**4. Conclusions**

268 Viscoelasticity – From Theory to Biological Applications

τ: relaxation time.

**Figure 4.** Relaxation modulus, G (t) vs time of dough from soft wheat cultivars, at 15% of deformation.

The relaxation time was the parameter showing the greatest difference among the soft wheat cultivars. However, the differences obtained in τ among dough from the soft wheat cultivars were less than estimated. This despite to the range of low protein content of the soft wheat cultivars (10 to 12%, approximately), and besides, the fraction of gliadin and glutenin were of low molecular weight and approximately similar in all the samples (70% gliadin and 30% glutenin of low molecular weight, data not shown). This could indicate that tests used to evaluate the viscoelasticity in dough were high sensibility being capable to characterize dough from different soft wheat cultivars. Characterization and differentiation of dough was better with the stress-relaxation test than with the dynamic test, coinciding with others authors (Lee and Mulvaney, 2003; Rao et al., 2000; Uthayakumuran et al., 2002; Wikström &

Eliasson,, 1998; Yadav et al., 2005; Safari-Ardi et al., 1997).

correlations *(r)* were performed.

*3.2.3. Correlations between viscoelastic characteristics and other determinations* 

To determine if there were significant relations among the viscoelastic properties of dough from soft wheat cultivars, and physicochemical and rheological evaluations in flours, simple

Five significant correlations were found among the viscoelastic characteristics and physicochemical determinations. Regarding to the stress-relaxation test, there were four highly significant correlations (p<0.01). The relaxation time (τ) showed a strong correlation The viscoelastic characterization of dough made from flours of soft wheat cultivars was achieved by fundamental tests. The soft wheat cultivar showed to be a determinant factor in all characteristics of the flour. Apparently, the strength of the gluten network is critical in the rheological and viscoelastic characteristics of dough. All the cultivars presents more viscous behavior than elastic behavior (Tan δ>0.5). Wheat varieties evaluated showed a range τ of between 0.33 to 0.41 s.

The stress-relaxation test was better than the dynamic test in differentiating the viscoelastic characteristics of the soft wheat dough. This is confirmed by the highest number of correlations relative to the stress relaxation test, compared with the dynamic method. In our case, τ offers more information than that of G0, making it an important parameter for characterizing dough. Parameters most affecting τ was content and quality of the protein moisture content and falling number in flours. The stress-relaxation test is a simple and rapid method to perform viscoelastic evaluations, and it is believed to be a technique suitable for the characterization and differentiation of viscoelastic characteristic among dough made from soft wheat cultivars, which is important for determining the final use.
