which the gluten was extracted. Addition of gliadin, in all cases, resulted in decreased mixing times, while addition of glutenin resulted generally in increased mixing time, bandwidth and work input. Doughs prepared by mixing to 1 minute past peak were subjected to creep recovery (large deformation) and dynamic (small deformation) measurements in shear mode to provide information on both extensibility (indicated by creep maximum % strain) and ‘strength.’ Gliadin addition resulted in decreased storage moduli (G’) and increased tan delta (G”/G’) relative to the corresponding doughs with added gluten, and increased extensibility as measured by creep maximum % strain. In contrast, enrichment with glutenin led to increased G’ and loss moduli (G”) and decreased tan delta relative to their corresponding gluten enriched doughs, and decreased creep maximum % strain. Qualitative differences in gliadin and glutenin fractions appeared to have little influence on either oscillatory or creep results.