**Variation of the Nutritional Composition of Quinoa According to the Processing Used †**

#### **Pablo Mezzatesta, Silvia Farah, Amanda Di Fabio and Raimondo Emilia \***

Laboratorio de Investigación en Nutrición Aplicada, Facultad de Ciencias de la Nutrición Universidad Juan Agustín Maza, Lateral Sur del Acceso Este 2245 Dorrego Guaymallén Mendoza, CP 5519, Argentina; pablomezzatesta@gmail.com (P.M.); farahsilvia1@hotmail.com (S.F.); amandadifabio@gmail.com (A.D.F.)


Published: 4 August 2020

**Abstract:** Quinoa is consumed as a seed, flour, expanded, sprout (germinated) and activated (hydrated). The objective of this work was to determine the nutritional composition of the different preparations. The same batch of quinoa seeds was processed as flour, expanded, hydrated and germinated. It showed that there is a statistically significant difference of nutrients between all groups. For proteins, it varies from 12.78 ± 0.02 g/100 g in whole seed to 5.25 ± 0.01 g/100 g in the hydrated seed. In total fats, it varies from 7.80 ± 0.02 g/100 g in flour to 0.72 ± 0.01 g/100 g in sprouts. For fiber, the germinated quinoa provides the highest content (23.50 ± 0.01 g/100 g), whereas the hydrated quinoa the lowest content (8.71 ± 0.02 g/100 g). This shows how different preparations influence the nutritional contribution of quinoa. With this information, one can recommend different types of preparations depending on the type of nutrient that is wanted for consumption.

**Keywords:** expanded seed; flour; germinated seed; hydrated seed; quinoa

#### **1. Introduction**

According to Food and Agriculture Organization of the United Nations FAO [1], quinoa (*Chenopodium quinoa* Willd.) is a millenary crop that contributes to world food security. The protein content varies from 13 to 21% depending on the variety; it's essential amino acids profile is one of the most complete in the vegetable kingdom. That makes it an ideal food for populations with protein malnutrition [1]. Quinoa has an adequate content of dietary fiber, which decreases grain digestibility. The fiber contributes to granting satiety. It has been shown that the fatty acids of quinoa maintain quality due to the high natural value of vitamin E, which acts as a natural antioxidant [2]. Quinoa provides omega 6 polyunsaturated fatty acids (50% of their fat content) and omega 9 monounsaturated fatty acids (25% of their fat content) [3].

In Argentina, it is cultivated especially in the northwest; however, in the area of Mendoza, the crop shows good yields. Due to the type of harvest, it is ideal for small-scale production, benefiting small producers. In this context, Juan A. Maza University, the Provincial Legislature and the Family Agriculture Secretary of National Government are working on a project of the agronomist engineer Amanda Di Fabio [4].

In a global context with a strong demand for natural and nutritious products, quinoa is one of the Andean and ancestral crops most requested by consumers and with better economic prospects in recent years [5].

#### *Proceedings* **2020**, *53*, 4

It is consumed as a seed, flour, expanded, sprout (germinated) and activated (hydrated). The popular belief is that all these forms have the same nutritional contribution. Taking into account this belief, the objective of this work was to determine the nutritional composition of the different forms of preparation for consumption of this grain.

#### **2. Materials and Methods**

This study was based on the same lot of quinoa, purchased from a local producer, which was washed, dried and free of saponins [6].

#### *2.1. Ways of Preparation*

Quinoa seed: It was washed and dried. This form of consumption is common.

Quinoa flour: The seed was grounded until a granulometry of 60 meshes (0.25 mm) was reached. In the present study, a laboratory mill was used and sieved prior to its analysis.

Activated quinoa (hydrated): Quinoa seeds were placed in water, at a room temperature of 20– 25 °C, in a ratio of 1 part of seeds to 3 parts of water. They were left for 5 h. Then they were drained, cooked and used in different preparations. This method is common among vegans and vegetarians.

Quinoa was moistened overnight, drained, and placed in a glass jar upside down with a canvas as a lid for breathing. The next day it was moistened, drained and left face down again. The bottle was placed in the light and within 3 days the seeds began to sprout.

Expanded quinoa: A frying pan was heated over direct heat, with a small amount of oil. Quinoa seeds were added and after 5 min, they began to expand. The pan was removed from heat and the rest of the grains expanded.

