**6. Saponins**

Saponins are secondary metabolites or glycoside compounds that form the family of compounds structurally constituted by steroids (C27) or triterpenoids (C30) [27]. **Figure 3** presents an amphiphilic character [39]. Saponins are found in the pericarp or

**Figure 3.** *Structures of sapogenins: steroid (a) and triterpenoid (b) [38].*

outer part of the seed, interfering with its palatability and digestibility, making it necessary to eliminate them before consumption, as well as imparting a bitter taste and tending to foam in aqueous solutions [2]. Bitter taste can be easily separated from the seed either by the wet method, i.e., by rinsing the seed in cold alkaline water or by the dry method, i.e., by roasting and then rubbing the grains to remove the outer layers [40]; however, both methods do not achieve the total removal of saponins, so it is necessary to develop new methods of saponin removal from quinoa seeds.

The amount of saponins present in quinoa seeds depends on the variety so the content in bitter genotypes varies from 140 to 2300 mg/100 g dry weight, while on sweet genotypes ranges from 20 to 40 mg/100 g dry weight [40]. Up to 87 complex triterpene saponins from the quinoa seed coat have been identified [41] as well as the transcription factor involved in the control of seed triterpene saponin synthesis has also been identified [42], so it is expected that this finding will allow progress in the selection of sweet quinoa varieties with low saponin content.

Chemistry and pharmacological studies of properties of saponins documented that saponins possess many biological properties in which their analgesic, antiviral, antimicrobial cytotoxic, antifungal, anti-inflammatory, hypocholesterolemic, surfactant, antioxidant, hemolytic, immunoadjuvant, antiadipogenic, and molluscicidal activities stand out [1, 42]. These properties are of utmost importance as they can be processed and by-products are obtained for the food, cosmetic, and pharmaceutical industries [43]. Saponin possesses natural surfactants, which can lower the surface tension forming foams at the time of agitation and thus forms colloidal solutions, and soaps, creams, detergents, and shampoos can be obtained [44]. On the other hand, research has shown that saponins are good fungicides because they can control phytopathogenic fungal pests [45].

#### **7. Bioactive compounds of quinoa**

According to Melini, V. & Melini, F. (2021), through a systematic review, they show that the most sought-after and investigated functional compounds in quinoa seeds are phenolic compounds, of which flavonoids are the most studied while flavonodes and isoflavones have been studied on a smaller scale. Furthermore, only three studies have been reported for hydrophilic betalains. Additionally, among the lipophilic functional components, the most studied are the tocal ones, followed by the carotenoids [46].

Functional components of quinoa seed.

To begin with, the functional components have a great diversity of molecules that can modulate one to more metabolic processes in humans. In addition, they can be hydrophilic, of which we have phenolic compounds and betalains, or lipophilic; there are carotenoids, tocoles, and phytoecdysteorids [46].

#### **7.1 Hydrophilic compounds**

#### *7.1.1 Phenolic compounds*

They are secondary plant metabolites that have a variety of chemical structures that have in common the presence of one or more hydroxyl groups on aromatic rings. On the other hand, the different results of the detection of phenolic compounds in

#### *Nutritional Value, Methods for Extraction and Bioactive Compounds of Quinoa DOI: http://dx.doi.org/10.5772/intechopen.101891*

quinoa seeds in the world, in the first place, are that the crops analyzed in China were of a white and pigmented variety, where the grain was subjected to grinding to observe to what extent this can affect the content of these components; it is known that phenolic compounds are present in the outer layers of the grain, where the total phenolic content of the pigmented varieties were 2–3 times higher than white varieties. This difference in phenolic content may be due to the fact that the genotypes are different and the different pedoclimatic conditions, thus being the crops from China those that had high phenolic content compared with other parts of Asia [46]. On the other hand, studies of samples from Peru, Chile, Brazil, Argentina, and Colombia were carried out; where the free phenolic content was made in quinoa grown in Peru and Chile, where quinoa grown in Peru showed higher values than those of Chile. Finally, flavonoids have been found in samples of quinoa from Peru, the United States, and Korea, with Peru having a higher total flavonoid content than the others. However, other studies show that Korean crops have a higher content of total flavonoids than the Peruvian culture [46].

#### *7.1.2 Betalains*

They are pigments that are soluble in water and are responsible for the color of plant tissues; they can be classified into betacyanins and bexanthins [46]. Regarding the content of betalains in quinoa, the content of betalains has been determined in quinoa samples from the Peruvian highlands, where values that are in the range of 0.15 and 6.10 mg have been found. In several betalains, proline-derived betaxanthin was found in varieties with light yellow seeds and only in a black variety [46].

### **7.2 Lipophilic compounds**
