Nutritional Value, Methods for Extraction and Bioactive Compounds of Quinoa

Abstract

Quinoa (Chenopodium quinoa Willd.) is a crop belonging to the Chenopodiaceae family that originated in the high Andean region of South America. Currently, the main producers of quinoa are Bolivia and Peru; this crop groups around 250 species and 3000 varieties. It has a high adaptability, which allows it to be cultivated in cold climates in the high Andean regions, as well as in subtropical conditions, and grows from sea level to more than 4000 meters above sea level. Due to its high nutritional value and nutritional properties, quinoa is considered “one of the grains of the 21st century.” It is high in protein without gluten, polyunsaturated fatty acids, carbohydrates, vitamins, minerals, and fiber, as well as high levels of bioactive compounds such as flavonoids, phenolic acids, bioactive peptides, phytosteroid betalains, phytosterols, and saponins. From quinoa, a protein concentrate of high biological value can be extracted due to its content of the nine essential amino acids, as well as an oil with high antioxidant activity due to its high levels of tocopherols. These by-products have a high economic and commercial value and can be produced on an industrial scale for use in the food, cosmetic, and pharmaceutical industries.

1. Introduction

Quinoa is a plant of the Chenopodium genus original from South America and well distributed in countries that belonged to the Inca empire, located on the Andean mountain range, from southern Colombia through Ecuador, Peru, Bolivia, and up to northern Chile [1]. It is considered one of the oldest crops in the Americas. Archeological findings in Chile have shown that quinoa was cultivated around 3000 B.C. In the case of Peru, in Ayacucho, it has been shown that quinoa was cultivated before 5000 B.C. [2]. It has a great edaphological and climatic adaptability and grows at different altitudes, from sea level to the altitude of the Bolivian altiplano withstand low temperatures down to −8.0°C, alkaline soils (pH 8), and salinity of 52 mS/cm, which has allowed the expansion of large cultivation areas in different geographical areas, thus promoting the exploitation of its diverse nutritional and pharmacological properties [3]. The main survival mechanism of quinoa against frost is to avoid the formation of ice by an internal reduction in temperature. Quinoa has a high soluble sugar content that can cause decrease of the freezing point and therefore the lethal temperature of the leaf tissue [4]. It is designated as a “pseudocereal” and even as an oleaginous “ pseudocereal” [5], and due to its characteristic of resistance and tolerance to stress and its nutritional and biological properties, quinoa has been described as “one of the grains of the 21st century” [6].

2. Botanical aspects

Quinoa was initially classified based on the color of the plant and its fruits and then based on the morphological types of the plant. Although due to a wide variation observed, quinoa has been classified as a race. Quinoa from Bolivia, Peru, and Ecuador has been classified into 17 races. Thus, one of the most useful classifications is the one that describes five ecotypes: sea level, valley, subtropical, salt flat, and altiplano [2]. Other authors [7, 8] mention that quinoa has the following systematic classification:

Kingdom: Plantae,

Division: Magnoliophyta.

Class: Magnoliopsida.

Order: Caryophyllales.

Family: Amaranthaceae.

Subfamily: Chenopodiaceae.

Genus: Chenopodium.

Species: C. quinoa Willdenow.

Common name: Quinoa.

Although the name quinoa is the most widespread, there are numerous names used by different ethnic groups in the vast production territory; for example, arrocillo, Inca wheat, in some parts of Peru.

The annual herbaceous plant has an average height between 1.0 and 3.0 m depending on the variety and planting density; its central stem is woody and can be branched or unbranched (Figure 1A), also varying in color (green, red, or purple); its roots can reach up to 30 cm depending on the depth of planting. Leaves are formed by the petiole and lamina, are rich in calcium and oxalate crystals that reduce excessive transpiration allowing the maintenance of adequate humidity inside the plant. The color is very variable, ranging from green in young plants to red or violet with different shades in more mature plants [10]. In many areas of the Andean region, the young leaves before flowering are suitable for human consumption due to their high nutritional value attributed to their vitamin, mineral, and protein content. The panicle appears from the leaf axil along the stem or may arise from the top of the plant (Figure 1B); the flowers are self-fertilized, although it can also be produced by cross-pollination [8]. The seeds are small, round, and flat with a length of 2.5 mm and 1.0 mm in diameter (Figure 1C); seed colors can vary from white to gray and black, or it can be yellow and red. Seeds have three main components: embryo, perisperm, and episperm. Embryo is formed by two cotyledons and constitutes 30% of the total volume of the seed and contains between 35 and 40% of the total seed protein. Perisperm represents almost 60% of the seed surface and contains only 6.3–8.3% of the total proteins. Pericarp contains the saponins that give the characteristic bitter taste to the seed [11].

