*Red Beetroot (*Beta Vulgaris *L.) DOI: http://dx.doi.org/10.5772/intechopen.106692*


#### **Table 4.**

*Vitamin content of beetroots per 100 g.*

#### **Figure 2.** *Bioactive components in beetroots [17].*

content was detected in the beetroot. NEMZER et al. [25] isolated highly unstable phenolic components from the beetroot peel, which were dimers of 5,5,6,6-tetrahydroxy-3,3-biindolyl and 5,6-dihydroxyindole carboxylic acid. In addition, two phenolic amides, N-trans-feruloyltyramine and N-trans-feruloyl homovanillylamine were detected in the beet seed wall. MARAIE et al. [39] reported that beetroots contain significant amounts of hydroxybenzoic acid and hydroxyquinamic acid derivatives, including epicatechin, catechin hydrate, rutin, p-coumarin, caffeic acid, proline, and monoterpene dehydrovomololol. VASCONCELLOS et al. [40] compared the total phenol content of beetroot juice, beetroot chips, beetroot powder, and roasted beetroots. In their experiment, they found that beetroot juice (3.67 GAE mg/g) and roasted beets (2.79 GAE mg/g) had higher total polyphenol contents than beet chips (0.75 GAE mg/g) and beetroot powder, but the lowest value was detected in raw beetroot.

Flavonoids are among the biologically active components because they have excellent antioxidant potential and a number of positive health effects [17]. Flavonoids are characterized by a C6-C3-C6 backbone. The basic structure offers an extremely large number of variations, 4000 types of flavonoids with different structures are currently known. The degree of antioxidant properties of flavonoids depends fundamentally on the structure of the particular molecule, and the potency of the antioxidant is strongly and positively correlated with the degree of hydrolysis [41]. Flavonoids occur in higher plants and are secondary metabolites responsible for coloring the stems, leaves, flowers, and fruits of plants. Flavonoids can produce a variety of colors, such as yellow, orange, red, violet, and blue, but some are colorless [42]. Numerous studies have shown that beetroots contain significant amounts of flavonoids. It includes among others catechin, epicatechin, rutin, betagarin, and betavulgarin. VULIC et al. [43] reported the main group of flavonoids in beetroots.

Saponins are bioactive compounds that plants produce against pathogens and herbivores. According to previous studies, 11 triterpene saponins are found in beetroots. Each of the saponins contained oleanolic acid derivatives. Betovulgarosides I, II, III, IV, VI, VII, VIII. saponins were identified from the root, while betonulgarosides I, II, III, IV, V, IX, and X saponins were detected in leaves [33, 44]. MIKOLAJCZYK-BATOR et al. [45] also reported the presence of 26 triterpene saponins in beetroots, of which 17 triterpene saponins were not previously isolated in beets and 7 triterpene saponins were identified as new compounds.

### *5.3.2 Betalains*

Betalains are pigments of higher plants, nitrogenous and water-soluble compounds found in plants belonging to the *Caryophyllales* order [46]. Ten of the families in this order were identified as producing betalain. The *Chenopodiaceae* family, i.e. the *Beta vulgaris* family, is one of them. The name comes from the Latin name for beetroots (*B. vulgaris*), as it was the first plant from which they were identified. Betalaines are generally classified according to their characteristic structure (**Figure 3**). A total of 70 betalains are known, which have diazoheptamethine base frame. Betalains can be divided into two subgroups: betacyanin compounds, which give a reddish−violet color, and betaxanthines, which are responsible for yellowish colors [48]. The structural resonance of the parent compound of betalains, diazo-heptametin, results in its color. Accordingly, it can be distinguished the two major groups [49]. Betacyanins present in plants include betanin, isobetanine, protetanine, and neobetanin, and betaxanthines include vulgaxanthin, miraxantine, portulaxanthin, and indicaxanthin [50]. Plant physiology is uncertain about the role of betalains in plants, but KIMLER [51] reported the fungicidal properties of betalains.

Betalains were initially referred to as "nitrogen anthocyanins," but it was later found to be incorrect to assume structural similarity between colorant [52]. *Red Beetroot (*Beta Vulgaris *L.) DOI: http://dx.doi.org/10.5772/intechopen.106692*

Both betalains and anthocyanins are water-soluble pigments found in the vacuoles of plant cells. However, betalains are structurally and chemically completely opposite to anthocyanins and no evidence has been found to occur in the same plant. Each betalain is composed of a glycoside sugar and a colored part (**Figure 3**). Their synthesis is facilitated by light [53]. Factors influencing the stability of betalains are shown in **Figure 4**.

Each colorant group is characterized by R1-N-R2 moieties. More than 50 betalains have been described with the same basic structure. Betalain has been used as a food

**Figure 4.** *Effects affecting the stability of betalains [17].*

 **Figure 5.**  *Structural diagram of betanin [ 17 ].* 

coloring since the 20th century. Initially, a betalain-containing Phytolacca esculenta was used to imitate the color of red wine [ 48 ].

 The most abundant betaline compound in beetroots is betanin ( **Figure 5** ), a secondary metabolite of betacyanins. The storage is located in the root, where it can reach concentrations of up to 0.5 g/kg [ 54 ]. In addition to betanin, its isomer is also found in the colorants of the plant. This compound is isobetanin, and the two substances together can account for up to 88−93% of colorants [ 55 , 56 ]. For the four beet cultivars analyzed by HPLC by KUJALA et al. [ 57 ], the detected vulgaxanthin I and II were between 1.4 ± 0.3 mg / g and 4.3 ± 0.4 mg / g DW; betanin 7.6 ± 0.1 mg / g and 2.9 ± 0.2 mg /g DW, isobetanin 0.02 ± 0.01 mg /g and 3.1 ± 0.1 mg/g DW.

 Beetroot colorants are available in the form of a concentrate as a natural colorant, which is typically prepared by vacuum evaporation or spray drying. The chemical degradation of colorant is affected by the duration and temperature of the heat treatment as well as the pH and water activity of the product [ 25 ]. By fermentation, approximately 75% of betacyanin content can be maintained by lowering the pH to about 4. With this acidic medium, the negative effect of the heat treatment process on reducing antioxidant capacity can be avoided [ 58 ].

#### *5.3.3 Carotenoids*

 Carotenoids are a group of phytochemicals that are responsible for the color of various fruits and vegetables. The carotenoids present in beetroots also function as antioxidants, anticarcinogens, and immune enhancers, in addition, their protective role and attribute mutagenesis inhibitory activity can reduce the risk of developing cancer [ 59 ]. Beetroot leaves contain β-carotene and xanthophylls such as lutein [ 17 ]. REBECCA et al. [ 31 ] detected 1.9 mg/100 g carotene in beetroots.