#### *2.2. Laboratory Analysis*

To determine the nutritional composition of the different preparations of quinoa, the following laboratory determinations were made:

Humidity: Method of A.O.A.C 950.46. This was an indirect method that involved drying in an oven at 100–105 energy value (kcal) = (protein × 4) + (carbohydrates × 4) + (fat × 9). C, until constant weight was achieved.

Total fats: The direct method by extraction with ethyl ether (crude fat), Soxhlet gravimetric method (A.O.A.C. 960.39, 1990) was used.

Fibers: Dietary fiber (AOAC, 15th edition 1990) [7] was used.

Crude protein: The Kjeldahl method, (A.O.A.C. 928.08, 1990), determining nitrogen, using 6.25 as a protein conversion factor, was used.

Ashes: The direct Method (A.O.A.C. 923.03, 1990), involving incineration in a muffle (at 500 ± 10 Energy value (kcal) = (protein × 4) + (carbohydrates × 4) + (fat × 9). C), until constant ash weight was achieved, was used.

Carbohydrates: Carbohydrates were determined by difference, using the following formula:

100 ƺ (Weight in grams [protein + fat + water + ash + ębers]), in 100 g of food.

Energy value: Energy value was calculated according the following equation:

Energy value (kcal) = (protein × 4) + (carbohydrates × 4) + (fat × 9).

The conversion is 2000 kcal = 8400 kJ.

#### *2.3. Statistical Analysis*

The same batch of quinoa was taken and processed (treatment) as flour, expanded, hydrated and sprout. The samples were analyzed in triplicate. For the statistical analysis, ANOVA was applied first and then a multiple comparison test was applied to discriminate between the means, and the honestly significant difference procedure (HSD) of Tukey was also applied.

#### **3. Results**

#### *3.1. Nutrients Content for Each Type of Preparation*

There were statistically significant differences (a < 0.05) between the nutrients of each type of preparation (seeds, sprouts, expanded, hydrated and flour).

A statistically significant difference was shown between all groups of nutrients. For proteins, it varied from 12.78 ± 0.02 g/100 g in whole seeds to 5.25 ± 0.01 g/100 g in the hydrated seed (Figure 1). In total fats, it varied from 7.80 ± 0.02 g/100 g in flour to 0.72 ± 0.01 g/100 g in sprout (Figure 2). For fiber, the germinated quinoa provided the highest content (23.50 ± 0.01 g/100 g) and the hydrated the lowest content (8.71 ± 0.02 g/100 g). The energy value was (kJ/100 g): whole seed 1299, flour 1430, germinated 291, hydrated 594 and expanded 1368 (See Table 1).

#### *3.2. Statistical Analysis of the Data*

The ANOVA statistical test was applied to analyze differences in means, and the HSD Tukey Multiple Ranges test was subsequently applied to analyze the difference between groups. The ANOVA result was statistically significant (*p* = 0.000) for all the variables analyzed (protein, carbohydrates, total fat, saturated fat, ash, fiber, moisture, sodium, and energy value).

The HSD Tukey Multiple Range test gave the following results:

*Proteins*: showed statistically significant differences between all levels, with the whole grain being the one with the highest content and the activated seed being the one with the lowest content.

*Carbohydrates*: showed statistically significant differences between all levels, with the expanded being the one with the highest content and the outbreak being the one with the lowest content.

*Total fats*: showed statistically significant differences between all levels, with the flour being the one with the highest content and the sprout with the lowest content.

*Saturated fats*: There were three homogeneous levels (sprout-activated-expanded) and this group showed statistically significant differences with flour and grain levels. The flour was the one with the highest content and (sprout-activated-expanded) the one with the lowest content.

*Ash*: There were two homogeneous levels (activated-expanded) and this group showed statistically significant differences with the flour, sprout and grain levels.


**Table 1.** Centesimal composition of quinoa, for different forms of preparation a.

a Mean (SD); b Indicates the highest value; c Indicates the lowest value; d n.d., not detected.

The HSD Tukey Multiple Range test gave the following results:

*Proteins*: showed statistically significant differences between all levels, with the whole grain being the one with the highest content and the activated seed being the one with the lowest content. *Carbohydrates*: showed statistically significant differences between all levels, with the expanded

being the one with the highest content and the outbreak being the one with the lowest content.

*Total fats*: showed statistically significant differences between all levels, with the flour being the one with the highest content and the sprout with the lowest content.

#### *Proceedings* **2020**, *53*, 4

*Saturated fats*: There were three homogeneous levels (sprout-activated-expanded) and this group showed statistically significant differences with flour and grain levels. The flour was the one with the highest content and (sprout-activated-expanded) the one with the lowest content.

