**5. References**

256 Viscoelasticity – From Theory to Biological Applications

(w/w)/GX=0.42-0.7% (w/w) (Figs. 10 (a,b,c).

**4. Conclusions** 

**Author details** 

 \*

*Hermosillo, Sonora, México* 

Corresponding Author

Luis Carlos Platt-Lucero, Benjamín Ramírez-Wong\*

Patricia Isabel Torres-Chávez and Ignacio Morales-Rosas

*Universidad de Sonora, Departamento de Investigación y Posgrado en Alimento,* 

Maximum force**.** Changes in MF of tortilla made from ENCFs were affected by the linear term of moisture content (MC, p < 0.01), quadratic of moisture content (MC)2, p < 0.01) and the combinations of temperature-moisture content [(T)(MC), p < 0.10] and temperature-gum

The regression model explained 82% of the total variation (p < 0.01) of MF of tortilla made from ENCFs. Figs. 10(a,b,c) show the effect of MF in tortilla made from ENCFs as a function of T, MC and XG, observing that at any value of moisture content for conditioning starting at approximately the midpoint of the matrix, the maximum force is increased due to the quadratic effect. The lowest value (46.16 kPa) was shown at T=115 - 130°C/MC=30.69-34.87%

The superimposition of contour plots of the effect of variables of the extrusion process (T, MC and XG) on WAI of flour, Gʹ, Gʹʹ and Tan δ of masa, and MF of tortilla made from ENCFs, was used to obtain Figs. 11 (a,b,c), which in turn was utilized to determine the best combinations of the extrusion process variables. The central points of the regions of optimization in Figs. 11 (a,b,c) correspond to the values of the process variables of T=111.77°C/MC=28.84%, XG=0.66%/T=122.17°C and XG=0.65%/MC=29.42%, respectively. The optimal combination for the operation conditions of the single-screw extruder derived from the averages of those values were: T=116.67°C/MC= 29.13%/XG = 0.65%. The optimal conditions were validated using experiments, which were similar to those values predicted by RSM. These values can be used to obtain ENCF with the highest WAI and WAC, and

The viscoelastic parameters (Gʹ, Gʹʹ, and Tan δ) were affected by xanthan gum concentration, inducing a weakening of the existing structure of masas from extruded nixtamalized corn flour. Tortillas from masas with high values of Tan δ improved their textural characteristics. The optimal combination of variables to obtain ENCF using a single-screw extruder was: T=116.67°C/MC= 29.13% / XG= 0.65%. The optimal conditions were validated experimentally, and results were similar to those values predicted by RSM. Besides the information of basic nature that can be obtained with the dynamic method, it can be considered a practical

rhelogical tool capable of differentiating masa from extruded nixtamalized corn flours.

,

tortillas with less firmness (softer) and more flexibility (more rollable).

0 0 <sup>0</sup> <sup>2</sup> Y 14.75 – 7.36MC – . 4 T MC – 1.17 T XG .2 MC MF (5)

[(T)(XG), p < 0.01]. The prediction model in terms of original variables for MF was:


Harper. J.M. 1989 Foods extruders and their applications. In "Extrusion Cooking". C. Mercier, P. Linko y J.M. Harper (ED). American Association of Cereal Chemists. St. Paul, MN, EUA. Pp. 1-15.

**Chapter 12** 

© 2012 Magaña-Barajas et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

**Use of the Stress-Relaxation and Dynamic** 

**of Dough from Soft Wheat Cultivars** 

called soft, and they are used in products such as cakes and cookies.

Elisa Magaña-Barajas, Benjamín Ramírez-Wong, Patricia I. Torres-Chávez and I. Morales-Rosas

Additional information is available at the end of the chapter

dough, so it can be handled and utilized properly.

fraction of glutenin contributes to the resistance of the dough.

http://dx.doi.org/10.5772/45993

**1. Introduction** 

**Tests to Evaluate the Viscoelastic Properties** 

Wheat is the only cereal capable of produce strong and cohesive dough, qualities responsible for the wide variety of food products made from it. In Mexico, wheat is classified into five groups based on functionality; those wheat varieties in group three are

Wheat dough is classified as viscoelastic material (Faubion & Hoseney, 1990) which has elastic and viscous characteristics conferred by gluten. Gluten network is formed by hydrophobic interactions between water and protein polymers of the flour (mainly glutenins and gliadins). The nature of the glutenin mainly influences the functional properties of strength and elasticity, while the gliadin fraction provides extensibility and viscosity to the dough (Lu & Grant, 1999). Studies have been conducted in search of those factors that influence dough's viscoelastic properties to better understand the behavior of

Smith et al. (1970) utilized the dynamic test in a gluten-starch-water system and found that high protein content is reflected in high values of the storage module (G´) and loss module (G´´). Besides protein content, it has been found that the soluble protein fraction is a determinant factor for the rheological properties of dough by acting as a lubricating agent (Rouille et al., 2005). The importance of the total gliadin fraction in the structure of gluten was observed by Lee & Mulvaney (2003). Gupta et al. (1993) utilized an extensograph to evaluate doughs and found a high correlation between unextractable proteins and maximum resistance (Rmax), which led them to believe that a high molecular weight

and reproduction in any medium, provided the original work is properly cited.

