# Effect of Cooking Methods on Bioactive Pigments in Purple Carrots (_Daucus carota_ L.)
## 3 Results and Discussion  
Figure 1 depicts purple carrots subjected to different cooking methods. Table 1 represents the water content of purple carrots estimated gravimetrically after cooking. Table 2 summarizes TCC (\(\mu\)g \(\beta\)-carotene equivalent g\({}^{-1}\) DW), TPC (\(\mu\)g Trolox equivalent g\({}^{-1}\) DW) and TAC (\(\mu\)g C3G equivalent g\({}^{-1}\) DW) in purple carrots cooked by different procedures. Data are expressed as mean values (\(n=2\)) \(\pm\) SD. Different lowercase letters between the sample subjected to each cooking method and fresh carrots (used as a reference) indicate differences at \(p<0.05\). First, it is interesting to highlight the contents of bioactive \begin{table}
\begin{tabular}{c c} \hline \hline
**COOKING METHOD** & **WATER CONTENT (\%)** \\ \hline Fresh & 85.3 \\ \hline Freeze-drying & 14.1 \\ \hline Boiling & 93.0 \\ \hline Steaming & 86.4 \\ \hline Roasting (10 min) & 81.2 \\ \hline Roasting (20 min) & 73.0 \\ \hline Roasting (30 min) & 58.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Water content (%) of purple carrots cooked by different methods. Figure 1: Purple carrots (_Purple Haze_ variety) cooked by different methods. pigments in fresh purple carrots. As seen in the table, particularly high TCC was measured in uncooked carrots (i.e., 1136.66 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW). Contradictory results on TCC in purple carrots have been reported in the literature. Whereas some authors have found considerably lower TCC in purple carrots than in typical orange varieties [4], others have described twice the \(\upalpha\)- and \(\upbeta\)-carotene content in purple carrots as compared with orange carrots [21]. In any case, carotents in carrots have been reported to vary within a wide range depending on various factors such as genotype, climatic factors, degree of ripening, etc. [22]. From Table 2, TPC and TAC values measured in the fresh material were slightly lower than those reported in the literature for purple carrots [18; 23]. In fact, TPC data were closer to those published for the typical orange carrots than for purple carrots [18]. Regarding the influence of cooking, it was seen that different effects were observed according to the method used. Freeze-drying resulted in significant (\(p<0.05\)) losses of TCC (51.2% off) when compared with fresh carrots. It is possible that the accessibility of carotenoids decreases as a consequence of the extremely low water content in freeze-dried samples. Although freeze-drying is a well-known technique to preserve food quality, optimization of variables is regarded as essential to avoid losses of bioactive phytochemicals [24]. However, TPC and TAC values increased significantly (\(p<0.05\)) in freeze-dried carrots with respect to the fresh material (from 66.71 to 2919 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW and from 4.83 to 364.78 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW, respectively). The promoting effect of freeze-drying on phenolics has already been observed in other vegetables [25]. It is believed that freeze-drying brings about structural changes during the freezing in such a way that different metabolic pathways may lead to the conversion of other compounds into phenolic compounds and their accumulation. Further, large molecular weight phytochemicals might break down into smaller compounds, which can increase the measurements. In contrast to freeze-drying, boiling resulted in the highest values of TCC (3245.61 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW) but the lowest values of TPC (15.71 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW) and TAC (1.41 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW) out of all the cooking methods. In fact, the drop of TPC (from 66.71 to 15.71 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW) and TAC (from 4.83 to 1.41 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW) measured in boiled purple carrots was particularly significant (\(p<0.05\)) as compared with uncooked samples. These results are directly associated with the different polarity of the pigments studied.