*Ash*: There were two homogeneous levels (activated-expanded) and this group showed statistically significant differences with the flour, sprout and grain levels.

**Figure 1.** Content of proteins in quinoa for each of the treatments.

**Figure 2.** Content of total fat in quinoa for each of the treatments.

*Humidity*: There were two homogeneous levels (flour-grain) and this group showed statistically significant differences with the outbreak levels, activated and expanded. The outbreak was the one with the highest content and the expanded one with the least content.

*Fiber*: They showed statistically significant differences between all levels, the sprout being the one with the highest content and the activated seed the one with the lowest content.

*Energy value*: They showed statistically significant differences between all levels, the flour being the one with the highest content and the sprouts with the lowest content.

#### **4. Discussion**

The values found for the whole seeds are similar to those of the bibliography [8], except the fat content, which showed to be lower, since the grain was not ground for its determination. The determination of lipids was done in this way to simulate what would happen at the digestive level if the cuticles of the seed were not to be destroyed in the stomach. In the case of flour, the values are similar to those in the literature [1,8]. By making the lipid fraction more bioavailable, the energy contribution increases.

#### *Proceedings* **2020**, *53*, 4

During the germination process, (quinoa sprout) nutrients diminished and the proportion of fiber increased, which made it ideal to grant satiety.

When the quinoa seed was placed in water (activated quinoa) it was hydrated by 205%, which meant that the content of all nutrients was reduced.

Finally, expanded quinoa increased its carbohydrate content, decreasing its protein and lipid value, and maintaining its fiber content.

#### **5. Conclusions**

This shows how different preparations influence the nutritional contribution of quinoa. With this information, it is possible to recommend different types of preparations depending on the type of nutrients that are relevant to add in a diet plan and wanted for consumption.

**Funding:** This research received no external funding.

**Acknowledgments:** This work was supported by Ia ValSe-Food-CYTED grant (119RT0567) and Juan Agustín Maza University.

#### **References**


f (accessed on 8 May 2019).

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

### *Proceedings* **Making Nutritious Gluten-Free Foods from Quinoa Seeds and Its Flours †**

**Patricia Miranda Villa 1,2, Natalia Cervilla 1,3, Romina Mufari 1,4, Antonella Bergesse 1,2 and Edgardo Calandri 1,3,\***


Published: 5 August 2020

**Abstract:** Celiac disease is affecting around 1% of the world population and an effective treatment needs to exclude gluten. Quinoa is a high-quality gluten-free protein, and starch-rich endosperm, like the cereals. Protein contents and theoretical Protein Digestibility Corrected Amino Acid Score (PDCAAS) were evaluated in quinoas from Northwest and Centre of Argentina. A batter-type gluten-free quinoa bread was developed, showing good volume, taste, nutritional quality and a good long-lasting texture. Malted quinoa seeds' quality indicators rose until 48 h of germination; after that, an unpleasant taste was developed. Muffins made with that flour showed acceptable taste.

**Keywords:** amino acids; breads; germinates; muffins; proteins; quinoa

#### **1. Introduction**

Celiac disease is one of syndromes associated with irritable bowel and the most important of the enteropathies related to gluten [1]. Quinoa seeds possess a high-quality gluten-free protein and also have a starch rich endosperm, which makes this grain resembles cereals, and for this reason, it is usually called a pseudocereal. Quinoa protein has high levels of the essential amino acids and also is a good source of fiber, minerals and antioxidants [2]; but the lack of prolamins preclude quinoa protein from keeping the particular structure of bread crumb [3] and must be replace by starches and gums [4]. Therefore, the preparation of gluten-free breads requires the help of technology in food to satisfy the expectations of consumers.

The malting of seeds, which consists of allowing their germination in a controlled manner, can improve the absorption of nutrients because biochemical processes, which start when the seeds are moistened, release substances such as free amino acids, simple sugars and fatty acids, small molecules that easily overpass the intestinal epithelium.

The present work reassembles the studies accomplished by the group with quinoa seeds of the Centre and Northwest of Argentina and its employ in the development of batter type, gluten-free breads and muffins, with a focus on the nutritional quality of the products but also improving their taste and palatability.