Figure 1.

Characterization of the quinoa plant. A. Growth habit: (1) Simple, (2) Branched to the lower third, (3) Branched to the second third, (4) Branched with undefined main panicle; B. Panicle shape: (1) Glomerulate, (2) Intermediate, (3) Amarantiform; C. Grain shape: (1) Lenticular, (2) Cylindrical, (3) Ellipsoidal, (4) Conical [9].

3. Production

Countries with the highest production of quinoa are Bolivia and Peru, which account for more than 90% of total world production [12]. Until 2000, world quinoa production did not exceed approximately 50,000 metric tons (t) per year. From 2003 to 2018, quinoa production in the Andean region has increased by about 165,000 t (Figure 2A). This growth has made it possible to meet export demand, and more than half of the quinoa produced in South America (Peru, Bolivia, and Ecuador) is exported mostly to the United States and Europe. In an average of 30 years (1983–2013), the yield in Bolivia was 0.55 tons per hectare (t/ha) with a range of 0.43–0.68 t/ha. In Peru from 2007 to 2014, yield efficiencies have doubled from 0.97 to 1.93 t/ha; being as of 2018, the average yield in the region of 1 t/ ha (Figure 2B) [13].

Figure 2.

Dynamics of quinoa production (A), yield (B), and area (C) in three countries of the Andean region between 1961 and 2018 [13].

Cropland has increased significantly. Bolivia increased more than four times in the last 30 years. Since 2007, harvested areas have increased from 32,959 to 55,000 ha in Peru. In Latin American Peru, Bolivia, and Ecuador recorded a total of 172,000 ha harvested in 2018. In these three countries, quinoa is produced under diverse agroecological conditions and production systems. Traditional production systems are characterized by medium plots (up to 10 ha) and small scale (<2 ha) with low input technology [13]. Production costs for Peruvian quinoa are $2200 USD/t, and farm gate prices range from $4000–4500 USD/t (conventional) to $5200 USD/t (organic) [12].

4. Composition and nutritional value

Quinoa is rich in protein, lipids, fiber, vitamins, and minerals. The grain contains an excellent nutritional profile (Table 1), starch (32–60%), protein (10–18%), fat (4.4–8.8%), fiber (1.1% and 13.4%), ash (2.3–3.7%), formed mainly from potassium and phosphorus [18, 19]. Quinoa also contains a high amount of vitamin B and vitamin E.

4.1 Protein

The average protein content is higher (12 to 23%), compared with other grains such as barley (11% dry basis), rice (7.5% dry basis) or corn (13.3% dry basis), and is comparable to wheat (15.4% dry basis) [14]. The proteins present in quinoa are of high quality, including albumins (35%) and globulins (37%) and, to a lesser extent, prolamins. The quality of these proteins is comparable to the protein present in milk (casein) [8]. It contains all the essential amino (Table 2), which is why it is considered a complete food [23], and it is also low in prolamine (0.5–7.0%), indicating that it is not allergenic [24].

Components	Jancurová et al. [2]	Hussain et al. [8]	Vilcacundo & Hernández-Ledesma [6]	Abugoch James [14]	Wright et al. [15]	Bruin [16]	Lalaleo et al. [17]
Protein	16,5	10–18	13,1–16,7	12–23	16,7	15,6	12,5
Fat	6,3	4,4–8,8	5,5–7,6	1,8–9,5	5,5	7,4	8,5
Fiber	3,8	1,1–13,4	7–11,7	7–9,7	10,5	2,9	1,92
Ashes	3,8	2,4–3,7	ND	ND	3,8	3,2	3,7
Carbohydrates	69,0	32–60	32–69	32–69,2	74.7	69,7	60,0
Kcal /100 g	399	ND	ND	ND	ND	ND	ND

Table 1.

Chemical composition of quinoa (g /100 g dry weight).

ND, not detected.

