*2.7. HPLC Analysis for Total Phenolics*

The HPLC chromatogram classified the phenolic acids and flavonoids in natural juice, and ethanolic (OEM) extracts of peels, leaves, and stems (Table 2). Chlorogenic (32.96 µg/g), gallic (25.19 µg/g), syringic (2.74 µg/g), and cinnamic acid (0.35 µg/g) were recognized in juice as phenolic acids in addition to catechin (93.56 µg/g). This result indicated not only the composition of juice but also the pomace. More phenolic acids and flavonoids were observed in peel extract, where catechin and gallic acid recorded the highest content than other parts being 184.50 and 137.23 µg/g, respectively. The obtained resulted compounds in peels were disagreed with the phenolics identified by Koubaier et al. [32] and El-Beltagi et al. [29]. The obtained results indicated that, the stems contained abundant phenolic compounds than the other parts, where rutin was the highest content followed by catechin being 241.58 and 149.9 µg/g, respectively. However, gallic and chlorogenic acids were not recognized in stem extract, which is disagreed with Koubaier et al. [32]. These differences in the level of phenolic compounds in different parts may refer to changes in growth conditions, especially availability which plays a crucial role in the accumulation level of phenolic compounds in different plant parts [33]. The higher of level of the phenolic compounds is responsible for the higher DPPH scavenging activity of all parts of the plant.

**Figure 4.** Betaxanthin, betacyanin, and betalain content of beetroot parts (mg/g); (I): IEM; (II): OEM at −20 ◦C.


**Table 2.** Phenolic acids and flavonoids identification of beetroot plant parts.

ND \* Not detected.
