foods Article Comparison of the Chemical and Technological Characteristics of Wholemeal Flours Obtained from Amaranth (Amaranthus sp.), Quinoa (Chenopodium quinoa) and Buckwheat (Fagopyrum sp.) Seeds Phara De Bock 1,* , Lori Daelemans 1, Lotte Selis 1, Katleen Raes 2 , Pieter Vermeir 3, Mia Eeckhout 1 and Filip Van Bockstaele 4 1 Research Unit of Cereal and Feed Technology, Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, Valentin Vaerwyckweg 1, 9000 Ghent, Belgium; [email protected] (L.D.); [email protected] (L.S.); [email protected] (M.E.) 2 Research Group VEG-i-TEC, Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, Gr. Karel de Goedelaan 5, 8500 Kortrijk, Belgium; [email protected] 3 Laboratory for Chemical Analysis (LCA), Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Valentin Vaerwyckweg 1, 9000 Ghent, Belgium; [email protected] 4 Food Structure and Function Research Group (FSF), Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium; fi[email protected] * Correspondence: [email protected]; Tel.: +32-(0)9-243-24-94 Citation: De Bock, P.; Daelemans, L.; Selis, L.; Raes, K.; Vermeir, P.; Abstract: A sound fundamental knowledge of the seed and flour characteristics of pseudocereals Eeckhout, M.; Van Bockstaele, F. is crucial to be able to promote their industrial use. As a first step towards a more efficient and Comparison of the Chemical and successful application, this study focuses on the seed characteristics, chemical composition and Technological Characteristics of technological properties of commercially available pseudocereals (amaranth, quinoa, buckwheat). Wholemeal Flours Obtained from The levels of starch, fat, dietary fiber and minerals were comparable for amaranth and quinoa seeds Amaranth (Amaranthus sp.), Quinoa (Chenopodium quinoa) and Buckwheat but the protein content is higher in amaranth. Due to the high amount of starch, buckwheat seeds are (Fagopyrum sp.) Seeds. Foods 2021, 10, characterised by the lowest amounts of fat, dietary fibre and minerals. Its protein content ranged 651. https://doi.org/10.3390/ between that of amaranth and quinoa. Buckwheat seeds were larger but easily reduced in size. foods10030651 The lipid fraction of the pseudocereals mostly contained unsaturated fatty acids, with the highest prevalence of linoleic and oleic acid. Palmitic acid is the most abundant unsaturated fatty acid. Academic Editor: Felicidad Ronda Moreover, high levels of P, K and Mg were found in these pseudocereals. The highest phenolic content was found in buckwheat. Amaranth WMF (wholemeal flour) had a high swelling power but Received: 20 February 2021 low shear stability. The pasting profile strongly varied among the different quinoa WMFs. Buckwheat Accepted: 15 March 2021 WMFs showed high shear stability and rate of retrogradation. Published: 19 March 2021 Keywords: pseudocereals; amaranth; quinoa; buckwheat; wholegrain; chemical composition; mi- Publisher’s Note: MDPI stays neutral cronutrients; technological properties; pasting behaviour with regard to jurisdictional claims in published maps and institutional affil- iations. 1. Introduction The demand for healthy foods has increased over the last years as consumers have become more aware of the relation between diet and health [1,2]. Besides highly nutritious, Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. cereal foods are considered to be rich in health-beneficial bioactive compounds [3,4]. The This article is an open access article development of wholegrain products has been growing, especially as the bran and germ distributed under the terms and fraction of the grain contains high contents of nutrients and phytochemicals. Moreover, conditions of the Creative Commons the gluten-free food market is expanding due to the higher prevalence of gluten-related Attribution (CC BY) license (https:// disorders, such as celiac disease or gluten sensitivity. Cereals, such as wheat, maize and creativecommons.org/licenses/by/ rice, are commonly used for the production of wholegrain and/or gluten-free products but 4.0/). pseudocereals are promising alternatives [5,6]. Foods 2021, 10, 651. https://doi.org/10.3390/foods10030651 https://www.mdpi.com/journal/foods Foods 2021, 10, 651 2 of 22 Pseudocereals are grown for the same purpose as true cereals but they are not a part of the Gramineae family [7]. From an ecological point of view, pseudocereals have better resistance to biotic and abiotic stresses than conventional cereal crops [8,9]. Their cultivation is possible in regions with a harsh climate and poor soil conditions, which can help to ensure food availability in these types of regions [4,10]. The most