45 Comparison of small and large deformation measurements of wholemeal rye doughs.

K. AUTIO (1), R. Heinonen (2), and A. Kinnunen (3). VTT Biotechnology and Food Research, P.O. Box 1500, FIN- 02044 VTT.

The rheological properties of ryeflour-water-salt doughs prepared from different flour types (different falling number and coarseness) at different water levels were studied after mixing and after 90 min incubation (30 and 80% humidity). Both the effect of water and the coarseness of the flour had significant effects on both storage modulus (G’), measured by oscillatory test in the linear viscoelastic region, and on compressional force measured at large deformation. The results of the two rheological methods correlated very well with each other (correlation coefficients varied in the different doughs in the range of 0.975– 0.999). Both measurements suggested that falling number did not have a statistically significant effect on dough rheology after mixing or incubation. Although the two rheological methods correlated well, the responses for incubation were different. In the small deformation method, the storage modulus of all doughs, independent of the falling number, decreased during incubation whereas in the large deformation method, only the hardness of doughs made from flours with lower falling number decreased during incubation.