# Retention of Antioxidants from Dried Carrot Pomace in Wheat Bread
## 3 Results and Discussion
### The Influence of Carrot Pomace on Bread Properties
#### 3.3.2 Antioxidants in Bread
Thus, carrot pomace contains relatively small amounts of total phenols compared to other plant materials such as blueberries, purple potatoes and cherries, where their content is 41,800, 7810 and 20,980 mg/kg, respectively [43]. Analyzing the contents of polyphenols in carrot pomace, it could be stated that, according to many authors [38; 39; 40], there are many factors which could influence the final results of polyphenol determination in the sample. They include the applied method of analysis, extraction conditions, including the extractor composition, temperature and time of extraction, proportion between solids and liquids and storage conditions. Also, the variety, plot location and agronomic conditions could influence the total content of polyphenols in plants [44; 45]. The juicing method and processing conditions are the final factors for establishing pro-health properties of the pomace. It has been shown that wounding stresses and UV radiation could increase the level of polyphenols both in fresh-cut carrot [46] and in processed pomace [42]. The flavonoid content of carrot pomace is at 72.26 mg rutin/100 g d.m., while phenolic acids account for only 20.77 mg per ferulic acid. According to [PERSON] et al. [42], chlorogenic acid is the only phenolic compound identified in carrot pomace immediately after juice extraction, indicating that other phenolic compounds normally present in carrot roots (protocatechic acid, derivatives of gallic acid, 3,5-dicaffeoylquinic acid, 3-hydroxydihydro chlorogenic acid, 4,5-dicaffeoylquinic acid, p-coumaric acid and ferulic acid) are removed with the juice [47; 48]  
The content of polyphenols in control bread was on the level of 22.56 mg catechin/100 g, which seems typical for cereal products. Nevertheless, the control bread proved to be deficient in polyphenols, while the addition of carrot pomace during its preparation caused a significant increase in their level, much larger (almost 8 times) than could be expected from the level of addition. This may suggest that the baking step is partly responsible for the increase in polyphenols. Indeed, it is known that Maillard reactions occurring under high temperature result in the increase of TPC values. The content of total polyphenols in the control bread is most likely to be explained not only by the polyphenols from the wheat flour but also by the Maillard reaction products present in it, which could influence the results because of the side reactions with a broad range of constituents [49; 50]. According to [PERSON] et al. [51], fermentation could also increase the proportion of polyphenols in the final bread. The confirmation of this influence was earlier reported by [PERSON] et al. [52] found, who measured the content of total polyphenols in starch-based gluten-free bread at the level of 5.2 mg catechin/100 g d.m. Similar increase in the level of polyphenols were earlier reported for gluten-free bread with an addition of apple pomace [53]. The volume of flavonoids, phenolic acids and flavonoids in breads with 15% addition of carrot pomace was 9 times, 2 times and 8 times higher compared to the control, respectively. An unexpected increase (higher than 15% pomace addition) of the above-mentioned polyphenol compounds can be explained by the concerted action of many factors. Most likely, this is related to the subsequent stages of bread production, because, according to [PERSON] et al. [51] the quantity of phenolic acids increases during the yeast fermentation process, as well as during dough mixing. In addition, this may in part be due to the thermal breakdown of quercetin derivatives, especially quercetin trutinoside, which generates phenolic acids [54; 55; 56]. In the case of flavonoids, which include quercetin derivatives according to [PERSON] et al. [55], their heat resistance is relatively high compared to phenolic acids and anthocyanins. Nevertheless, the baking temperature used (230 \({}^{\circ}\)C) may have led to their partial breakdown, as evidenced by the appearance of the aforementioned phenolic acids in the breads.