Amino acid	Kozioł [20]	Dini et al. [21]	Repo-Carrasco et al. [22]	Wright et al. [15]
Histidine	3.2	2,0	2,7	3,1
Isoleucine	4,4	7,4	3,4	3,3
Leucine	6,6	6,1	6,1	5,8
Methionine + cysteine	4,8	4,5	4,8	2,0
Phenylalanine + Tyrosine	7,3	7,5	6,2	6,2
Threonine	3,8	3,5	3,4	2,5
Valine	4,5	6,0	4,2	4,0
Lysine	6,1	4,6	5,6	6,1
Tryptophan	1,2	ND	1,1	ND

Table 2.

Essential amino acid profile (g protein/100 g).

ND, not detected.

4.2 Lipids

The fat content in quinoa seeds averages 2–10% and is considered as an alternative to oilseeds due to its lipid composition. Triglycerides are the main fraction of fats and constitute more than half of the neutral lipids [25]. Quinoa and soybean oils present a very similar fatty acid composition, with linolenic acid (18: 2n-6: 52%) and linolenic acid (18, 3n-6: 40%) being the most representative (Table 3) [27]. Quinoa oil has a high antioxidant quality, a high content of polyunsaturated fatty acids including omega-3 and omega-6 fatty acids (63% of the total), and a significant amount of tocopherols (2.5 mg/g oil) [28]. On the other hand, linoleic acid is metabolized to arachidonic acid and linolenic acid to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) [29]. Polar lipids account for about 25% of the total, composed mainly of phospholipids (lysophosphatidylethanolamine and choline), of the neutral lipids (glycerides and sterols), triglycerides account for 74% and diglycerides for 20%, while monoglycerides and waxes account for 3% [8].

Fatty acid	Abugoch James [14]	Kozioł [20]	Repo-Carrasco et al. [22]	Ruales & Nair [26]
Oleic C18:1	22,8–29,5	23,3	26,0	24,8
Linoleic C18:2 (n-6)	48,1–52,3	53,1	50,2	52,3
Linolenic C18:3 (n-3)	4,6–8	6,2	4,8	3,9

Table 3.

Saturated fatty acid (g/100 g of oil extract).

4.3 Carbohydrates

Quinoa has a significant amount of carbohydrates and represents between 67% and 74%, of which starch is the most important carbohydrate and represents approximately 58.1–64.2% of dry matter, variation of which is attributed to differences in genotypes and growing conditions [24]. Its granules have a polygonal shape with a diameter of 2 μm, being smaller than those of common cereals. Due to its size, it can be used as a biodegradable filler in polymer containers [23]. It is also an ideal thickener for frozen foods and other applications where resistance to retrogradation is desired, because of its freeze–thaw stability [30]. Carbohydrates include amylose with a content of about 11%, and other carbohydrates, which have been documented, include monosaccharides (2%) and disaccharides (2.3%), crude fiber (2.5–3.9%), and marshmallows (2.9–3.6%) [27]. Sucrose is also present in significant amounts compared with other sugars [23]. It contains a low proportion of glucose (19.0 mg/100 g) and fructose (19.6 mg/100 g). This is important in the fermentation of malted beverages [31].

4.4 Fiber

Quinoa is considered an important source of dietary fiber accounting for about 2.6–10% of the total dietary fiber weight. Approximately 78% of the amount of fiber in quinoa is insoluble and 22% in soluble form [24]. Although washing and abrasion processes are performed to remove saponins, this does not influence the fiber content [25]. Research reports that the dietary fiber content of quinoa is equal to that of other cereals and grains. Although, the fiber composition of quinoa is different from other cereals, biochemistry and therapeutics are still important to study the potential of quinoa and thus understand its specific physiological impact [8].

4.5 Minerals

Quinoa has a high content of calcium, iron, magnesium, iron, copper, and zinc (Table 4), covering the amounts needed to maintain a balanced human diet of calcium, phosphorus, potassium, and magnesium of 874, 2735.0–4543.3, 9562.2, and 1901.5 mg/kg, respectively [24]. In general, many of these minerals are higher than those reported for most cereal crops such as barley oats, rice, maize, or wheat [23].

Minerals	Kozioł [20]	Repo-Carrasco et al. [22]	Ruales & Nair [26]	Bhargava et al. [32]	KONISHI et al. [33]	Dini et al. [21]
Ca	1487	940	874	1274	863	275
P	3837	1400	5300	3869	4110	4244
Mg	2496	2700	260	ND	5020	ND
Fe	132	168	81	20	150	26
Zn	44	48	36	48	40	27.5
K	9267	ND	12,000	6967	7320	75
Cu	51	37	10	ND	ND	ND

Table 4.

