## 3 Results and Discussion
### Quality Characterization of the Gluten-Free Bread  
#### 3.3.1. Bread Crumb Texture and Hardening Kinetics  
Bread crumb firmness is an important parameter used to evaluate the bread quality, that influences the consumers acceptability. To measure the effect of Cc addition on bread firmness, during 4 days of storage time (96 h), a puncture test was applied [12; 16; 18], to mimic the teeth chewing of the human sensory perception. The mean values of bread crumb firmness (BCF) of CB and CcB are illustrated in Figure 3, showing that for all Cc amounts tested, bread crumb was softer than for CB, as the Cc levels increase in GFB formulations. Figure 2: Rheology changes in viscoelastic functions, storage (G’, full symbols) and loss (G”, empty symbols) moduli, by the additions of curd cheese to dough (CcD5% up to CcD20% _w/w_), compared with viscoelastic profile of the control dough (CD) (black round symbols): **(A)** CD vs. Cc5%; **(B)** CB vs. Cc10%; **(C)** CB vs. Cc15%; **(D)** CB vs. Cc20%. Initial and final values of BCF varied from 2.70 N to 6.50 N for CB and 1.12 N to 2.30 N for CeB20%, representing a reduction on the firmness of around 55% (initial) and 65% (final). This behavior suggests a high functionality of the denatured WP in breadmaking performance. Higher firmness values of CB seem to be consistent with high viscosity and viscoelastic moduli values exhibited for CD, probably due to stiffer structure effect promoted by xanthan gum, reducing the dough expansion, consequently leading to firmer breads. Similarly, [PERSON] et al. [21] reported an increase of BCF by xanthan gum addition in GFB. Staling of bread during the storage time is a consequence of humidity loss, and subsequent starch crystallization/retrogradation phenomena, leading to an increase of crumb firmness values [28]. Linear correlations were determined to describe the staling kinetics of the GFB, under controlled storage conditions (96 h at room temperature). The obtained linear parameters, summarized in Table 4, reflects the influence of Cc incorporations on the bread staling rate (Equation (2)). The Cc bread staling rate values were substantially lower than CB value, ranging from 0.032 N/h for lower incorporation (CcB5%) to 0.012 N/h for higher additions (CcB20%), compared to 0.040 N/h obtained for CD, a reduction about 70% of staling. Results reported by [PERSON] et al. [13], by evaluating the effect of dairy powder addition on GFB shelf-life, are similar with those obtained. These findings are also in line with those obtained by other researchers [12], by testing the fresh dairy products addition to improve the wheat bread quality. The functionality of the Cc protein should be considered to explain these results of bread texture and bread aging rate, whose positive effects can be associated to the capability of these proteins to bind with water and retain moisture, retarding the starch retrogradation and hence the increase of bread hardness [14]. On the other hand, these results suggest that the denatured WP relaxes the \begin{table}
\begin{tabular}{c c c c} \hline
**Cc Levels** & **Staling Rate (N/h)** & **Firmness (N)** & **R2** \\ \hline CB & 0.040 \(\pm\) 0.001 a  & 2.70 \(\pm\) 0.23 a  & 0.996 \\ CcB5\% & 0.032 \(\pm\) 0.002 ab  & 2.21 \(\pm\) 0.40 ab  & 0.998 \\ CcB10\% & 0.022 \(\pm\) 0.001 c  & 1.90 \(\pm\) 0.30 b  & 0.981 \\ CcB15\% & 0.020 \(\pm\) 0.003 c  & 1.57 \(\pm\) 0.09 c  & 0.979 \\ CcB20\% & 0.012 \(\pm\) 0.002 d  & 1.12 \(\pm\) 0.15 d  & 0.972 \\ \hline \end{tabular} Different superscripts (a, b, c, d) indicate significant statistical differences between CB and CcB: CcB5% up to CcB20% (at \(p\leq\) 0.05, Tukey test); A and B linear parameters were obtained by Equation (2): Firmness = A \(\times\) time + B.  
\end{table} 
Table 4: Linear parameters derived by linear correlation (R2 \(>\) 0.972): A—bread staling rate (N/h) and B—initial bread firmness (N), for control bread (CB) and curd cheese bread obtained (CcB).