#### **2. Materials and Methods**

#### *2.1. Raw Materials*

Northwest quinoa seeds were harvested from departments Molinos (2007–2008) and La Poma (2009–2011), Province of Salta, Argentina. Quinoas from the Centre region were originally Chilean "sea level" ecotype, varieties—Pichaman, Faro and Baer—cultivated in Río Cuarto, Argentina (2011). Bread preparation: quinoa, lupin and rice flours, hydroxypropyl methylcellulose (HPMC), sodium stearoyl lactylate (SSL), sugar and salt were mixed dry into a bowl. Fresh yeast was added, previously dispersed in warm water (28 °C), while mixing in a planetary mixer (280 rpm, 5 min). Water addition was completed in this step. The final mixture was loaded in a mold and leavened at 35 °C and relative humidity of 60% for 1 h. Finally, the dough was placed in the oven for 35 min at 180 °C. The bread loaf was left to cool at room temperature for 2 h before analysis.

#### *2.2. Gravimetric Measures*

The tests were carried out as described Cervilla et al. [5], Proximal Analysis, amino acid profile, Chemical Scoring (CS) and protein digestibility corrected amino acid score (PDCAAS), as described in Cervilla et al. [6]; the physical characteristics of products were determined as in Mufari et al. [7]; affective testing (consumer testing) and statistical analysis applied according to in Miranda-Villa et al. [8].

#### **3. Results and Discussion**

#### *3.1. Physical Properties*

Northern seeds were larger than those of the central region (Table 1). The weight of 1000 seeds (W1000) varied from 2.05 to 2.70 g for the central region, quite different to the northern ones, with values no lesser than 3.0 g for one thousand seeds, but the bulk density fluctuated between 0.55 and 0.73 g mLƺ1, without a clear distinction between seed types. The size for northern seeds (equivalent diameter) was between 1.64 and 2.01 mm and can be classified as medium to large size, according to IBNORCA [5], while seeds for central region should be considered as just medium size. The apparent density values (Table 1) provide useful information for the analysis of heat transfer through grains, in quality control, and in the evaluation, calculation and design of transport systems, cleaning and classification. Real density results are important in the design of storage, packaging, dehydration and transportation systems.


seed width, d2 = seed length, e = thickness of the seed. b P, P1 and P2 Pichanan varieties; F, F1 and F2, Faro varieties; B, B1 and B2, Baer varieties, Ch: harvested in Chile. Rc: harvested in Rio IV. c ordered by harvest year. 

#### *Proceedings* **2020**, *53*, 5

#### *3.2. Chemical Properties*

As shown in Table 1, ash content tends to be a little higher in seeds from Centre region and the opposite seems to be happening with lipids. Calcium and Magnesium being the main components of minerals present in quinoa while heavy metals like Pb and Cd are negligible [2], which mean that this grain can be considered as a valuable source of minerals, such as Ca, Mg, K, P, Fe, Cu and Zn.

Quinoa oil present good nutritional qualities [9] and can be considered as having potential for oil extraction. Carbohydrate contents shown in Table 1 are lower than those of common cereals but close enough to consider the quinoa grains as similar to cereal, i.e., pseudocereal [10]. The total protein varied from 13.75 to 18.25%, but quinoas from the Centre region showed rather higher value. Table 2 compares the amino acid contents for the five northern quinoas with bibliographic data for cereals and milk. The clear advantages of quinoa in histidine, methionine and lysine can be seen. In Table 3, the Chemical Scoring (CS) and Protein Digestibility Corrected Amino Acid Score (PDCAAS) of quinoa protein for preschools, schoolchildren and adults are presented. Data were calculated for 2009 and 2010 lots of northern quinoas, and in both cases the limiting amino acids were methionine and cysteine for all the age groups. Nevertheless, in seven of the amino acids of Table 3, the CS of the two quinoa batches covers 86% or more of the needs. The Protein Digestibility Corrected Amino Acid Score (PDCAAS), shown in Table 3, were estimated from a protein digestibility of 80% [11]. These results reflect the high disposability of quinoa amino acids and are similar to those from [12] in spite of these authors employing a higher factor for PDCAAS calculations.

#### *3.3. Products Development*

As can be seen in Table 3, quinoa is deficient in sulfur-rich amino acids, which makes it necessary to improve the nutritional quality of quinoa products by appealing to other grains, such as legumes. Accordingly, a batter-type gluten-free bread, with quinoa and lupin as the main ingredients, was developed, including 41% of quinoa, 29% of rice and 18% of lupin flours. This formulation has notable advantages when compared with commercial breads This formulation has notable advantages when compared with commercial breads, such as reducing carbohydrates and lipids and at the same time, increasing the polypeptides' content. The presence of sulfur-rich amino acids and also of histidine and serine are important. The final formulation was the result of many assays in which the effect of the main flours and minor components such as starches, gums, stabilizer, antioxidants and preservatives were statistically evaluated through experimental mixture designs. It was observed that water content and granulometry of the quinoa meal directly influenced the firmness and specific volume, while leavening and hydrocolloids other than HPMC did not have a significant effect on the quality of the loaves.