common pseudocereals are amaranth (Amaranthus sp.), quinoa (Chenopodium quinoa) and buckwheat (Fagopyrum sp.). The Amaranthus genus includes approximately 60 species but only A. hypochondriacus, A. caudatus and A. cruentus are cultivated as grain species. Quinoa is one of the approximately 250 species of the Chenopodium genus. Both sweet and bitter quinoa varieties exist, depending on the saponin content. Within the Fagopyrum genus, F. tataricum and F. esculentum are the most consumed and cultivated species [11,12]. Pseudocereals produce seeds with high nutritional value. The protein content of the seed is high and characterised by a well-balanced amino acid profile. The seeds are a good source of unsaturated fatty acids, dietary fibre and essential micronutrients. Furthermore, they contain a large variety of bioactive compounds [3,8,13,14]. Due to the lack of gluten, these pseudocereals are interesting ingredients for gluten-free products as well [15]. However, the presence of antinutrients may restrict the use of pseudocereals in the human diet. Some of the reported antinutrients in pseudocereals are phytic acid, saponins, tannins and protease inhibitors [9,16,17]. Several techniques of industrial processing, such as heat treatment, extrusion, roasting, or mechanical abrasion, are used to inactivate or reduce these antinutrients [16,18,19]. Pseudocereals can be used as a supplement to enrich traditional foods or for the production of new food products. Nevertheless, these pseudocereals lack dough-forming, and thus, baking properties due to the absence of gluten. The dough-forming properties of raw material are essential for all food products that demand dough preparation (bread, bakery products, pasta, etc.). Traditionally, these type of food products are made of refined wheat flour. Up to a certain amount, pseudocereal can be added to wheat-based products to improve the nutritional properties of the resulting food product. However, the addition of high amounts results in technological challenges due to the high fibre content and the dilution effect on gluten. Complete substitution of wheat comes with the challenging task of replacing the functionality of the gluten and cannot be carried out without the addition of specific ingredients or adaptations of the process conditions [6]. From a nutritional point of view, pseudocereals are promising ingredients for the production of wholegrain and/or gluten-free food products [5]. Nevertheless, the sensorial and textural properties of the final product depend on the composition of the macronu- trients and the interaction of these components during processing [20]. The properties of pseudocereal wholemeal flour (WMF) to a large extent depend on the composition and properties of the starch fraction but non-starch components (i.e., protein, lipid, fibre) are also likely to have an effect. The chemical composition of pseudocereals is rather different from that of common cereals and furthermore differs among the different types of pseudocereals [5,21]. Sound fundamental knowledge of the seed and flour character- istics of pseudocereals is crucial to be able to promote their industrial use. As a first step towards a more efficient and successful application, this study focuses on the seed char- acteristics, chemical composition and technological properties of commercially available pseudocereals (amaranth, quinoa, buckwheat). The characteristics of the pseudocereal WMFs are discussed in relation to the seed characteristics and the chemical composition and compared among the different types of pseudocereal. 2. Materials and Methods 2.1. Material Commercially available amaranth, quinoa and dehulled buckwheat seeds were col- lected from different suppliers in Belgium and the Netherlands. An overview of the pseudocereal samples is included in Table1. Foods 2021, 10, 651 3 of 22 Table 1. Overview of amaranth, quinoa and buckwheat samples. Type Code Origin AM1 India AM2 India AM3 Peru AM4 India amaranth AM5 India AM6 Unknown AM7 Unknown AM8 India QU1 Peru QU2 Unknown QU3 Belgium quinoa QU4 Belgium QU5 Belgium QU6 Bolivia QU7 Bolivia BU1 Unknown BU2 Germany BU3 China BU4 unknown BU5 China buckwheat BU6 unknown BU7 Czech Republic BU8 unknown BU9 unknown BU10 China For chemical and technological analyses, grains were milled WMF by a Hammertec mill (mesh size: 0.8 mm) (Foss, Hilleroed, Denmark). 2.2. Characteristics of Seeds Test weight (kg/hL) was determined by a Grain Analysis Computer (GAC 2100, Dickey-john, Auburn, AL, USA). Thousand kernel weight (TKW, g) was calculated based on the weight of 300 kernels, selected by a Contador seed counter (Pfeuffer