Comparison of small and large deformation measurements of whole meal rye doughs

The rheological properties of rye flour-water-salt doughs prepared from dif ferent flour types (different falling number and coarseness) at different w ater levels were studied after mixing and after 90 min of incubation (30 de grees C and 80% rh). Both the effect of water and the coarseness of the flo ur had significant effects on 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 differen t doughs at r = 0.975-0.999). Dough rheological measurements suggested that falling number did not have a statistically significant effect on dough rh eology after mixing or incubation. Although the two rheological methods cor related well, the responses for incubation were different. In the small def ormation method, the storage modulus of all doughs, independent of the fall ing number, decreased during incubation, whereas in the large deformation m ethod, only the hardness of doughs made from flours with lower falling numb er decreased during incubation. The rheological measurements of doughs afte r mixing and the viscosity measurements of flour-water suspension at 30 and 40 degrees C did not correlate with each other. Total pentosans have great effect on viscosity measurements of flour-water suspensions, whereas flour particle size and soluble pentosans correlated more with rheological prope rties of doughs (r = 0.851 between G' and soluble pentosans).