# Effect of Cooking Methods on Bioactive Pigments in Purple Carrots (_Daucus carota_ L.)
## 3 Results and Discussion
These compounds are able to stabilize anthocyanins by interaction with the resulting aglycone during thermal degradation. All in all, boiling was the cooking method with the highest ability to release carotenoids from purple carrots, whereas freeze-drying would be recommendable in terms of TPCs and TACs. That said, it is also important to bear in mind the relatively high contents in bioactive pigments, in general, in roasted purple carrots. This, together with the palatability attributed to roasting, makes this cooking method an attractive procedure, from both sensorial and nutritional standpoints. Table 3 represents the individual anthocyanins identified and quantified in fresh purple carrots (i.e., uncooked) and cooked by different methods by HPLC-DAD. Data are expressed as mean values (\(n=2\)) \(\pm\) SD. The HPLC chromatograms corresponding to the anthocyanin profile of purple carrots cooked by different methods are depicted in Figure 2. From Table 3 and Figure 2, it is observed that purple carrots contain basically acylated anthocyanins. The major anthocyanins were cyanidin-based, containing different sugar moieties non-acylated (numbered as 1 and 2), or acylated with sinapic acid (number 3), ferulic acid (number 4) and coumaric acid (number 5). The predominant anthocyanin was cyanidin-3-xylosyl-glucosyl-galactosyl acylated with ferulic acid (numbered as 4), which is typical of purple carrots. Its content was 9.76 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW in fresh purple carrots and represented more than 50% of the total anthocyanins in all cases. Both the anthocyanin qualitative profile and the total content measured in fresh purple carrots agreed well with the literature [18; 32]. It is worth mentioning that the total amount of anthocyanins measured was in general higher than the TAC values previously observed (see Table 2). This is most likely due to interferences in the TAC method, which might prevent anthocyanins from exhibiting. As expected, the effect of the different cooking methods on individual anthocyanins was the same as that previously observed in TAC (see Table 2). As seen in both Table 3 and Figure 2, boiling resulted in major losses of anthocyanins (5.72 \(\upmu\)g\(\cdot\)g\({}^{-1}\) vs. 12.56 \(\upmu\)g\(\cdot\)g\({}^{-1}\) in fresh carrots) while freeze-drying was the method that enabled them to be preserved the most. In fact, total anthocyanins in freeze-dried carrots increased considerably with respect to the reference value measured in the fresh material (1937.39 \(\upmu\)g\(\cdot\)g\({}^{-1}\) vs. 12.56 \(\upmu\)g\(\cdot\)g\({}^{-1}\)). Similar to TAC, steaming did not lead to the loss of anthocyanins. This reflects that steaming is a procedure gentle enough for anthocyanins not to be degraded. Once more, roasting also  
represented a more moderate option, particularly when applied for 20 and 30 min. As seen, anthocyanins did not increase as much as they did after freeze-drying (i.e., 1937.39 \(\upmu\)g-1), but their improvement was in any case noteworthy (i.e., 103.75 and 198.21 \(\upmu\)g-1 after roasting at 20 and 30 min, respectively, vs. 12.56 \(\upmu\)g-1 in uncooked samples). These results are also in accordance with those reported elsewhere [18]. Table 4 indicates the AA in terms of free radical scavenging activity measured by DPPH (mg Trolox equivalent g-1 DW) and ABTS (mg Trolox equivalent g-1 DW) assays. 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  
Figure 2: HPLC chromatogram of the purple carrots cooked by different methods recorded at 520 nm (**a–e**). Anthocyanin identification: 1. Cyanidin 3-xylosylglucoseoside, 2. Cyanidin 3-xylosylgalactoside, 3. Sinapic acid derivative of cyanidin 3-xylosylglucoseosylgalactoside, 4. Ferulic acid derivative of cyanidin 3-xylosylglucoseosylgalactoside, 5. Coumaric acid derivative of cyanidin 3-xylosylglucoseosylgalactoside. differences at \(p\) < 0.05.