## 3 Results and Discussion  
### Evaluation of the Physicochemical Properties  
The results obtained for moisture and color of the different samples of rice subjected to thermal treatment are shown in Table 1. In both rice samples, we observed a decrease in moisture content as the thermal treatment time increased (48.8-28.5 for white rice, and 55.7-38.8 for paella rice). Paella rice samples showed a higher moisture content, which may be due to the other added ingredients. Other researchers have determined the moisture distribution in rice grains during thermal treatment and obtained similar results where the moisture decreased with treatment time [20].  
Color is one of the most important sensory attributes for consumers. In this study, the color parameters (according to the CIELab color space) of the WR and P subjected to thermal treatment at different times were analyzed. Regarding the brightness parameter (L*), we observed higher values in WR compared to P (Table 1). This is in agreement with the CIELab space, in which more positive values of L* are associated with the color white. In both samples, L* decreases with increasing thermal treatment time. On the other hand, the a* parameter (green (\(-\)) to red (\(+\))), showed values close to 0 for white rice, suggesting grayish-white tones. However, in paella rice, the a* parameter showed higher positive values for treatments P1 to P3 (10.9-11.8), but decreased in P4 (4.1). These values justify the change in color of paella rice from yellow-orange for the first sampling times, to toasted-burnt on the last sampling time. Regarding the parameter b* (from blue (\(-\)) to yellow (\(+\))), higher values were obtained in paella rice due to the coloring added in its preparation. However, this color decreases with cooking time, appearing darker (brown), which coincides with a decrease in the values of the b* parameter. In white rice the b* parameter increases with the heat treatment, going from white to yellow tones. Other researchers have determined the color and other parameters to observe the temperature effect on the kinetics of the drying of cooked rice and its quality after rehydration [21],  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Treatments**} & \multicolumn{4}{c}{**White Rice**} \\ \cline{2-5}  & **Humidity (\%)** & **L* & **a* & **b* \\ \hline WR1 & 48.8 \(\pm\) 2.3 a & 73.4 \(\pm\) 3.0 a & \(-\)1.3 \(\pm\) 0.2 & 8.6 \(\pm\) 0.9 d \\ WR2 & 44.7 \(\pm\) 1.2 b & 67.4 \(\pm\) 3.2 b & \(-\)1.0 \(\pm\) 0.4 & 10.2 \(\pm\) 2.0 c \\ WR3 & 37.7 \(\pm\) 1.2 c & 60.9 \(\pm\) 5.0 c & \(-\)0.4 \(\pm\) 0.5 & 14.4 \(\pm\) 2.7 b \\ WR4 & 28.5 \(\pm\) 2.5 d & 45.3 \(\pm\) 6.9 d & 2.5 \(\pm\) 1.3 & 21.1 \(\pm\) 3.6 a \\ \hline \multirow{2}{*}{**Treatments**} & \multicolumn{4}{c}{**Paella**} \\ \cline{2-5}  & **Humidity (\%)** & **L* & **a* & **b* \\ \hline P1 & 57.7 \(\pm\) 1.2 a & 55.1 \(\pm\) 3.8 a & 10.9 \(\pm\) 1.3 a & 54.2 \(\pm\) 4.0 a \\ P2 & 51.1 \(\pm\) 1.1 b & 57.3 \(\pm\) 6.2 a & 11.8 \(\pm\) 1.4 a & 56.7 \(\pm\) 6.3 a \\ P3 & 47.8 \(\pm\) 1.1 c & 47.4 \(\pm\) 3.5 b & 11.8 \(\pm\) 0.6 a & 48.9 \(\pm\) 3.2 b \\ P4 & 38.8 \(\pm\) 2.2 d & 18.7 \(\pm\) 2.9 c & 4.1 \(\pm\) 2.2 b & 11.4 \(\pm\) 6.1 c \\ \hline \hline \end{tabular}
\end{table}
Table 1: Moisture and CIELab color of white rice and elaborated paella. Results are expressed as mean \(\pm\) standard deviation (SD) of three replicates. Different lowercase letters mean statistically significant differences between samples (\(p<0.05\)). WR: white rice; P: paella.  
and they have also determined the color in samples of olives subjected to heat treatments, observing their evolution towards a brownish shade.