Mineral composition (mg/ kg dry weight).

ND, not detected.

4.6 Vitamins

The vitamin content of quinoa is interesting. It has high levels of vitamin B6 and total folate, whose amounts can cover the daily requirement of children and adults, as for riboflavin content, 100 g provides 80% of the daily needs of children and 40% of adults [14]. The niacin content does not cover the daily requirement; however, it is beneficial for the diet, the values of thiamine in quinoa are lower than those of oats and barley, but those of niacin, riboflavin, vitamin B6, and total folate are higher (Table 5).

Vitaminas	Kozioł [20]	Ruales & Nair [26]
ácido ascórbico	4	16,4
$\alpha -$tocoferol	5,37	2,6
Tiamina (B1)	0,38	0,4
Riboflavina (B2)	0,39	ND
Niacina B3	1,06	ND

Table 5.

Concentration of vitamins (mg/100 g dry weight).

ND, not detected.

5. Processed uses and current situation

At present, the processed uses given to quinoa are mainly from the flour obtained from it, which can replace that of corn and wheat, since various levels of quinoa flour substitution have been reported, for example, in sweet biscuits (60% quinoa), in noodles and pasta (30–40%), and in bread (10–13%) [27]. Other uses or innovations include quinoa beer that meets the sensory acceptance requirements, reaching a high alcoholic content (between 48 and 74°GL) and for the production of chocolates with quinoa filling with good physicochemical, organoleptic, microbiological, and nutritional characteristics [34].

There are other potential products derived from quinoa, which are obtained by extracting compounds from quinoa and for the creation of value-added products. Examples of these products are oil extraction, protein concentrates and isolates, starches, bioactive compounds, among others, for use in the food and pharmaceutical industry (Table 6, [35]). Compared with the starch content of wheat and barley, quinoa starch has a higher viscosity, greater water retention, and expansion capacity, as well as a higher gelatinization temperature, which translates into better performance as a thickening agent. Due to these properties, quinoa starch is very suitable for the production of prepared frozen baby foods, as it shows good freeze–thaw stability [36]. Due to its protein and starch content, quinoa can be used for the production of edible films and as an emulsion stabilizing agent, specifically for Pickering emulsions [37]. Even incorporation of quinoa into food products has been shown to help extend shelf life and reduce microbial spoilage of food products.

Quinoa-derived product	Production method	Uses
Treated seeds	Superheated steam treatment to expand the seeds and reduce cooking time. Mechanical abrasion, washing, or a combination to debitter seeds.	Superheated steam treatment to expand the seeds and reduce cooking time. Mechanical abrasion, washing, or a combination to debitter seeds
Beverages	Seeds are soaked, malted, kilned, mashed, cooled, and fermented with yeast	Gluten-free fermented alcoholic beverage
	Mixing of quinoa extract, tiger nut (Cyperus esculentus), and α-amylases for hydrolysis of starches to thermostable maltodextrin within a beverage formulation.	Substitute for animal or plantderived milk
Protein concentrate	Extraction and precipitation via alkali or enzyme treatment	Used in foods, animal food, or sports performance and recovery
Lipid	Extraction and molecular distillation to obtain a refined oil	Dermatological use
Carbohydrate	Extraction of maltodextrin via alkali or enzyme treatment of quinoa flour to produce a gel-form to deliver quinoaderived peptides. Use of quinoa starches of specific shape and particle size	Cream substitute that mimics the mouth feel of fat/cream in food

Table 6.

Uses and processing methods.

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 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.

Figure 3.

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

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 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

7.2.1 Carotenoids

Also known as natural pigments that give a yellow to orange-red color to plant tissue. We also find carotents and xanthophylls as major subgroups of carotenoids [46]. Additionally, the consumption of carotenoids has beneficial effects for human health such as protection against cardiovascular diseases, cataracts, cancer, and muscle degeneration [46].

On the other hand, regarding the content of carotenoids, they have been studied in samples of quinoa grown in Egypt and Finland, as in commercial samples, where B-carotene and lycopene were found in five genotypes of quinoa grown in Egypt, also B-carotene could be found in a commercial white quinoa sample, but high levels were found in pigmented quinoa sample. Furthermore, regarding the Finnish sample, six carotenoids were found in quinoa samples [46].