Leavening and hydrocolloids other than HPMC did not have a significant effect on the quality of the loaves. Between the emulsifiers, just SSL improved the texture, the specific volume and structure of the bread crumb. The incorporation of defatted flours of quinoa and lupine improved bread flavor, but it made the structure collapse [13]. The optimized formulation almost doubles the protein content of commercial quinoa breads and, at the same time, exhibits lower levels of lipids and carbohydrates, with higher content of essential amino acids. Despite being in the lowest proportion, lupin is the main protein source in the formula. The actual offer in gluten-free products is superabundant in carbohydrates and poor in proteins, as some studies show [14]; alternatives such as those described above tend to overcome the problem.


**Table 2.** Amino acid profiles of western quinoa seeds.

proteins. Rome Italy. Results expressed in g/100 g of seed four. 



Malting is the result of allowing a controlled seed germination, during this process many nutritious substances are released, particularly small sugars, amino acids and peptides [15], easily absorbed by the gut [10]. Muffins are batter-type formulations similar to the above-described bread [8], commonly consumed for breakfast and snacks. In muffins, the leavening stage is not needed and, after shaking, the batter is directly baked and then cooled at room temperature. Three formulations were assayed, with 30% quinoa (whole flour, and germinated whole flours for 24 and 72 h) and 70% rice flours and compared with a control muffin made just with rice flour. While the taste and flavor of rice muffin was preferred, that with quinoa flour germinated for 24 h presented a good taste and a texture barely less accepted than the control. Non-germinated quinoa flour formulation had negative comments regarding a bitter aftertaste, making it not eligible. The muffin formulation made with flour of quinoa germinated during 72 h presented a disgusting taste, frequently described as strong vegetal-like aftertaste, and it was also discarded. It is possible that the bitter taste in the first case was due to residual saponins present in seeds, but the unpleasant flavor perceived in the last one should be related to the germination process and the release of new substances. Untrained judges are often not familiar with gluten-free products, which normally provide great sensory changes, and explain their preferences for rice formulation. The slight disadvantage in flavor of the 24-h germinated formulation with respect to Control is compensated by the improvement observed at the nutritional level. As can be seen in Figure 1, quinoa protein seems to rise up until 24–48 h of germination, when it stabilizes, while lipids seem to keep increasing. Conversely, carbohydrates describe a negative tendency, as a consequence of the metabolic activity in seeds building, among others, proteins and lipids. Similar tendencies can be seen in Figure 2 for free essential amino acids; with the exception of valine, the others show a plateau at 24–48 h of germination. This behavior is also observed in the soluble matter (Figure 2), where the six substances seems to mimic their tendencies, giving flat curve segments between 24–48 h, all maxima. Many of them are small molecules which can go across the inner gut membrane with relative facility.

**Figure 1.** The change in proximate composition of quinoa flours along the germination time. All values expressed in dry base.

**Figure 2.** Changes in soluble components in quinoa flours, along the germination time.

#### **4. Conclusions**

In the present work, the nutritional quality of quinoa seeds and flours was shown. Quinoas from the Centre region where smaller than northern ones, with slightly higher protein content, but in all cases surpassing those of cereals. Lipid content was also greater than in cereals, and minerals ranged between 3% and 4%. Quinoa protein was rich in some essential amino acids but poor in methionine and cysteine, and mixing with sulfur-rich grain, such as legumes, is recommended. Gluten-free breads prepared with a mixture of quinoa and lupine flours showed good taste and texture and an improved nutritious quality. Muffins made with malted quinoa grain flour for 24 h showed a higher content of essential amino acids and soluble substances of small size, easily absorbed by the gut.

**Funding:** Authors wish to thank the Secretary of Science and Technology of the Universidad Nacional de Córdoba for the economic support.

**Acknowledgments:** This work was supported by grants Ia ValSe-Food-CYTED (119RT0567) and Secretaría de Ciencia y Técnica de la Universidad Nacional de Córdoba, Argentina.

#### **References**


© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

#### *Proceedings*
