## 2 Materials and Methods  
Materials: raw organic amaranth seeds (_Amaranthus cruentus_ L.) grown in Latvia and produced by individual merchant \"Grauds ar dveseli\"; raw organic buckwheat seeds (_Fagopyrum esculentum_ Moench) grown in Latvia and produced by farm \"Bebri\"; wholegrain oat (_Avena sativa_) flour (Rigas Dzirnavnieks, Riga, Latvia), beetroot powder (Fity, Latvia), and organic plantain powder (Super Garden, Latvia) were purchased in grocery store. The plantain powder was added for binding purposes as amaranth and buckwheat four are gluten-free. The nutritional value and energetic value of materials are reflected in Table 1. The data were taken from the label of the ingredients indicated by the manufacturer. Pasta dough preparation for extrusion: amaranth and buckwheat seeds were milled to a fine flour using Muhle 2 (Hauvo's, Obrigheim, Germany). According to the recipe (Table 2), betroot and plantain powders were added to flour and then water was added during further mixing to obtain a dough consistency suitable for extrusion. The amount of water added differed among the samples due to the water absorption capacity of different flours. Buckwheat flour is characterized by a higher water absorption capacity (1.46 g/g) compared to oat (1.26 g/g) and amaranth (0.96 g/g) flour [24], which affected the amount of added water in the samples. Extrusion: the prepared samples were extruded using the food extruder PCE Extrusioner L-Serie (Gottfert, Buchen, Germany) where the temperature profile for AMAR was 92/100/106 \({}^{\circ}\)C and, for amaranth pasta blends with buckwheat or oat, it was 89/95/102 \({}^{\circ}\)C. After extrusion, pasta samples were dried in the convective-rotary oven (SVEBA DAHLAN, Fristad, Sweden) at a temperature of 90 \({}^{\circ}\)C for 210 min, followed by cooling to room temperature. As a result, dry pasta samples were obtained, which were used for further analysis (Figure 1). As a control sample, wheat pasta (ingredients: durum wheat semolina, water) was purchased in the grocery. The research design is given in the Figure 2.  
All pasta samples including the control sample were subjected to the following analysis: moisture content was determined using the ISO 712:2009 standard method; total protein content--ISO 1871:2009 standard method; total fibre content--ISO 5498:1981 standard method; fat content--ISO 11085:2009 standard method; fatty acids content--the GC/MS method; starch content--LVS EN ISO 10520:2001 standard method; amino acids content--LVS EN ISO 6498:2012 standard method, iron content--LVS EN 14082:2003 standard method; and sugar content--using the high-performance liquid chromatography (HPLC) method. Carbohydrate content and energetic value were calculated according to EU Regulation No. 1169/2011 of the European Parliament and the Council. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Nutrients/Energetic Value** & **Amaranth Seeds** & **Buckwheat Seeds** & **Oat Flour** & **Beetroot Powder** & **Plantain Powder** \\ \hline Fat, g & 7.7 & 1.7 & 7.9 & 0 & 0.8 \\ including saturated fatty acids, g & 0.7 & 0.4 & 1.6 & 0 & 0.14 \\ Carbohydrates, g & 61.2 & 70.1 & 55.4 & 57 & 3.7 \\ including sugars, g & 1.3 & 0.3 & 1.2 & 51 & 0.2 \\ Fibre, g & NI & 3.7 & 11.8 & 40 & NI \\ Protein, g & 15.8 & 9.1 & 12.7 & 9 & 2.1 \\ Salt, g & 0.024 & 0.03 & 0.003 & 0.6 & 0 \\ Energetic value, kcal & 377 & 339 & 367 & 265 & 31 \\ Energetic value, kJ & 1594 & 1437 & 1544 & 1110 & 130 \\ \hline \end{tabular} \({}^{*}\) Data from food labelling. NI—no information.  
\end{table} 
Table 1: Nutritional value and energetic value of ingredients \({}^{*}\).