7.2.2 Tocoles

They are methylated phenols with a saturated side chain; in addition, tocopherols exist in four isoforms, α-, β-, γ-, and δ-tocopherol differing in the position of the methyl group on the chromanol ring [46]. On the other hand, the tocol content has been moderately investigated in quinoa seeds, carrying out a study of four varieties of quinoa grown in Peru, where the main isomer of tocopherol was α-tocopherol that presented values in the range of 463 and 1444 ppm [46]. In addition, the highest content of α-tocopherol and total tocopherol was found in the yellow variety of Maranganí. Additionally, in Buenos Aires, four tocopherol vitamers were found, where y-tocopherol was the one with the highest content, followed by α-tocopherol, where its content was 0.9 and 3.1 mg [46]. Continuing, tocopherol investigations were also carried out in nine varieties of quinoa from four countries, counting Peru again, Bolivia, Colombia, and Denmark; the results showed two isoforms of tocotrienol and the β isoform of tocopherol were not present in the pigmented and non-pigmented varieties. Finally, Melini, V. & Melini, F mention that through all their research, α-, β-, γ-, and δ-tocopherol have been identified in 39 pigmented and non-pigmented quinoa samples, where γ- tocopherol was the most abundant, and the black genotypes were more abundant than the white varieties [46].

7.2.3 Phytoecdysteroids

They are a broad group of plant steroids where their structure is characterized by having a 5 β-cholestanol steroid skeleton that contains a 6-ketone ring B and a hydroxyl group at the C-14 α position. On the other hand, the study of phytoecdysteroids in quinoa and few investigations have been reported, such as the investigation of Chilean quinoa varieties and commercial samples of quinoa, where the total content of phytoecdysteroids was in the range of 224 and 570 μgg⁻¹ fw in Chilean samples, and in commercial samples it presented 138 and 568 μgg⁻¹ f [46].

Additionally, they were also carried out in 15 varieties of quinoa grains in Peru, department of Puno, for the content of phenolic compounds where they obtained a variation of 35.29–139.94 mg gallic acid per 100 grams [47] (Table 7).

Flavonoids	Phenolic acids
Myricetin	Caffeic
Quercetin	Ferulic
Kaempferol	p-Hydroxybenzoic
Isohamnetin	Vanillinic
Routine	Gallic
Orientina	Cynamic
Vitexin	Protocatechuic
Morina	p-Cumaric
Hesperidin	—
Neohesperidin	—

Table 7.

The flavonoids and phenolic acids identified in quinoa seeds.

Source: Taylor et al. (2014).

In relation to other bioactive compounds in quinoa seed ecotypes, the content of deidzaine isoflavones was found in a range of 0.7–1.15 mg per 100 grams and 0.05–0.25 mg of genistein per 100 grams. On the other hand, a carotenoid content in the range of 1.69–3.88 mg per kilogram has also been recorded [48].

8. Quinoa oil production methods

The process for the extraction of quinoa oil is described and is as follows [49]:

8.1 Receipt of the quinoa seed

The quinoa is received in bags of double Kraft paper material weighing 25 kg, later stored at room temperature and in a dry environment (Figure 4).

Figure 4.

25 kg bags of quinoa.

8.2 Cleaning

Cleaning is carried out manually in order to eliminate any impurities, such as defective seeds, stones, etc. (Figure 5).

Figure 5.

Cleaning the quinoa grains.

8.3 Washed

Cold water was used for washing in order to eliminate the amount of saponin, which generates a detergency that is visualized by the creation of foam. At this stage, the seed has been polished, since the outer layer is removed (Figure 6).

Figure 6.

Washing the quinoa.

8.4 Drying

The drying stage was carried out in a forced air oven at a temperature of 80° C with a time of 3 hours until a humidity of 8% is achieved (Figure 7).

Figure 7.

Forced air stove.

8.5 Grinding

The milling was carried out with a hammer mill; this allows to reduce the size of the particles of the quinoa seeds, which allows us to break the cells, which makes the release of the oil feasible. In addition, the average size is 240 u of the particles (Figure 8).

Figure 8.

Hammer mill.

8.6 Solvent extraction (hexane or petroleum ether)

The machine used to extract the oil was a Soxhlet extractor, which has a capacity of 3 kg. For this process, the already ground quinoa is placed in a basket in which it is in contact with the solvent. Finally, the duration of the process is observed until no more oil remains can be seen inside the machine (Figure 9).

Figure 9.

Soxhlet extractor.

8.7 Solvent evaporation

In this stage, the solvent is mixed with the quinoa oil; for this, it is evaporated in a rotary evaporator, where the solvent is divided with the oil (Figure 10).

