## 2 Phytochemicals Present in Beetroot
### Phenolic Acids and Flavonoids
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Beetroot** & \multicolumn{5}{c}{**Antioxidant Activity**} & **Ref.** \\ \cline{2-7}
**Material** & **DPPH** & **ABTS** & **FRAP** & **ORAC** & **CURPAC** & \\ \hline Beetroot & 70 (\% & - & - & - & - & [PERSON] et al. [41] \\ pulp & inhibition) & & & & & \\ \hline Beetroot & - & - & - & 200.3 \(\mu\)mol & - & [PERSON] and [PERSON] [45] \\ leaves & - & - & - & TE/g DM & - & [PERSON] et al. [18] \\ \hline \multirow{3}{*}{Beetroot powder} & 65 (\% & - & - & - & - & [PERSON] et al. [18] \\  & inhibition) & & & & & \\ \cline{2-7}  & 7140 mg & 429 mg & 1275 \(\mu\)mol FE & - & - & [PERSON] et al. [46] \\  & TE/g & AA/100 g & + 2/100g & & & \\ \hline \multirow{3}{*}{Fresh beetroot} & - & - & - & 18.21 \(\mu\)mol & - & Ninfali and Angelino [45] \\  & - & - & - & TE/g DM & - & Ninfali and Angelino [45] \\ \cline{2-7}  & 137 mg & 190 mg & 181 mg TE/100 & - & 3889 mg & \\  & TE/100 g & TE/100 g & g & & TE/100 g & \\ \hline Boiled & 131 mg & 158 mg & 126 mg TE/100 & - & 3376 mg & \\ beetroot & TE/100 g & TE/100 g & g & & TE/100 g & \\ \hline Dried & 143 mg & 188 mg & 170 mg TE/100 & - & 3567 mg & \\ beetroot & TE/100 g & TE/100 g & g & & TE/100 g & \\ \hline Pickled & 114 mg & 122 mg & 66 mg TE/100 & - & 2413 mg & \\ beetroot & TE/100 g & TE/100 g & g & & TE/100 g & \\ \hline Beetroot jam & 127 mg & 160 mg & 126 mg TE/100 & - & 2931 mg & \\  & TE/100 g & TE/100 g & g & & TE/100 g & \\ \hline Beetroot & 139 mg & 186 mg & 148 mg TE/100 & - & 3529 mg & \\ puree & TE/100 g & TE/100 g & g & & TE/100 g & \\ \hline \multirow{3}{*}{Beetroot juice} & 110 mg & 126 mg & 112 mg TE/100 & - & 2397 mg & \\  & TE/100 g & TE/100 g & g & & TE/100 g & \\ \cline{2-7}  & 56.7 \(\mu\)mol & 95 \(\mu\)mol & 184.7 \(\mu\)mol & - & 22.8 \(\mu\)mol & [PERSON] et al. [20] \\ \cline{2-7}  & TE/g DM & TE/g DM & TE/g DM & & TE/g DM & \\ \cline{2-7}  & 315 (IC\({}_{50}\) & 515 (IC\({}_{50}\) & & - & - & [PERSON] et al. [47] \\  & \(\mu\)g/mL) & & & & \\ \hline \multirow{3}{*}{Beetroot extract} & - & - & 33.9 \(\mu\)mol & - & [PERSON] et al. [9] \\  & - & - & TE/L & & \\ \cline{1-1} \cline{2-7}  & 254 (IC\({}_{50}\) & 359 (IC\({}_{50}\) & & - & - & [PERSON] et al. [47] \\  & \(\mu\)g/mL) & & & & \\ \cline{1-1} \cline{2-7}  & 14.2–90 (\% & & 1250–4100 & - & [PERSON] et al. [38] \\  & inhibition) & & - & \(\mu\)M TE/L & - & [PERSON] et al. [36] \\ \cline{1-1} \cline{2-7}  & - & 4.8–6.9 mol/L & - & - & [PERSON] et al. [36] \\ \cline{1-1} \cline{2-7}  & 0.32–0.57 mg & & 4.10–4.74 mg & & & \\ \cline{1-1} \cline{2-7}  & TE/g & - & TE/g & - & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Antioxidant activity in different beetroot sources. Based on previous research studies, the most important phenolic compounds in beetroot extracts were 4-hydroxybenzoic acid, benzoic acid, ferulic acid, vanmillic acid, protocatechuic acid, chlorogenic acid, caffeic acid, (phenolic acids), vanillin, catechin, catechin hydrate, epicatechin, and rutin (flavonoids) [13; 38; 40]. In a recent study, [PERSON] et al. [49] observed that isoferulic acid, protocatechuic acid (phenolic acids), epicatechin, and apigenin (flavonoids) were predominately found in beetroot products (fresh, fermented, and juice). However, the same authors detected a total of 20 phenolic compounds, including 10 other phenolic acids (m-hydroxybenzoic acid, chlorogenic acid, caffeic acid, syringe acid, sinapic acid, ferulic acid, p-coumaric acid, p-hydroxybenzoic acid, 3,4-dihydroxyphenylacetic acid, and trans-cinnamic acid) and 6 flavonoids (vitexin, rutin, luteolin, quercetin, kaempfer, and orientin). These compounds are in agreement with those reported in beetroot juice [20]. [PERSON] et al. [49] also reported that total phenolic acids and flavonoids were different among the beetroot products. Raw beetroot presented the highest amounts of both phenolic and flavonoids content (32.21 and 33.02 g/g DM, respectively) when compared with fermented beetroot (17.51 and 18.10 g/g DM, respectively) and commercial beetroot juice (3.19 and 4.0 g/mL, respectively).