## 3 Results and Discussion  
In general, for each variety, sweet potatoes with peel had a higher total phenolics profile when compared to sweet potatoes without peel that were prepared through the same cooking method, which indicated that the peel retained this property even when different culinary processes were used (Figures 1-3). However, exceptions were observed in boiled and microwaved purple sweet potatoes (Figure 1) and boiled orange sweet potatoes (Figure 2). The raw purple sweet potato with peel, when compared to the purple sweet potato without peel, had an anthocyanin content 4.5 times higher when expressed in cyanidin-3-glucose equivalents and 4.4 times higher when expressed as malvidin-3-glucose (Figure 1). It was also observed that, for the same culinary process, purple sweet potatoes with peel presented a better antioxidant activity when compared to purple sweet potatoes without peel. The peel enriched the sweet potato regarding the phenolic compounds and/or anthocyanins, thus leading to higher antioxidant activity. The purple sweet potato, with and without peel, presented higher phenolic compounds and anthocyanins when cooked in a microwave (Figure 1). This result was in line with the antioxidant activity of the microwave-processed purple sweet potato, which was higher than that of pressure and boiling treatments (Figure 1). For this variety, microwave processing proved more advantageous than the other cooking methods. Since the samples were not immersed in water as in the other processes, there were fewer structural changes in the microwaved samples [16]. This sweet potato variety also presented higher values of phenolic compounds than the other varieties subjected to the same processing conditions (Figure 1). When comparing the three varieties, the purple sweet potato had the highest antioxidant capacity. This association between total phenols and antioxidant activity, determined by the antiradical activity, was also observed in previous studies [17]. Figure 1: The results obtained for purple sweet potatoes without peel (**a**) and purple sweet potatoes with peel (**b**); the mean values within the same set of results for each variable with different letters are significantly different (\(p<0.05\)). Pressure-cooked purple sweet potato without peel had a lower anthocyanin value than the other culinary processes. However, the results of the boiled and pressure-cooked purple sweet potatoes with peel were similar (Figure 1). After the different culinary processes, the sweet potato variety that demonstrated the lowest antioxidant activity was the yellow sweet potato (Figure 3). These findings agreed with previous studies that proved that purple sweet potatoes have a higher antioxidant activity compared to the orange and yellow varieties [18]. Previous studies have shown many differences in their results [11] that can be influenced by several factors such as the cooking time, the temperature to which food is subjected, and the presence or absence of water during cooking, as well as the pH and oxygen present in that water [11]. Figure 3: The results obtained for yellow sweet potatoes without peel (**a**) and yellow sweet potatoes with peel (**b**); the mean values within the same set of results for each variable with different letters are significantly different (\(p<0.05\)). Figure 2: The results obtained for orange sweet potatoes without peel (**a**) and orange sweet potatoes with peel (**b**); the mean values within the same set of results for each variable with different letters are significantly different (\(p<0.05\)). In most cases, for total phenols, the pressure treatment proved to be a more effective extractive process compared to the boiling treatment (Figures 4-6), except for the cooking water from the processed purple sweet potatoes without peel and the yellow sweet potatoes with peel (Figures 4 and 6). Under pressure conditions, there was an increased extraction of phenolic compounds, as these cooking water had higher total phenols' values.