Figure 10.

Rotavapor.

8.8 Storage

Finally, the oil that is extracted and placed in glass bottles with an amber color and protected from light.

9. Quinoa-based protein concentrate

The process of obtaining protein concentrate based on quinoa will be shown below [50]:

9.1 Sample preparation

The grain was cleaned and classified, subsequently a washing was carried out with distilled water and followed by drying at a temperature of 75°C for 8 hours. Furthermore, the saponin-free grains were ground, and a particle size of 25 μm was reached with a sieve.

9.2 Alkaline solubilization

A flour suspension was made, using distilled water with a 1:10 (w / v) ratio, and the pH is regulated with 1 N NaOH until reaching pH 9. Additionally, this suspension was moved for a time of 1 hour, the supernatant was taken (first extraction (and the precipitate was re-carried out in the solubilization process (second extraction).

9.3 Isoelectric precipitation

From the previous step, the collected supernatants, their pH were regulated with citric and hydrochloric acid until reaching a value of 4.5. The samples were centrifuged for a time of 15 minutes. Subsequently, the supernatant was discarded and with the precipitate, they were lyophilized at a temperature of −30°C. Finally, the samples obtained were placed in polyethylene material sleeves.

10. Economic evaluation at industrial scale of the production process of quinoa protein hydrolysates

A new method was proposed to obtain protein hydrolysates from quinoa, using supercritical fluids extraction (SFE), CO₂ and ethanol as cosolvent as a previous step to separate the fat and phenolic compounds in a single extraction process, and this was compared with the conventional solvent extraction (CSE) [51]. The production of quinoa protein hydrolysate (QPH) using two technologies to extract the oil and separate the phenolic compounds (PC) prior to enzymatic hydrolysis was evaluated: (1) Supercritical fluid extraction (SFE) and (2) Conventional solvent extraction (CSE). The aim of this study was to compare the oil extraction yield, remaining PC and QPH yield. Furthermore, an economic evaluation and sensitivity study was performed using SuperPro Designer 9.0 software; quinoa grain batches of 1.5 kg (laboratory) and 2500 kg (industrial scale) were considered, as shown in Figure 4. Results revealed that SFE allows higher oil yield and separation of PC. The cost of manufacturing (COM) was lower in SFE compared with CSE, US$ 90.10/kg and US$ 109.29/kg, respectively, and higher net present value (NPV), US$ 205,006,000 and US$ 28,159,000 compared with CSE. The best scenario is when the sale of both by-products (oil and saponins) is included, the COM is reduced to US$ 28.90/kg (SFE) and US$ 57.06/kg (CSE), and profitability also improves. In addition, the significance the COM and NPV was statistically evaluated, there are no significant differences on an industrial scale. Both processes are economically promising, especially when the QPH and by-products are produced in large scale and sold at the current market price (Figure 11).

Figure 11.

Simulation flowsheet designed with SuperPro Designer 9® for the QPH production process using (a) SFE and (b) CSE.

11. Conclusions

Quinoa is a food that is produced mainly in Peru, Bolivia, and Ecuador and has nutritional characteristics superior to many vegetables. It is recognized as a complete food due to the quality of proteins, fiber, minerals, and vitamins; in addition to being gluten-free, it has allowed the development of new food products and is even used in an unconventional way as a nutraceutical, in the production of edible films, and as a stabilizing agent for emulsions.

However, quinoa grains have saponin, an anti-nutritional factor that can be eliminated by wet or dry methods, although there are some disadvantages such as high-water consumption, loss of essential nutrients such as vitamins, minerals, and amino acids, among others. It is therefore important to promote new methods of saponin elimination together with the development of breeding programs for quinoa varieties with low saponin content to improve yields per hectare.

The type of pretreatment with SFE and CSE applied to quinoa flour prior to enzymatic hydrolysis influences on the oil yield, remaining phenolic compounds and hydrolysate yield. The significance analysis of the factors considered shows that there is no significant effect on the COM and NPV of the QPH production at industrial scale between each technology; however, the pretreatment with SFE allows obtaining a lower COM and higher NPV, the sensitivity study and the evaluated scenarios show an additional income generated by the sale of by-products such as saponins and oils. Finally, it is corroborated by the values obtained, which as the scale of production increases, the manufacturing cost decreases for both technologies, making the production of quinoa protein hydrolysate viable at an industrial level.